DOCSLIB.ORG

Magnetospheric Interchange Motions

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Magnetospheric Interchange Motions JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 94, NO. A1, PAGES 299-308, JANUARY 1, 1989 Magnetospheric Interchange Motions DAVID J. SOUTHWOOD AND MARGARET G. KIVELSON1 Institute of Geophysicsand Planetary Physics, University of California, Los Angeles We describe flux tube interchange motion in a corotating magnetosphere,adopting a Hamiltonian formulation that yields a very general criterion for instability. We derive expressionsfor field-aligned currents that reveal the effect of ionospheric conductivity on interchange motion and we calculate instability growth rates. The absenceof net current into the ionospheredemonstrates the bipolar nature of interchangeflow patterns. We point out that the convection shielding phenomenon in the terrestrial magnetosphereis a direct consequenceof the interchangestability of the system.We concludethe paper with an extended analysis of the nature of interchange motion in the Jovian system. We argue that centrifugally driven interchangedrives convection and does not give rise to diffusion of Io torus plasma. Neither a large-scaleconvection nor other forms of unstableinterchange overturning appear adequate to explain the plasma distributions detectedat Jupiter. INTRODUCTION The dominant forces in interchange motions vary from one Steady interchange motion (convection or circulation) of the case to another. The plasma pressure gradient forces are plasma explains much of the known morphology of the terres- dominant in interchange in the terrestrial ring current. In the trial magnetosphere (see, for example, Cowley [1980]) and is inner terrestrial magnetosphere, within the plasmasphere, believed to govern transport in other magnetospheres.Inter- gravity and centrifugal force associatedwith the Earth's rota- change motions can be split into two classes,driven and spon- tion can be important (see, for example, Lernaire [1974]). In taneous. In the latter case, the system is interchange unstable the Jovian magnetosphere,gravitational and centrifugal forces (see, for example, Southwood and Kivelson [1987]). Gold are also important [Southwood and Kivelson, 1987]. Our ap- [1959] first suggestedthat the terrestrial magnetospherewas proach subsumesall these forces. interchange unstable, but Nakada et al. [1965] and many sub- We shall, however, ignore the effects associated with the sequent studies showed that the energetic particle population Coriolis force in a rotating system (see, for example, Hill is stable to interchange instability. The cold (plasmaspheric) [1984]). Coriolis forces can arise in interchange in a rotating population can be unstable in the outer magnetosphere[Le- system but are negligible when the ambient magnetic field and maire, 1974]. However, global terrestrial interchange motions planetary ionospheric conductivity are sufficiently strong to have to be driven by momentum transfer from the solar wind. impose close to rigid corotation. In Jupiter's magnetosphere,the moon, Io, is a substantial Often work on interchange instability has ignored the iono- source of plasma deep within the magnetospherewhich, by sphere [e.g., Southwoodand Kivelson, 1987]. As we shall show, continuity, must be transported away, probably outward, ulti- the ionosphere has no influence on the onset of interchange mately into the solar wind. Transport has been proposed to be motion; thus stability criteria derived in works such as that of• through large-scale convection I-cf. Hill and Liu, 1987] or a Southwood and Kivelson are unmodified. The ionosphere acts small-scaleturbulent interchangecausing diffusion [e.g., Siscoe as a frictional drag on motion in the magnetosphere [Dungey, et al., 1981]. In the regions where the magnetic field energy 1968], and it follows that one expectsit to control the speedof greatly exceeds the internal plasma energy, the centrifugal interchange motions. Here we show that both the growth/ energy associatedwith corotation, or the gravitational energy damping rate of unstable/stable interchange flow pertur- of the plasma, any such motions will be of interchange form bations and the equilibrium velocity of a steady flow are in- and likely to be spontaneouslydriven. versely proportional to the ionospheric conductivity. In cases In this paper we derive general formulae associated with where the system