Atomic and radiation physics of laboratory photoionized plasmas relevant to astrophysics
R. C. Mancini1, D. C. Mayes1, R. Schoenfeld1, J. J. Rowland1, K. J. Swanson1, V. Ivanov1, B. Bach1, G. P. Loisel2, J. E. Bailey2, J. Abdallah, Jr.3, I. E. Golovkin4, R. Heeter5, D. Liedahl5, S. P. Regan6
1 Physics Department, University of Nevada, Reno, NV 2 Sandia National Laboratories, Albuquerque, NM 3 Los Alamos National Laboratory, Los Alamos, NM 4Prism Computational Sciences, Madison, WI 5Lawrence Livermore National Laboratory, Livermore, CA 6Laboratory for Laser Energetics, University of Rochester, NY
SSAP Symposium, 16-18 February 2021 Students, post-docs, and collaborators
• Current students, – Kyle Swanson, Ryan Schoenfeld, Enac Gallardo, Jeffrey Rowland
• Former/Current post-docs, – Ricardo Florido, ULPGC, Spain – Iain Hall, Diamond Light Source, UK – Georges Jar
• Collaborators, – Guillaume Loisel, Jim Bailey, Greg Rochau, Stephanie Hansen, Taisuke Nagayama, SNL – Robert Heeter, David Martinez, Duane Liedahl, Riccardo Tommasini, LLNL – Joe Abdallah, Christopher Fontes, LANL – Sean Regan, LLE
• Former students, – 12 former students continue working in HEDLP, 11 of them at NNSA’s national labs – Igor Golovkin (Ph.D. 2000, Prism Comp. Sciences), Peter Hakel (Ph.D. 2001, LANL), Manolo Sherrill (Ph.D. 2003, LANL), Trevor Burris-Mog (M.S. 2005, LANL), Leslie Welser-Sherrill (Ph.D. 2006, LANL), Taisuke Nagayama (Ph.D. 2010, SNL), Heather Johns (Ph.D. 2013, LANL), Tirtha Joshi (Ph.D. 2015, LLE), Tom Lockard (Ph.D. 2016, LLNL), D. T. Cliche (Ph.D. 2020, LLNL), D. C. Mayes (Ph.D. 2020, UT Austin/SNL), K. R. Carpenter (Ph.D. 2020, LLNL) 2 Plasma atomic spectroscopy • A spin off of our research on atomic and radiation physics of high-energy density plasmas at UNR has been a unique, graduate level course on plasma atomic spectroscopy • Topics, – Atomic processes in plasmas – Spectral line shapes and Stark broadening – Spectroscopy quality radiation transport – Data analysis and uncertainty estimation • Broadcasted in real-time through internet since 2005, so students and junior scientists at other institutions can benefit as well • Recent offering in 2020 spring semester: 10 UNR students + 48 students/postdocs/scientists/managers from 17 institutions in US and Europe
3 Photoionized plasmas
• Widespread in space, e.g. active galactic nuclei warm absorbers, x-ray binaries, accreting disk surrounding black holes • Plasma ionization is driven by an intense, broadband distribution of photons • Unlike plasmas driven by a distribution of particles, photoionization and photoexcitation dominate atomic kinetics and drive plasma ionization • The complexity of the astrophysical environment makes the spectral analysis challenging laboratory experiments are important1
Goals • Guided by experimental observation, we seek to test and establish what physics models are needed to describe the plasma • Focus on x-ray heating, electron temperature, and ionization • Question: for a given x-ray flux, plasma element and density, what is J. Miller et al Nature (2006) the electron temperature? NASA website Artists impression of binary system GRO J1655-40, 11,000 lights years away in constellation Scorpius 4 1R. C. Mancini, J. E. Bailey, T. Kallman et al, Phys. Plasmas 16, 041001 (2009) Ion areal densities are extracted by spectroscopic analysis
Neon photoionized plasma transmission data from Z gas cell experiment and color-coded model calculation
Characterization does not use atomic kinetics calculations1
�#� • Ion areal densities: H-, He-, Li-, and Be-like neon ions �# = ��!"! 2 • NiL found by χ fitting to the transmission
• Transmission: ��!"! = �#� # • Gives fractional populations fi , charge state distribution, and their uncertainties D. Mayes Poster 5 1D. C. Mayes, R. C. Mancini, T. E. Lockard, I. M. Hall et al, in preparation for publication (2021) Electron temperature Te extraction
• Li-like neon satellite lines arise from levels in 1s22s and 1s22p • Areal densities can be extracted from transmission spectrum analysis without atomic kinetics modeling • For laboratory photoionized plasmas, Li-like neon population ratio R = f(1s22p)/f(1s22s) is dominated by collisions • Assuming equilibrium, we can extract the
electron temperature Te from population ratio R DE • Idea tested with atomic kinetics modeling, - R = ge kTe and analysis of synthetic data g = 3 • Neon gas cell experiment: D = • T = 24 ± 4 eV for P = 7.5Torr and P = 15Torr E 16eV e • Te = 26 ± 5 eV for P = 30Torr dTe kTe dR = ( ) Te DE R • Si foil experiment: T = 33 ± 7 eV e 6 R. C. Mancini, T. E. Lockard, D. C. Mayes, I. M. Hall, G. P. Loisel, J. E. Bailey et al, Physical Review E 101, 051201(R) (2020)
Heating, radiation cooling, and electron temperature
• X-ray heating and radiation cooling are critical for plasma energy balance • Electron temperature depends on net plasma heating and is important for atomic kinetics • Impacts electron-driven radiative and dielectronic recombination • Four findings:1 o Novel method to extract Te o Thermalization of photoelectrons and Maxwellian nature of electron distribution o Dramatic effect of photoexcitation on population of excited states o Astrophysics codes, Xstar and Cloudy, significantly overestimated measured Te
1R. C. Mancini, T. E. Lockard, D. C. Mayes, I. M. Hall, G. P. Loisel, J. E. Bailey et al, Physical Review E 101, 051201(R) (2020) Astrophysics models overestimate Te, why?
