THE PLASMA MANTLE: COMPOSITION and OTHER CHARACTERISTICS OBSERVED by MEANS of the PROGNOZ-7 SATELLITE R. Lundin, B. Hultqvist, N

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THE PLASMA MANTLE: COMPOSITION AND OTHER CHARACTERISTICS OBSERVED BY MEANS OF THE PROGNOZ-7 SATELLITE R. Lundin, B. Hultqvist, N. Pissarenko and A. Zackarov KGI PREPRINT NO 81:1 MARCH 1981

KIRUNA GEOPHYSICAL INSTITUTE KIRUNA SWEDEN THE PLASMA MANTLE: COMPOSITION AND OTHER CHARACTERISTICS OBSERVED BY MEANS OF THE PROGNOZ-7 SATELLITE by R. Lundin and B. Hultqvist Kiruna Geophysical Institute, Box 704, S981 27 Kiruna, Sweden and N. Pissarenko and A. Zackarov Space Research Institute, Soviet Academy of Sciences, Moscow, USSR

KGI Preprint No 81:1 March 1981

Printed in Sweden Kiruna Geophysical Institute Kiruna 1981 ISSN 0349-2656 THE PLASMA MANTLE: COMPOSITION AND OTHER CHARACTERISTICS OBSERVED BY MEANS OF THE PROGNOZ-7 SATELLITE

R. Lundin and B. Hultqvist Kiruna Geophysical Institute, Box 704, S981 27 Kiruna, Sweden

and

N. Pissarenko and A. Zackarov Space Research Institute, Soviet Academy of Sciences, Moscow, USSR

Abstract PROGNOZ-7 measurements in the nigntside plasma mantle dre described and analyzed. Some of the results are the following: In the nightside mantle not f >*> far from midnight the properties of the mantle are sometimes / f. istent with the open magnetosnhere model. An exception is found i rrg most magnetic storm situations when 0+ ions appear in the mänt fr. ii so large proportions and with so high energies that direct ii;: r. -ion of ionospheric ions by acceleration along the magnetic fielij ;ines appear to be the most likely source mechanism. This acceler-i on process has been shown to give equal amounts of energy to all ' magnetosphere model does sometimes not fit at all with the- PROGNOZ-7 observations. There the flow of the plasma is often lC: or absent. The 0+ content is high (up to 20%) and the energy spectrum of both ions and electrons may be very hot, even up to the level of the ring current plasma.

The 0+ content in the plasma mantle is positively correlated with the magnetospheric activity level. The mantle, however, does not appear to be the dominating source for the stcrm time ring current. Direct acceleration of ionospheric ions onto the closed field lines of the plasma sheet and ring current is most likely the main source. - 2 -

Contrary to the predictions of the open magnetosphere model, the magnetopause on the nightside and along the flanks of the Magnetosphere appears to be a fairly solid boundary for mantle ions of ionospheric origin. This is especially evident during periods with high geomagnetic activity, when the mantle is associated with fairly strong fluxes of 0+ ions. An interesting observation in most of the mantle passages during geomagnetically disturbed periods is the occurrence of intense, magnetosheath like, regions deep inside the mantle. In some cases these regions with strong antisunward flow and with predominant magnetosheath ion composition was observed in the innermost part of the mantle, i e marking a boundary region between the lobe and the mantle. These magnetosheath "penetration" events are usually associated with strong fluxes of accelerated ionospheric ions in nearby parts of the mantle. Evanescent "penetration" regions with much reduced flow properties are frequently observed in the flank mantles. 1. Introduction. Only two satellites have hitherto been launched into orbits well suited for investigation of the high latitude boundary region of the magnetosphere. HEOS-2 revealed the existence of j layer of plasma inside the high latitude inagnetopau^e - the plasma mantle - on the poleward side of the polar cusp and separated on the nightside from the hct, low density, magnetospheric plasma of the plasma sheet and the ring current by the dlmo.'.t airiDty high latitude lobes (Paschmann et al., 1974; Rosenbauer et ai., 1975; Sckopke et al., 1976; Bavassano-Cattaneo and Fonriisano, 1978). HEOS 2 datd also showed that electrons of energies as high as in the MeV range exist in the high latitude boundary region (Pane et al., 1973; Domingo et al., 1974, 1977).

The PROGNOZ-7 satellite carried the fir it mass-analyzing plasma experiment through the high latitude magnetopause region. A few initial results of the PROMICS-1 experiment on Doard PROGNOZ-7 were presented by Galeev (1979), Hultqvist et al. (1979), Lundin et al. (1979) and Lundin et al. (1980). In the present report a more comprehensive description of the characteristics of Lne plasma mantle, as observed with the PROMICS-1 experiment, is given.

Observations of the mantle were in fact reported even before the HEOS-2 results became available by Akasofu et al. (1973) in the near earth tail. Hardy et al. (1975, 1977) observed the mantle at the moon. The first suggestion of the existence of the mantle seems to have been made by Dungey (1967) and Soeiser (1969) on the basis of the open magnetospheric model. Pilipp and Morfi 11 (1976) and Cowley (193C) have discussed in some detail the formation of the mantle. Summaries of the HEOS-2 observations have been presented by e.g. Sckopke and Paschmann (1978) and Paschinann (1979).

The importance of the study of the plasma mantle is immediately obvious since the mantle is one of the major plasma populations in the rnagnetosphere and its relations to other populations, such as those in the cusp region and the plasma sheet, dre probably quite important in determining their characteristics (see eg Hill and Reiff, 1980). - 4 -

The HEOS-2 observation of the mantle can with some simplification be summarized as showing a region with similar properties to the magnetosheath but with lower flow speed and number density and somewhat higher temperature than outside the magnetopause (see e.g. Sckopke and Paschmann, 1978). A secondary peak in the energy spectrum, believed to show the occasional presence of 0+ ions in the mantle plasma has been observed at the lunar orbit (Hardy et al. 1977). In the present report, besides similar observations as reported from HEOS-2, fairly different observations of flow and energy spectrum of H+ ions are presented from the flanks of the magnetosphere. The emphasis is on the compositional characteristics of the ions but electron observations d,re also reported.

The plasma mantle is obviously a boundary region of the magneto- spere. Its relation to the boundary layers along other parts of the magnetopause is, however, not quite clear. According to Formisano (1980) the mantle cannot be considered as the high latitude extension of the low latitude boundary layer. Especially in the intermediate latitude ranqe along the flanks of the inagnetosphere no clear boundary between the mantle and the low latitude boundary layer has been established. In the present study we use as working definition of the mantle at the flanks of the magnetosphere that there exists an empty lobe inside tne mantle along the orbit of PROGNOZ-7 (for which the line of apside makes an angle of 88° with the ecliptic plane). For tne kind of topology that is involved in the presently discussed magnetospheric models this definition should not lead to the conclusion that the satellite is in the mantle when it is not (the risk is probably greater - although small - that some passes through the lower- most latitude region of the mantle along the flanks shall be misin- terpreted as passes through the low latitude boundary layer).

The PROMICS experiment and the PROliNOZ-7 orbit dre described in Sec- tion 2 & 3. In Section 4 the observational results are presented and the observations are discussed from various points of view in Section b. - 5 -

2. Instrumentation. The PROGNOZ-7 spacecraft was launched on 31 October, 1978, into a highly elliptic orbit with 65° inclination and a line of apside which was almost perpendicular to the ecliptic plane (88°) The apogee was at a geocentric distance of ~31 RP , the altitude of the pergigee was varying between ~500 and —1000 km and the orbit period was ~98 hours The platform was spin stabilized with the spin axis always pointing towards the sun (±5^) and with a spin rate of about 0.5 rpm. Tne PROGNOZ-7 orbit was therefore fairly similar to the HEOS 2 orbit, i e highly suitable for studies of the high latitude boundary layer of the magnetosphere. A significant difference between PROGNOZ-7 and HEOS 2 was the orientation of the spin axis which for PROGNOZ-7 was along the ecliptic X-axis, whilst the HEOS 2 spin axis was mostly along the ecliptic Z-axis. The so called PROMICS-1 experiment (Prognoz Magnetospheric Ion Compo- sition Spectrometers) was the first in a series of Swedish-Soviet collaborative experiments. A second experiment (PROMICS-2), fairly similar to PROMICS-1, was launched on PROGNOZ-8 in December 1980. PROMICS-1 consisted of three energetic ion composition spectrometers (ICS) for the energy range 0.2 - 17 keV/q and mass (M/q) range 1 - 20 Amu. Two ICS:s were oriented perpendicular to the spin axis, thereby scanning the ecliptic YZ-plane, and a third ICS which covered the energy range 0.65 - 5.1 keV/q was oriented 25° with respect to the spin axis. The experiment also comprised three E/q charged particle spectrometers using cylindrical electrostatic analyzers and channel multipliers, measuring positive Ions and electrons in the energy range ~0.01 - 50 keV/q. The orientation was similar to that for the ICS:s i e one electron and one ion spectrometer oriented perpendicular to the spin axis and one combined election-and positive ion spectrometer oriented 25° with respect to the satellite spin axis.

The IC3,s were all of the type with Wien filters placed in front of hemispherical electrostatic analyzers und with funnel-mouthed channel multipliers ao sensor elements. In the crossed-field analyzers (Wien filters) permanent magnets of a samarium cobolt alloy were used (pole - 6 - gap fields from 0.15 to~O.3O Tesla). Specially developed electronics made it possible to have full digital control of the plate voltages in the velocity analyzer and the energy analyzer, with a reference control coupling between them. This enabled e g energy sweeps to be taken at fixed mass-settings. By using logarithmic energy sweeps versus time and sampling over the full sweep period, it was possible to obtain an "analog" integration of the number of particles per (cm2s sr) over the full energy range of the ICS:s (0.2 - 17 keV). The PROMICS-1 experiment had two basic modes of operation (plus one "emergency" mode). One standard, low speed, mode which used a low bit-rate (~8 bps) and where the data was taken during ~10 seconds and was read out over periods of either ~82 s or —164 s. To increase the time resolution for H+ and 0+ ions, an integral flux mode was used which provided flux measurements (in particles per (crn^s sr) over the energy range 0.2 - 17 keV) for both ion species every ~20 second. The other mode (h'ign speed) was only used about 1.5 hours per orbit (~98 hours) which means that we have a fairly poor data coverage with this mode. Yet in at least 8 passages through the magnetopause high speed data has been obtained. The high speed data will, however, not be discussed in this paper. The data aquisition rate was in high speed mode about 500 times higher than that in low speed. The energy coverage was alco much better, expecially at low energies, and mass scans were performed for individual energy settings of the ICS:s.

All spectrometers were calibrated in the calibration facility at tne Kiruna Geophysical Institute. This facility comprises an electron and positive ion (e g H+, H2+, He+, Ar^+ and Ar+) source-accelerator, producing a fairly wide (~10 cm) and homogeneous electron/ion beam in the energy range ~0.5 - 40 keV for electrons and ~0.2 - 20 keV for positive ions. By means of an automatic angular scanning device it is possible to determine e g the absolute value of the geometric factor versus energy for a particle spectrometer. In-flight calibration has shown that these values di^ not change significantly during the life time of PROGNOZ-7 (~8.5 months). In-flight calibrations have also proved that the most difficult part, the calibration of the ICS:s, was succesful. In fact, the flux obtained from each energy level of the ICS:s summed over the four major ion constituents, has been found to agree very well with the flux obtained from the ion E/q spectro- - 7 - meters at similar energy levels, i e we get the same total ion spectra irrespectively of choice of ion spectrometer (provided, of course, they sample in the same direction). The main characteristics of the PROMICS-1 experiment is summarized in Table 1.

3. Observations, general PROGNOZ-7 was launched into an orbital plane for which the inbound part was at a local time of about 1900 and the inbound orbit moved into the dayside after launch. The satellite provided during its eight and a half months lifetime mantle data mainly from the flanks of the magnetosphere and the midngiht dawn local time sector but not very much data from the dusk-midnight sector. The present study has been based on 32 mantle passes of PROGNOZ-7. A few more still remain to be reduced but are not expected to change the main picture to be described very much. The location of the magnetopause crossings for the 32 mantle passes are shown in GSM coordinates in Figure la and in SM coordinates in Figure lb. As mentioned in the introduction, as working definition of the mantle in those regions, where the satellite could possibly be in som other kind of boundary layer, has been used the presence of a low flux density lobe inside the mantle. A lobe has in fact been present in all passes shown in Figure 1. A few mantle passes when the satellite was close to the pole on the dayside or dawn region was excluded for the reasons mentioned above. During these passes the trajectory was such that it either passed through the cusp region or passed di- rectly from the plasma sheet at dawn before entering the mantle. As can be seen from Figure 1, only 3 mantle passes on the dayside (i e before 18 nours and after 06 hours in GSM coordinates) have been included in the data base. This is due to the fact that the satellite dayside magnetopause passes were located mainly at lower latitudes, i e in the cusp, entry layer and low-latitude boundary layer regions. Some numerical data and comments about the 32 mantle passages are presented in Table 2. The notation "Seans" is used in connection with PROGNOZ-7 data to indicate a data taking period. ,-'or the low speed mode of operation of the PROMICS-1 experiment the seanses are generally quite long (up to ar, orbital period of 4 day?N and are generally interupted by high-speed data taking seanses. A seans has generally an inbound part, denoted "In" in column 2 of the table, and an outbound part (denoted by "Out"). In the early part of the satellite's life time the inbound part of the orbit trajectory passed through the mantle, but later on the inbound trajectory passed through the dayside magnetopause below the mantle latitudes and the outbound part of the orbit provided mantle data. Towards the end of the life time there were orbits for which both the inbound and outbound orbits passed through the mantle.

The magnetopause location has not always been \/ery obvious in the particle and magnetic field records. An ~sign in front of the magnetopause crossing time indicates uncertainties in the magnetopause location. Sometimes there are multiple magnetopause crossings, in which cases the innermost has generally been documented in Table 2. Most of the "Mantle characteristics" given in Table 2 should not need any further explanation. The "Rough thickness" value is the difference in the radial distance along the satellite trajectory of the inner boundary of the mantle and the magnetopause. Sometimes the trajectory passed obliquely through the mantle and the satellite may spend up to 11 hours in the mantle (Seans Out 60). It is likely that the magnetopause location moves inward or outward during many of the mantle passages, especially the long duration ones. Such movements have not been taken irto account in defining the mantle thickness. This is one of the reasons why it has been given with only one significant figure (but even that figure may thus be wrong). Finally some magnetospheric

disturbance information (lKp and Dst for 12 respectively 6 hours around the magnetopause corssing) has also been included in the table. They will be used in the discussion of the mantle data.

In the examples discussed below the data are presented in three different kinds of plots. The first kind is shown in Figure 2. It is called the flux plot below as it contains the integral fluxes of H+ and U+ separately integrated over the energy range (().? - M keV) of - 9 - the Ion Composition Spectrometers (ICS) which look perpendicular to the spin axis (01 and D2). One flux value for each of the two ion species are obtained every 20.5 seconds. This is the highest time resolution that the PROMICS-1 experiment can provide in low-speed mode. As the spin period is around 120 seconds, 6 samplings per spin are obtained, which is enough to provide a good measure of the angular variation of the flux s in the spin plane (approximately the eeliptic YZ-plane). The background level of the instrument is usually less than 1 count per second, corresponding to a background flux value of about

5 x 10^ cnT^s'-'-sr"! (eXcept in the inner radiation belts of the magnet osphere, where the background count rate goes up to hundreds of counts per second). The plots of type 1, shown in Figure 2, also contain the mean energy of the. ions taken from the E/q spectrometer D3 (oriented perpendicular to the spin axis), the integral flux (0.1 - 48 keV) and mean energy of the perpendicular electron component (D4) and the 0+ flux taken from the ICS measuring in the sunward direction (25^ with respect to the spin axis, i e the sun-earth direction). These plots represents one value for every 164 seconds. Finally the plot in Figure 2 contains some magnetic field data, namely the magnitude of the magnetic field and its component along the sun-earth direction (the X-axis in the GSE-coordinate system). The reason that these two kinds of magnetic field data are included is that they are available from the magnetic tape where the particle data are stored. The other components as well as the attitude data, are on a separate magnetic tape. To derive the complete attitude information, e g the magnetic field orientation in an absolute coordinate system, requires more elaborate computations than tbat needed to obtain the plot shown in Figure 2. A second kind of data plot used in presenting the mantle observations can be seen in Figure 3. I. contains in the four top frames ion density, ion composition, temperature and pressure data, together with electron temperature and magnetic pressure. The lower frames give magnetic field and flow velocity components in the XY and YZ Solar Ecliptic coordinate planes. The time and space coordinates (in Solar Magnetic, SM, coordinates) are given along the horizontal axis. These plots are referred to as the NTPVB-plots below. - i: -

Three different kinds of density information c^n I found in the NTPVB-plots. The solid line shows the ion density of ained with the use of the E/q spectrometers D3 (perpendicular to th. spin axis) and D5 (25^ from the spin axis). It thus takes into account the anisotropy over the sunward hemisphere. As there is no spectrometer measuring in the antisunward direction, the flux distribution in that hemisphere is unknown. To integrate the density over the full sphere we therefore Udd to assume that the flux distribution in the antisunward direction was similar to that in the spin plane i e could be determined by the perpendicular spectrometers. The values represented by the crosses and the rings in the N+ frame have been obtained separately for H+ ( + ) and 0+ (o) from the ICS:s 01, L)2 and D6. The H+ density is determined from the perpendicular ICS:s Dl and ,D2 only (assuming symmetry over both hemispheres). For a proton dominating plasma, as for example in the masnetosheath, a comparison with the solid line in the N+ frame therefore gives a measure of the density anisotropy over the sunward hemisphere. The 0+ density is, however, obtained using all three ICS:s.

Notice that in the calculations of the ion density from D3 and D5 (solid line) the proton mass is used. Whenever the total ion density obtained from the ICS:s exceeded that from D3 and 05 (e g when 0+ was + more abundant than H ), the solid line in the N+ frame instead represents the total ion density obtained from the ICS:s. The frame denoted "Ion Density Composition" gives the number density composition of H+ (+), He2+ (A), He+ (*) and 0+ (o) in percent of the total ion density obtained from the ICS:s. Concerning the accuracy of the density composition it should be noted that each ion species is only measured at four energy levels perpendicular to the spin axis (0.36, 1.1, 3.8 and 12.7 keV) and two energy levels towards the sun (1.1 and 3.8 keV). This means for example that when strong magnetosheath (antisunward) flows are present, the He^+ abundance tends to become too high with respect to that for ' The main reason for this + is the limited coverage below 1 ke» wr>: the H flux usually maximizes in the magnetosheath. The He^+/H+ ratio is discussed in more detai1 in Section 5.7, - 11 -

In the third frame the temperature for positive ions and electrons have been plotted. The solid line represents the ion temperature as deduced from a least squares fitting technique onto a Maxwellian for the data from the ion spectrometer D5. The broken line gives the electron temperature using a similar least squares fitting technique for the 04 electron data. Plus ( + ) and rings (o) gives the H+ and 0+ temperature using a flux integration technique similar to that em- ployed for the density integration (see e g Appendix 1). The main reason for employing the two different techniques was the nonthermal feature of the particle spectrum fairly often observed (poor fits on- to Maxwel1ians). Several tests using both techniques were performed. Both methods, discussed in more detail in Appendix 1, generally agreed within a factor of two.

