IAEAInternational Atomic Energy Agency
Atomic Processes Modeling In the IFE studies
H. K. Chung
Atomic and Molecular Data Unit
Nuclear Data Section
March 22, 2010
IAEA
Collaborators (mostly in LLNL)
• Theory and Modeling:R. W. Lee, M. H. Chen, H. A. Scott, M. Adams, M. E. Foord, S. J. Moon, S. B. Libby, S. B Hansen, K. B. Fournier, B. Wilson, S. C. Wilks, A. Kemp, R. Town, M. F. Gu, B. McCandless, M. Tabak, Y. Ralchenko, A. Bar-Shalom, J. Oreg, M. Klapisch, M. S. Wei, R. B. Stephens
• Experiments:P. Patel, R. Shepherd, C. A. Back, S. Glenzer, J. Koch, G. Gregori, N. Landon, M. Schneider, K. Widmann, J. Dunn, R. Heeter, H. Chen,Y. Ping, M. May, R. Snavely, H-S. Park, M. Key, K. Akli, S. Chen, F. Beg
• Reference: H.-K Chung and R. W. Lee“Applications of NLTE population kinetics” High Energy Density Physics 5 (2009) 1–14
IAEA
Outline
• Motivation
• Atomic Processes ModelingNLTE (non-local thermodynamic equilibrium) Kinetics
• Applications of NLTE Kinetics Modeling in High Energy Density Physics relevant ICF.
• IAEA Atomic and Molecular Unit Activities
IAEA
Advances in plasma generation access new regimes of matter
USP: Ultra short pulse laser(RAL, LULI, Titan, Texas)
XFEL: X-ray free electron lasers (SLAC, DESY, Spring-8)
Pulse Power: X-Pinches, Z-Pinches... (Sandia, Cornell, UNR)
NIF (National Ignition Facility)
Hotter and denser matter Transient states of matter
Warm dense matter Astronomical X-ray applications
XFEL
IAEA
A new state of matter achieved experimentally requires new theories and modeling capabilities
• the strong coupling parameter is ratio of the interaction energy to the kinetic energy
• µ is the degeneracy parameter
HDM occurs in:• Supernova, stellar interiors,
accretion disks
• Plasma devices : laser, ion beam and Z-pinches
• Directly driven inertial fusion plasmas
WDM occurs in:• Cores of large planet
• Systems that start solid and end as a plasma
• X-ray driven implosion
Hydrogen phase diagram
(R.W. Lee)
IAEA
Modeling capabilities essential for high energy density physics
• Radiation-Hydrodynamics simulations are required to understand transient, non-uniform plasma evolution
• Fluid treatment of plasma physics- Mass, momentum and energy equations solved
• Plasma thermodynamic properties (Ne, Te, Ti, Tr, Vr, Vi .. )• LTE (Local Thermodynamic Equilibrium) (assumed)
• PIC simulations provide non-equilibrium electron energy distributions• Particle treatment of plasma physics
- Boltzmann transport and Maxwell equations solved
• Electron energy distribution function (fe ..)• Simple ionization model (assumed)
• Non-LTE kinetics models provide spectroscopic observables • Atomic processes in plasmas
- Rate equations are solved for a given electron energy distributions (fe)
• Atomic level population distributions • Plasma conditions (Ne, Te) (assumed)
IAEA
Example of Spectroscopic Diagnostics : 5J 500 fs COMET laser on Al/Ti targets
X-ray streaked camera at the front side to measure time-dependent Al He and Ti K: highly transient plasma evolution of non-thermal and thermal e-
t
E
Ti-K
Al-He
Electron energy [keV]
Electron spectrometer at the back side measures non-equilibrium electron temperatures
Space-resolved time-integrated spectra are collected at the back side to measure non-uniform thermal electron Te distributions
Thick Ti
Thin AlTi K-
Al K-shell emission
Time resolved x-rayspectrometer
Schematic diagram
IAEA
Experiments require integrated simulations:Rad-Hydro, Electron transport, and NLTE Kinetics
Hydro Code
LSP
PICNLTE-Kinetics
Code
Predicted Spectrum
Provides estimate of pre-plasma to PIC
PIC sends back hot electronestimates to Hydro.