is unstable and a turbulent spectrum of interchangemotions and point out some unifying featuresof interchange motions develops, the form of the spectrum de- interchange processes.We give general expressions for the pends strongly on whether the free energy goes into plasma field-aligned current associatedwith interchange motions. We inertia or into frictional dissipation [cf. Hassam et al., 1986]. use these to examine the effect of the ionosphere on inter- FIELD-ALIGNED CURRENT AND INTERCHANGE MOTION change instability, to illustrate the relation between stable in- terchange configurations and the occurrenceof the convection Continuity of current governsinterchange flow patterns in a shielding phenomenon, to discussthe evolution of interchange magnetospheric system [Fejer, 1964; Swift, 1967a, b; Vasy- instability and to analyze the structure and development of iiunas, 1970]. In the ionosphere,current flow is directly related spontaneousinterchange motions. We close with a critique of to the electric field [Wolf, 1974], which is quasi-static and also work on the Jovian problem. present in the magnetosphere.The two regions are coupled by the field-aligned current fed into the ionosphere, •Also at DepartmentoI earth and SpaceSciences, University of div I = jll sinZ (1) California, Los Angeles. where I is the height-integrated horizontal ionospheric current Copyright 1989 by the American Geophysical Union. and ;• is the inclination of the magnetic field to the horizontal. Paper number 88JA03629. The field-alignedcurrent, J ll, acts as a sourcefor the iono- 0148-0227/89/88JA-03629 $05.00 spheric (and thus also magnetospheric) electric field [e.g., 299 300 SOUTHWOOD AND KIVELSON: MAGNETOSPHERIC INTERCHANGE MOTIONS Vasyliunas, 1970, 1972]. If the ionosphere is locally uniform • = (Sm) = --(1/q)(r3Km/r3fl)= --(1/q)r3K/r3fl and B is vertical, the current and electric field are related in (6) fl = (fl,,) = (1/q)(r3K,,/r3y) = (1/q)r3K/r3y terms of the height-integratedPedersen conductivity •;e by Here the angle brackets denote a bounce average and K is the div E = jli/Z e (2) bounce averaged Hamiltonian. It is convenient to expressf as The ionospherecan be treated as a two-dimensionalsystem. a functionof theadiabatic invariants/• and J, withJ = 2• ds We shall show that field-aligned currents associatedwith in- vii alongthe bounceorbit. (Note that our definitionsof/• and terchangemotions occur in balanced pairs. The most primi- J differ by factors proportional to rn from the customary defi- tive source is a two-dimensional dipole (i.e., oppositely direc- nitions). In the absenceof sourcesor losses,the particle distri- tedcurrents Iii flowinginto and out of theionosphere a hori- bution function for particlesof speciesi, fDt, J, •,/9, t) satisfies zontal distanced apart). The electric potential on the field line the Liouville equation in the form at (p, 0) (in locally horizontal ionosphericcoordinates aligned r3f•/r3t+ •(r3f•/c3y)+ ]J(r3f•/r3fl)= 0 with and centered on the current dipole) is then or I d cos 0 (I)--I1_•_.• (3) 2• E v p )f•/•t -- q- '(r3fdr3y)(r3K/r3fl)+ q- '(r3f•/r3fl)(r3K/r3y)= 0 (7) By analogy one can see how more complex distributionsof Our normalization convention for integration over velocity current "generate" electric fields. Inclusion of geometrical ef- (d3v)or overthe tt, J, •, fi coordinatesis fects and inhomogeneity does not change the principles behind this result. d•zdfl • d3vfi= d•z dfl ds vd• II •b dJ• THE HAMILTONIAN APPROACH = dyaft • ni(s,t)= dyaft •i (8) We shall follow Northrop and Tellet's [1960] treatment of particle motion in a magnetospherelikefield configuration ['cf. where n• is the number densityof particlesof speciesi and % is Swift, 1967a]. We use the magnetic moment and longitudinal the bounce period; •i is the correspondingflux tube content adiabatic invariants, t• and J, as velocity space coordinates [Hill, 1984]. [Schulz and Lanzerotti, 1974]. The phases (gyro and bounce) Calculation of Field-Aliqned Current associated with each invariant are also regarded as coordi- nates. (In this paper all distributions are assumedto remain In the •, fl coordinate system the current density flowing in independent of these coordinates.) Like Northrop and Teller the y direction at any given point is given by [1960], we do not use the third invariant as a coordinate but introduce variables • and fl, the magnetic Euler potentials [Stern, 1967], which are constant on field