The ion pressure, Pp, in the fourth frame represents the product of the full line N+ and T+ values of frame 1 and frame 3. The magnetic pressure is given by |B|^/2p0. Notice that the magnetic field data used I,ere has an upper measurement limit of about 70 nT for each component. Below an altitude of about 8 Re these magnetometer channels are therefore saturated. One full line in the N, T and P frames represent the average over about 8 minutes of measurements. The separate H+ (+) and 0+ (o) values of the N and T frames as well as the values of the density composition are four minute averages. Although a complete magnetic field vector may be determined by the magnetometer on board PROGNOZ-7 within ~10 seconds, the vectors given in the NTPVB-plots represents values averaged over one complete spin period (about 2 minutes). In evaluating the flow velocity vector the direct measurement by the PKOMICS-1 experiment of the integral ion flux have been used. These values are generally of good accuracy. They are, however, available only in the spin plane (i e in the YZ-plane). To obtain the X-component of the flow vector, fluxes at two energy levels from the ICS:s Dl, D2 and D6 have been used. The flow component in the X-direction have then been derived from a limited number of flux samples by inte- grating over simple surfaces assuming isotropy over sectors where no data points were available. Again the lack of data in the antisunward - 12 - hemisphere means that an isotropic extrapolation of the perpendicular fluxes into the antisunward hemisphere had to be used. The absolute accuracy of the flow vector components of Figure 3 is consequently not very high, especially for the antisunward flow component and when the count rates are low. The most uncertain flow component, that along the X-axis, has been checked with a completely different method (based on shifted Maxwellians in phase space; see Appendix 1). The two methods have been found to agree fairly well, the adopted method providing a somewhat lower flow velocity. The direction of the flow relative to the magnetic field lines are believed to be fairly accurate in practically all cases shown. Where the 0+ count rates are high enough, separate flow vectors have been de.-ived for the 0+ component. They are shown by the broken 1 i nes. A more comprehensive description of the technique for deriving the plasma parameters and flow vectors are given in Appendix 1. The third form of data representation is shown in Figure 4. This represents spectrograms (flux vs energy vs time) taken from the perpendicular spectrometers Dl, D2 (ICS), D3 and D4. To the left, individual four point energy spectra for the four major ion constituents are depicted. The two spectrograms to the right represent the E/q ion spectra from D3 (0.1 - 30 keV) and the electron spectra from D4 (0.1 - 48 keV). Notice that the flux in the four point energy spectra for the four major ion constituents is given in differential energy flux (keV cm~2s-lsr~lkeV~l) whilst the flux in the 16 point E/q spectra is in differential flux units (particles cm"^-'^sr^^

4. Examples of data from the mantle passes As can be seen from Figure 1, the great majority of the PROGNOZ-7 mantle observations were taken in the midnight-dawn local time sector. We start therefore by presenting a number of mantle passages through the GSM longitude sector 200 - 245° during different magneto- spehric activity levels. - 13 - j^jj 1_: 21 - 22 February 1979, magnetic storm (seans Out 95). PROGNOZ-7 passed out of the Magnetosphere approximately at 0200 UT on 22 February. It entered the mantle at about 2120 UT on 21 February and thus passed through the mantle during the peak of the storm. Dst reached its peak negative value of -98 nT in the hour 21-22 UT on the 21 February and increased to -76 nT to the time of the PROGNOZ-7 magnetopause crossing. ZKp had the value 41 on the 21 February and 34 on the 22 February. During the 12 hour period centered around the mantle crossing the ZKp was 20. Figure 2 shows the integral fluxes cf H+ and 0+ ions (0.2 - 17 keV) and the electron integral flux (0.1 - 48 keV) together with mean energies ana magnet"'; field data, as described in Section 3. As can be seen in this figure the perpendicular H+ flux reached well above 10^ cm'2 s~l sr"l in the mantle and the perpendicular 0+ flux to about ,10b cm~2 s"*- sr"*. The ion fluxes are strongly spin modulated, which implies flow of the plasma. However, there is an appreciable isotropic component present in the flux, we shall see other examples where the spin modulation goes (almost) down to the background level. The mantle flux perpendicular to the spin axis is in Figure 2 even greater than that in the magnetosheath. The mean ion energy in the magnetosheath is also unusually high, so the magnetosheath part of the diagram in Figure 2 is not very typical. The electron flux values shown in Figure 2 are very high in the mantle and quite low just outside the magnetopause, another unusual feature. Further out in the magnetosheath the electron flux reaches normal levels. Figure 3 contains the NTPVB information for this storm time mantle pass. As in Figure 2 the^e are large variations (in time or space) within the mantle. We shall, however, see mantle examples with much stronger temporal/spatial structure. As can be seen, the toLal ion density reached \/ery high values. The density values of H+ deduced from the perpendicular ICS:s are about an order of magnitude lower in the peak region. This means that the fluxes along the X-axis, i e in the direction from the sun, are responsible for the high density values. Actually, the density obtained from the perpendicular ICS:s - 14 - even shows a decrease where the total density maximizes. The temperature of the ions and the electrons do not vary very much during this mantle pass. A slight increase of the ion temperature in the most intense region can, however, be observed. In particular the 0+ temperature increases markedly towards the edges of the intense flux (high density) region. Inside this region the 0+ flux disappears. Because of the high density the ion pressure also exceeds the magnetic pressure there. The magnetic field data in Figure 3 show that a discontinous change in the direction of the field lines occurs at the edges of the high density region. The flow in that region is dominated by a strong antisunward component, as concluded already above on the basis of the various density values. So, the characteristics of this high density region in the middle of the mantle seem to resemble more those in the magnetosheath than those in otner parts of the mantle. However, if one compares the magnetic field direction in the magnetosheath proper (after 0200 UT) on finds that the 6-vector had both different direction and magnitude in the two regions (e.g. Bz is positive in the magnetosheath). So this fairly long discussion of a fraction of the mantle data in Figure 2 and 3 does not permit any other conclusion than the one that the satellite may for an hour have passed out into a magnetosheath of unusual characteristics, or the mantle had very extreme characteristics in that period. We will see from other mantle passages that the situation described above is not unusual. Concerning the composition results, the quite high 0+ abundance in the mantle should be noted. Except for the high density, magnetosheath like, region the 0+ abundancy was up to 10% of the total ion density (single values up to 20% were recorded). Notice also, the fairly sharp decrease of the 0+ density (and abundancy) near the magnetopause and the complete lack of 0+ in the magnetosheath (and the 'nagnetosheathiike region). The magnetopause evidently represents a distinct composition boundary. The temperature diagram shows that the temperature of the 0+ ions is 2 to 4 times higher than that for the H+ ions in the mantle. - 15 -

Both the H+ (solid line) and 0+ (broken line) flow vectors are generally directed close to the magnetic field lines, but in the opposite direction of the magnetic field direction. Although the difference is fairly small, the 0+ flow velocity appeared to be higher than that for H+ in the mantle. This is mainly related to a higher antisunward flow component of 0+ while the flow component in the YZ-plane on the average was somewhat smaller for 0+ than that for H+ . The general flow picture during this mantle crossing is that of a taiiward, field aligned, flow of both 0+ and H+ ions, quite similar in magnitude and direction but with a tendency of a higher flow velocity for the 0+ ions.

The flow direction suggests that the ions are flowing outward from the ionosphere of the northern hemisphere. The energy spectra of the individual ion species as well as the energy .spectra taken from the E/q positive ion and electron spectrometer:; are shown in Figure 4 for the mantle passage on 21 - 22 Februcry, 1979. Notice the gradual increase of the ion flux and the gradual hardening of the ion spectra when going from the lobe region into the mantle. The presence of He2+ throughout the entire mantle region indicates a significant abundance of solar wind (magnetosheath) ions. As we can see in Figure 3, He^+ was in general more abundant than 0+ in this mantle. The gradual softening of the ion spectra towards the lobe, first described by Rosenbauer et al., 1975), is most probably a convection feature caused by the dawn-dusk electric field which separates the ions with respect to their initial velocities as described by e g Reiff et al. (1977).

n+ ions are generally observed on the highest energy levels only, indicating a higher mean energy for the ionospheric ions as compared to those originating from the magnetosheath. This difference in mean energies may at first be interpreted as a velocity effect, i e all ions have the same mean velocities (giving 16 times higher mean energy for U+ than for H+). However, a more careful analysis of tie spectrogram reveals that an energetic component for H+ also exists in the mantle. We will later see from other mantle crossings that this is a common feature, i e that energetic 0+ and H+ components fairly often appear together. Sometimes an increase in the highest energy channel of He^+ is also observed but in many of these cases this is - 16 -

mainly due to a "contamination" from the highest energy channel of H+. [he fact that fairly high energy 0+ and H+ occur together is of course not unexpected since both constituents may originate from the ionosphere. An important feature of these ionospheric ions is that they seem to have been accelerated to about the same energy, and not to the same velocities.

E_xjimj)lie _2: 3-4 April 1979, magnetic stonn (Seans Out 127). A fairly different magnetic storm mantle was observed in very similar latitude and longitude ranges as that of Example 1 on 3 - 4 April 1979. The storm, peaking on the 4th of April, was one of the largest in terms of peak Ost-value in the lifetime of PROGNOZ-7. PROGNOZ-7 entered the mantle at 2025 UT on 3 April and passed the magnetopause probably at 0010 UT on 4 April, 1979, but possibly not until 0130 UT (the time of ,the magnetopause crossing will be discussed later). The mantle passage took place in the early expansive phase of the storm. The Dst-value was -69 nT in the hour 20 - 21 UT and it decreased to -164 nT in the first hour of 4 April and continued decreasing to a peak value of -197 nT between 03 and 04 UT. Afttar the peak the storm recovered unusually quickly and Dst reached positive values already 27 hours later. The mantle observations in Example 1 were made from the time of the peak Dst into the early recovery phase of the magnetic storm. IKp had the value 33+ on 3 April and 34+ on 4 April. During the

mantle passage of the satellite Kp had the values 7-, 8 and 7- and IKp for a 12 hours period around the mantle passage was 28-. The magnetospheric disturbance level was thus generally higher during this mantle passage than during the previously described one. The maximum 0+ content was also higher and was actually the highest recorded during the lifetime of the PROGNOZ-7. Due to the spacecraft orientation versus the earth magnetic field, significant 0+ fluxes were only observed sporadicaly with the perpendicular ICS:s (IF- mode). Most of the 0+ flux was instead recorded with the ICS 06, which was oriented 25° from the satellite spin axis (see e g Figure 5). On the basis of the data contained in Figure 5 it appears iiiost likely that the magnetopause was crossed at 0130 UT on 4 April. At that time the electron flux increased to the full inagnetosheath value and the mean electron energy came down to the more or less constant magnetosheath level. Also the ion mean energy was lower after this time than before. It may seem more natural to place the low "perpendicular" flux region between 0000 UT and 0130 UT in the Magnetosphere than in the magnetosheath. we see, however, from Figure 6 that the magnetic field data rather favours 0010 UT on 4 Apri i as the time of the magnetopause crossing. At that time there was a sudden change of the magnetic field direction into the one that characterizes most of the rnagnetosheath. Although the fluxes seen perpendicularly to the X-axis were low between 0010 UT and 0130 UT, the plasma density was in fact not lower than in the rest of the magnetosheath. The exact location of the magnetopause is not of importance for the further discussion of the" mantle.

Both By and Bz were mostly negative both inside and outside of the magnetopause. By was generally much larger than Bz in the magnetosheath, as can be seen in Figure 6. B2 stayed negative also when the satellite had left the magnetosheath, whereas By was mostly positive

in the solar wind (these data are not included in Figure 6). Both By and B2 thus had opposite signs in the magnetosheath for the two magnetic storms discussed as Examples 1 and 2.

We see in Figure 6 an intense mantle region at the inner edge, in which the magnetic field changed direction. The characteristics of plasma and field there were quite similar to those of the intense region at the center of the mantle in Figure 2. In the case of Figure 6, the fact that the intense region with associated magnetic field change was found at the inner edge of the mantle makes it very unlikely that the satellite came into the magnetosheath for the limited time interval between -2030 and -2110 UT. This is then also a support for the most intense part of the mantle observed on 21 - 22 February really being a part of the mantle (and not the magnetosheath). If this interpretation is correct it means that yery intense localized regions with magnetosheath like plasma may penetrate deep into the mantle region. We will later present other examples of magnetosheath like "clouds" in the inner mantle, one of them even more spectacular than the ones presented up to now. - 18 -

Similar to the mantle observed on 21 - 22 February (Example 1), the ir.agnetosheath like region was characterized by the lack of 0+ ions whilst in other parts of the mantle appreciable amounts of 0+ were observed. In the present case the 0+ abundance was much more variable, with number uensity fluxtuations of up to two orders of magnitude. The maximum 0+ density (~10^ m"^) was Lhe highest found in any of the mantles studied. Occasionally the 0+ abundance even surmounted that of H+. Notice also the very high He+ content in this mantle. Sometimes He+ even became the secondmost abundant ion species. Actually this is the only case where we have found a He+ abundance sometimes exceeding 10% in the plasma mantle. Tne flow diagram of Figure 6 shows that, except in the intense (mag- netosheai.nl ike) structures, the flow is essentially field aligned flowing towards the tail. The beam width for the 0+ ions is fairly narro.v (some 30^ within the magnetic field direction or less). The bulk part of the H+ ions, however, has a significant thermal spread which makes them detectable by the perpendicular ICS:s (scanning the YZ-plane). The perpendicular flow values (YZ-plane) obtained from the PROMICS-1 data are based on measurements from the perpendicular ICS:s as described in section 3. This means that whenever the magnetic field direction comes close to the Ecliptic X-axis and when the flow beam is narrow, our flow computations gives the antisunward flow component only. This is then the reason why the 0+ flow in Figure 6 appears to be antisunward only when it actually was field aligned. A noticeable variability in the flow of H+ and 0+ ions can be seen in Figure 6. Regions with fairly high 0+ flow velocity are associated with low H+ antisunward flow velocities and vice versa. This may possibly be related to mass separating mechanisms discussed more in detail in connection with another mantle example and in Section 5. On the average, however, the total flow velocity appears to be about the same for both 0+ and H+ ions. This is then consistent with a reconnection type of acceleration mechanism, i e all ions gain equal velocities independent of mass (see e g Cowley, 1980). On the other hand, as we will demonstrate more in detail later on, the energy peak in the 0+ spectrum may also be observed in the H+ spectrum, indicating an acceleration mechanism that provides equal energy to ions irrespectively of mass. The determined H+ flow velocity in the mantle - 19 -

refers to the bulk part ot the K+ ions which are predominantly of magnetosheath origin. Whereas the flux varies by order of magnitude within the mantle, the ion and electron temperatures recorded in Figure 6 stay stable within about a factor of three. The ion and electron energy spectra observed in the mantle and in the innermost part of the magnetosheath are shown in Figure 7. From u,zt figure one can see that there are slightly more energetic H+ spectra in some parts of the mantle than in the magnetosheath, that there are also electron spectra in the mantle with significantly higher fluxes above 1 keV than in the magnetosheath and that the few 0+ ions Ob- served were collected in the highest energy channel of the instrument. As already mentioned in connection with Figure 5, most of the 0+ ions were observed with the ICS-D6, data which is not represented in this figure. An important feature in Figure 7 is, however, the energetic H+ ions seen in the highest energy channel and the associated lack of such a component for He^+, suggesting that this energetic component is of ionospheric origin.

Examj)le_ _3: 22 March 1979, Small magnetic storm (Seans Out 118). The data from this mantle passage were obtained in the early phase of a small magnetic storm. The satellite reached the mantle just before 1300 UT on 22 March and crossed the magnetopause at about 1445 UT. The crossing time was thus much shorter than in the previous cases.

The mantle "thickness" was about ?. Re. All this can be derived from Figure 8. The Dst reached its peak negative value of -74 nT between 1600 and 1700 UT. During the mantle passage of PROGNOZ-7 the Ost values were -13 and -26 nT. Three hours before the satellite passed in- to the mantle Dst was positive. Kp had the value 7- for the interval

1200 to 1500 UT, the lKp for the 12 hours period 0600 - 1800 UT was

23 and the ZKp for the day of March 22 was 31. Figure 8 shows the kind of typical mantle, as found from the HEOS-2 measurements: flux values somewhat lower than in the magnetosheath for both ions and electrons, strong ion flux, intermediate temperatures. The ion fluxes in the mantle are about an order of magnitude lower than in the previous cases. - 20 -

Froifi Figure 8 it also appears that the ion flow is faster in the mantle than in the inagnetosheath. The spin modulation within the mantle is much stronger than in Figure 2. One has, however, to remem- ber that the data in Figure 8 was taken with detectors measuring perpendicularly to the spin axis and thus to the X-axis. Figjre 9 shows that the magnitude of the ion flow in the mantle is quite similar to that in the magnetosheath. Other characteristics of the flow are, however, different. As for the previous mantle examples this one is also associated with a high density, magnetosheath-like, region adjacent to the lobe. Again the intense magnetosheath-1 ike region is associated with a complete reorientation of the magneti.: field vector without a significant change of the magnitude of total magnetic field. The flow in this region also differs from that in tv? magnetosheath by the almost complete lack of a flow component in the YZ-plane, i e the flow is essentially antisunward. In the outer part of the mantle the flow is field aligned and a significant amount of U+ ions is present (up to 10% of the total ion density).

The magnetopause crossing, around 1445 UT, is characterized by a significant magnetic field change in direction as well as in magnitjde. It is also associated with a change in the perpendicular flow pattern. In the magnetosheath Bz was negative just outside the magnetopause but further out the Bz component was highly variable becoming Doth negative and positive. As we can see in Figure 9 this mantle example represents an even more convincing case against the satellite really being in the magnetosheath in the mentioned high density mantle region and for the existence of intense (inagnetosheath like) structures in the mantle it- self. In this case both the magnetic field and the flow pattern in the "intense" region differed markedly from that observed in the magnetosheath. The composition data and the magnitude of the flow indicate, however, that only particles of inagnetosheath origin were present in these regions.

Except for a slight increase of the ion temperate in the outer part of the mantle, the temperature for both ions and electrons stayed rather constant throughout the whole mantle and into the magnetosheath region. Since most of the 0+ ions detected in this mantle passage were observed by the ICS-D6 (the 0+ ions beaming within a fairly narrow angular interval around the magnetic field lines), not included in the temperature analysis, the statistics is usually too poor for an accurate 0+ temperature determination. The lb point energy spectrum of tiie ions in th° mänt le can be seen in Figure 10. It generally peaks around 1 keV and is similar in shape t > the iiiaijnetosheat.h spectrum (magnetopause at ~l44b ;JT) out is more variable and at lower flux levels. There dru in fact sone mantle spectra which peak well above i keV. On tiie whole, however, the characterization of tne ion ener.-jy spectrum as "magnetosheath like" is most appropriate in this case for the ions as well as for tue electrons. A peculiar difference in the electron spectra outside and inside of the magnetopause should be pointed out. Out1., ide, an energetic component (above 1 keV) is present all the way out to the bowshock, a component which is not observed inside the mangnetopause.

The few a+ counts obtained from Uie perpendicular ICS:s during this mantle passage were all at the highest energy level of the four moni- tored. Notice also that a similar energetic component can be seen in the Hf mantle spectra but not in the He^+ spectra. Outside the magnetopause an energetic H+, and soviet, imes also He'+, component nay also be observed but in his case it appears more like an energetic tail when compared with the lb point tori energy spectra. This may possibly be related to the heating effect observed for the electrons.

Example 4: 11 - 12 April, 19/9; Fairly low activity level (Seans Out 134).

A fairly different, kind of mantle is shown in Figure 1L. Thesi; data were taken in a period jf low magnetic activity. i)st was almost constant, during the 11-12 April, varying between + 1.S and -9 nT. During

the mantle crossing the list values were 2, 2, / and b nT. The K() value was ?. for the two .4-hour intervals before and after UOUU UT on i\'. April, trie LK.p tor the \2 hour period around the magnetopause crossing was ti*- and tne IK,, tor the 11 and \2 April was \? and ?A- respectively. M period witn medium magnetic activity seemed to start on the \'t. Apr i 1.

According to tne data in Figure 11, the mantle was characterized by an unusually high "perpendicular" flow, even higher than that in the magnetnsheath. The 0+ content was, however, much lower than in the previous examples. - 22 -

Figure 12 shows that the magnitude of the flow in the mantle was indeed quite high, although the total flow velocity was not as high as in the maynetosheath. Several magnetopause crossings appear to have been present in this case, the first one possibly around 0030 UT. The situation is, however, far from clear since this first possible magnetosheath encounter was not associated with magnetosheath flow characteristics. The innermost region with magnetosheath characteristics (flow) occured during the time period -0100-0130 UT. Further out we have again a region with mainly mantle properties, i e strong field aligned flows (~0130-0240 UT). This boundary region is therefore a very complicated one involving multiple magnetopause crossings and very strong flow in the mantle.

The ion composition is also highly variable with locally very high 0+ aoundance in tne inner mantle and a strongly fluctuating He^+ content (low in the mantle and fairly high in the magnetosheath).

The magnetosheath Bz and By components were both mostly positive, but narrow regions with negative Bz were also found further out in the magnetosheath. The spectrogram for ions and electrons from this mantle passage is depicted in Figure 13. Notice that the ion spectra in the inner mantle very much resemble the picture drawn by Rosenbauer et al. (ly75) i e a softening of the ion spectra towards the lobe. Notice also that in the time interval ~O030-O23O UT, where we expected several magnetosheatn encounters to occur, no ion spectra with "typical" maynetosheath characteristics (as found further out) were observed. This raises the question whether we really were in the magnetosheath during this time period and not just in a very complex boundary layer.

Example b: 14 March, ly/9, Quiet conditions (seans Out 112) Tnis final example in this group of mantle passages between GSM longitudes 200 and 245° represents very quiet geomagnetic conditions. PROGNO/-/ passed the magnetopause at 1155 UT on 14 March. Ost was almost constant at +b to +8 nf far many hours before this time and stayed at low positive values for the rest of the day. IKp was 0+ for tne 12 hours centered at noon and lKp was b- for 14 March. A magnetic storm that peaked late on 1U March had subsided completely already two days later. Figure 14 demonstrates that in this very-low-activity case naraiy any significant mantle is present. A few spikes of H+ flux with peak values conparable with the magnetosheath flux can be seen close to + the liia-jnetopause. In a ~1 Re thick region inside these spikes an H Hux slightly above background can be seen. No 0+ flux appears to be present in the mantle. The electron flux is low both inside and outside of the magnetopause. The NTPVU diagram of Figure 15 shows that the magnetopause cresting, although being distinct in many respects, was characterized y a fairly smooth reorientation of the magnetic field vector components. A slignt. density increase was present just outside the magnotopause as compared to other parts of the magnetosheath. The characteristics of the H+ flow was also different in this region from those in the rest of the magnetosheath, the dominating flow component being the perpendicular one. The overall flow situation in the magnetosheath was character ••zed by a much smaller flow velocity than in the previous cases uiscusseo. "!he temperature and density were also much smaller in this low-activity case. The very thin mantle-like region inside the magnetopause was characterized by a very low density, fairly high temperature and the lack of flow. Another remark able feature in this quiet case was that the only significant amount of 0+ ions in the time period of Figure 14 was found in the outer magnetosheath close to the bow-shock. These 0+ ions must therefore ha v o escaped out cf the magnetosphere somewhere at the days id? Ti-v.jn-t-)- pause. Notice in this context that the 3Z component in the manjpto- sheath was mostly positive or close to zero. As is further jv;cii$sea in section 5, 0+ ions in the magnetosheath outside the ni'jht'jide boundary layer have only been seen when the magnetosphtT ic Jistur- bance level has been very low.

After this group of mantle data from the longitude sector 2O'j-?4b°, two examples of mantle passages closer to midnight and hefo^e mid- nujh_t_- ono during fairly disturbed conditions and one in low magnetic disturbance - are presented.

_E_x_a_rnjjl_e_ 6: ?.'å April 19/9, fairly disturbed conditions f'^eans Ojt

d'jrift kally the 28tn of April 1979 was a fairly disturbed day, - ?L

witnout being a real storm day. Dst reached -II nT in the early morning (0200-0300 UT) and was more or less coitinously oelow -30 to -40 riT from the 25 April storm peak to the end of the month. These observations were thus made in so;iie kind of recovery phase of the big storm on 25 April or perhaps of a small storm with peak in the night between April 27th and 28th. Kp was 4+ in the three hour interval in which most 3f the mantle was passed and it as 17+ summed over a 12 hour period around the mantle passage. IKp was 33+ on April 23th. Based on the earlier examples one would expect a rather thick mantle, perhaps with a lower degree of spin modulation than in Figures 3 and 11, i e more similar to the storm condition illustrated in Figure ?. This was not at all the case in the premidnight pai., shown in Figure

ID. The mantle was thin (only 1-2 Re) and extremely structure'). In terms of the 0+ content the mantle was one of hign-magnetic-activity-level (intense bursts). On the whole the vdf-aoility of the condition in the mantle was very high.

The NTPV8-plot for this mantle pass (see Figure 17} shows that the basic time scale used for this plot (S min.) was too long for resolving the fine structure in this mantle. The average characteristics of the mantle were on the low side both with regard to thickness and number density. The exact location of the magnetopause is also fairly difficult to determine. Actually both the Bz and the Cx component had the sam:- sign inside as well as outside the Magnetosphere in this region (except for some parts near the magnetopause). Notice for instance that Bz was negative throughout, the whole magnetosheath region

as well as in the inner mantle and outer lobe regione. Even the 3Z magnitude was about the same in cne outer lobe and inner magneto-

sheath. The only component different in sign was that of 8V which was positive inside and negative outside the Magnetosphere. This.case should therefore 'oe tie ideal one in terms of magnetic field topology for resolving the open versus closed Magnotospnere controversy.