• Astrophysical modeling codes Cloudy1 and Xstar2 were used to calculate x-ray heating and electron temperature Te • Self-consistent solution of collisional-radiative atomic kinetics, energy balance, and radiation transport • Both models overestimate the experiment by factors of 2
4 Experiment Experiment (eV) Cloudy Te (eV) Xstar Te (eV) Neon gas cell 26 ± 5 55 65 Silicon expanding foil 33 ± 7 73 69
• Recent Te extracted from RRC analysis of the Cygnus X-3 x-ray spectrum recorded with Chandra are overestimated by Xstar3
1G. Ferland et al, Publ. Astron. Soc. Pacific 110, 761 (1998) 2T. Kallman and M. Bautista, Astrophys. J. Sup. Series 133, 221 (2001) J. Rowland Poster 3T. Kallman et al, Ap. J. 874, 51 (2019) 4R. C. Mancini et al, Phys. Rev. E 101, 051201(R) (2020) Trends in ionization measured with ionization parameter
• Data from neon gas cell experiment at Z (He) • First systematic observations of charged state distribution trends in laboratory photoionized plasmas (Li)
• Set stringest test on laboratory and astrophysics theory/modeling codes
• Measurements reveal the net result of the competition between photoionization and radiative and dielectronic recombination driven by electrons Be Li He H D. Mayes Poster
1D. C. Mayes, R. C. Mancini, T. E. Lockard, I. M. Hall et al, in preparation for publication (2021) Photoionized plasma experiment at OMEGA EP
• Achieving photoionization equilibrium in the laboratory is a standing challenge of photoionized plasma experiments • Steady state requires more than 10ns • We have developed a new experiment at OMEGA EP to produce and sustain a photoionized plasma for up to 30ns • OMEGA EP: 4 beams, 10ns duration, 4kJ/beam UVOT o long duration x-ray flux to achieve steady state o separate backlit probe to test steady state • GatlingGun x-ray source: 3 Cu hohlraums, TR=90eV, Δt=30ns • Plastic embedded Si sample driven by Gatling-Gun x-ray flux, and backlit with RRC from Ti laser-produced plasma
10 OMEGA EP experiment schematic
B2, B3 and B4 (10ns each) fire sequentially in time producing an x-ray flux for 30ns • TIM10: SSCA/SXS B1 (1ns) is independently fired to drive Ti BL streaked spectrometer for K-shell transmission spectrum of Si plasma B4 TPS7 • TIM11: SFC1/VSG_1 gated spectrometer for Cu x-ray flux
z-axis • TIM12: ASBO diagnostic y-axis for VISAR, hohlraum x-axis radiation temperature • TIM13: Ti BL B3 B1 • TIM14: XRFC5/VSG_2 gated spectrometer for TPS83 imaging Si L-shell B2 TIM13 emission spectroscopy 11 Gatling-Gun x-ray source • Driven by 3 OMEGA EP UV beams, the Three Cu hohlraum G-G Gatling-Gun x-ray source produces a drive with an average TR = 90eV for 30ns • Beam energy/duration: 4kJ/10ns • Cu plasma blow-off diagnosed with 4ω probe • Measurement performed with CEA’s
Diluted Planckian: Trad=90eV, gdf=0p009368328, Tb=28eV 8 miniDMX shows time-history of T 1.6x10 rad ’Fnu_Trad_90_gdf_0p009368328.txt’
8 1.4x10 Geometry diluted Planckian Integrated flux = 6.3x1010W/cm2 8 1.2x10 Radiation temperature = 90eV
8 Brightness temperature = 28eV 1x10 eV) 2
Beam 1 Beam 2 Beam 3 7 8x10
7 Fnu (J / s cm 6x10
7 4x10 Ne-like Si Li-like Si 7 2x10 Ip = 167eV Ip = 524eV