lines and provide a j•,•=Zi q• f d3v h•• (9) two-dimensional spatial coordinate system transverse to B. In (9),we have introduced the scale factors h• andh a, where They are related to the magnetic field by h,ha= B-•. The subscripts is neededto indicatethat Ja,m is proportional to the local value of the rate of change of the B = V• x Vfi (4) coordinate • at a position s on the flux tube. Evidently, the The coordinates are a canonical set and the system can be velocity may vary along the flux tube even though • is inde- described by a Hamiltonian as long as drifts of second order pendent of s. The current in the fl direction is defined analo- in the electric field are ignored [Northrop and Teller, 1960]. gously. The Hamiltonian of a particle of mass rn and charge q can be The divergenceof the perpendicular
Load more

Recommended publications
  • Twisted Flux Tube Emergence Creates Solar Active Regions
    Direct evidence: twisted flux tube emergence creates solar active regions MacTaggart D.1, Prior C.2, Raphaldini B.2, Romano, P. 3, Guglielmino, S.L.3 1School of Mathematics and Statistics, University of Glasgow, Glasgow, G12 8QQ, UK 2Department of Mathematical Sciences, Durham University, Durham, DH1 3LE, UK 3INAF-Osservatorio Astrofisico di Catania, Via S. Sofia 78, I-95123 Catania, Italy The magnetic nature of the formation of solar active regions lies at the heart of understanding solar activity and, in particular, solar eruptions. A widespread model, used in many theoretical studies, simulations and the interpretation of observations1,2,3,4, is that the basic structure of an active region is created by the emergence of a large tube of pre-twisted magnetic field. Despite plausible reasons and the availability of various proxies suggesting the veracity of this model5,6,7, there has not yet been any direct observational evidence of the emergence of large twisted magnetic flux tubes. Thus, the fundamental question, “are active regions formed by large twisted flux tubes?” has remained open. In this work, we answer this question in the affirmative and provide direct evidence to support this. We do this by investigating a robust topological quantity, called magnetic winding8, in solar observations. This quantity, combined with other signatures that are currently available, provides the first direct evidence that large twisted flux tubes do emerge to create active regions. Twisted flux tubes are prominent candidates for the progenitors of solar active regions. Twist allows a flux tube to suffer less deformation in the convection zone compared to untwisted tubes, thus allowing it to survive and reach the photosphere to emerge2,9,10.
    [Show full text]
  • THEMIS-SOHO-Hinode - 2009 SCIENTIFIC PROPOSAL
    OBSERVING TIME PROPOSAL FORM FOR THEMIS-SOHO-Hinode - 2009 SCIENTIFIC PROPOSAL 1 General Information Principal Investigator: Brigitte Schmieder A±liation: Observatoire de Paris, LESIA Telephone: +33 1 45 07 78 17 Email address: [email protected] Co{Investigators(s): G. Aulanier, E.Pariat, J.M. Malherbe, T. Roudier, Guo Yang, Chandra R., V.Bommier, Lopez Ariste A. PIs of other instruments: E. DeLuca, A. Fludra, L. Golub, P.Heinzel, S. Gunar, P. Kotrc, N. Labrosse, Deng Y.Y., Li Hui, W. Uddin, Y. Kitai, A. Berlicki, T. Berger, Gosain S. A±liation(s): Observatoire de Paris (LESIA, LERMA), THEMIS IAC Spain, Observatoire Midi-Pyr¶enn¶ees,NRL (USA), SAO Harvard (USA), Rutherford Appleton Laboratory (UK), UIO (Norv`ege),HAO (USA), Ondrejov (Czech Rep.), University of Wales Aberystwyth, Huairou Solar Observing Station (China), Purple mountain Observatory (China), ARIES, Nainital (India), Hida Observatory (Kyoto, Japan), Bialkov (Poland) Title of Project: JOP157 Activity of magnetic features in the solar atmosphere (emergence, shear, dispersion) Specify the observation modes: MTR [X] IPM [] MSDP [X] Number of days requested: September 23 to October 10 2009 THEMIS - Observing time 2009 proposal 2 2 Proposed programme A - Scienti¯c rationale Concise scienti¯c background of the project, pertinent references; previous work plus justi¯cations for present proposal. The Scienti¯c Objectives and justi¯cation are the following: Emerging magnetic flux and reconnection Young Active Regions and new emerging magnetic flux produce MMFs associated with Eller- man Bombs (EBs). The models of emerging flux tubes assuming an Omega-shape are commonly accepted (observations of Arch Filament Systems, coronal loops).