R number jf iiiägrietosheath like regions with pl.tsma characteristics similar to tho-j^ in the magnetoshe^th, but. with magnetic field properties cons H-jrably different from thuse in trie maqnetosheath can be seen near the maynetopause. The first one, around 1117 'JT in the inner mantle, was associated with a slight decrease of the 3-field - 25 - magnitude (diamagnetic effect ?). The second one started around 1205 LIT and lasted till about 1230 UT when the first magnetopause encounter probably occured (By became negative). Notice that in the second

event neither the Bx nor the Bz component had the same sign as in the magnetosphere or in the magnetosheath. The third event started around 1305 UT and lasted till about 1330 UT. In this case the main signa-

ture was that of a positive Bz component. Except for the first ;nagnetosheath like evtnt, where a large fraction of 0+ was observed, they were all from the composition point of view very similar to the magnetosheath plasma. The 1 !>.'•< was somewhat different in that a much stronger -y component was present in the innermost cases. A plausible explanation for the magnetic field signature of these events may be in terms of current layer(s) in the magnetopause region

Based on the fairly nigh magnetic disturbance level and the observa-

tion of a rather strong negative component of 3Z in the magnetosheath one would expect to find a much thicker mantle with much higher 0+ densities in it. Only very locally was hign 0+ densities found in this case. One way of interpreting this very thin and low density mantle would be that the earth magnetic field in this region really threads with the interplanetary magnetic field (open magnetic field model) allowing the mantle ions to escape out into the magnetosheath. This means that we should be able to detect the escaping 0+ ions in the magnetosheath. However, no significant amount of 0+ ions were found in the magnetosheath either. In Figure 13 the ion and electron spectra for this mantle pass are shown. Notice the very "spiky" feature of the 0+ ions whenever observed. Notice also that an energetic H+ component is present throughout most parts of the mantle (final magnetopause encounter at 133G UT). This energetic component is also observed in the 16 point ion energy spectra, sometimes as small peaks at higher energies. This energetic component does not disappear at the magnetopause encounter. Actually, further out in the magnetosheath, a fairly broad region where the energetic H+ component is present, can be seen (Figure 18, 1600 - 1730 UT). Notice the almost complete lack of an energetic - 26 -

He^+ component indicating that these H+ ions possibly are of ionospheric origin. We have furthermore in this region a slight indica- tion of an increase of the countrate in the 0+ channel above the background. These observations are therefore in support for an open magnetosphere where, at least occasionally, the mantle ions may escape through the magnetopause into the magnetosheath. The very thin and weakly developed mantle may then be the result of such an escape process.

Exampje 7_: 26 - 27 May, 1979, Medium magnetic activity level (Seans Out 174). In Figure 19 H+ and 0+ flux values from a mantle passage around midnight (GSM longitude 18U°) d.re shown. Dst was of small magnitude during this pass. It was almost constant at -10 to -15 nT from the fore-

noon of the 26th to the forenoon of the 27th of Hay. The two last Kp

values on 26 May and the first one on the 27th were 3. The sum of Kp for the 12 hour period centered around the mantle crossing was 12-.

Earlier on the 26th somewhat higher Kp values occurred and the rKp was 30+ for that day. For the following day it was 25+. We classify the situation as one of fairly low magnetic activity level (but not quiet conditions).

The magnetopause appears to have been crossed by PROGNOZ-7 some 20 minutes after 2400 UT. The mantle passed by the satellite before it reached the magnetopause was a highly structured one with high-flux regions interspersed with empty regions (in space or time). Fairly little but yet significant amounts of U+ were detected by the sunward oriented ICS-Ub. The high degree of variability characterized ions as well as electrons. The NTPVB diagram in Figure 2U shows tl-, at the magnetopause crossing was associated with a drastic change of the magnetic field orientation (at 0020 UT on 27 May). The very structured mantle region observed inside the magnetopause had fairly high ion densities and the ion flow was more or less aligned with the magnetic field (but in the opposite direction). Again the most intense parts of the mantle - 27 -

were associated with a decrease of the magnetic field and a directional change that can be related to current layers. The innermost (at -2230 UT) and outermost (at-2340 UT) regions were inagnetosheath like both in flow speed and in terms of composition, whilst the middle one (at 2320 UT) was associated with less flow speed and the presence of 0+ ions. When statistics were sufficiently good for a conclusive composition analysis, the 0+ content in this mantle was of the order 10% or less. Outside the magnetcpause no significant amount of 0+ ions was found.

The temperature of the ions in the inagnetosheath like mantle region was also fairly similar to that found ir. the magnetosheath (~10'? K). In the intermediate (low flux) mantle regions the temperature was 2 - 4 times lower them in the more intense parts.

Notice also that in this case the Bx and Bz components had the same sign in the lobe and mantle as well as in the magnetosheath. However,

Bz was more variable, sometimes becoming positive in the magnetosheath, but on the average it was slightly negative. From this one would expect a similar situation as in the earlier Example 6. The ion energy spectrum in Figure 21 shows that although this case and the one in Example 6 had much in common with respect to the temporal-spatial and the spectral structure, the energetic H+ component was not so obvious in the present case as it was in the former one. There were some indications of an energetic component, e g around 0200 UT, but it could, very well ha\/e been related to a hot magnetosheath component (energetic He^+ observed as well). So although the situation was fairly similar to the one in Example 6, we are not in the position to state that the Magnetosphere was really magnetically open. On the contrary, the very marked boundary for the 0+ ions seems to indicate the opposite.

Iy79, Longitudinal scan through the nightside mantle for medium magnetospheric activity level (seans Out 1502) Figure 22 contains the H+ and 0+ flux distribution in the mantle at latitudes between 70° and 80° over the wide nightside longitude interval from about 145° to 24b°. The magnetopause was crossed at -1840 UT. - 28 -

During the satellite passage through the mantle Dst varied between -20 and -24 nT, increasing from a peak negative value of -40 nT in the first hours of the day. The lKp value for 2 May was 21+ and during the mantle pass the Kp values were 2+ and 3-. The iKp for the 12 hour period arund the mantle pass was 9+. The nightside mantle shown in Figure 22 was one with very little oxygen ions in it,.characterized also by a fairly strong flow, perpendicular flux values up to those in the magnetosheath and witn strong flux variations in time and/or space. The electron flux and mean energy also showed a more or less gradual increase, respectively decrease through the mantle towards the magnetosheath values. On the whole, the mantle in figure 22 is fairly similar to the one in Figure 19, considering the different kinds of satellite trajectory in the two cases. Together with the other examples of low activity mantles shown above, they demonstrate that the deep nightside fairly low to medium activity mantle generally contains little 0+ and has the other characteristics mentioned in this paragraph. More about this later on.

The NTPVB diagram of Figure 23 shows that the magnetopause was crossed around 1840 UT. The mantle here was characterized by a very low density, a quite high field aligned flow velocity and fairly low ion temperature (of the order that of the electron temperature in the innermost part of the mantle). Also the rnagnetosheath was characteristic for that of a low activity perod (low ion density, fairly low temperature and flow speeds). The only significant amount of 0+ ions was found in the innermost part of the mantle.

The ion and electron spectra shown in Figure 24 clearly demonstrate that the plasma population was extremely soft in the inner part of the mantle. Notice that both H+ and He^+ was present throughout the whole mantle region, the abundance ratio being fairly constant (see e g Figure 23) and similar to that in the magnetosheath. The gradual softening inwards towards the lobe is most probably a convection feature of magnetosheath plasma which has entered the magnetosphere on the dayside as was discussed in relation to Example 1. Notice also the lack of an energetic H+ component in this mantle. Further out in the magnetosheath, however, an energetic H+ component can be observed. Again this component is characterized by the lack of an energetic - 29 -

H9^+ component, indicating d pobiible ionospheric or magnetoopheric (if H+ dominated) origin. After the above demonstration of some characteristics of the mantle in the nightside magnetosphere well away from the flanks, a number of examples of mantle data obtained in the dawn and dusk will be presented. We start with mantle observations at the dawn flank of the magnetosphere.

E/am£le 9_': 3-4 January ly79, small magnetic storm (Seans Out 60) Early January in 1979 was a geomagnetical ly fairly disturbed period but there was no strong storm, rather a series of small storms. Such a small storm started at about 2100 UT on 3 January, when PRQGNOZ-7

just reached the inner edge of the mantle at about 13 Re geocentric distance, a latitude of 56° and a longitude of 254° (GSM). Dst decreased during the mantle passage from a value of -35 nT between 21 and 22 UT to a peak negative value of -70 nT in the hour 23 - 24 UT and then increased continuously to a value of -50 nT in the middle of the forenoon. Kp was only 3+ for the last three hour interval on 3 Janury but increased to 4+, 5 and 5- during the first 9 hours of 4 January. The sum of Kp for a 12 hours period centered to the mantle

crossing was 18-, the !Kp was 27- for 3 January and 30- for the 4th. The latter day was the most disturbed day of the month of January. The mantle passage of PROGNOZ-7 in late 3rd and early 4th of January is an unusual one in terms of the time it took to pass the mantle and in terms of the apparent mantle thickness found. This is illustrated by Figure 25. The satellite crossed the magnetopause at 1040 UT on 4 January and thus stayed in the mantle for 13 hours. The geocentric distance of the satellite when it entered the mantle, after having

spent several hours in the high-latitude-lobe, was 13 RP and when it

left it 24.5 Re. The apparent thickness was thus 11.5 Re. While in the mantle the satellite moved from a GSM latitude of 56° to one of 39°, staying in the longitude range 245 - 260° (most of the time within an inteval of a few degrees of longitude). PROGNOZ-7 in this mantle passage thus provided us with a latitudinal scan from medium latitudes to the pole in the dawn regio In SM-coordinates the trajectory was fairly different from that in GSM coordinates. In SM- coordinates the mantle was first entered at 56° latitude and 280° longitude. The magnetopause was crossed at an SM-latitude of 67° and - 30 -

a SM-longitude of 4°, i e close to noon. In terms of the classification made by e g Haerendel et al. (1978) the magnetopause crossing and large parts of the trajectory, except for the innermost part of the mantle, should have been located in the entry layer and not in the mantle. As we will see later, the plasma along the outer part of the trajectory, rather than the inner, was characteristic for that of the "classical" mantle. The magnetic field configuration in the mantle as well as the presence of the empty lobe inside it demonstrate that PROGNOZ-7 really was in the mantle when these measurements were made.

Figure 25 demonstrates that there were appreciable amounts of 0+ ions present in the mantle, except at the highest GSM latitudes. The ion fluxes were very strongly spin modulated in most of the mantle. Only near the inner edge there was a considerable isotropic component in the H+ flux. In this region also the electron flux was very high. Outside/poleward of this region the electron flux increased gradually towards the magnetosheath level. The electron mean energy decreased slowly through this region. All fluxes shown in Figure 25 varied a lot. This mantle thus showed both the characteristics of the one in Example 1 and those of the mantle in Example 2 in different parts of it.

In the innermost/lowest-latitude part of the mantle, where Figure 25 shows a large isotropic component, the flow was irregular, as expected. Notice also the effect on the magnetic field associated with this fairly intense plasma structure in the inner mantle. Again we have an example of high density plasma structures well inside the magnetopause. These regions have all in common that a considerable effect can be seen in the magnetic field component and that they are dominated by magnetosheath plasma. In this case a significant amount of 0+ ions can be seen throughout the whole structure, however, it is mostly completely dominated by ions of magnetosheath origin (0+ content usually less than 1% in the center of the structure). The effect on the magnetic field appears here more like a diamagnetic one (decrease of the B-field magnitude and a fairly small change in the direction). The high plasma pressure in these structures (g £ 1), indeed the signature of a magnetosheath type of plasma, means that - 31 -

diamaqnetic effects were important. The fairly stronq -nit isunward flow velocity, in many cases with a large component perpendicular to the ambient (earth) magnetic field, means that these structures may very well have acted as MHD-dynamos for field aligned currents. The existence of such inagnetosheath elements in the boundary layer(s) and their physical implication was first discussed by Lemaire (1977) and Lemaire and Roth (1978). More about this in Section 5.

The overall flow situation in this unusually "thick" mantle was, except maybe for the innermost part, that of a field aligned-tailward one. Both 0+ and H+ iorib flowed with about the same velocities (200- 300 km/s), although local differences between 0+ and H+ often were seen.

A significant difference between the mantle shown in Figure 26 and those in Figures 3 and 6 is the low ion density in most of the nantle in Figure 26. Also the N+ distribution in the inagnetosheath is different in this case as compared to those in Figure 3 and 6: less structured and on the average lower. During fairly long periods the 0+ content was on the average 10% and significant 0+ fluxes were recorded for a period as long as 6 hours (corresponding to an altitude

range of ~b Re). Notice that this was a situation when all three magnetic field compo-

nents had the same signs in the mantle and in the rnagnetosheath (Bx

positive, By positive and b7 negative). The energy spectra of the various ions from the mass spectrometers, the total ion spectrum and the electron energy spectrum are shown in Figure 27. Some characteristics to be noted there are the following. The total ion energy spectrum was appreciably more energetic in most parts of the mantle than in the magnetosheath. The total ion spectrum was sometimes double peaked due to low energy protons forming the peak at lower energy and mainly 0+ ionv the high energy one (see e.g. at ~02JU IJ[ on 3 January) in large regions of the mantle. - 32 -

The oxygen ions were found mostly only in the highest energy (13 keV) channel but occasionally also in the second highest (3.8 keV) energy channel. In relation to this it is of particular interest to study the time period ~0200 to 0530 on 3 January, i e where the double peaked ion spectrum was particularly marked. Throughout this time period the high energy peak in the total ion spectrum appeared to be located in the energy range 10 to 20 keV. In the inner part, only 0+ ions was associated with the high energy peak (-0200-0300 UT). In the oucer part (~O43O-O53O UT), the high energy peak consisted of H+ ions only. The intermediate time interval was characterized by a mixing of H+ and 0+ in trie peak. No He^+ ions could be observed in the high energy peak. An obvious conclusion is, therefore, that this energetic ion component originated in the ionosphere. The spatial/temporal shift of the ion peak versus mass can be understood in terms of convection, but more about this later (Section 5). It is, however, important to note already here that this energy peak most probably was caused by a mass-independent acceleration mechanism.

In the outermost/highest-latitude part of the mantle the ion spectrum was even softer than in the magnetosheath. In that region no 0+ ions at all were found. The electron spectrum was in parts of the mantle appreciably harder than the normal magnetosheath spectrum. These harder electron spectra occured only irregularly in the mantle. Between them more "magnetosheath like" spectra were measured. It is of interest to note also that the harder ion and electron spectra were observed only in the inner/lower-latitude part of the mantle.

10_^ 7-8 January, 1979, Small magnetic storm (Seans Out b2) A small magnetic storm started in the middle of 7 January reaching a peak negative Ost value of -94 nT between 20 and 21 UT. From there on Dst recovered continuously to a value of -50 nT in the middle of 3 January. PROGNOZ-7 entered the mantle region at 2300 UT on 7 January and crosse.1 the magnetopause at ~0200 on 8 January. During tha three hour long mantle passage the Dst values were -81, -74 and -66 nT. In - 33 - spite of the fairly big Dst values Kn was only 4 far the last three hour interval of 7 January and 3+ for the first one of the 8th. The sum of Kp for a 12 hour period including the magnetopause crossing was 19 and IKp for the 7th and 8th of January were 23+ and 16-, respectively. The disturbance level was thus similar to that in the previous example. The picture of the mantle shown in Figure 28 is quite different from the one in Figure 25, even in the low latitude part, where the satellite was in very closely the same region of the Magnetosphere. In the present example the H+ fluxes show very little spin modulation in most of the mantle. The H+ flux is lower than in Figure 25, but not the 0+ flux. The 0+ flux therefore amounts to about 10% of the H+ fljx in a large part of the mantle and very locally to even more. The electron mean energy is higher in the mantle in Figure 28 than in Figure 25. The magnetosheath ion and electron fluxes dre lower and more irregular than in Example y. Whereas in Example 9 the magnetic field did not change significantly from the mantle to the magnetosheath which occurred at a very high latitude (GSM), (see Figure 26), in the present case the magnetic field direction switched ~180°, as can be seen in Figure 29. In the outer part of the mantle the magnetic field was quite irregular. Bz was positive and By negative in the magnetosheath. A regular flow could be observed in the mantle only in a narrow region near 01 UT (where also Figure 28 shows strong spin modulation). In the remainder of the mantle the computer process of flow vector evaluation produces very variable values, in agreement with the isotropy indicated in the flux plot in Figure 28. The ion densities in the mantle shown in Figure 29 were mostly lower than in the previous example and much lower than in the nightside mantles described earlier. As can be seen, the 0+ density was occasionally equal to the H+ density in the mantle, the average 0+ abundance beeing about 20% in the innermost part. Both the ion and electron temperatures were higher in this mantle passage than in any of the earlier cases. This is obvious also from the energy spectrum plot shown in Figure 30. As can be seen there, this case is different from all the earlier ones shown in that the - 34 -

H+ energies were higher than the 0+ energies in most parts of the mantle. Whereas almost all ion counts in earlier examples have been found in the very highest or in the two highest energy channels of the ICS:s, 0+ ions wer.j here also found in the lowest energy channels. The H+ differential energy flux spectrum peaked at the top energy in the innermost part of the mantle which is quite different fro.n the situation in the nightside mantles and from the magnetosheath conditions, as shown in Figure 30. The total ion detector even occasionally recorded spectra in which there were no ions at the lowest energies of the instrument.

This mantle differed strongly from the nightside mantles and was more extreme than the previous flank examples also with regard to the electron spectrum. As is evident from Figure 30, the electron spectrum was much harder than in any of the other cases and showed significant fluxes even above 10 keV in parts of the mantle. This case is an extremum also as a flank mantle and to illustrate that we present another example from about the same region of the magnetosphere at about the same activity level.

E_xam£l£ l_lj_ 26 May, 1979, Medium disturbance level (Seans In 174) Figure 31 shows a flank mantle more similar to the nightside ones. It was observed in a period with low Dst values (the whole month of May contained no magnetic storm). In the period from 4 hours before the magnetopause crossing to the end of the mantle passage at ~0400 UT Dst varied between -40 and -21 nT with the lower value at the end. The auroral zone activity was, however, fairly high. Kp for the last 3 hours of 25 May and the first 9 hours of 26 May was 4-, 5-, 4+ and 3+ respectively. The time of the magnetopause crossing is not very well defined from the flux plot of Figure 31, but, as we will see later in the NTPVB-plot, the first inagnetopause encounter occurred at 03b0 UT. This mantle is evidently a highly structured one with much stronger flow than in the previous case and, most important, with much less 0+ in it than in the two earlier examples of dawn flank mantles. It is thus mur1? more like a nightside mantle than the earlier two. - 35 -

The flow properties of the mantle are shown in Figure 32. As we can see in this figure the total ion density in the fairly "arrow mantle structures was higher than in the previous flank mantles, i e more similar to the deep nightside mantles. The magnetopause encounter can be seen around 0350 UT as a fairly distinct reorientation of the magnetic field vectors. A second magnetopause encounter appears to have occued at 0410 UT but again the magnetic field vector in this magnetosheath-1ike region is not oriented in the same direction as it was further out in the magnetosheath. A tendency towards a dia;nagnetic decrease of the magnetic field intensity in this rnagnetosheatn-1ike region can also be seen. We therefore believe that this is another example of magnetosheath plasma which has penetrated through the magnetopause.

Although the 0+ density was fairly low in this mantle it was yet sufficiently high to provide an abundance ratio of 2 - 6% of the total plasma density (single values up to 10% were found). The ion temperature in the magnetosheath was fairly high (~10'7 K) and the ion temperature decreased slowly towards the inner edge of the mantle (down to about 2 x 106 K).

Notice also that both Bx and Bz had the same sign in the inner magnetosheath and in the mantle. The only component differing in sign was thus By. Further out in the magnetosheath the magnetic field was more variable and both Bx and Bz often changed sign there. The energy spectrum characteristics of this mantle are shown in Figure 33. On the whole the spectral characteristics were very similar to those of the deep nightside examples, i e fairiy magnetosheath like electron and ion spectra in the mantle. Finally, two examples of mantles at the dusk flank of the magnetosphere will be shown.

Exain£l_e iAi. 2-3 November, 1978, Medium disturbance level (Seans In 7) Tne magnetopause crossing occurred at ~2215 UT on 2 November, 1978 at 53° latitude and 107° longitude (GSM) and the inner edge of the - 36 - mänt 1e was reacned at ~0130 UT on the 3rd. Dst was fairly high during several days in early November after a fairly big storm that occurred on 30 October (-114 nT). Ouring the mantle passage Dst varied between -40 and -50 nT and it was in that range also during several hours before and after the mantle pass. The last Kp values on 2 November and the first on 3 November were 2 and 3-, The sum of Kp for a 12 hour period around the mantle crossing was 11 and the iKp for 3 November was 21. The H+ and 0+ fluxes shown in Figure 34 were fairly strongly spin modulated in part of the mantle, mainly the inner half, whereas the outer mantle had a strong isotropic flux component. 0+ ions were present in most of the mantle. The ion mean energy varied fairly much within the mantle; the mean energy of the electrons was more steady.

In Figure 35 the magnetopause at ~221b UT stands out more clearly tnan in Figure 34. In the magnetosheath B2 was positive and Bx negative. The plasma flow in the mantle was much more irregular than that in the inaqnetosheath, but jtill generally directed outward from the northern hemisphere along the magnetic field lines. A strong flow component perpendicular to the magnetic field direction in the innermost part of the mantle indicates a strong convection motion there. Another peculiarity in the flow is seen in the magnetopause -egion. The rotation in the flow vector there (checked and found to be a significant feature) appears to follow the magnetic field line rcta- tion. High ion density regions associated with diamagnetic effects were also found in this mantle. Although the density in these regions were almost as high as in the :nner magnetosheath, they contained an appreciable amount of 0+ ions which means that they were no longer "magnetosheath like" as in the previous cases discussed. The flow in tnese regions was also very much reduced.

The density values were similar to those of the earlier shown flank mantles and the 0+ abundance varied between 2 and 10%. The ion and electron temperatures were mostly similar to the nightside mantle temperatures and lower than in the dawn flank shown in Figure 26 and 7.1. A decrease of the ion temperature towards the inner nantle can also be seen. - 37 -

Figure 36 demonstrates that in the outer part of the mantle the energy spectra of ions contained higher fluxes at higher energies. Again this energetic component was mainly associated with 0+ and H+ ions. Some energetic He+ ions were also observed. The electron energy spectrum did not deviate much from the typical magnetosheath spectrum. However, as shown by Hultqvist et al. (1979), there was a small high energy component also in this mantle electron spectrum.