0 R. Schoenfeld Poster 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 Photon energy (eV) Plastic-tamped silicon sample • Silicon sample: 2mm diameter embedded in 2.5mm diameter CH disk Face on • CH tamping: front and back, and edge • Silicon sample thickness 0.1, 0.2, 0.4 μm • Si sample expands to mm-scale • TIM10 LOS samples central 1mm region • Null samples, no Si, for reference shots Edge on Hohlraum • Distance to Gatling-Gun is 7 – 10 mm • Uniform irradiation: expected x-ray flux variation on Si sample is 1 – 2 % 2.800±0.010 VISRAD x-ray flux model, GG hohlraum Trad=90eV Flux=6.74TW/cm2 4.5 ’Flux_vs_distance.txt’ u 1:4 0.100 0.020 Front view: schema.c of silicon sample rela.ve to Gatling-Gun hohlraum array CENTER OF HOHLRAUM BOX 4
R0.700±0.010 3X 3.5 1.090±0.010 3X 2.321 3 R0.550 3X MAX 2.5 Front view of R0.950±0.010 3X DETAIL A Gatling-Gun SCALE 80 : 1 2 and Si sample A 1.5 (Standard deviation/mean)*100 1 1.888 3X 0.5 [mm] 0 120.0°±1.0° 3X 5 6 7 8 9 10 11 13 Material: Copper (UNS C10100) Si - GG hohlraum distance (mm) Dimensions: mm
Dimensions: mm Gated imaging of Si L-shell emission • TIM14 VSG instrument
• Gated imaging of C- and B-like Si n=3-2 L-shell emission lines in the (a) t = 5ns 210 - 280 eV photon energy range shows the expansion of the silicon photoionized plasma, (a) & (b) (b) t = 7ns • Expansion measurement gives the density of silicon plasma x Si A B C • A: cold carbon K-edge, 282eV from VSG’s filter (c) t = 9ns • B: He-lke C Hea line hν • C: H-like C Lya line
• Null target test shows no Si lines as expected, (c) 14 Streaked Si K-shell absorption spectra: 1μm+1μm tamping 31812 31815 31817 31818 8ns 25ns 28ns
F-like Si n=1-2
Ne-like Si n= 1-3 F-like Si n=1-3 Si K-edge Si K-edge 1839eV 1839eV 1.2
Tamping: .5μm+.5μm 1
Aluminum K-shell 300eV 1e21/cc 50mic rp1000 32981 0.8 ’aluminum_kshell.ppd’ 1.8x1017 0.6 17 18ns 1.6x10 Reference Al K-shell spectrum Transmission spectrum of Si Transmission photoionized Hea Ne 17 0.4 1.4x10 plasma without instrumental broadening n:1-3
eV) 17 2 Lya 1.2x10 (red), with a resolving power of 0.2 1000 (blue), 1729eV 1x1017 and a resolving power 32980500 (green). Aluminum K-shell 300eV 1e21/cc 50mic rp1000 8ns Heb 0 1700 1725 1750 1775 1800 1825 1850 1875 1900 16 1.2 17 ’aluminum_kshell.ppd’ 8x10 1869eV Photon energy (eV) 1.8x10 Heg 16 17 Reference Al K-shell spectrum Intensity (erg/ sr s cm 6x10 1.6x10 Hea Transmission spectrum of Si photoionized 1 1 4x1016 Lyb F He 17 Hed F 1.4x10 plasma without instrumental broadening 1745eV 1865eV Hee 2x1016 0.8 eV) 17 0.8 2 1.2x10 Lya (red), with a resolving power of 1000 (blue), O 1729eV 0 Li 1x1017 and a resolving power 1500 1550 1600 1650 1700 1750 500 1800 ( 1850green 1900 ). 1950 2000 2050 2100 N 0.6 Heb Photon energy (eV) O F 0.6 16 Transmission 8x10 1869eV C Heg n:1-3 16 1e+18 0.4 Intensity (erg/ sr s cm
6x10 ’Ti_run_1_spectrum.ppd’ Transmission 1 Titanium backlighter emission 0.4 16 Lyb F He 4x10 Hed n:1-2 F O N C 1745eV 1865eV 0.2 Hee 8e+17 2x1016 0.8 0.2 32981 18ns Li 0 0 1700 1725 Be 1750 1775 1800 1825 1850 1875 1900 1500 1550 1600 1650 1700 1750 1800 1850 1900 1950 2000 2050 2100 N 1.2 6e+17 Photon energy (eV) Photon energy (eV) O 0.6 0 1725 1750 1775 1800 1825 1850 1875 Photon 1 energy (eV)
1e+18 4e+17
’Ti_run_1_spectrum.ppd’ Transmission I (erg / sr s cm2 eV) 0.4 F Titanium backlighter emission E/ΔE=500 0.8 Si K-shell lines range 8e+17 2e+17 E/ΔE=1000 1-3 0.2 0.6
Be Transmission 6e+17 0 N 1600 1650 1700 1750 1800 1850 1900 1950 2000 0.4 0 1725 1750 1775 Photon 1800 energy (eV) 1825 1850 1875 Photon energy (eV) 0.2 4e+17 I (erg / sr s cm2 eV) 32982 25ns 0 Si K-shell lines range 1700 1725 1750 1775 1800 1825 1850 1875 1900 2e+17 Photon energy (eV)