    [Show full text]
  • Plasma and Magnetic-Field Structure of the Solar Wind at Inertial-Range Scale Sizes Discerned from Statistical Examinations of the Time-Series Measurements
    REVIEW published: 20 May 2020 doi: 10.3389/fspas.2020.00020 Plasma and Magnetic-Field Structure of the Solar Wind at Inertial-Range Scale Sizes Discerned From Statistical Examinations of the Time-Series Measurements Joseph E. Borovsky* Center for Space Plasma Physics, Space Science Institute, Boulder, CO, United States This paper reviews the properties of the magnetic and plasma structure of the solar wind Edited by: 6 Luca Sorriso-Valvo, in the inertial range of spatial scales (500–5 × 10 km), corresponding to spacecraft National Research Council, Italy timescales from 1s to a few hr. Spacecraft data sets at 1AU have been statistically Reviewed by: analyzed to determine the structure properties. The magnetic structure of the solar wind Bernard Vasquez, often has a flux-tube texture, with the magnetic flux tube walls being strong current sheets University of New Hampshire, United States and the field orientation varying strongly from tube to tube. The magnetic tubes also Yasuhito Narita, exhibit distinct plasma properties (e.g., number density, specific entropy), with variations Austrian Academy of Sciences (OAW), Austria in those properties from tube to tube. The ion composition also varies from tube to Julia E. Stawarz, tube, as does the value of the electron heat flux. When the solar wind is Alfvénic, the Imperial College London, magnetic structure of the solar wind moves outward from the Sun faster than the proton United Kingdom plasma does. In the reference frame moving outward with the structure, there are distinct *Correspondence: Joseph E. Borovsky field-aligned plasma flows within each flux tube. In the frame moving with the magnetic [email protected] structure the velocity component perpendicular to the field is approximately zero; this indicates that there is little or no evolution of the magnetic structure as it moves outward Specialty section: This article was submitted to from the Sun.
    [Show full text]
  • Simultaneous THEMIS Observations in the Near-Tail Portion of the Inner and Outer Plasma Sheet Flux Tubes at Substorm Onset V
    JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 113, A00C02, doi:10.1029/2008JA013527, 2008 Click Here for Full Article Simultaneous THEMIS observations in the near-tail portion of the inner and outer plasma sheet flux tubes at substorm onset V. A. Sergeev,1 S. V. Apatenkov,1 V. Angelopoulos,2 J. P. McFadden,3 D. Larson,3 J. W. Bonnell,3 M. Kuznetsova,4 N. Partamies,5 and F. Honary6 Received 23 June 2008; revised 13 August 2008; accepted 22 August 2008; published 19 November 2008. [1] We analyzed the measurements made by two Time History of Events and Macroscale Interactions during Substorms (THEMIS) probes in ideal observational conditions (quiet background, near midnight, inside the substorm current wedge) during two distinct isolated substorm onsets, with probe P2 measuring the inner plasma sheet at 8 Re and P1 near the plasma sheet–lobe interface at 11–12 Re. The earliest onset-related strong perturbations were observed by P1; they include the increase of both Bz (dipolarization) and Ey (a few mV/m) as well as the simultaneous drop in total pressure, indicating the unloading process. This was also accompanied by fast inward plasma motion (up to 100 km/s, toward the neutral sheet) and fast plasma sheet thinning while the poleward auroral expansion was in progress in the conjugate ionosphere. These perturbations were followed after 6–8 min by the rapid expansion of the already heated plasma sheet. While in the adjacent lobe during this thinning phase, probe P1 continued to observe intense flux transfer toward the sheet center plane. The inner probe observed intense dipolarization and inward plasma injection but with a smaller flux transfer and starting 1–2 min after the perturbations at P1, supporting the conclusion that onset instability took place tailward of 12 Re.