E_xamp_le_ L3^_ 27 November, 1978, Medium disturbance level (Seans In 31) This mantle passage occurred very close to dusk at a GSM-latitude of only 36 - 37°. A clear lobe between the mantle and the plasoiasheet/ ring current can be seen in Figure 37. Therefore, it seems quite clear that what we here call the mantle really was the mantle. The inagnetopause was crossed by PROGNOZ-7 just before the time interval included in Figures 37-39, as shown by the magnetometer on Doard. Unfortunately there was a data gap for the particle instrument between two data taking seanses during the magnetopause crossing. This mantle passage occurred in the late recovery phase of the magnetic storm which peaked on 25 November with a Dst value of -183 nl\ In the course of the mantle passage the Dst-values were -62, -65, -o4,

-70 and -76 nT and similar values characterized the whole day. Kp was

3+, 3, 3 and 3 for the period 03 - 15 UT and lKp was 26- for 27 November. The H+ flux values in this mantle crossing (Figure 37) were generally lower than those in the previous examples and similar to those shown in Figure 28. The mantle record in Figure 37 resembles that in Figure 23 also in respect of the low degree of spin modulation in the mantle. Although the spin modulation is slightly larger in Figure 37 than in Figure 28 it is much smaller than in Figure 34 or in Figure 2b, which represent the high flow mantles on the flanks. The oxygen ion flux in this mantle passage was somewhat lower than in the earlier examples of flank mantles, but 0+ ions were present in most parts of it. Tne ion nean energy varied within the mantle in about tne sa:ne way as in t.he previous example: it was larger in the outer part than in the inner part. Also the electron flux and mean energy were highly variable in the mantle, with tne highest mean energies in the outer part. Tne temperatures of ions and electrons shown in Figure 38 are also highest in the outer part of the mantle. The temperature values are in some reyions of Figure 38 even higher than in the example of high temperature mantle from the dawn flank of the Magnetosphere (see Figure 29). The ion density was low in this mantle as illustrated by Figjre 33. The densities obtained from the various detectors agreed fairly well in this case as in the otner cases of flank mantles shown earlier. The 0+ abundancy varieo between 1 and 10%, the highest values recorded in the innermost part.

The plasma flow was rather irregular during this mantle passage. Mow- ever, whenever a flow was present it was generally field aligned as in most of the mantle cases. Notice also the mangetosheath like structure around 1210 UT which was associated with a strong antisunward flow, a change in tne magnetic field direction and a magnetosheath ion composition. High density, high plasma pressure structures, associated with diamagnetic effects couid even be observed fairly deep inside the mantle region (e.g. at 1400 UT).

That the ion and electron energy spectra were quite hard in parts of the mantle is shown by Figure 39. The low energy fluxes in this figure are generally lower than in the previous case (Figure 36). For the electrons the difference is very large. This example of a dusk flank mantle thus showed ion and electron characteristics which were very different from those of the magnetosheath and the notation "maynetosheath like" is certainly not applicable to it (or to Example 10). h. Discussion The examples of mantle observations presented above show that the mantle characteristics are very variable both in a single mantle pass and from one mantle passage to another. The single satellite observations of course offer no information about whether the variations are - 39 -

nain'.v temporal, i e the mantle properties wary in the course of the individual mantle observations, or mainly spatial, i e the satellite moves through a spatially structured mantle which varies little in the time the observation takes place, or both temporal a

b.l Observed N, T and P characteristics of the plasma mantle The way in which the number densities (N-j), temperatures (F-j) and pressure (P) are calculated is described in Section 3 and Appendix 1. It may be emphasized here that the PROMICS-1 experiment contains detectors pointing 'db° and 90° from the solar direction (i a few degrees because of limited numbers of satellite attitude corrections - 40 - in orbit). In tne best case, i e when the magnetic field lines make an angle of 2b° with the direction to the sun, the experiment covers the pitch angle range 0-50° and 65-115° (or in the northern hemisphere on the nightside rather the supplement values, 130-180° and 65-115°). In the worst case of the field lines aligned with the solar direction, measurements are only obtained at pitch angles 25° and 90°. In this case a narrow beam may certainly be missed oy the instrument and a too low density be obtained. However, in the nightside 'nagnetosheath and the mantle, the magnetic field lines generally form a sizable angle with the direction to the sun, an angle which generally varies. The risk of missing significant parts of the plasma population with the PROMICS-1 experiment is, therefore, considered to be low.

The variability of N, T and P within the mantle, which can be seen in the various figures in Section 4, is generally higher than in the examples of HEOS-2 passages which have been published. Whether- this is due to certain selection effects or to a solar cycle variation of the mantle characteristics is not known. In a few cases, when the ion beams were narrow and when the satellite spin was such as to cause a sampling beat frequency, a periodic fluctuation of e.g. N could be seen (see e.g. Figure 6 in the inagnetosheath). In most, cases, however, this samp 1 ing effect was of minor importance for the variabi- 1ity observed.

The number density in the mantle has occasionally been found to reach 70-80 cin~3 in the deep nightside during storms, a value that has appeared in published HEOS-2 diagrams only in the inagnetosheath. The density has occasionally Deen found to be higher in tht mantle than in the magnetosheath (see e.g. Figure 3), which may be the result, or time variations. Along the flanks of the magnetosphere the number density in the mantle appears to be generally much lower than in the deep nightside (compare e.g. Figure 9 with Figures 29 and 35). The low density of the mantle plasma at the flanks is associated with several other- differences in characteristics which are discussed below in Subsec- tions 5.5 and 5.8. - 41 -

The method of calculating temperatures is described in Section 3 and Appendix 1. Tne values found in the nightside mantle fairly often reaches as high as lO'' K, which is higher than most published HEOS-2 mantle temperatures by at least a factor of two. Since the reason for this difference may be in the method of deriving the temperature we have introduced two different methods for calculating the temperature. The result was only that the method that should be tne most appropriate one gave an even higher temperture (shown by tne solid line in the NTPVB-diagrams). For that reason we have only cited tne lower of the two figures (the H+ temperature, i e the plus in the NTPVB-diagram). Whenever the 0+ temperature was derived with a statistical signifcance it was generally higher than the H+ temperature by a factor of 2-10 (except for the dawn-flank mantle of Example 10 where it was lower).

The temperature of the mantle plasma at the magnetosphere flanks is in most cases (but not all) signficantly higher than closer to midnight and may reach 10^ K (see e g Figures 29 and 38). These strongly heated spectra dre, however, generally far from MaxwelHan and a temperature is not very meaningful. The plasma pressure is derived from density and temperature as described in Section 3 and Appendix 1. Inspection of the pressure diagrams for the various mantle passages documented in Section 4 mostly show a distinct crossover of the plasma and magnetic field pressures at the magnetopause, corresponding to 3=1 at the magnetopauS'.? and a pressure balance between plasma and magnetic field. It i b true that in some cases the exact location of the magnetopause is difficult to determine from the PROGNOZ-7 measurements and that in others no distinct cross over of plasma and magnetic field pressure.-, i-. found, but on the whole it may be concluded that the pressure data are consistent with theoretical models and earlier1 observations in the magnetopause region.

What seems not to have been reported before is the existence of ,-.Z 1 regions in the mantle even far away from the magnetopause (see e g Figures 3, 6, 9, 20, 26 and 35-. In some of these cases one may dis- pute about whether the satellite was in the mantle or had riade an excursion into the magnetosheath. However, because of a number of arguments, including the existence of 04 in some of these regions, we - 42 -

prefer to consider them as part of the mantle, but obviously a spe- cial part, frequently associated with strong currents. They do yener- ally not represent an excursion in a simple geometry through a magnetopause discontinuity into a rnagnetosheath with properties encounter- ed at the final exit from the magnetosphere. There are basically two extremes which characterizes these high s regions. One extreme is that which is very "magnetosheath like" with respect to both the flow and the ion composition but where the direction and magnitude of the magnetic field may be much different from that in the magnetosheath (even the flow direction may differ). This one may oe associated with strong sheet currents. The other extreme is that rfhich is associated with a fairly small flow and a significant abundance of 0+ ions (but yet dominated by ions of magnetosheath origin). This, latter, type of region is usually associated with a diamagnetic decrease of the total magnetic field only, i e fairly small directional changes of the magnetic field is found within it. The fact that they usually occur at greater depths in the mantle seems to indicate that these, less "active", regions are simply evanescent structures.

These observations of limited regions containing plasma with magnetosheath characteristics bring to mind the entrance into the magnetosphere of spatially localized regions of magnetosheath plasma Dy "im- pulsive penetration", as has been suggested by Lemaire (1977) and Lemaire and Roth (1978). One important aspect of such a penetration of magnetosheath bloos into the mantle is that they may act as dynamos for field aligned currents associated with auroral structures and the acceleration of particles.

5.2 On the relation of the mantle characteristics to the properties of the interplanetary magnetic field IMF data for the operational period of PROGNOZ-7 have unfortunately not yet become available to us. Some attempts to relate the mantle properties to those of the magnetic field in the magnetosheath region have not given any consistent results. From observations in the midnight-dawn sector of By < 0 and Bz < 0 in the magnetosheath, after passage through the mantle, one would on the basis of the reconnection model expect to find a thick and dense mantle in figure 5 and a tnin and meagre one in Figure 1 (ef. e g Crooker, 19/9). Rather the opposite is found. There are several other cases of similar disagree- ment between magnetosheath field and the thickness and flux of the mantle according to the open magnetosphere model, but there are also mantle observations which are consistent with the open model. How- ever, as the great majority of mantle passages on the nightside described in this report were outbound ones, the only information we have had as yet is the magnetosheath field obtained after the mantle passage. As we have seen PROGNOZ-7 data where By and/or Bz change sign even at the bowshock and as the relation of the magnetosheath field direction to that of the magnetic field in the solar wind appears to be frequently unclear, no detailed investigation of the mantle characteristics for different magnetic field directions in the magnetosheath has been carried out, but the availability of solar wind magnetic data will be awaited.

5.3 Dependence of mantle characteristics on geomagnetic activity The few examples of nightside mantles observed during different levels of geomagnetic activity, which have been discussed above indicate that there is a relation between the thickness of and ion fluxes in the mantle on one hand and the activity level on the other. The lower the activity, the thinner the mantle. The relation is, however, not a very clear one. This can be seen from Figure 40 in which the product of the thickness of the mantle and the peak proton flux observed during the passage is plotted for all the 32 mantle passages of Table 2. The peak proton flux was then the integral flux (0.2 - 17 keV) taken from the "perpendicular" ICS:s. As magnetic activity parameter the sum of Kp over a 12 hour period, given in Table 2 for each mantle passage, has been plotted. The döts are for the nightside mantles and the triangles represents flank mantles. As can be seen, the exclusion of the flank mantles does not change the relation between the two variables. A positive correlation between the product of thickness and peak flux and the activity level during a 12 hour period around the mantle passage can be seen. The correlation is, however, not a very strong

one. The scatter is large, especially at low Kp values, and fairly good mantles are found also at low activity. - 44 -

Similar scatter diagrams has been prepared with only the thickness and with a rough value of the integral of the logarithm of the peak proton flux during a spin over the width of the mantle along the satellite trajectory replacing that product thickness * peak flux for each mantle pass. Those kinds of scatter diagrams do not differ significantly from the one in Figure 40, but shows rather a larger scatter. Plots have also been made with the sum of the two Kp values, representing best the period of mantle passage, along the horizontal axis instead of the sum of Kp over 12 hours, but those diayrams

If we prepare a similar scatter diagram as shown for the proton flux in Figure 40 for the G+ ion flux, we arrive at the diagram in Figure 41. Although the degree of scatter is still fairly large, especially for low Kp values, the correlation is here much better than that of Figure 40. Actually the correlation coefficient was as high as 0.H2 for an exponential dependence of the sum of Kp versus the peak flux * width of the mantle. Again there do not appear to be a significant difference between the flank mantles and the nightside ones with respect to the level of disturbance. Notice that dots and triangles with a arrow represents fluxes close to or below the statistical measurement threshold ( 3 x 10^ ions cm'^s'^sr'^-) and where this lower flux limit then was used.

The difference between the point distributions in Figures 40 and 41 is ooviously consistent with the existence of a magnetic-activity- independent source of mantle H+ ions, in addition to the activity dependent source(s).

5.4 Electron observations For electrons the open magnetosphere model predicts no signficant. difference in energy spectrum between the magnetosheath an.-j the mantle because the energization of the electrons in the current layer at the magnetopause is expected to be neglible (the flow speed in the - 45 - magnetosheath beeing small in comparison with the Iner^l sp^ed of the electrons). The observations reported above show that in the nights ide mantle, well away from the flanks, the electron spectrum generally deviates ^ery little from the magnetosheath spectrum but that locally in the mantle energy spectra with a somewhat larger high energy component than in the magnetosheth may be found (see e g Figure 4 and Figure 7 around 0000 UT in both cases). Along the flanks of the magnetosphere the electron energy spectrum in the mantle frequently deviates very much from the magnetosheath spectrum. This is seen in Figure 21 for trie early part of the mantle passage, which occurred at lower latitudes than tne later parts, and in Figures 30 and 39 for most of the mantle passage. Even in the flank mantle shown in Figure 36 a careful analysis sh.nvs the presence of a high energy component of electrons in the mantle (Hult^vist et al., 1979; Lundin et al., iy79).

These heated electron populations, found in tha flank mantle fairly frequently and at other local times only occasionally and in very limited regions, obviously require some different source mechanism than the magnetosheath like electron population in the mantle. Some process accelerating ionospheric electrons upward seems most likely. Such upward electron accelerating may be associated with downward ion acceleration observed by means of e g the I:SRO 1 and S3-3 satellites (see e g Hultqvist, 1979, for a discussion). Counterstreaming electrons associated with downward acceleration of electrons and upward beamed ions have been observed by Johnson et al. (1979) from the S3-3 satellite. In relation to this it is interesting to note that in the only case where we have studied the pitch angle distribution in the mantle so far (Example 9), the highest and most energetic electron fluxes were observed when the spectrometer was close to the magnetic field direction i e the most energetic electrons appeared to emerge from the same source region as that of the ions. - 46 -

5.5 Ion flow in the mantle Considering the limited degree of accuracy of the velocity vector in three dimensions that the PROMICS-1 experiment provides (see e g Appendix 1), it is in the first hand the presence or absence of flow, its main direction and the relative variation of the flow vector show.; in the various figures of Section 4 that is of interest. For the majority of PROGNOZ-7 passat,.; through the mantle, illustrated in Section 4, which are from the northern hemisphere, a flow approximately along the magnetic field lines in the direction out. of the northern hemisphere can be seen. Sometimes the ion flow velocity has in parts of the mantle a strong component perpendicular to the magnetic field lines corresponding to a convection flow. When this happens is generally of the order of unity or even above in the mantle (see e g Figure 6 at 21 hours and 23 hojrr- UT; and Figure 9 at 1330 LIT). Some of the mantle flow diagrams presented in this report differ from the HEOS-2 diagrams, which have been published, in that the mantle flow vector is more variable than shown earlier. There Are limited regions within the records from many mantle passages of PROGNOZ-7 where conditions are strongly different from the majority situation. A tendency for the flow to be more regular and more equal to the magnetosheath flow near the magnetopause than far away from it can be seen in several of the mantle crossings (see e g Figures 26, 35 and 38). But there are other mantle crossings where virtually no ordered flow is found (see e g Figure 29). The mantle passages dominated by little or no flow have been found on the flanks but not in the deep nightside. They are also mostly characterized by a heated plasma, ions as well as electrons (compare e g Figures 29 with 30 and 38 with 39). Another characteristics of these non-flowing flank mantles is tne generally lower plasma density than in the normal night side mantles with flow.

It is not clear at present why observations of a hot mantle, with little or no flow, at the flanks of the inagnetosphere has not been discussed in more detail earlier. Sckopke et al. (1976) reported about a hot and "Stagnant" type of plasma in a few HEOS-2 mantle encounters. However, no serious attempt to relate this fairly contro- versial observation to the "classical" mantle model appears to have been made. Possibly their frequency of occurrence may also be related to the solar cycle. The HEOS 2 observations were made mainly in 1973 on the downleg of th^ previous solar cycle wiuh the monthly av^rge - 47 - values of the Zlirich sunspot number varying between 20, and 61, whereas the PkOGNOZ-7 measurements were taken in the period November 1978 to June 1979 when the mentioned average sunspot number was 93 to 166. These observations of slowly flowing to isotropic ion fluxes along the magnetosphere flanks at latitudes where there is a high latitude lobe inside the boundary layer, were clearly made in the mantle according to our definition, but in a mantle dominated by different processes than the high density fast flowing ;nantle seen in the "deep" nightside. The low density, hot, more or less isotropic plasma (ions and electrons) with high 0+ content (up to 20% 0+ of the total number density) indicates that inagnetosheath [J 1 as

In concluding this discussion of the mantle flow, it should oe emphasized that the mantle plasma with little or no flow has been observed only near the border plane between day and night sides of the earth and that even there more normal flow is sometimes seen (see e g Figures 26, 32 and 35), It has not yet been possible to relate the different situations to different IMF conditions because no IMF data has yet been available to us.

5.6 Varitions of mantle plasma composition and energy spectrum witn the distance from the magnetopause According to the open magnetosphere model, discussed most recently and in most detail jy Cowley (1980), the mantle plasma is expected to be flowing tailward with a macroscopic velocity roughly equal to the magnetic field line velocity which in turn roughly equals the plasma flow velocity in the magnetosheath. This is according to the model true for the mantle plasma of magnetosheath origin as well as for the ionospheric ions which have been accelerated in the dayside magnetopause current layer, but not for the ring current particles and unaccelerated ionospheric ions which also may enter the mantle. The latter kinds of particles will disappear with increasing distance from the cusp, in the former case because the particles will pass in- to the rnagnetosheath and be lost, in the second case because they will be E_ x j3 drifted out of the mantle into the lobes and on towards the neutral sheath. The E. x B_ drift distance away from the magneto- pa jse will be larger the longer n particle is affected by the fields before reaching the satellite, i e the lower its velocity along the magnetic field line is. An original distribution of ion velocities around the macroscopic flow velocity at the injection into the mantle will, therefore, show up at some distance from the cusp as a decreasing particle energy with increasing distance from the magnetopause. This effect was observed by means of HF.OS 2 (see Rosenbauer et al., Iy75 and Paschmann, 1979).

For particles with different masses the model described above pre- scribes that the ionospheric cold ions in the current layer of the magnetopause will obtain energies proportional to their mass, i e the average energy of the 0+ ions will oe 16 times greater than that of the protons (the unaccelerated ionospheric ions and the ions of ring current origin are not expected to be seen in the nigntsiae mantle as - 49 - mentioned above). The distribution over the distance from the manne- topause will be the same for various ion species in the first approx- imation (provided that the spatial distribution of the injection into the mantle and the distribjtion of velocities around the macroscopic flow velocity are similar for the different masses). Time variations in the injection rate of ions into the mantle, which are shorter than the travel time from the injection region to the point of observation in the mantle, will show up at the satellite at any moment as a time variation for ions of energies corresponding to the velocity required for an ion to reach the satellite at tnat particular moment. This velocity is independent of mass and, therefore, the time variation will be seen at 16 times higher energy for U+ ions than for protons. If the duration of the time variation is not short compared to the travel time but comparable in length, the variation observed will be smoothed out in time and energy but niay still be possible to identify in the data. However the travel time for ions from say the entry layer to the mantle at dawn or dusk will only be b - 10 minutes, so the effect cannot be easily distinguished in the records shown in this report.

Let us now compare the PR0MICS-1 observations described in this report with the above predictions of the open Magnetosphere nodel. Obviously, if there are temporal and spatial variations of various kinds and intensities in the injection process(es) and/or in the source plasma and/or in the convection electric field, etc., one can not expect to see clearly all the effects predicted by the model. If, on the other hand, we are able to find examples of observational results which are simple and clear enough to relate them to the model, we may suppose that the physicasl effect is present also in more variable and complex situation, although hidden by various variations. We will, therefore, in this section mainly discuss examples of observations which clearly suggest certain interpretations.

The softening of the ion energy spectrum with decreasing geocentric distance in the plasma mantle can mostly be distinguished in the PROMICS-1 records only at toe inner edge of the mantle, but sometimes the tendency can be found through the wnole mantle, examples of this can be found in e y Figures 4, 13, 24, 36 and 39. Cases where no - 50 - decrease of the mean energy in the inward Mirer): ion (except possibly at the very edge) can be seen are found in e g Figures 7, 10 and 30. i«je can, therefore, assume also on the basis of the PROMICS-1 data that the spatial separation of pcrticles with different energies works in the mantle, although the result of it is not always visible because of superimposed variations of various kinds. Occasionally it is possible to identify peaks in energy spectra of different ion species and relate them to each other witn reasonable certainty. Conclusions can then be drawn about the :nass dependence of the acceleration process. An interesting example of this kind can be found in Figure 27. From about 0200 UT to 0430 UT fairly big 0+ fluxes were recorded over a geocentric distance of about 2 Re in the highest energy channel of the ICS. In the early part of this period (up to about 1)315 UT: trie proton spectrum was a soft magnetosheath spectrum. At about 031b dT a peak appears also in the proton energy spectrum and it stays for about one hour more than in the Q+ spectrum, correspo'iding to ~1 Re in the direction towards the magnetopause. The energy per charge data for positive ions also shown in Figure 27 demonstrates that the flux peak is at identical energies for 0+ and H+. There thus appears to be a spatial separation of tne u+ and H+ ions with the lighter ions further out than the heavier ones( with some overlap). Less clear indications of the same kind can also be found in other mantle passages for which data have been included in this report. When 0+ appears only in trie highest energy channel (12.3 keV) of tne ICS, a corresponding peak in the proton spectrum is generally found further out towards the magnetopause. [n other words, the energetic 0+ peak is mostly observed first in the outbound passages that ara the majority in this report (see e g Figure 7 at -2330-0030 UT, and Figure 10, at -1300-1400 UT but even better examples have been found in data not presented in this report). High energy peaks are sometimes found only in the proton spectrum, in most cases of which the absence of energized He^+ ions clearly indicates that the accelerated protons dre of ionospheric origin and not from the solar wind.