0 1600 1650 1700 1750 1800 1850 1900 1950 2000 Photon energy (eV) Photoionized plasmas at 1MA Zebra
• 1MA Z-pinch x-ray flux drives a supersonic gas jet
• X-ray flux is not attenuated due to windows and/or tamping layers • Gas jet targets benefit from close positioning to z-pinch x-ray source
• A mm-scale volume of gas moves 10’s of microns in a 10ns time scale
• Driven by x-ray flux, a volume of photoionized plasma can be produced that is essentially ”frozen” in space for the time scale of interest
• Diagnostics: laser shadowgraphy and interferometry, soft x-ray grating spectrometer, and x-ray crystal transmission spectroscopy Supersonic Gas Jet Experiment – Zebra Generator • Z-pinch produces broadband x-ray flux – Cylindrical wire-array with 8 Au or W wires – Heats and backlits neon gas jet Laser Diagnostic • Opening Gas jet distance: 5 – 10 mm Spectrometer – X-ray flux at gas jet: 1010 – 1011 W/cm2 LOS • Neon gas jet pressures: 300 – 800 psi – Number density: 1018 - 1019cm-3 • Crystal spectrometer observes neon x-ray K-shell Wire Array line absorption spectrum • Grating spectrometer records z-pinch x-ray flux • Laser diagnostic: 2-color interferometry Gas Jet Nozzle Zebra Generator: – Peak current ~ 1 MA – X-ray power ~ 0.5 TW Laser – Total x-ray energy ~ 20 kJ Diagnostic Opening and – X-ray pulse ~ 25 ns Mirror
K. Swanson Poster 18 Zebra x-ray flux drive based on diluted Planckian
4x108 Integrated x-ray flux F = 7.9x1010W/cm2 Radiation temperature TR = 44.3eV Brightness temperature TB = 29.6eV 3x108 Argon Neon eV)
2 Nitrogen
2x108 Flux (W / cm
1x108 Ne F O M L He L 0 0 25 50 100 200 300 400 500 600 Photon energy (eV) Photoionized neon gas jet transmission • K-shell line absorption spectra: C-, B-, Be-, Li, and He-like, neon ions • Ion areal densities can be extracted from the analysis of the transmission spectrum • The set of ion areal densities gives the charge state distribution and fractional populations
C He Li B Li Be
20 Charged state distribution • Ion areal densities can be extracted from the analysis of the transmission spectrum • The set of ion areal densities gives the charge state distribution and fractional populations
• A temperature Te = 13eV can be extracted from the analysis of initial level population ratios of line absorption features in B-, Be- and Li-like neon ions • Laboratory photoionized plasmas populated with L-shell neon ions
Fraction Neon gas jet C 0.011 Li B 0.111 Be Be 0.320 B He Li 0.462 C He 0.095
< Z > 6.52 21 Summary
• Method for extracting electron temperature Te applied to two different photoionized plasma experiments at Z • Photoelectrons thermalize quickly and are well characterized by a single Maxwellian • Photoexcitation plays a dramatic role in populating excited states and radiation cooling • Astrophysical codes CLOUDY and XSTAR significantly overestimate
Te, why? • The Z experiment has motivated two new experiments to achieve steady-state conditions: o Zebra: photoionized gas jet, 25ns o OMEGA EP: − long duration x-ray flux, 90eV / 30ns − independent backlit source – first observation of steady-state laboratory photoionized plasma
This work is supported by DOE NNSA HEDLP Grant DE-NA0003875, DOE NNSA NLUF Grant DE-NA0003533, the Wootton Center for Astrophysical Plasma Properties, and the Z Facility Fundamental Science Program of SNL