    [Show full text]
  • Magnetic Flux Ropes in Space Plasmas
    Magnetic Flux Ropes in Space Plasmas Mark Moldwin UCLA 2007 Heliophysics Summer School With thanks to Mark Linton at NRL Goal of Lecture • Introduce one of the most ubiquitous features in space plasmas • Describe their Origin, Evolution, Structure, and impact • Will present combination of simulations, observations, and synthesis models What is a Flux Tube? • Ideal MHD’s frozen-in flux condition • Equation of motion has the pressure gradient and Lorentz term on RHS • Magnetic force has two components - magnetic pressure term acting perpendicular to field and a tension term along field. • Can think of flux tubes as mutually repulsive rubber bands Pop Quiz • BACKGROUND: Spacecraft X observes a magnetic field change over Y units of time. • How do you know if the observed change in B is due to the relative motion of a boundary past the spacecraft or dynamics/global change/transient in the background configuration? Lesson • Must make models to understand global structure and dynamics • Must use statistics to understand global structure and dynamics • Must make multiple, simultaneous, distributed measurements to understand global structure and dynamics What are Flux Ropes, and Who Cares? • Magnetized plasmas can form structures on various scales - shocks, discontinuities, waves, flux tubes, current sheets etc. • Some are created by magnetic reconnection and can have sharp and clear boundaries • Provide evidence of dynamics AND can give rise to significant energy and momentum flow from one region to another Coronal Mass Ejections are the primary driver of major Geomagnetic storms Their structure determines their geomagnetic effectiveness Pop Quiz • Draw a cartoon model of the structure produced by magnetic reconnection in the lower corona to make a CME.
    [Show full text]
  • Dynamics of Magnetic Flux Tubes in Close Binary Stars
    A&A 405, 303–311 (2003) Astronomy DOI: 10.1051/0004-6361:20030584 & c ESO 2003 Astrophysics Dynamics of magnetic flux tubes in close binary stars II. Nonlinear evolution and surface distributions V. Holzwarth1,2 and M. Sch¨ussler1 1 Max-Planck-Institut f¨ur Aeronomie, Max-Planck-Str. 2, 37191 Katlenburg-Lindau, Germany e-mail: [email protected] 2 School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews KY16 9SS, UK Received 28 February 2003 / Accepted 18 April 2003 Abstract. Observations of magnetically active close binaries with orbital periods of a few days reveal the existence of starspots at preferred longitudes (with respect to the direction of the companion star). We numerically investigate the non-linear dynamics and evolution of magnetic flux tubes in the convection zone of a fast-rotating component of a close binary system and explore whether the tidal effects are able to generate non-uniformities in the surface distribution of erupting flux tubes. Assuming a synchronised system with a rotation period of two days and consisting of two solar-type components, both the tidal force and the deviation of the stellar structure from spherical shape are considered in lowest-order perturbation theory. The magnetic field is initially stored in the form of toroidal magnetic flux rings within the stably stratified overshoot region beneath the convection zone. Once the field has grown sufficiently strong, instabilities initiate the formation of rising flux loops, which rise through the convection zone and emerge at the stellar surface. We find that although the magnitude of tidal effects is rather small, they nevertheless lead to the formation of clusters of flux tube eruptions at preferred longitudes on opposite sides of the star, which result from the cumulative and resonant character of the action of tidal effects on rising flux tubes.
    [Show full text]
  • Magnetosheath Flow Near the Subsolar Magnetopause∷ Zwan&Hyphen;Wolf and Southwood&Hyphen;Kivelson Theories
    GEOPHYSICAL RESEARCH LETTERS, VOL. 22, NO. 23, PAGES 3275-3278, DECEMBER 1, 1995 Magnetosheath flow near the subsolar magnetopause- Zwan-Wolf and Southwood-Kivelson theories reconciled DavidJ. Southwood I and Margaret G. Kivelson2 Instituteof Geophysicsand PlanetaryPhysics. University of California.Los Angeles Abstract. We reconcilethe superficiallycontradictory theories the flow upstreamof the magnetopause,the magneticfield should of flow immediately upstreamof the subsolarmagnetopause. decreaseand the gaspressure and plasmadensity should increase We show that the formation of a layer of enhancedfield and whilst Zwan and Wolf [1976] predict a region where the field depresseddensity immediately adjacent to the magnetopauseas increasesand the densityand pressuredecrease. Southwoodand predictedby Zwan and Wolf appearsto requirethe presence Kivelson[1992] acknowledgedthe differencebetween the Zwanand upstreamof a regionof enhancedpressure and field rarel•tction Wo/f[1976]predictions and their own theory. It is thepurpose of aspredicted by Southwoodand Kivelson. We thusargue that the thispaper to link thesetwo apparentlycontradictory notions and to detachedregions of enhanceddensity and the depletion layer arguethat not only do botheffects occur in practicebut they arepart adjacentto the magnetopauseare actually manifestationsof a of one and the same effect. singlephenomenon. The models of the solar wind flow around the Earth's magnetospherein the gas dynamic limit include the field only Introduction kinematically [Spreiter and Alksne, 1969; 1970]. The approach would be entirely adequateif the gas pressurebehind the shock The structureof the magnetosheathfield and flow patternnear everywheregreatly exceededthe magneticpressure. As Zwan and the magnetopauseis of greatinterest in solarterrestrial physics, the Wo/f[1976] point out, it is implicit in Alksne's[1967] calculations region marking as it does the interface between solar wind and that there alwayswill be a regionnear the magnetopausewhere field terrestrialplasma regimes.