An obvious way of interpreting this observation is in terms of a field aligned acceleration of 0+ and H+ ions to the same energy, re- sulting in higher speed of the protons along the magnetic field lines and therefore [ x & drift over a shorter distance from th^ magnetopause than for the 0+ ions. With reasonable assumptions one finas the required electric field to be ;).3 - 0.5 mV/ir,, whkh is a rodtso.iable value according to existing models. The accelerat iori process .'us to be present for several hours with rather stable characteristics for the effects to be so clear as in Figure 27. The data shown in Figure 27 for the time period around 0/\<0 UT -nay alternatively invite to an interpretation in terms öf >'.i+ and H+ ions Deeing accelerated to the same velocities. The pe-iks ar-~ coirj.-letely separated at 0230 UT and the data aro consistent with i6 t.rt;es higher energy for 0+ than for H+ alT:-iough the energy range and energy resolution of the spectral data dre insufficient to prove th3t the ratio is exactly 16. Such an interpretation would, however, inean that no magnetosheath ions entered the mantle in this period, which would not be consistent with the observed presence there of He?"1" ions, and that the cold ionospheric ions which found their way to the maqnetopause and were accelerated in the current layer consisted of quite a high proportion of 01". This seeins much less reasonable than to assume that the H+ ions measured by the mass spectrometers at 0230 UT are mainly magnetosheath ions, as indicated by the ^-particle presence, and that the 0+ ions have been accelerated along the magnetic field 'ines, in or near the cusp region, or even at the days ide at 1 a t i t •; -.J :? s oelow that of the cusp, together with protons and dispersed spatially as described above.

This favoured interpretation is consistent with acceleration of the ions in a magnetic field aligned electric potential drop at fairly low altitudes, of the kind which has ber-n well documented for instance by the S3-3 experimenters. Again we have thus founci evidence in support of acceleration of ions along the magnetic field lines fairly near the ionosphere Deeing the dominant source mechanism for ionospheric ions in the Magnetosphere, and not the polar wind or plasma blobs from the plasma sphere, being accelerated at t.h; inagnetopause, which Cowley (1980) has predicted. This example Joes of course not rule out the possibility that åc:eler dt ion at the Kiaqneto- pause may be of importance for the various magnetospher ic plasma populations, but it demonstrates that field aligned acceleration of ionospheric ions to fairly high energies sometimes is the most important source process and is likely to be important in most situations, contrary to what Cowley and others have argued. Toe presence of acceleration of ola-:>? in tri" •li..'^-!' u ..^.is• r ". ;rrent lay^r is i'i fact supported 'oy Pr\OKiCS-l . ii"»^ -_?'•" v at ions : a ;•- ;>: fo low-1at ituae ooundarv i aye»" ne-.v noci • • i o f. repov"ej *••?•-- . !r tor:r region we iiave founc strong upward (ôn.j * he ecii,r:i.. •'-"•:• s. .:<-•• ••. of He+ ions inside i:he maqnetcpaus ?. Trie oftservai". i>'• ro-;!" eer i:;i>s i these bea..is were ru.icn more abundant than the JT io-r: ;. ••••:'.•--.tes pi as ndsphere source as su^jestpj by Cowiev. rn<-; present.v•^v. o- -i; data will appear in tne near fuiurp. Howeve'", '•• ?J-^ •j'i:.:-.: ~.U~ -i-r aounoanr.e is ..iswally very s.r.all ac ro-r-p-.j-'^.i c.".. t'1- 'J*" .. :/-;i•:, mr catini t h .-a r. the oei-ied •te'r i vi . ôsoi'i". v •:•' '• •' •'• •'"; •• -: '-'O'1 t h current layer acceleration nvir the r.^l'isîa-" poiin, •J" •••'.;. --a:-' 'ji

'iiantle. T no jniv :ihse-"-'5h i or? of ni-^r ;•-':" uoiri'ia'i-'e ;'" ". •-• :••:":*. :-: .•. -v

:iid:i-i darin.j st.'V";;; oo'"nii •:ions •,-;ht;r, the -i-'1" lo'v; ;:•.•.-• M. I .• ••• .'. •.-;< :5v orij nateu dire;t!y "TD,1 trie iorvj-ipfit-ri-i.

b.7 On the use of HeL:*7M+ nu--ilj--r rle-isity r,t;- ^ .. •'•!!••••" '•;••;?

spheric protons f'"oni solar wind protc-ns

The absence of -i-par"L ides aco-rieratea to the oea< "lor •/ •;: fn upper eno of the PROi'iiCS-l energy ranjii ii rKjure '•:'•''. wiir-i M.^:*••,' peak contained only -if and 0f, ratrior definite;;/ -I--.- •• ' •

! ionospher i c origin of the H*~ ioris '.v/en in the reg i in .»/'V. h-, • J ' O':S

r are found in this spectrum peak, as ient io^ed in r.f-e 11 !.i - section, un other occasions we h.we :.s :d tne or:sMr.--.- •-: ' ir'.1-.

1 proof for solar' wino origin of the (:• I a - na. ^owo ;•_"", w-: hj. - n.;f ,se*. any quantitative figure for the He^Vd*" r;itio r:^ öefe-^n' v.1;*' '•-.,.-

tion of an H+ population that is of lono'pherii. i.-.»-i-:i:-, -;•> - /..-lat

fraction coines from the solar wind. The r-.-ij for '•;••, ,ir-."- '-.iir.

The first one is related to the innif-ii ,icc vr-v, -.< ;n .; •, :•• -in i;-. ; •.•!.• composition in the solar ijirecton (only two ene; :y ,1',:,.•-, r ;; t-ir

ICS-D6) which cons ider.ioly influences the dnnsi".y a i; ;' v. ;'.> iv. T^e

secona one is Lint at higher energies the tail or •-.h-..- .,r.'-.rv; ois'.v-i- bution cont a'ninates the He-+ channel in th" PK'J'-U" ,-; Wistru'iient

(when operated in low-speed .node with preset :iiä:i s/ener-j/ char;');-:Is)

for He^+ ratios of the order 10"^ or sw M-r. T', is ff:-;:: srv.'.i'd, however, not be too important since the density con*, r \i> it i on ->•. t'.K

ener;jy level (1?./ keV) is usually fairly soia 1 1 . lm- thi^i 'in--:, ^nicn

is related to trie second, is that the high fMierrjy p.jrt r' ff;c> spec-

trum, rthero tne '^nerqy pe^ks at. fi *" is usually OIJ-/-^^1, r .<-,'• •• ii;.jr -. .

very little to trv- total density. Th- fourth .mj c"irMl r.-v, i" is i *> ;'-. - 53 - we have found from the PROMICS-1 measurements the He'>+ content in the magnetosheath plasma to be fairly variable. Party this is inherent in the degree of accuracy of the measurements as described above, but it could in many cases not explain the variaDility found. For some of the cases the He2+/H+ ratio was checked by using only the perpendicular ICS:s (covering a more extended energy range) for the density calculation. The main result of this was that the He2+/H+ ratio became somewhat smaller and closer to the expected 4A in the magnetosheath. The variability, however, stil i remained in the maynetosneHh region, in particular close to the >nagnetopause, and especially in the mantle (as expected). So far we nave found no systematic variation of the He^+/H+ ratio with the distance to the magnetopause in the mantle. Both ratios increasing and decreasing with distance fro.n the magnetopause have been found.

5.8 The Sources of the Mantle Plasma The existence of a high latitude boundary plasma layer insioe the magnetopause - the particles of which are given a magnetic field aligned velocity component in a reconnection process on the dayside of the magnetosphere - and a "shadow zone" (the magnetospheric high latitude lobes) inside of this boundary layer was discussed in quali- tative terms already by Dungey (1967) and Speiser (1J69). The picture they arrived at was quite similar to the one obtained from observations by means of HEOS 2 (Rosenbauer et al., 197b) and the ion detectors deployed on the lunar surface during the Apollo 12, 14 and 15 missions (Hardy et al., 1975, 1976, 1977) several years later. Already in 1966 Dessler and Michel published an estimate of the contribution to the magnetospheric tail plasma density of the ionosphere by the polar wind. Their conclusion was that the polar wind contribution is negligible, which Dungey (1967) applied to the mantle. Cowley (1980) in a resent detailed discussion of the plasma populations in an open magnetosphere concluded that the polar wind - which is supposed to drive mainly ionospheric H+ and possible some Me+, but virtually no 0+, to the magnetospheric tail - should 5e of importance as a source for the inner part of the plasma sheet but not for the plasma mantle (except possibly at its inner edge fairly close to the polar cusp). - 54 -

Cowley (1980) also discussed the importance as a mantle source of ionospheric ions accelerated upward above discrete auroral forms - as found by means of the S3-3 satellite (Ghielmetti et al., 1977, Mizera and Fennel, 1977) - and concluded that these ion injections under usual conditions are likely to contribute only a small fraction of the source, but tnat they may be a signficant source of the plasma sheet (not of the mantle) during substorms and storms when the nightside auroral region is much expanded. The magnetosheath plasma remains therefore as the dominating mantle source, as discussed already by Dungey (1967) and Speiser {1969,' and later by Rosenbauer (1975), Pilipp and Morf•> 11 (1976), and Cowley (1980). Cold ionospheric plasma is estimated to make an order of magnitude smaller contribution to the mantle plasma density than the magnetosheath plasma according to Cowley (1980). Ionospheric ions may be accelerated in the current layer at the magnetopause to energies of several hundred electron volts before they enter the mantle. The hot ring current ions which may pass through and be accelerated in the dayside magnetopause current sheet are not expected to be found in the mantle on the nightside but rather outside the magnetopause according to Cowley (1980). In conclusion then: in the open magnetosphere model t'.-- plasma mantle - is composed of mainly magnetosheath plasma, - which streams along the magnetopause in the antisunwarj direction with speeds of hundred of kilometers per second, and - has characteristic energies well below 1 keV. - The ionospheric ions accelerated above auroral forms in, or near, the cusp region into the mantle are expected to contribute only a \iery small part. - Significant amounts of "ionospheric" ions in the mantle are expected to originate mainly from the magnetopause current layer on the dayside, where they are accelerated to energies of the order a few hundred eV. Most likely the composition of these ions should be that of the plasmasphere. How do the above predictions compare with the observations reported here? Some relevant observations results from PHOGNOZ-/ obtained in the near earth mantle (the magnetospheric flanks) may be summarized as follows: - 55 -

- Of the mantle number density, locally up to some tens of percent "lay be 0+ ions during disturbed conditions, with several percent of 0+ ions beeing present throughout most of the mantle. - The 0+ ions frequently all have energies above several keV and ion energies above 30 keV have been found. - The 0+ abundance is usually much higher than the He+ abundance indicating that the source for these ions in the mantle is predominantly the ionosphere and not the plasmasphere. - The H+ ions sometimes contain a magnetosheath like component and a higner energy component. - The antisunward flow may be '/ery low and even totally absent in the mantle (as far as can be judged from the PROMICS-1 measurements). - The electrons show irregular hardening of the energy spectrum in the mantle with a high energy component sometimes reaching above 10 keV. - The mantle is mostly very irregular in flux, energy spectrum and compos i t ion. The above observational results have been listed because they do not fit into the open magnetosphere model of Cowley (1980). If we limit ourselves to the "deep nightside", well away from the inagnetosphere flanks, we find a somewhat better agreement with the open model. There - 0+ ions are mostly found in significant amounts only in locally restricted regions (which may correspond to narrow acceleration regions above discrete auroral forms); - the mantle plasma is flowing into the tail with speeds of the order of hundreds of kilometers per second; - the energy spectrum of the protons, although mostly harder than in the magnetosheath, does not deviate very much from the magnetosheath spectrum; - the electrons in general do not appear to be signficantly accelerated compared with the magnetosheath electrons; - the irregularity of the flux as measured by the satellite is in general even higher than on the flanks - occasionally He+ may become the secondmost abundant ion species (Example 2). - 56 - de thus see that in the deep nightside mantle the observations are in general reasonable agreement with the simple open magnetosphere model. "Additional processes" give rise to very different mantle characteristics, especially along the flanks of the magnetosphere (near the dawn-dusk meridian plane) and occasionally also at other local times. These "additional processes" appear sometimes to - select 0+ ions and accelerate them to tens of keV in feeding them into mantle, probably by applying acceleration fields along the magnetic lines at so low altitudes in the ionosphere, that 0+ is the dominating ion species; - randomize not only the 0+ ions in the mantle but also the H+ ions, thereby reducing or even eliminating the flow; - inject also keV electrons into the mantle. Particle energies found by PROGNOZ-7 in the flank mantle are occasionally so high that they surpass what is seen in the ion spectra above auroral farms (so far only by S3-3) and the upward beamed ion spectra that can be inferred from the precipitated electron spectra associated with discrete auroral forms. This is not easily understood in terms of a simple field aligned acceleration above auroral forms, especially as in the cusp region the S3-3 observations generally did not show beam ion energies above one or a few keV (Ghielmetti, private communication ). Acceleration regions extending well above the peak altitude of S3-3 and some secondary retarding process for the electrons below the main interaction region (e g as discussed by Hultqvist and Borg, Iy78) seem to be required to fit all the observations into a model.

5.9 The Mantle Plasma as Source of the Plasma Sheet and the Ring Current. The concept of plasma and magnetic field lines being convected from the high latitude boundary regions inward towards the neutral sheath in the distant tail, where reconnection occurs and the new closed field lines move towards the earth and further towards the dayside magnetopause is inherent both in the closed magnetosphere model as discussed by Axford and Hines (1961) and in Oungey's (1961) open model. The plasma mantle as source for the plasma sheet has been dealt with by many authors in the last few years (e g Pillipp and - 57 -

Morfill, 1976, Cowley, 1980 and Hill and Reiff. 1980). These authors agree in concluding that the plasma mantle can supply sufficient number of particles to the plasma sheet, to account for all known losses, provided the X-type neutral point under usual conditions is located sufficiently far down-stream in the tail (beyond ~ 100 RG). As mentioned before the main plasma component in the mantle, in terns of the total number, is according to Cowley (1980) and others expected to be magnetosheath plasma having entered through the dayside magnetopause, with cold unaccelerated ionospheric plasma and accelerated ionospheric ions returned from the dayside magnetopause as important minor contributors. None of these populations should ^a\/e characteristic energies above a few hundred electron volts. Most of them will, therefore, not move faster along the magnetic field lines in the tail than the magnetosheath flow speed and they will therefore stay on the inside of the magnetopause, i e in the mantle. The ions which have a higher parallel velocity than the flow velocity outside the magnetopause, will in the open niödel discussed by Cowley (198U) pass into the magnetosheath and be lost.

The PROMICS-1 observations show frequently ion energies in the mantle well above 1 keV. In particular the 0+ ions, which may amount to up to 20% (locally even more) of the total number density, mostly have energies above a few keV corresponding to v,, values above 200 km/s. They are, therefore, not expected to wove inward toward the neutral sheet of the tail out insted to pass through the magnetopause and disappear. It thus appears that most of the 0+ ions observed in the mantle will not appear in the ring current. The contribution from the mantle to the ring current will thus be almost exclusively magnetosheath protons (some a particels too) of energies below a few hundred electron volts. So, although the mantle ions frequently have composition and energy distributions different from those assumed for the open magnetosphere model discussed by Cowley, his conclusion concerning the mantle contribution to the ring current still seems to hold.

Besides the mantle, the main source of trie ring current is assumed by Cowley to be the polar wind, which consists of practically no 0+ ions at all. The polar wind protons are expected to have energies in the keV to tens of keV range in the inner Magnetosphere, which is the energy range of the PROMICS-1 experiment. - 58 -

For ionospheric 0+ ions, other than the ones in the mantle, which were discussed above, to be a substantial contributor to the ring current plasma, some acceleration of the ions from altitudes where 0+ is a significant constituent, is required. On closed field lines the accelerated 0+ ions are further accelerated in the neutral sheath current layer of the tail and are transported into the inner ring current, where they may reach energies of several tens of keV. According to Cowley (1980) the polar wind contribution to the ring current is expected to dominate Delow energies corresponding to 2 - 20 keV at geostationary distances because of the high fluxes of polar wind ions over large parts of the earths surface (poleward of the plasmasphere). The ring current is thus expected to consist almost only H+ ions below 20 keV both on the basis of Cowley's model for the polar wind contribution and of the application of his model to the mantle as observed by means of the PROMICS-1 experiment. However, the mass spectrometer measurements by means of GEOS 1 and 2 (Salsiger et al., 1980 and Young et al., 1930), SCATriA (Johnson et al., 1930) and PROGNOZ-7 (Lundin, Lyons and Pissarenko, 1980) in the inner .nagnetosphere, snow that during disturbed conditions 0+ ions may even dominate the ring current, especially on the dayside. An extreme example of that situation is shown in Figure 42. The data in this figure were in fact obtained in the same PROGNOZ-7 passage through the magnetosphere as the storm time mantle observations shown in Figure 3. The 0+ number density was about 4 times higher than the proton density in most of this dayside ring current. From the earlier discussion in this subsection we are obviously led to the conclusion that such a ring current can only be produced by the acceleration upwards along the magnetic field lines of 0+ ions. This has either to occur in the altitude range of the ionosphere where the 0+ number density domi- nates over the proton density, i e in the main body of the ionosphere, or 0+ ions may selectively be extracted out of the ionosphere, for instance in a way corresponding to the one proposed for protons by Ungstrup et al. (1979), and brought up to the acceleration region at greater altitudes. Actually, to have any significant amount of 0+ ions escaping upwards into the magnetosphere, the extraction mechanism (acceleration and/or heating) must be located below the 0+/H+ cross-over altitude (Moore, 1980), if not, charge exchange should prohibit any significant amount of 0+ from escaping upwards. - 59 -

The contributions to the ring current of protons from the polar wind and the mantle may in the stonn situation shown in Figure QZ be similar to those of the undisturbed situation (or slightly enhanced, we cannot tell). However, 0+ ions are virtually always found in significant amounts in the ring current. We thus conclude that, contrary to the expectations expressed by Cowley (1980), acceleration processes involving electric and/or magnetic forces always play a significant role in feeding ionospheric ions into the ring current and dominate during magnetic storms. We also conclude from the PROMICS-1 composition result that the large majority of these ionospheric ions (at least the 0+ part) do not pass into the inner Magnetosphere along the open field lines of the mantle but along closed field lines on the nightside in or near the plasma sheet and probably also to a large extent in the days ide magnetospnere.

4.10 Open or Closed Magnetosphere. A characteristic of the 32 passages through the plasma mantle and the magnetopause into the magnetosheath on the nightside, or close to the terminator, which have been analyzed for this report, has been the absence of significant fluxes of O+ ions, detectable by means of the PROMICS-1 experiment, outside the magnetopause. In some of the described events, observations in the middle and even inner part of the mantle of regions with magnetosheath like conditions, but frequently containing some 0+ ions, have been mentioned as possibly due to an excursion of the satellite into the magnetosheath. However, we have found these magnetosheath like events to be in some repects so different from the characteristics further out in the magnetosheath that we favour the classification magnetosheath like regions in the mantle insted of excursion into the magnetosheath. The only case in which we have observed significant amounts of 0+ (yet very little) outside the mdgnetopause in the nightside mangetosheath represented

an extremely quiet situation (3Z and By were both positive in the magnetosheath) when the mantle was almost absent.

Are the reported PROMICS-1 observations consistent with an open magnetosphere model of the kind proposed by Dungey (1961) and analyzed most recently by Cowley (1930)? The answer appears to be no because of the following circumstances. - 60 - bons of magnetospheric origin - cold ionospheric or rather piasma- sp'neric ions, accelerated in the magnetopause current layer to energies of the order of hundreds of electron volts as well as .nore energetic ring curreit ions - sre, according to the open magnetosphere model, expected to be found mainly outside of the magnetopause current layer along the open field lines, as discussed in some detail by Cowley (1980). It is true that not all field lines are supposed to be open according to the model, but still it appears highly improba- ble that PKOGNOZ-7 should have missed the open ones on all those rnagnetopause passages studied, which have show1 significant Jr fluxes in tne mantle. In addition, whenever there was a high magnetic dis - turoance level and the abundance of 0+ in the riantle was high, the magnetopause was a very sharp ion composition boundary with respect + to the 0 percentage. Whether the By and/or Hz component was positive or negative further out in the magnetosheath did not seem to 'natter at all. Cowley (19;dU) expects the most energetic ions even to be found preferrably outside of the magnetopause. As shown earlier in this report the ions of ionospheric origin frequently have yery ;,tuch higher energies in the mantle than the solar wind ions have.

All this does not mean that we here are in the position to state that an acceleration of e g ionospheric ions and ring current ions could not take place in the magnetopause current layer near the subsolar point, ions which may be found outside the magnetopasue as described by Cowley (1980). On the contrary, we hd\'e found several examples of an energetic H+ component (sometimes also a !le^+ one) in the magnetosheath which may be related to such an acceleration and escape process. It then only remains to be explained why energetic 0+, sometimes the most abundant ring current ion species, is not observed there too.

The limiting ratio of ion fluxas inside and outside of the magnetopause which wds detectable witn the PROMICS-1 experiment varies with the 0+ flux in the mantle. Those passes in the "deep nightside" of the tail, where very little or no 0+ ions were found in the mantle, of course provide no information on the matter under discussion. In many cases, however, (see e g Table 2) the 0+ count rate in the mantle was an order of magnitude or more above the backyround even without any extended integration time. On the basis of the PROMICS-1 data we can, therefore, conclude that the nightside maynetopause appears to be a fairly solid border for the heavy ionospheric ions, of a kind not easily understood in terms of the open >nagnetosphere model as described by Cowley (1980).

5.11 Summary of some major physical implications of the PROMICS-1 measurements in the plasma mantle The PROMICS-1 results presented in this report have demonstrated that the open magnetospheric model, as described in nost detail by Cowley (1930), may be consistent with the mantle observations in the nightside mantle well away from the flanks öf the magnetosphere except in most magnetic storm situations, when the 0+ content of the mantle may become so high and the 0+ ions achieve so high energies that direct injection from the ionosphere through a process which provides the ionospheric ions with energies of the order of up to ten keV appears to be the most likely kind of source process.

Examples have been found where H+ and Q+ iois in the mantle have been accelerated to identical energies. This clearly indicates acceleration in a potential drop along the magnetic field lines and is inconsistent with acceleration in the magnetopause current layer. Along the flanks of the Magnetosphere the open magnetosphere model does generally not fit at all with the PROMICS-1 observations. There the flow of the mantle plasma is often low or absent. The 0+ content may reach up to 20%, the number density is usually lower than HI the deep nights ide, the energy spectrum of both ions and electrons is hotter, even to the level of the ring current plasma. The energization processes giving rise to this hot flank mantle plasma appear to be complex and are not understood. In particular, they tend to pro- duce high energies and broad distributions in botn energy and pitch angle for both ions and electrons.

The variation of the mantle composition with the level of magnetospheric disturbance 15 in the same direction as that of the ring current but no so strong. Whereas the ring current may even become dominated by 0+ ions during magnetic storms, the mantle plasma has never been found to contain above a few tens of percent of the total number density as 0+ ions. The observed variation ,nay be understood - 62 -

as caused by an extension in space and time of the field aligned acceleration regions with increasing magnetic disturbance level. The mantle is not the dominating source for the storm time ring current. Instead, direct acceleration of ionospheric ions into the closed field lines of the plasma sheet and ring current is the most likely main source. This does not mean that we claim that solar wind ions are not fed into the ring current via the mantle during storms, but only that such a source is of lower intensity than the ionospheric injection during strong storms. Contrary to the prediction of the open magnetosphere model, the magnetopause on the nightside and along the flanks of the magnetosphere appears to be a fairly solid boundary for the mantle ions of ionospheric origin. Thus, only one case representing a very quiet situation has been identified where 0+ ions definitely was present in significant amounts on the magnetosheath side of the magnetopause on the nightside of the dawn-dusk plane. In conclusion: The open magnetosphere model is in certain respects consistent and in other respects inconsistent witn the PROMICS-1 results. In particular, it has to be complemented with regard to its prediction for the mantle, especially along the flanks, with additional processes and during storms when the ionosphere frequently is a more important source of inagnetjspheric hot plasma in the plasma sheet and ring current than the solar wind.

Appendix 1. (Determination of the plasma parameters from PROMICS-1 The main plasma parameters, such as the number density, N, the mean flow velocity , the temperature, T, and the pressure, P, can be deduced from the zeroth, first and second moments of the plasma distribution function.

N = Jf(v_) d3v

> = - 63 - where f(v) it the plasma distribution function and _u is the mean drift velocity vector. Having these parameters we can derive the "local temperature", T, from the symmetric pressure tensor P-j-j

Pi i = 3NkT = m J|v_ - u\z f(v_) d3v

where k is the Boltzman constant and m the mass of the particles. The hydrostatic pres .are finally is given by

P = N k T .

Since PROGNOZ-7 had its spin axis directed towards the sun (within ~10°) it is convenient to use polar coordinates for the integrations with the x-axis as the rotational axis (approximately the ecliptic

X-axis) i e vx = v • cosa, v = v • sinn cosy) and vz = v • sina sin^. The differential directional flux measured by the spectrometers, j(E,a,ip), is related to the plasma distribution function, f(v,-,,,p), by the relation

fv3dv •> jdE and the moment equations can then be written as:

N ./| /// KL^isel . sinil dE dfl fr

ux = = fl /// j(E,a,ip)«sin.-i cosa dE d>, dtp

= " H M$ J(E,a,(p)«sin a COSI^I dE da dtp

1 7 uz " ~ JJ III J(E,rt,ip) sin n sirup dE da dip

? 1 /~2 -- 3 Cv ¥ ^ m JlJ J (E >a,tp) • /E'Sin a dE da dcp - 64 -

The tp-nper^t'jre, T, in the one-dimensional case reduces to

T = 2T:

A three-dimensional measurement of the flux, j (£,••• ,^) > r"'jr eacn Par" ticle species would then be sufficient for determining the plasma parameters dt a given time Prom the above expressions. The PROMICS-1 experiment, however, on.y measured in a limiteo number of directions over the sunward hemisphere as shown in Figure 43. To make a numerical integration of tne moment equations, certain assumptions had to be made: 1) The ant i sunward hemisphere was assumed to be isotropic in flux, the flux given by the averaye flux from the perpendicular spectrometers scanning the YZ-plane. 2) The sunward hemisphere was divided in six sectors, three equally spaced in azimuth and two in elevation, within each sector the flux was assumed isotropic given by tne flux measured in each sector. One complete set of data (approximately equally spaced) was taken within 4 spin periods (~'J minutes). Since the perpendicular ICS:s aquired an "azimuthd! scan" within 2 spin periods e g the number density calculated from the IC'J:s was ''refreshed" every ~4 min with respect to the "perpend i OJ]^r" sectors. 3) The H+ and 0+ flow velocities in trie ecliptic YZ-plane, were determined from the integral flux mode in which the energy integration was performed automatically. For each spin period (~2 minutes) b samples per ion species were taken. It was then assumed that the density, N, fur each ion species as deduced according to the assumptions 1) and 2), was constant, within 2 spin periods. The consequence of using the first assumption should probably not be too serious in regions where strong ant i sunward flows are present, such as in the magnetosheath and l.ne plasma mantle, or where no or almost no, flows are expected at all (e g in ths ring current). The major effect should be an overestimation of the density and an under- estimation of the flow. The assumption does of course not hold when considerable sunward flows are present. - 65 -

The fact that the sunward hemisphere is divided in only 6 segments for determining e g the number density (N) may impose the most severe restriction on the accuracy of the result, in particular when the particle beams are narrow. When narrow beams are present, an under- estimate of the number density may frequently occur. The direction of the flow should be determined with a reasonable accuracy (±15° in the YZ-plane arid ±25° with respect to the ecliptic X-axis whenever the thermal spread of the beam is "sufficient" for beeing detected). The major discrepancy should be in the magnitude of the flow which critically depends on the accuracy of the determination of trie number density also. This was mainly true for the ant i sunward flow component since no measurements were performed in the opposite hemisphere. Density calculation Only the ion densities have been plotted in the NTPVB-diagrams. The reason for not including the electron density is mainly because of the poor coverage at low energies (below ~0.1 keV) where the bulk part of the electrons in the magnetosheath and plasma mantle usually lies. For ion density calculation this limitation at lower energies is usually not a problem (except for some cases in the innermost part of the mantle).

From the ion spectroineters 03 and U5 the ion density was calculated by assuming protons as the major ion constituent. Oat a taken during 3 minutes (3 data format cycles) actually corresponds to •-4 spin periods. Each data sample (a 16 point energy spectrum taken within 10 s) was separated in azimuth by about 1^0° (varyi,,g between 110° and 135° depending on the spin period), giving three almost equally spaced directions in aximuth. The statistical error in determining the ion density from D3 and D5 corresponds to about 100% for ~5 x IQ3 (ni"3) and 10% for a density of ~5 x 105 (>TT3). The statistical error is therefore not very important in most of the mantle data. The fairly poor coverage in three dimensions was, as mentioned earlier, a more important limitation for the accuracy of the result. The density figures based on the Ion Composition Spectrometers {ICS:s} Dl, 'J?- and 06 were obtained within half the time period yiven above (i e in two satellite spin periods) by "refreshing" the data taken every ~<3 minutes from ICS-06 (25° from the spin axis) with new data taken every ~4 minutes from the ICS:s oriented perpendicular to the satellite spin axis. The most severe restriction for these calculations is the limited number of energy levels taken in low-speed mode (4 energy levels from 01, D2 and only 2 from 06). Tne statistical error is fairly similar to that for D3 and Db, but the mass term puts the threshold four times higher for 0+ than fcr H+.

For reasonably high densities (i e when statistical effects were small) the number densities obtained from the ICS:s å.,j from the 03 and DS spectrometers agreed fairly well in proton dominated plasmas (e g the magnetosheath plasma). If the statistical error was sub- tracted the difference between the two dens i t iy values was usually less than 50*. The abundancy ratio between H+ and He'-+ in the magnetosheath, where the highest fluxes were measured by the ICS-D6 (at 1.1 and 3.8 keV), should be strongly affected by the lack of data points below ~1 keV in the sunward direction (H+ often peaks at energies Delow 1 keV there). A common situation is that the Hec+ abundance becomes about a factor of 2 too high. By using only the perpendicular IC3:s a more resonable He^+/H+ was generally obtained. Whenever the total ion density obtained from tne ICS:s (0.36 - 12.7 keV) exceeded the ion density obtained from 03 and 05, as sometimes happened when the 0+ was high (e g in the ring current region), the number density obtained from the ICS:s replaced the D3-D5 density in the NTPVB-plot (solid line). The H+ density in the first frame of the NTPVB-plot (marked by +) was calculated from the two perpendicular ICS:s .assuming isotropy with respect to the elevation angle. The difference between the total density (solid line) and the H+ density therefore crudely demonstrates the density anisotropy which initially characterizes the magnetosheath. The 0+ density, however, was calculated using the data from all three ICS:s. - 67 -

Temperature caicjlation Although a temperature is a questionable means of describing the plasma observations wnen the particle distribution function is non- Maxwell i an, it w-, t-'.-ir comparison reasons included as a basic parameter. The tciiip.-1 uure concept may, however, be meaningful even under such conditir' ..hen »-elated to the pias.nd pressure as the '"Midden" kinetic ene•• •..> or the spread in the velocity distribution. In fact, the ion ijistr i but ion function in the mantle was frequently not in thermal equilibrium as demonstrated by many of the figures containing energy spectra.

Two different methods was used in assigning a "temperature" to the plasma. In the first method, the mean squared velocity and the square of the mean drift velocity j _u |'- was used (as described above). In the second method a least square fitting procedure of the data onto Maxwellians was used. Since the first method involves sub- traction of large number (squared velocities) it is very sensitive to statistical fluctuations and the error becomes large at low count rates. The second method, which is less sensitive tc countrate statistics, is more sensitive to the high energy tails frequently observed in the plasma mantle. The least squares fitting wa-> therefore limited to the bulk part of the plasma and the procedure was based on that the correlation coefficient should be better than 0.9. Whenever the correlation coefficient was less than 0.9 the energy range was expanded on an iterative basis until the whole enu'-jy range was covered.

After having tested both methods fairly extensively, tne least squares fitting scheme was adopted for calculating the ion "teiiipt-rature" from the D3 and Ub spectrometers and the electron "temperature" from the 134 spectrometer. To demonstrate the difference between the two methods the first scheme was adopted for calculating the Hf and 0+ "temperatures" 'marked by + and o in the NTPVB-diagram). Only data from the iCS:s 01 and 1)2 data was used in this case and the "temperature" should consequently be related to the mean thermal spread in the spin plane, .ach point represent averages over ~4 minutes. The calculation of the plasma pressure plotted in the NTPVB-d i a'jram was based on the "temperature" and density as calculated from the [)3 - 68 - and 05 spectrometers (solid lines in the first and third frames in the NTPVB-diagram). The magnetic field pressure (dotted line in the fourth frame) was simply calculated from the expression P» = 3^ /2p0 where B is the magnetic field intensity. Drift velocity calculation As was mentioned previously, the drift velocity calculation is based on a fairly rough determination of the plasma distribution function in three dimensions. The result also critically depends on the accuracy of the number density calculation. To supress statistical fluctuations a minimum number density was therefore required. When statistics was sufficiently good, the direction term in the integral should be accurate to within the values already mentioned (

u : IOV; -'jij- cily i-.'Siiiuonenl, Dit if. was Mener ulv within a factor' o ;• two or the

value calculate! t)y i"ti- i f 11 *•- ;jr~ .* 1 :i->"tho'i

f j r Flow vectors wt?re also .;,i!ri,! ai.t-i for' :i \S<

lines) by means of the ls;,->i Jt.-\ Tn,; Mittqrul f1^ TIOI'1; [ It: --no-ie -J ied

för H h and 0+ ions v/ai v^tv usor\; i f-:vo I-1,, purpose s i r:,: j it provided

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I r: ! i j if>' <\'\ WO f|.;/i j i ••'.[•!: i.cil ,;': • • • i',i;i ! •'' ;F :u--\ . ;i>i.-' tr";.ii ti.iT

d 111 i.'i i-'il. !-iii;'i"(j ics i)i>!.a i'i -;! l.y 'ii>:ri i\ .if i iii- Inr»-'. !;.%;'.; ;i.ji'i"O a -liqh

i,|it..f!l .i.jt.ri I .ik inij |i':i"ii>.l wli''M I.!:--' loiiififyo/-- / -.ai.f'• 1 i I.e f.,:-'-.scd tnro'.u'jh

1 t IT- pi Mil.-> ; -nt !o i-i tin- <\<-v:l Mi,, )!. , i .If. - 70 -

Acknowledgement The authors are very much obliged to the magnetic field experimenters on PR0GN0Z-7, Principal Investigator Or E. Eroshenkc, IZMIRAN, for their providing the magnetic field data. The contributions by the technical staffs at Kiruna Geophysical Institute and Sweaish Space Corporation to the success of the PROMICS experiment are gratefully acknowledged. The Swedish part has been financed partly be means of grants from the Swedish Board for Space Act. i vit. ies. Akasufu, S.-I., t.W. Hones, Jr., S.J. Bane, J.R. Asbridge, and A.I'.Y. L'.i;, Maqnjljtai 1 and boundary 1 dyer plasmas at a geocentric

distance of ~lo Re: Vela b ami 6 observations, J. Geophys. Res., To, /757, 1973. Axforti, W.I., and Co. Nines, A unifying theory of high-latitude geophysical phenomena and geomagnetic storms, Can. J. Phys. _39_, .1433, 1961. rialsiyer, A., P. L herlidri.1t, J. Geiss, and D.f. Young, Magnetic storm injection of n.9 to lfc keV/e solar and terrestrial ions into the hi'.ui altitude magnetosphere, .J. Lieophys. Res., 8b, 1645, 1980. !3av,.issano-Cat laneo, M.B. and vr. Fur•:!is.ino, Low energy electrons and protons in the magnetosphet t:, Planet, Space Se i., 26, 51, 1978. Cow ley, S.W.H., Plasm.-» populations in a simple open model magneto- spht-re, :,pai>; Z<:\. Rev., ?•*, 'l\i. lytiO. Crooker, N.ll., (Jays ide ner .j i ng and cusp, geometry, J. Geophys. Res., H4, MS I, 19/y. Uessler, A.,)., and i -.C. Micnel, rMdiiiSj in the geomagnetic tail, J. Geophys. Kos. 71, I4Z1, 1^66. Domingo, V., D.K. ('ago, and K.-P. A'PO/HI, Eiieraetic electrons at the irid'inetopause, vi !).;;. fJ.)(je (tci.): "Correlated Interplanetary and Mcignetospher ic uoservat luns", 159, D. Keidel Pub 1. Comp., !>onJrecht-Ho1 land, 1.9/4. Uo!innc|O, V., U.t. !J

Dunqey, .I.W., I nt.^rp 1 apetary magnetic field and rtijroral /ones, Phys. kev. Letter, b, 47, 1961. [Jungey, J.W., The theory of the guW.it iitcnJr:t-''.osphc-ric, in ,].W. King and W.S. U^wman (Fds.); "c.o I dr-forrest r i al Physics", 91, Academic Press, London, 1%/.

rornnsTio. V., rltuS-!' observations i;t ;.h<.- lionndary lay^r from the magnetopatise to the ionosptu;re, iManet. Space Se i., 28, 24B, 19H0. (jaleev, A., Plasma imia .nreniutiLs on iio.ird PKOGNO/-7, in "Magneto- spnccic study lsV9", i\'ft>( . 1 ntern.-jt Workshop on Selected Topics ot MagncLospheric Physi.s,, Tokyo, March, l'.'/9), 'Mi, 1979. - 72 -

Ghiehnetti, A., E.G. Shelley, R.G. Johnson, and R.O. Sharp, The morphology of upward flowing field aligned energetic ion fluxes, Paper GA 126 presented at the IAGA/IAMAP Joint Assembly in Seattle, Aug. 22 - Sept. 3, 1977. Haerendel, G., G. Paschmann, N. Sckopke, and H. Rosenbauer, The frontside boundary layer of the magnetosphere and the problem of reconnect ion, J. Geophys. Res., &3, 3195, 1978. Hardy. D.A. U.K. Hills, and J.W. Freeman, A new plasma regime in the distant geomagnetic tail, Geophys. Res. Letters, 2_, 169, 1975. Hardy. I).A., J.W. Freeman, and H.K. Hills, Double-peaked ion spectra in the lobe plasma: evidence for massive ions, J. Geophys. Res., 82, bb29, 1977. Hardy, D.A., J.W. Freeman, and H.K. Hills, Plasma observations in the magnetotai1, in B.M. McCormac (Ed.): "Magnetospheric Particles and Fields", 69, D. Reidel Publ. Comp., Dordrecht-Holland, 1976. Hill, T.W., and P.H. Reiff, Evidence of magnetospheric cusp proton acceleration Dy magnetic merging at the dayside magnetopause, J. Geophys. Res., 82, 3623, 1977. Hill, T.W., and P.H. Reiff, On the cause of plasma-sheet thinning during magnetospheric substorms, Geophys. Res. Letters, _7_, 177, 1980. Hultqvist, B., and H. Borg, Observations of energetic ions in invert- ed V events, Planet. Space Sci., 26, 673, 1978. Hultqvist, 8., The hot ion component of the magnetospheric plasma and some relations to the electron component - Observations and physical implications, Space Sci. Rev., 23, 581, 1979. Hultqvist, B., R. Lundin, I. Sandahl, M. Pissarenko, and A. Zackarov, First observations of a heated plasma component in the plasma mantle, in " Proc. Magnetospheric Boundary Layers Conference, Alpbach, 11-lb June, 1979, 83, ESA SP-148, 19/9. Johnson. R.G., R.D. Sharp, E.G. Shelley, and S. K aye, Ion composition observations up to 32 keV with the SCATHA satellite, Paper presented at the VII Lindau Symposium on Ionic Composition, 1980. Lundin. K., I. Sandahl, [J. Hultqvist, A. Galeev, 0. Likhin, A. Oinelchenko, N. Pissarenko, 0. Vaisberg, and A. Zackarov. First observations of the hot ion composition in the high latitude magnetospheric boundary layer oy means of PROGNOZ-7, in "Proceedings of Magnetospheric Boundary Layers Conference, Alpbach, 11-15 June, 19/9, 91, ESA SP-148, 1979. - Ii -

Lundin, R., L. Lyons, and N. Pissarenko, Observations of the ring current composition at L < 4, Geophys. Res. Letters, 7, 425, 1980. Mizera, P.F., and J.F. Fennel I, Signatures of electric fields from high and low altitude particle distributions, Geophys. Res. Letters. 4_, 311, 1977, Moore, I.E., Modulation of terrestrial ion escape flux composition (oy low-altitude acceleration and charge exchange chemistry), J. Geophys. Res., 8b_, 2011, 1930. Page, 13.E., V. Domingo, 0. K'dhn, B.G. Taylor, K.-P. Wenzel, and P.C. Hedgacock, High-energy electrons at the magnetopause above the north pole, Space Res., 1_3, 631, 19/3. Paschmann, G., H. Grunwaldt, M.D. Montgomery, H. Rosenbauer, and N. Sckorke, Plasma observations in the high-latitude magnetosphere, in O.E. Page (Ed.): "Correlated Interplanetary and Magnetospheric Observations", 249, D. Reidel Publ. Comp., Dordrecht-Holland, 1974. Paschmann, G., Plasma structure of the magnetopause and boundary layer, in "Proceedings of Magnetospheric Boundary Rayers Confe- rence, Alpbach, 11-15 June 1979, ESA SP-148, p. 25, 1979. Pilipp, W., and G. Morfill, The plasma mantle as the origin of the plasma sheet, in B.M. McCormac (Ed.), "Magnetospheric Particles and Fields", 5b, D. Reidel Publ. Comp., Dordrecht-Holland. 1976. Reiff, P.H. T.W. Hill, and J.L. Burch, Solar wind plasma injection at the dayside magnetospheric cusp, J. Geophys. Res., 82^ 479, 1977. Rosenbauer, H., H. Grunwaldt, M.D. Montgomery, G. Paschmann, and N. Scopke, Heos 2 plasma observations in the distant polar magnetosphere, The plasma mantle, J. Geophys. Res., 80, 2723, 1975. Sckopke, N., G. Paschmann, H. Rosenbauer, and D.H. Fairfield, Influ- ence of the interplanetary magnetic field on the occurrence and thickness of the plasma mantle, J. Geophys. Res., 81^, 2687, 1976. Sckopke, N., and (j. Paschmann, The plasma mantle. A survey of magnetotail boundary layer observations, J. Atmosph. Terr. Phys., 40, 261, 1978. Speiser, T.W., Some recent results using the Dungey model, in B.M. McCormac and A. Omholt (Eds.): "Atmospheric Emissions", 337, Van Nostrand Reinhold Comp., New York, 1969. Ungstrup. E., O.M. Klumpar, and W. Heikki la, Heating of ions to superthermal energies in the topside ionosphere by electrostatic ion cyclotron waves, J, Geophys. Res., 84, 4289, 19/9. - 74 -

Figure captions Figure la View of a model magnetopause (Fairfielo magnetic field model). Dashed lines indicate constant latitude and local times in 10° and 1 hour intervals, respectively. Locations of the PROGNOZ-/ magnetopause crossings in GSM coordinates for the '32 mantle examples given in Table Z are marked by circles. Short lines emanating from the circles indicate the YZ(bSM) component of the magnetospheric field inside the m^gnetopause (only for those cases where a complete attitude reconstruction have been made).

Figure lb Same as Figure la but with the PROGNO/-/ magnetopause crossings in solar magnetic (SM) coordinates. Figure 2 Integra] flux data for the plasma mantle crossing of Example 1 (21-22 February, 1979]. The two top panels shows integral fluxes for ll+ and 0+ o ve1" the energy range 0.2 - 1.' keV taken from the perpendicular 1CS: s (scanning the ecliptic YZ-plane). The third panel shows the 0f flux in the energy range 1.1 - 3.8 keV as taken from the ICS looking in the sunward direction (25° with respect to the satellite spin axis). The fourth panel rrum the top gives the average energy for ions as deduced from the perpendicular E/q ion spectrometer. The firr.n an;) sixth panels gives the integral flux and average energy of electrons in the energy range ~O.l - 4U keV taken from trie perpendicular electron spectrometer. The bitt.o.n panels shows the magnetic field vector in the sunward direction and the total magnetic field (logarithmic scale used) as taken from the on-board magnetometer. The time and space coordinates (geocentric radial distance in earth radii, latitude and longitude in GSM) are given along the horizontal axis. Figure 3 Plasma parameters and magnetic field data (in metric units) for the plasma mantle crossing of Example L (21 - 22 February 1979). The uppe»" panni shows the ion niHiij-v density (N+) as deduced from the E/q spectrometers arid assuming the ions were all protons (solid line). Plus (+) represents the density fo H+ as deduced from the perpendicular ICSs (assuming isotropy) and circles (o) represents the number density of 0+ using all ICSs. The second panel from the top represents the percentage of the four major ion constituents with respect to the total number density (logarithmic scale used). The third panel shows the temperature of ions (solid line] and electrons (broken line)' as deduced from the E/q electron and ion spectrometer data fitted onto Maxwellians. On the some panel the "perpendicular" H+ ( + ) and 0+ (o) temperature have been plotted (using the method described in Appendix 1). The fourth panel shows the ion plasma pressure (solid line) and magnetic field pressure (dotted line).