    [Show full text]
  • 5 Magnetic Flux Tubes and the Dynamo Problem
    5 Magnetic flux tubes and the dynamo problem Manfred Schüssler and Antonio Ferriz-Mas The observed properties of the magnetic field in the solar photosphere and theoretical studies of magneto-convection in electrically well-conducting fluids suggest that the magnetic field in stellar convection zones is quite inhomogeneous: magnetic flux is concentrated into magnetic flux tubes embedded in significantly less magnetized plasma. Such a state of the magnetic field potentially has strong implications for stellar dynamo theory since the dynamics of an ensemble of flux tubes is rather different from that of a more uniform field and new phenomena like magnetic buoyancy appear. If the diameter of a magnetic flux tube is much smaller than any other relevant length scale, the MHD equations governing its evolution can be considerably simplified in terms of the thin- flux-tube approximation. Studies of thin flux tubes in comparison with observed properties of sunspot groups have led to far-reaching conclusions about the nature of the dynamo-generated magnetic field in the solar interior. The storage of magnetic flux for periods comparable to the amplification time of the dynamo requires the compensation of magnetic buoyancy by a stably stratified medium, a situation realized in a layer of overshooting convection at the bottom of the convection zone. Flux tubes stored in mechanical force equilibrium in this layer become unstable with respect to an undular instability once a critical field strength is exceeded, flux loops rise through the convection zone and erupt as bipolar magnetic regions at the surface. For parameter values relevant for the solar case, the critical field strength is of the order of 105 G.
    [Show full text]
  • A Hydrodynamic Model for Plasmasphere Refilling Following
    A Hydrodynamic Model for Plasmasphere Refilling Following Geomagnetic Storms K Chatterjee, R.W. Schunk (Center for Atmospheric and Space Sciences, Utah State University, 4405 Old Main Hill, Logan, UT 84322-4405; Email: [email protected], [email protected]) The refilling of the plasmasphere following a geomagnetic storm remains one of the longstanding problems involving ionosphere-magnetosphere coupling. Both diffusion and hydrodynamic approximations have been adopted for the modeling and solution of this problem. The diffusion approximation neglects the nonlinear inertial term in the momentum equation and so this approximation is not rigorously valid immediately after a storm. The principle focus of this work is the formulation and development of a hydrodynamic refilling model (that includes the nonlinear inertial term) using the flux- corrected transport method, a numerical method that is extremely well suited to handling nonlinear problems with shocks and discontinuities. In a previous study, this model has been validated against exact analytical benchmark problems and in this study, the model is used to describe plasmasphere refilling. The plasma transport equations are solved along one-dimensional closed magnetic field lines that connect conjugate ionospheres and the model currently includes three ions (H+, O+, He+) and two neutral (O, H) species. In this study, each ion species under consideration has been modeled as two separate streams emanating from the conjugate hemispheres and the model correctly predicts supersonic ion speeds and the presence of high levels of helium during the early hours of refilling. The ultimate objective of this research is the development of a three-dimensional model for the plasmasphere refilling problem, and with additional development, the same methodology can be applied to the study of other complex space plasma coupling problems in closed flux tube geometries.