The lower frames of the NTPVB-plot gives the magnetic field and flow velocity components in the XY and YZ Solar Ecliptic coordinate planes. Solid line of the flow velocity represents the H+ flow vector and broken line gives the 0+ flow vector. The time and -.pace coordinates (in Solar Magnetic, SM, coordintes) are given along the horizontal axis. Figure 4 Spectrograms (flux vs energy vs time) taken from the perpendicular spectrometers for the mantle crossing of Example 1 (21 - 22 February 1979). To the left, individual four point energy spectra for the four major ion constituents are depicted (using Differential energy flux units). To the right, \b point energy spectra for positive ions and electrons (E/q spectrometers), using differential flux units, are plotted. Time and space coordinates (in GSM-coordintes) are given along the inclined vertical axis.

Figure 5 Integral flux data for the mantle crossing of Example 2 (3 - 4 April 1979). The format is the same as in Figure 2. - 76 -

Figure 6 Plasma parameters and magnetic field data for the mantle crossing of Example 2 (3 - 4 April 1979). The format is the same as in Figure 3. Figure 7 Ion and electron spectra for the mantle crossing of Example 2 (3 - 4 April 1979). The format is the same as in Figure 4. Figure 8 Integral flux data for the mantle crossing of Example 3 (22 March 1979). The format is the same as in Figure 2. Figure 9 Plasma parameters and magnetic field data for the mantle crossing of Example 3 (22 March 1979). The format is the same as in Figure 3. Figure 10 Ion and electron spectra for the mantle crossing of Example 2 (22 March 1979). The format is the same as in Figure 4. Figure 11 Integral flux data for the mantle crossing of Example 4 vll - 12 April 1979). The format is the same as in Figure 2. Figure 12 Plasma parameters and magnetic field data for the mantle crossing of Example 4 (11 - 12 April 1979). The format is the same as in Figure 3. Figure 13 Ion and electron spectra for the mantle crossing of Example 4 ((11 - 12 April 1979). The format is the same as in Figure 4. Figure 14 Integral flux data for the mantle crossing of Example 5 (14 Marcn 1979). The format is the same as in Figure 2. Figure 15 Plasma parameters anci magnetic field data for the mantle crossing of Example 5 (14 March 1979). The format is the same as in Figure 3. Figure 16 Integral flux data for the mantle crossing of Exarrple 6 (28 April 1979). The format is the same as in Figure 2. Figure 17 Plasma parameters and magnetic field data for the mantle crossing of Example 6 (28 April 1979). The format is the same as in Figure 3. Figure ifci ion and electron spectra for tne mantle crossing of Example 6 (.8 April 19/9). The format is the same as in F igure 4.

Figure 19 Integral flux data for the mantle crossing of Example 7 (26 - 27 May 19/9). The format is the same as in Figure 2.

Figure 20 Plasma parameters arid magnetic field data for tne mantle crossing of example 7 (26 - 71 May 1979). Trie format is the same as in '-'ig'ire 3.

Figure 21 Ion ana eleoir\;.n specira for the mande crossing of Example 7 (2b - 2/ ':-\&y 19••"^) . The format is the same as in F i gure 4.

Figure 22 Integral HIA .lar.a for the mantle crossing of Example 8 (2 May 19/9J. Inn ronnat is the same as in Figure 2.

Figure 23 P! as::;a parvm,er>--s ami magnetic field data for the mantle crossing \if LXcrnple o (? May 1979). The format is the same as in f- i gare i .

Figure 24 Ion and electron spectra fw the mantle crossing of Example o (2 Mjy 1979). The format is the sime as in Figure 4.

Figure 25 Integral flux data for the mantle crossing of Fxample 9 (3 - 4 January 19/9!. The format is the same is in Fi jure 2.

Figure 26a Plasma parameters and magnetic field oata for the jnantle crossing of f.sample 9(^-4 January 1979). The format is the same as in Figure .}.

Figure 26D Plasma parameters ^nd magnet it. field data for the ivantle crossing of Lxmiiplfe 9 (.1-4 January 1979). The format is the same as in figure i (cont inuat !on of Figure ?hn),

Figure 26c Plasma parameter-, arid n.vjn.-t K; field data for the .'riant le crossing of :..xample y (3 •• 4 JiriUd^y 1979). Figure showing the magnetop-jij'-.e crossing (^lu.4!) UT) and Bo^-shock crossing (rA'i.'i'i Ul). Continuation of Fiuures 26a and 26b. Figure 27 Ion nr id eieciriin spectra for parts or tne mantle ot Example y (3 - 4 -j^nnar-y 19/9). The format is the same as in Figure 4.

Figure 2o Integral flu* dat-i fvr rr>.e mantle crossing of example 10 (7 - H January 197y}. The format is the same as in Figure 2.

Figure 29 Plasma parameters ZM .i-.cjnet ic field data for the mantle crossing of Example 10 (7 - 8 January 1979;. The format is the same as in Figjr^ 5.

Figure 30 Ion and electron soeoira for the mantle crossing of Example 10 (7 - > Jaru-ary L979) . Tne format is the same as in Figure 4,

Figure 31 Integral flux data for the inbound mantle crossing of Example 11 (26 May 19/9.'. The format is the same as in Figure 2.

Figure 32 Plasma parameters a no magnetic field data for the inbound mantle crossing of Example li (26 Wiy I'i79). The format is the same as in F i gure .).

Figure 33 Ion ano electron spectra tor the inbound mantle crossing of Example 11 (<-'o May llj/9j. The format is the same as in Figure 4.

Figure 34 Integra! flux oat a t'.'" tne inbr)>jr:d mantle crossing of Example 12 [•' - \ 'jovenut"' 197>J). The (:ormat is the same as in M gun-' 2.

Figure 35 Plasma paranv.-ter^ ,-,ni n-jnetic field data for the inbound mantle crossing of Example 12 (2 - 3 November 1978). The format", is the same as u; Figure 3.

Figure 3b Ion and electron spo'.fra for toe inbound mantle crossing of Example 12 (2 • 3 rlov:mber 1978). The format is the same as in f igor^ 4.

Figure 37 Integral fiux data for tin- inbound mantle crossing of Example I i (27 November I'i/'H). The format is the same as in Figure '/. - 79 -

Figure 38 Plasma parameters and magnetic field data for the inbound mantle crossing of Example 13 (27 November 1978). The format is the same as in Figure 3. Figure 39 Ion and electron spectra for the inbound mantle crossing of Example 13 (27 November 1978). The format is the same as in Figure 4. Figure 40 Diagram showing the peak flux of protons (H+) times the estimated width of the plasma mantle versus magnetic activity for 32 mantle passages. The mantle width was taken as the difference in radial distance from the inner and outer (magnetopause) boundary of the mantle along the satellite trajectory. As magnetic activity parameters the sum of Kp over a 12 hour period has been taken. Figure 41 Same as Figure 40 bi"" for 0+ ions. The broken line represents an exponential least squares fit of the data points with a correlation coefficient of 0.82. Figure 42 An example of a storm time ring current when 0+ ions dominated completely over the entire dayside ring current region. The format of the plasma parameters is the same as in Figure 3 except for the magnetic field and flow vectors which are not included. Figure 43 Diagrammatic representation of the PROMICS-1 experiment on board PROGNOZ-7. The figure in the lower right corner shows how the sampling of data in low-speed mode is distributed over the sunward hemisphere. Figure 44 An example of the mass spectrum for different energies obtained by means of the three Ion Composition Spectrometers during a high speed data taking- period when the PROGNOZ-7 satellite passed through the plasma mantle in the deep nightside. - 80 -

Table 1

Spectrometer Energy Energy Levels Energy Field Conversion factor and orienta- range high low bandwidth of view tion (keV) speed speed (FWHM) (FW'JM) (cm^sr keV cts/part)

ICS-D2 (90°) 0.20-1.57 8 2 0.12 6°x8° 2.13 10"4 E(keV) ICS-01 (90°) 2.14-16.9 8 2 0.044 5°x6° 5.31 10"5 E(keV) ICS-06 (25°) 0.65-5.08 8 2 0.056 5°x7° 1.09 1O-4 E(keV)

IS D3 (90°) 0.02-30. 64 16 0.082 5°xl3° 1.09 10-4 E(keV) ES D4 (90°) 0.03-48. 128 16 0.055 4°xl4° 2.6 10"5 n(E)E(keV)- D5 (25°)- ES (e-mode) 0.02-45. 128 8 0.057 4°xl4° 2.8 10"5 n(E)E IS (p-mode) 0.15-45 128 8 0.057 4°xl4° 2.8 10"5 n(E)E

Abbreviations: ICS - Positive ion composition spectrometer IS = Positive ion spectrometer (E/q) ES = Electron spectrometer FWHM = Full width half maximum = Detector efficiency (n for electrons varies between ~1 and ~0.5 and n is about 0.6 for positive ions) 0-,T - rtntje Ha, f i ": fro* 4 hfo re IT

5ert«! Seans ! GSN SM Integra! flu* L 1Z hji,ri 2 no urs

No. Date or fle Lat. Long. Lat. LOM.

HP C^OStirj

1 In 7 2?. 10 17 S3 1CW b6 -9 'Mr -(U-.jy •^Mrtrjt 3 11 to -SL- 7P.-11-U.'

( 2 In 31 -11.00 16 36 >i7 33 »b :.4-;o« v-iob '- 4 4 13- -b; -81

7U-11-2? •A- -n r (j> )ut(?r

-Ib.OC 14 75 25

Out 60 OÖ.15 if i B8 248 b 7 4 i.4- I'j' ^r \ ^ •Jtnin-; •].-«, ^p* ^ti- 11 : H- -SJ -63 79-01-04 # 3 ij'jt bf -02.00 ID 62 256 54 106 --fj" 10^ ~J I'J* ''* a •"!')•' '•.•Amiji-: 4 -b4 -*> /9-01-OH 1 Out 71 M)H.30 I/ /i 231 b9 J. ? -!>;'' ^3 l.$ up ^-)<.r<)i}t- flu«es 3 -14 •» 7*-Ul-2O ; l> Uut M -11 .UiJ 17 74 u ' Jb JII-J ~1'J ~.i-lu H-,^: v;'.'op^ flj.es ') 13 -6b -i'

~~; 5 -12.10 lb 72 <^7 11 2r*9 ~UJ -2-iU" vt'y if •"uttjre-. 2 12 -14 •30~~

~~fc 4 —1*#. 30 21 "i^ 257 bfJ "/ .oS-:i> 'i-10 I'.otrcpit inner T4nt }r 4 » -2b -?7 79-0,-Jl~~

~~11 Out Hi -19.LKJ 19 S9 2r>l 00 262 M-Vi* •> •34 •70 79- 02-0'j M 1/ Out Hb -19.1) •>' 246 «2 ,/.l.,^ •' -IS~~

~~13 Out 90 21.20 17 SJ 24/ bb o' -1U' •1 -b 79-02-13~~

~~Out 11 ?1.40 h SI 243 44 ) '' •"••' -•••"' •' •14~~

~~li Out 95 02. OS 1>1 5* 24» S9 2," ~.'-lo' ?•, -62 -9; 1 It- /-a 1b Out 04.20 1» hi 241 6S 2'J1 m- 10* 12 Jb -34 -4. •~~

~~17 Out 10b 08.20 16 70 214 77 240 ;i-lo7 18» • 5 -26 79- OJ-10 10 Out 112 12.00 IF, 72 21) 7/ .'11 -.2-11;'- 1~~

~~19 Ojt 111 -lb.00 1) 68 2)3 61 2l'l -/•!'.'' • 4 7S-J1-18~~

~~2U Out :iu 14.» 17 70 216 lil 211". «.lo' 21 •37 - /4~~

~~Uut 'l22 2 •..',•, 20 SH ?4, i1) 2(7 -llj' 79- ul-2b 1 .V Out 1.") ?/M; 20 b9 246 W 2itl -' - - lu' 79- U 1- iu 23 Out 1?/ 01.20 241, "•' *' '•"" •"•'"'~~

~~24 129 00.3'. 111 64 ,i ,„ ^.luo 7 -1 - J~~

~~Out 114 02. '.0 1'i 211 711 ',.' Ol • •' •1/ .2 '•(• U4-I2 141 I" 14.i)i 14 •1b ,•« 4-, ,!,•, -'I'.' '" -Jl -)9~~

~~|, il Uht ~12.i.»J ."J '11 I'.fl t. 1 . •• 1 ;' -sl •!-;~~

~~Uut I')U; --B.4J~~

~~Ju l« ]7J~~

~~Jl 'lut I "1 'JK.1U 17 /i H~~

~~3/ U,j' ''.'•; I \\AT\ \\\ \ \~~

~~GSM~~

Figure la View of a model magnetopause (Fairfield magnetic field model). Dashed lines indicate constant latitude and local times in 10° and 1 hour intervals, respectively. Locations of the PROGNOZ-7 magnetopause crossings in GSM coordinates for the 32 mantle examples given in Table 2 are marked by circles. Short lines emanating from the circles indicate the YZ(GSM) component of the magnetospheric field inside the magnetopause (only for those cases where a complete dttitude reconstruction have been made). ÖS" '•'••••/.. A / \

~~...... - r-».^ / / 20 X •' \ A i /-x / "i. yf \ i V V q,V V /\ .-V \ ! / ' V°\ \ ! / / \ s •• ; \ /n. \ i /. /"'•. ./~~

~~o k i Ä v / x.~~

~~\\ X \ A,. / "'"/- i \-'- •:~~

~~w/. --i. 7 i r" \ SM \x v/ "•••••f--4—v-"": •*>•-.., • j |"~~

~~~~I2~~

~~Figure lb Same as Figure la but with the PROGNOZ-7 magnetopause crossings in solar magnetic (SM) coordinates. HR06N0Z - 7 (P^DMICS-1! SEANS 95 START DATE 79-C2-21~~

~~O.J - 17 KEV~~

~~X 3 J L. 0.2 - 17 KEV J a< a Id h~~

~~1.1 - 3.8 KEV~~

~~POS.ION~~

~~MEAN Ef«WY~~

~~ELECTRONS ICM" stc 0.1 - 4J KEV~~

~~ELECTSTON~~

~~MEAN ENERGY 1TQ~~

~~22.00 00.00 02.00 13.5 15.8 17.8 43.9 51.1 55.1 6SM LUG 237.7 213.0 P45.6~~

Figure 2 Integral flux data for the plasma mantle crossing of Example 1 (21-22 February, 1979). The two top panels shows integral fluxes for H+ and 0+ over the energy range 0.2 - 17 keV taken from the perpendicular ICS:s (scanning the ecliptic YZ-plane). The third panel shows the 0+ flux in the energy range 1.1 - 3.8 keV as taken from the ICS looking in the sunward direction (25° with respect to the satellite spin axis). The fourth panel from the top gives the average energy for ions as deduced from the perpendicular E/q ion spectrometer. The fifth and sixth panels gives the integral flux and average energy of electrons in the energy range 0.1 - 48 keV taken from the perpendicular electron spectrometer. The bottom panels shows the magnetic field vector in the sunward direction and the total magnetic field (logarithmic scale used) as taken from the on-board magnetometer. The time and space coordinates (geocentric radial distance in earth radii, latitude and longitude in GSM) are yiven along the horizontal axis. PROGNOZ-7 (PROMICS-D SEANS 95 DATE 79-02-21

~~ION DENSITY COMPOSITION~~

~~T 200 1 (km/s)~~

~~*?.*~~

~~z.r 100 I km/s)~~

~~\ 1- UT 03.07 21.38 22.44 23.5P 00.55 02.01 18.8 R 13.0 14.4 16.7 17.8 T 60.5 SM : *, 53.2 55.5 'J6.9 58.5 281.5 SM t. ar c 243.6 251.6 259.4 266.9 274.1~~

Figure 3 Figure 3 Plasma parameters and magnetic field data (in metric units) for the plasma mantle crossing of Exarrple 1 (21 - 22 February 1979). The upper panel shows the ion number density (N+) as deduced from the E/q spectrometers and assuming the ions were all protons (solid line). Plus (+) represents the density fo H+ as deduced from the perpendicular ICSs (assuming isotropy) and circles (o) represents the number density of 0+ using all ICSs. The second panel from the top represents the percentage of the four major ion constituents with respect to the total number density (logarithmic scale used). The third panel shows the temperature of ions (solid line) and electrons (broken line) as deduced from the E/q electron and ion spectrometer data fitted onto Maxwellians. Or the some panel the "perpendicular" H+ (+) and 0+ (o) temperature have been plotted (using the method discribed in Appendix 1). The fourth panel shows the ion plasma pressure (solid line) and magnetic field pressure (dotted line).

The lower frames of the NTPVB-plot gives the magnetic field and flow velocity compon. nts in the XY and YZ Solar Ecliptic coordinate planes. Solid line of the flow velocity represents the H+ flow vector and broken line gives the 0+ flow vector. The time and space coordinates (in Solar Magnetic, SM, coordinfes) are given along the horizontal axis. PKKI3-1 LM-SPEC PHJHICS-1 LW-5PCL

~~5£tt£ 3S DATE 73-02-21 ST«H TM 50-32; 5EAN5 35 WE 73-02-22 STWT "DC : 00-21~~

J.5i 1'S 3.35 12.1 J.S i?.! J.» 13.! .'i 'Ii V* 12.? t.ii 12.J C«VI INEVl !KEVI iKEVl WEVi no* .KtV> iKEV! iKZVl .KE.V1 iKEVi Hi&=: H/M POS. 136 QJECTRM Figure 4 Spectv-oqrdms (flux vs. energy vs time) taken fro;n the perpendicular spectrometers for the mantle crossing of Example 1 (21 - 22 February 1979). To the left, individual four point energy spectra for the four major ion constituents are depicted (using differential energy flux units). To tiv- right, 16 Doint energy spectra for positive ions and electrons (E/q spectrometers), using differential flux units, are plotted. Time and space coordinates (in GSM-coordintes) are given along the inclined vertical 3xis. PR03NGZ - 7 [PBOMlCS-r SEAMS 12? START O A i t 79 -0-1-03

~~niÉtohiii kii,im*F nUl^^åållléN^tmSm^^^^^^^~~

~~0.2 - 17 Kt:v~~

~~u ' O " c~~

~~t. 1 - 3.8 KEV IJllI -I , !„ g^i.uLn.n r-ninH~~

~~1EV) 'i. . .r PQ5.I0N MEAN ENERGY~~

~~E.fCTRQNS~~

~~C.' - 4B KEV~~

~~ELECTRON~~

~~MEAN — ^N ,.-~~

~~TCTAt -a r 9 , 18.OD 20.09 22.00 00.00 02.00 [H. CO Oc.Oi: 13.2 15.5 13.4 21.0 :-?.5 23.5 SSK LA" 67.2 63.7 B1.D 60.; S3.1 67.4 7?..' S5M-L0M5 215.2 23?. 4 24'. 0 245.1 246.3 2-5S. 3 2 42.3~~

~~Figure 5 Integral flux data for the mantle crossing of Lxatnple 2 (3 - 4 April 1979). The format is the same as in Figure 2. PROGNOZ-7 (PROMICS-1) SEANS 127 DATE 79-01-03 10' fW ^ JVL/lAri •'"'' 'w~~

~~ION DENSITY COMPOSITION~~

~~100~~

~~1 20.11 21.19 '" 7?^/ 23.35 00.4-1 01.52 15.7 16.9 18.0 19.0 20.0 20,9 HB 56.0 57.5 59.3 6VJ 53, i Sf 218.6 27E.5 733.8 2-10. A 2€. 5 2V.S~~

~~Figure 6 Plasma parameters and magnetic field data for the mantle crossing of Example 2 (3 - 4 April 1979). The format is the same as in Figure 3. 1..GOt fL-U'J-' I .' (CMAKIHS SK S ZffVJ / o~~

~~J ¥ CTv~~

~~,7 \ t \ '- • u""> cu tc "< ' S (N f\j i/l 1/ ,-- J ; s ^LZ— ' CD (T\~~

~~OJ :..) O"- c^: cri LJ - . . • c—i '.o _r> 3 j Q. .... > ! U J j • LJ-1 O IXJ I ^ - ; ^ f CT3 j i i "3 r • f-j -o C~J X ': ( J J ^~i rs) Ln in UJ~~

~~! en ^ J s -. - - c i i —^i.~~

~~c ra jur e~~

~~OJ ii r: c~~

~~o I/I |+- ra ro OJ 13 1 "O (/I OJ CL Q~~

~~en «3 IT, OJ e O a~~

~~OJ PROGNGZ-? IPROMICS-l] SEA,: 6 118 L1ATE 79-33-2 Z H, *i~~

~~IHe~~

~~; COMPOSITION~~

~~I 1 I M i \ ! I i T , I , \ , i ..'\V, >•> I i \s ,\ \ v.7..1~~

~~1C0~~

~~[ : UT 12.09 13.1/ '• .26 •-.]! =) 13. -1 14.8 16.0 '9.3 sx LAT 618 b3.1 61. -1 53. fa SM LONG 189.8 195.5 201.g 208.9 ??3.5~~

~~Figure 9 Plasma parameters and magnptic field data for the mantle crossing of Example 3 {22 March 1979). The format is the same as in figure 3. LOU-SPEED~~

~~PROCCS-' IM-SKED i 9~~

~~"8 DATE 7U3-2? SW 'Bt -i-H SANS \\ * 'A'S' t Pi~~

~~1 > ••:, -v •>.V' ;'<\\v ., - > ^ \ i~~

~~•;\ -.;•• •~~

~~:> -,J ;.-•' \ \* . v '•)~~

~~'. > _ .~~

* \ • "

~~•v •••.••• Hvv--~~

~~U-+- -f~~

~~,.35 IHIV! liCV!~~

~~ITS \U '*•« 5-;= IKEVI~~

~~for PROGNOZ - 7 IPROMICS-11 5EANS 134 START DATE 79-04-11~~

~~0.2 - 17 KEV~~

~~X 3 J li. 0.2 - 17 KEV J cr ID liuu Id H Z H 1. 1 - 3.a KEV~~

~~JLHJU.JL nil • -.. .AW*\ II .nAJ\. I . .n I • .Hi k I I n li mm • filni n~~

~~lev) i^sjf^^0^ POS. ION MEAN ENER6Y~~

~~ELECTRONS (CM"2SEC"1SR"1I 0.1 - 4» KEV~~

~~10 ELECTRON IEV! MEAN ENEBSY~~

~~TOTAL-B 10 INT] + -1 a x -10~~

~~UT 20.00 22.00 00.00 02.00 04.00 06.00 08.00 10.00 R 10.3 13.0 15.4 17.4 13.3 20.3 22.4 23.8 6SM-LAT 67.1 66.1 65.7 67.6 71.2 75.2 78.4 80.0 SSM-L0N6 204.0 223.7 232.3 234.7 232.8 226.9 219.4 216.9~~

~~Figure 11 Integral flux data for the mantle crossing of Example 4 (11 - 12 April 1979). The format is the same as in Figure 2. PROGNOZ-7 (PROMICS-1) SEANS 134 DATE 73-01-11~~

~~2 10' (He *) N.~~

~~|M»H M + * % t ******* ION~~

~~(Zl 10 DENSITY~~

~~1 COMPOSITION~~

~~108 T- 107 IK) 10«~~

~~100 9 PB 10" »BUTJ 2 1 Mm" ) l0- ° 10~~

~~50 nT~~

~~X,Y~~

~~T 200~~

~~Bz,r~~

~~(km/s)~~

~~1— UT 23.11 01.27 02.35 03.44 04.52 00.19 R R4 16.9 18.0 19.0 20.0 15.7 SM LAT 60.8 66.1 69.3 72.1 74.6 63. G SM LUfJf, Z20.3 233.2 237,6 239.9 238.8 227.3~~

~~Figure 12 Plasma parameters and magnetic field data for the mantle crossing of Example 4 (11 - 12 April 1979). The format is the same as in Figure 3. -t 1—',~~

~~+ -+—-+-1 MÄC5-1 L» SPt£D 1~~

~~.. T~~

~~\ "A'V. ' \V«. ; '-^-- ÄS K ~"^\ ~^l " -'Av .pp. i^ ;~~

~~•<, .-ii V m<:*:- ,sn i::,?,M 1 ' ..:-- •~~

~~: J 1 : 'j . ;'-• /1 ••; i\^ä V:. rl-?..~~

~~I i » feg t^ •-*---' ... ::A ^B-:--H t —_-.-- J + V~-^~~

~~ItCV)~~

~~- 12 Apr i~~

~~for the «t.« -oss-, ,, ,„„ aod electron spectra '9° 7«. The f*-« is the Sa'"e i:~~

~~t 4 i ./~~

~~-=t~~

~~i Q. 4~~

~~cr> "5 c o i. (J~~

~~c OJ ro f~~

~~<*- ti ^0 nj > ; 4-> £~~

~~X) i/) > X 1 V, i- 4-> cn 13 (1* » J C O~~

~~•Tl" l..i tJC, i., f II PROGNOZ-7 (PROMICS-1) SEAN9 112 DATE 79-03-14~~

~~10 1 (•T ) 105 do*) .IH.*)~~

~~100 ION (Z) 10 DENSITY 1 COMPOSITION~~

~~L 101 T- 107 IK)~~

~~10* 100~~

~~IN*"') 10-« 10~~

~~50 nT~~

~~-TTT1I I 200 -L llrn~~

~~J r/F/i Z.Y~~

~~'Z.Y~~

~~(kirv's)~~

~~UT 10.39 11.48 12.56 14.05 15.14 15.22 R 16.3 17.4 18.5 19.5 20.5 21,4 SMLAT 711 71.9 69.3 66.6 63.9 61.4 SMLONG 211.1 210.9 213.0 216.8 221.9 227.6~~

~~Figure 15 Plasma parameters and magnetic field data for the mantle crossing of Example 5 (14 March 1979). The format is the same as in Figure 3. ORCSN2Z - 7 SEANS 150 START DATE 79-04-28~~

a *

~~10 \ 0.2 - 17 Kt V~~

~~iiLUMju.kiiiAi lldMifciifli» *riu«uJ«uinL4 (k.~~

~~1.1 - 3.8 KEV~~

~~i lin B. ..n M n ffn!l nr. Ij. n H n ii r. jillflr fi cm )H i!~~

~~l . 3 ; I' . POS.XCN . 2 i ^ MEAN ENFHOr I - i~~

~~Q.I ^8 Ki-V~~

~~J ! " J!~~

~~-.-. i — J'-'.V'- JLJ1-~~

~~-r '4, 00 "6. 00 IS. C? :>.3C GG. C0 3 20.3 •>? _ A 23.8 25. C 26. 1 21. 1 8G. 5 8".9 76.6 ;?.5 65. 7 B 3 . 6 63. ä 54. R 1B8 2^8 Q 24? 254 S 257.4 256. 4~~

~~Figure 16 Integral flux data for the mantle crossing of Example 6 (.28 April 1979). The format is the same as in Figure 2. PROGNQZ-7 (PROMICS-1) SEANS 150 DATE. 79-G4-28~~

~~10 ios! I,"~~

~~. -i~__~~

~~100 •n-''»*' * t^-^ M1I I ION DENSITY 10 j a AA iAA A A Aa J1 • AA A \* 4 ' d^ * *AAfijA*aAlU ÄA AftAäAAiAila- if COMPOSITION , i 1 10*} +~~

~~é 100~~

~~I! 50 nT !siN^^« ^ B^~~

~~i T\" i t 1 \ I 20C ! 1 ik/ Hi i~~

z, Yv*

~~.-/.'/•'ft, ii//,-, ...... n.'i/i.'.'i'i' VAT T too I~~

~~4— ...... i . -1 UT 11.10 12.19 :3.2/ ' uiis 15.43 16/52 7 R 18.5 19.5 0.5 ?1 4 22.2 23,0~~

~~5M I. AT 65.1 62.6 60.1 58.4 5b. 8 55.6 SM '.OtiG 167,1 172.5 IKi.a 193.5 201,3~~

~~;gure 17 Plasma parameters and magnetic field dato for the mantle crossing of Example b (?.ti April ]y/'J), The format is the same as in F iqure 3. PKMCS-1 LOi-SPEID PWUHS-I~~

~~SEM6 no »It 75-54-58 S SEAN5 no QME >5-tH 28~~

~~t.R "!.« S.'i 'M J.K '!.« *..i:. "!« *- s \n us \i\ vh n.s w> ".. »Ol lit*! MfO-t HIQ-2 HIO! CUCPCNS~~

~~Figure 18 Ion and electron spectra for the mantle crossing of Example 6 (28 April 1979). The format is the same as in Figure 4. i 4i~~

~~LO rg or) •--~~

~~t. q-.~~

~~rNi » - OD r-j~~

~~cr — r i~~

~~j ^ J n n •< J\ i co r-' » ro~~

~~11 ^ ii "51 c r: O Li O Ci 5|~~

~~^ - u~ ui •") CT CD LO PROGNOZ-7 (PROMICS-1) SEWS 174 DATE 79-05-26 1 1~~

~~T J1R- r1.-.-.v*---v..-~-..~-i t^i LJ i (o-i Jrf~~

~~ION DENSITY COMPOSITION~~

~~100 (bn/sl~~

~~1 1 UT 21.10 22.19 23.27 00.35 01.43 02.52 R 15.4 16.6 1/.8 18.8 19.8 SMUT 67.1 70.1 72.9 75.4 77.3 SMLONG 178.8 185.4 189.8 191.5 189.7 18J. 3~~

~~Figure 20 Plasma parameters and magnetic field data for the mantle crossing of Example / (?6 - 17 f^y 1 'J79}. Ine format is the same as in Figure 3. »CKICV1 LOU- PPOGES-1 LW-5PEE~~

~~SEANS \U QME 75-K-I6 S1WT TDt Q (ft '5 4 I pi rn r-H + i +i 4- t ;-\ •~~

~~•' \~~

~~6.S tt.l ».» 12.» t» tt.» (.13 « J.35 «.t S,5S 11.1 V» 15.? t.» «.» (t€V! IISV! B©H WÖI IKEV1 tttVI ll^Vl BCV1 IICV1 PC6.IOG PCB.ION5~~

~~Figure 21 Ion and electron spectra for the mantle crossing of Example 7 (26 - 27 May 1979). The format is the same as in Figure 4. The~~

~~F i for .»at is »e «:»«• as in F,gUrs 2. PROGNOZ-7 (PROMICS-1! SEANS 150 DATE 73GS-Q2~~

~~1-°' 105~~

!\v.t. .i\ nJl'i /i. t iv ii,; i;:,; *

~~I 1 1 UT H40 15.^8 16.57 18.05 19.13 20.2i R 19.8 20.7 21.6 22.4 23.2 2-1. 0 SMLAT 57.3 5S.1 55.-1 55.1 55.2 55.9 SM LONG 179.8 187.9 196.1 20-1.1 211.7 2'8.7~~

~~figure 23 Plasma parameters and magnetic field data for the mantle crossing of Example 8 (2 May 1979). The format is the same as in Figure 3. PBOOCS-1 UÄ-SPEED~~

~~3EAN5 150~~

~~"u"""°"'"" Figure ? The format is v.ue s m~~

~~,.s--* "3. en~~

~~a. 6~~

~~-S I en c~~

~~•y> to O i_ f o 0) ^ c O 1/1 s T: Jsk OJ~~

~~13 •< 0) •3~~

~~o en OJ~~

~~o y - ^7~~

~~O) i. ( JS S U1D] i i : en PROGNOZ-7 (PROMICS-1) SEANS 60 DATE 79-01-03~~

~~2 107t f AH) .(H. *) 6 ii 10 .. 3 U" ) 105 i>* ^x^y^y^^^^^ ION n,»,»*t»"»l • ! DENSITY~~

~~1 •• tort** COMPOSITION~~

~~T, 10v.~~

~~100 Ikw's!~~

~~t UT 21.09 22.17 23.25 CO. 34 01.42 G2.S0 R 13.0 14.3 15.6 16.8 18. C 19. C SMLAT 56.4 55.7 54.9 54.4 bl. 2 !)4.3 SM L Dr.G 281.3 288.6 298.0 303.7 311.8 320.1~~

~~Figure 2ba Plasma parameters and magnetic field data for the mantle crossing of Example 9 (3 - 4 January 1979). The format is the some as in Figure 3. PROGNOZ-7 IPROMICS-l) SEANS 60 DATE 79-01-01~~

~~ION 100 HI* *****t+*t+*++i++tt*n>>• *• t**ttt****** ***** •++++»•»++»»«•>***•+»>+ t <» 10 DENSITY 1 COMPOSITION~~

~~T» yf.. T- 10'£S^>/tttr^i.iTt c£SJgv?^5 (K) 10S~~

~~PP 10* pB 10"8 2 (N«- )10-« •• 10~~

~~50 nT~~

~~200 (tn/s)~~

~~1 (kn/sl~~

~~1._ UT »- 03.58 05.07 06.15 07.23 08.31 09.«. R 20.0 20.9 21.8 22.6 23.4 24.1 SMLAT 55.0 56.1 57.6 59.6 62.2 64.7 SMLONG 328.7 337.1 345.0 352.0 35/./ :.3~~

Figure 2bb Plasma parameters and magnetic field data for the mantle crossing of Example 9 (3 - 4 January 1979). The format is the same as in Figure 3 (continuation of Figure 26a). PROGNOZ-7 (PROMICS-1) SEANS 80 DATE 7*01-04

~~1 L ,~~

~~1 X.T TT! - IT T 200 11 ! \~~

~~\ 1 • / B~~

~~hi Jf/1-if' vZiT 100 (km/si~~

~~1 --f- UT 10.48 11.56 13.05 14.13 15.2' R 24.8 25.5 26.1 26.7 27.3 SM I AT 67.6 70.4 72.9 74.6 h.? 74. J 4.0 3.3 359.2 351.3 340.6 33C. 1~~

Figure 26c Plasma parameters and magnetic field data for the mantle crossing of Example y (3 - 4 January 1979). Figure showing the magnetopause crossing (~10.40 UT) and Bow-shock crossing (-13.3D UT). Continuation of Figures ?.(>n -md 2bb. WQKIC5-1 IW-SPEED

~~SE>16 Ml WE ?WS'-tH 51»T TBC 5EANS W »Tt (0~~

~~' - v ; • \ v~~

~~5.» 'Il t.R '?.« 5.1- 12.1 5.K ...t .li II.» Ui \l\ Wi 'l\ '»$ I1-* 5-1»~~

~~Figure 27 Ion and electron spectra for parts of the mantle of Example 9 (3 - 4 January 1979). The format is the same as in Figure 4. SEANS 62 S7ART 'JA-a /9-0' 3 7~~

~~0.} - 17 KEV~~

~~u Mnalail.i u jk-iftu~~

~~1.1 - 3.8 KEV~~

~~n " n n nrlri iif I j 111 8*» ^ w~\ nil n n n [tun n n api *S n nn nmnn nn c nn nn n p lip fin n pft~~

~~-wuil^ PO-i.ION MEAN ENERGY~~

~~ELECTRONS lCM ^^^ 0.1 - «8 KEV~~

~~ELECTRON~~

~~MEAN ENERGY~~

~~T1TAL-B~~

~~6SM-L.QN5~~

~~Figure 28 Integral flux data for the mantle crossing of Example 10 (7 - 8 January 1979). The format is the same as in Figure 2. PROGNOZ-7 (PROMICS-1) SEANS 62 DATE 79-01-07~~

.. JO*) .(He*

~~ION ^ DENSITY COMPOSITION~~

~~10" T- 107~~

~~IK) 10«~~

~~1 UT 23.09 00.16 01.23 02.30 03.37 04.44 R 13.0 14.3 15.6 16.8 17.9 18.9 SMLAT 53.6 53.8 54.1 54.6 55.4 56.7 SMLONG 284.9 293.2 301.6 310.2 319.0 327.7~~

~~Figure 29 Plasma parameters and magnetic field data for the mantle crossing of Example 10 (7 - 8 January 1979). The format is the same as in Figure 3. WÖCCS-1 LOU-SPEED TOWCS-1 LOH-SPED~~

~~5EM6 52 »TE 73-Q1-07 5T»ftT TDC 22-0? I SEANS 62 DATE 73-01-118 START 51 pH-, r+-h~~

~~6.3S 'I t ' v, " J t f " ( * v- ' I t» 11 5.15 12.» J.3i 11! o.» \n 1M 1XEVI IKEVI IKEVI iMVi PCB.19E QfCTRONS HiO'16 M/W M/f>2 M/O«1 P0S.HW5 tifxraos~~

~~Figure 30 Ion and electron spectra for the mantle crossing of Example 10 (7 - 8 January 1979), The format is the same as in Figure 4. CM~~

~~Q. ti~~

~~O) c 1/1 l/l o L)~~

~~01 CM 4-> 01 C S. E en~~

~~o .a c 00 fö~~

~~01 (.0~~

~~t. dl o~~

~~i. x O 3~~

~~r- l/l T o (N o o o 1.1 o c] o t) u n~~

~~ID ID~~

~~xmj PPOGfJOZ-7 (PPDMICS-1) SEANS 174 GATt 79-05-26~~

~~4 U"~~

~~100 ION ... <* fj DENSITY 10 II*"*»4, Ar*** COMPOSITION~~

~~T- 107 'Kl in8~~

~~pP 10" 100~~

~~PB iOn »BlnTJ~~

~~50 nT~~

~~200~~

~~Iknv/s)~~

~~1 h ...... ---• -i ( 07.12 08.21) 02.39 03.4/ 04.55 06. C4 R 17.8 16.7 15.5 14.? 12.8 11.3 SM I. AT. 4b. 5 47.4 49.0 43.9 Ti./ 48. Q~~

~~SM ID •JG 251.2 251.3 250.5 M.8 ?46.5 244,3~~

~~Figure },'/ i'ldsnid parameters and maynet it t-i^ld data tor the inbound '.idntle crossincj of Lxample 11 (?6 'lay i(J79). The format is trii-: sdiiiH a~~

~~en c~~

~~o o~~

~~v I~~

~~o E o- o (/I u- * u~~

~~1 «~~

~~I» II o o äi~~

~~"•" r1~~

~~0 i~~

~~c Ti 3 g OD O"» !./*> i g -- iig en~~

~~g o - - P 9ö en~~

—i

£2

~~o u" ui 0 t: -J (B ~ ~ fti ti T O t. O O D p O O O o o c o 5 3 C CVJ JS S u>3) 1 K U tD~~

~~xn-u ~lva33XNI~~

~~10 t 10» ,(0*) -(He*)~~

~~ION 100 **"""•%• ***************** * •*•t*t^***y******. 10 ./.JA - DENSITY 1 COMPOSITION~~

~~10' T. 107 (K) 10S~~

~~10* ; 100 -;: »BlnTl~~

~~• 10~~

~~50 nT~~

*x,r • ' 200 • ikn/g)

~~p^vw^sv^?^^^^?'~~

~~100 I !kn/s)~~

~~UT 22.59 00.07 01.16 02.24 03.32 04.40 Ft 16.5 15.3 14.0 12.5 10.9 9.2 SMLAT 52.0 48.4 44.0 38.6 32.3 SMLONG 85.8 815 83.1 84.6 88.0 92.9~~

~~Figure 35 Plasma parameters and magnetic field data for the inbound mantle crossing of Example 12 (2 - 3 November 1978). The format is the same as in Figure 3. PROMICS-1 LOW-SPEED~~

~~SEANS~~

~~.4/~~

~~å =~~

~~0.35 12.1 0.35 12.8 0.35 12.8 0.J5 12.8 30 0.12~~

~~IKEV) IKEVl IKEV) IKE" i IKEV) IKEV i H/0-16 M/OH M/Q=2 M/Q=1 PCS.IONS ELECTRONS~~

~~Figure 36 Ion and electron spectra for the inDound innm ]<•? crossing~~

~~of Example \'l (? - 3 November 1970). The f>;rn-,; i, the same as in Figure 4. 0.2 1 .' KEV mJaJtlWHf^ \I \mr>Mfo+*\*dli*Nt*t**.~~

~~1. t - J.B KEV '0 " 11 fr ,4» j !fl ,H n n n n /\^,h nni ^ H nrnnnM'ir- 10< - nr ———• POS.ION 1 10* y MEAN ENERGY~~

~~t,^^rl^>•A^^;^^>^V'^v O.I AS KEV~~

~~El ECTBOfl MtAr; ENER6Y~~

~~TOTAL -B~~

~~3 y~~

~~Figure 37 Integral flux data for the inbound mantle crossing of Example 13 (27 November 1978). The format is the same as in Figure 2. PROGNOZ-7 IPROMICS-1) SEANS 31 DATE 78-11-27~~

~~ION DENSITY COMTOITION~~

~~(km/s)~~

~~1 UT 12.28 13.36 14.45 15.53 17. Cl 18.03 R 15.0 13.7 12.2 10.6 6,8 6,8 SM LAT 34.2 35.0 35.8 36.0 35.1 31.4 SM LONG 76.6 78.2 79.5 80.3 80.8 81,7~~

Figure 38 Plasma parameters and magnetic field data for the inbound mantle crossing of Example 13 (27 November 1978). The format is the same as in Figure 3. PRDMIC5-1 LOW-SPEED 5EAN3 31 DAT[ 78-11-27 START TIME 11-19 I 9

?•

~~0.35 12.8 0.35 12.8 0.35 12.8 5.35 12.8~~

~~IKEV) IKEVI IKEV1 IKE VI IKEVI IKEV i M/Q-16 M/Q-H M/Q=2 M/Q=l POS. IONS flflTRGhG~~

~~Figure 39 Ion and electron spectra for the mboutri mantle crossing of Lxa-npie 13 {'/.I November 1978). The format is the same cis in Fiqijre 4. 1 1 1~~

H+

~~o 8 - 10 o o o in o (Vt o ^o o o o OO i o o o 7 o 10 - UJ~~

* X

~~£ o~~

~~1 1 1 10 20 30 2 Kp (12 hours)~~

Figure 40 Diagram showing the peak flux of protons (H+) times the' estimated width of the plasma mantle versus magnetic activity for 32 mantle passages. The mantle width was taken as the difference in radial distance from the inner and outer (magnetopause) boundary of the mantle along the satellite trajectory. As magnetic activity parameters the sum of Kn over a 12 hour periori has been taken. o*? "v» CM

~~X Q~~

* X

~~10 20 30 i Kp (12 hours)~~

Figure 41 Same as Figure 40 but for O1" ions. The broken line represents an exponential least squares fit of the data points with a correlation coefficient of 0.82. PROGNQZ-7 (PROMICS-1) SEANS 35 DATE 79-02-21 i M) .(He2"

~~^ } o(o-i -w:~~

~~i ION DENSITY COMPOSITION~~

~~i 100 50B(nT)~~

Figure 42 An example of d storm time ring current when O+ ions dominated completely over the entire dayside ring current region. The format of the plasma parameters is the same as in Figure 3 except for tne magnetic field and flow vectors which are not included. PROMICS-1 EXPERIMENT ON PROGNOZ-7

~~POS. IONS: 0.01 - 30 keV/q D1-D4 0.2-17 keV/q (90°) (M/q =1-20) ELECTRONS: 0.01 - 48 keV~~

~~POS IONS: 0.1 - 45 keV/q D5. D6 0 61- 4 9 keV/q (25°) (M/q = 1-20) ELECTRONS'- 0.1-45 keV~~

~~SPIN AXIS (towards sun)~~

~~LOW-SPEED SAMPLING~~

~~X A Tspin -120 s CJ5~~

~~\ r—-i \ Y<3 1-~~

Figure 43 Diagrammatic representation of the PFuiMIcs-i f.'/periment on board PROGNOZ-7. The figure in the "lower right corner shows how the sampling of data in low-^pe-'d mode h distributed over the sunward hemisphere. PRQGNOZ-7 (PROMICS-11 HIGH-SPEED ICS DATA

~~SEANS 170 79-05-22 2J. 44 -79-0S-22 23. S3~~

~~ACC. TIME'CHANNEL~~

~~~ 2. t? S~~

~~ICS D1~~

~~(CTSi~~

~~-u 10~~

~~ICS D2~~

~~ICTSJ~~

~~10 .-~~

~~10 ...~~

~~10 __~~

~~10 ...~~

Figure 44 An example of the mass spectrum for different energies obtained by means of the three Ion Composition Spectrometers during a high speed data takiny period when the PROGNOZ-7 satellite passed through the plasma mantle in the deep nightside.