    [Show full text]
  • THEMIS ESA First Science Results and Performance Issues
    Space Sci Rev DOI 10.1007/s11214-008-9433-1 THEMIS ESA First Science Results and Performance Issues J.P. McFadden · C.W. Carlson · D. Larson · J. Bonnell · F. Mozer · V. Angelopoulos · K.-H. Glassmeier · U. Auster Received: 5 April 2008 / Accepted: 25 August 2008 © Springer Science+Business Media B.V. 2008 Abstract Early observations by the THEMIS ESA plasma instrument have revealed new details of the dayside magnetosphere. As an introduction to THEMIS plasma data, this pa- per presents observations of plasmaspheric plumes, ionospheric ion outflows, field line reso- nances, structure at the low latitude boundary layer, flux transfer events at the magnetopause, and wave and particle interactions at the bow shock. These observations demonstrate the ca- pabilities of the plasma sensors and the synergy of its measurements with the other THEMIS experiments. In addition, the paper includes discussions of various performance issues with the ESA instrument such as sources of sensor background, measurement limitations, and data formatting problems. These initial results demonstrate successful achievement of all measurement objectives for the plasma instrument. Keywords THEMIS · Magnetosphere · Magnetopause · Bow shock · Instrument performance PACS 94.80.+g · 06.20.Fb · 94.30.C- · 94.05.-a · 07.87.+v 1 Introduction The THEMIS mission provides the first multi-satellite measurements of the dayside mag- netosphere, magnetopause and bow shock utilizing a string of pearls orbit near the ecliptic plane (Angelopoulos 2008). During a 7 month coast phase, the instruments were commis- sioned and cross-calibrated while spacecraft separations were adjusted from a few hundred J.P. McFadden () · C.W. Carlson · D.
    [Show full text]
  • Flux-Tube Ring and Glueball Properties in the Dual Ginzburg
    Flux-Tube Ring and Glueball Properties in the Dual Ginzburg-Landau Theory Y. Koma∗, H. Suganuma and H. Toki Research Center for Nuclear Physics (RCNP), Osaka University Mihogaoka 10-1, Ibaraki, Osaka 567-0047, Japan (October 13, 2018) Abstract An intuitive approach to the glueball using the flux-tube ring solution in the dual Ginzburg-Landau theory is presented. The description of the flux-tube ring as the relativistic closed string with the effective string tension enables us to write the hamiltonian of the flux-tube ring using the Nambu-Goto action. Analyzing the Schr¨odinger equation, we discuss the mass spectrum and the wave function of the glueball. The lowest glueball state is found to have the mass M 1.6 GeV and the size R 0.5 fm. G ∼ G ∼ Key Word: glueball, flux-tube ring, dual Ginzburg-Landau theory, Nambu- arXiv:hep-ph/9902441v1 23 Feb 1999 Goto action PACS number(s): 12.38.Aw, 12.39.Mk, Typeset using REVTEX ∗E-mail address: [email protected] 1 I. INTRODUCTION The existence of glueball states is naively expected in terms of the gluon self-coupling in QCD[1]. Recent progress of lattice QCD simulations predicts the masses of glueballs M(0++) = 1.50 1.75 ∼ GeV, M(2++) = 2.15 2.45 GeV [2–6]. Experimentally, there are some candidates; f (1500) ∼ 0 and f0(1710) for the scalar glueball, fJ (2220) (J=2 or 4), f2(2300) and f2(2340) for the tensor glueball[7]. However, the abundance of q-¯q meson states in the 1 3 GeV region and the possibility ∼ of the quarkonium-glueball mixing states still make it difficult to identify the glueball states[8].
    [Show full text]
  • 3-Dimensional Evolution of a Magnetic Flux Tube Emerging Into the Solar Atmosphere T. Magara
    NATO Advanced Research Workshop 3-dimensional Evolution of a Magnetic Flux Tube Emerging into the Solar Atmosphere T. Magara (Montana State University, USA) September 17, 2002 (Budapest, Hungary) We focus on three solar regions. Each region has a different type of background gas layers with which magnetic field interacts. • The corona (over the photosphere) ... low-density background gas layers • The photosphere ... abrupt change of background gas layers • The convection zone ... high-density background gas layers Corona : Because the background gas pressure is weaker than mag- netic pressure, the magnetic field continues to expand outward. (magnetic-field dominant region) A well-developed magnetic structure is formed. This structure is macroscopically static (force-free), however • outermost area... dynamic (solar wind) • prominence area... mass motion along B • coronal loops... mass motion along B Sometimes explosive events (relaxation of magnetic energy) happen in such a well-developed structure. These events are • flares (produce high energy particles & electromagnetic waves) • prominence eruptions (cool material erupts and disappears) • coronal mass ejections (large amount of mass is ejected into IP) To study various coronal processes, we initially assume a skeleton of magnetic field which provides a model of well-developed coronal structure. Then we in- vestigate its stability and evolution at both linear and nonlinear phases. Input stage: impose various type of perturbations to the system according to the primary purpose of studies
    [Show full text]