Hydro provides estimate of background electron temperature to NLTE-kinetics codes
Determines charge statedistribution
ExperimentalLaser/Target
conditions
Rad. Transport
Feedback?
(S. Wilks)
IAEA
Non-LTE kinetics is essential to predict charge state distributions, level populations, radiation intensity
Mean ionization states <Z>, Charge state distributions (CSD), Spectral intensity, Emissivity, Opacity, Equation of state (EOS), Electrical conductivity require population distributions of ions in the plasma.
Energy levels of an atom
Continuum
Ground state of ion Z
Ground state
of ion Z+1
B1
A3
A1
A2
BOUND-BOUND TRANSITIONS
A1A2+hv2 Spontaneous emission
A1+hv1A2+ hv1+hv2 Photo-absorption or emission
A1+e1A2+e2 Collisional excitation or deexcitation
BOUND-FREE TRANSITIONS
B1+eA2+hv3 Radiative recombination
B1+e A2+hv3 Photoionization / stimulated recombination
B1+e1 A2+e2+e3 Collisional ionization / recombination
B1+e1 A3 A2+hv3 Autoionization / electron capture
IAEA
FLYCHK Model : simple, but complete
• Screened hydrogenic energy levels with relativistic corrections • Dirac Hartree-Slater oscillator strengths and photoionization cross-
sections• Fitted collisional cross-section to PWB approximation• Semi-empirical cross-sections for collisional ionization• Detailed counting of autoionization and electron capture processes• Continuum lowering (Stewart-Pyatt)
(n) (nl) (nlj) (detailed-term)FLYCHK HULLAC / FAC / MCDF
IAEA
Available to the community at password-protected NIST website: http://nlte.nist.gov/FLY
Advantages: simplicity and versatility applicability• <Z> for fixed any densities: electron, ion or mass • Mixture-supplied electrons (eg: Argon-doped hydrogen plasmas)• External ionizing sources : a radiation field or an electron beam. • Multiple electron temperatures or arbitrary electron energy distributions • Optical depth effects
Outputs: population kinetics code and spectral synthesis• <Z> and charge state distribution• Radiative Power Loss rates under optically thin assumption • Energy-dependent spectral intensity of uniform plasma with a size
Caveats: simple atomic structures and uniform plasma approximation• Less accurate spectral intensities for non-K-shell lines• Less accurate for low electron densities and for LTE plasmas• When spatial gradients and the radiation transport affect population significantly
IAEA
Applications to Plasma Research
• Short-pulse laser-produced plasmas• Arbitrary electron energy distribution function
• Time-dependent ionization processes
• K- shifts and broadening: diagnostics
• Long-pulse laser-produced plasmas• Average charge states
• Spectra from a uniform plasma
• Gas bag, Hohlraum (H0), Underdense foam
• Z-pinch plasmas: photoionizing plasmas
• Proton-heated plasmas: warm dense matter
• EBIT: electron beam-produced plasmas
• EUVL: Sn plasma ionization distributions
• TOKAMAK: High-Z impurities
28eV 36eV32eV
SiO2-Ti foam exp
Time-dependent Ti K emissivities
Tin charge state distributions
IAEA
Example: Gold ionization balance in high temperature hohlraum (HTH) experiments
LASNEX simulation (D. Hinkel)
Ne/Ncr
Te
L-shell gold spectra (K. Widmann)
• High-T hohlraum reach temperatures: ~ 10 keV
• Spectrum from ne ~ 4x1021 cm-3, Te ~ 7-10 keV
measured for first time
Line of sight
Line of sight
IAEA
65
60
55
50
45
<Z
>
12x103
108642
Te[eV]
FLYCHK at Ne=1021
cm-3
FLYCHK at Ne=1022
cm-3
DATA for large-scale HO at 2.5 keV
HTH
Lower Te than the peak simulated Te: <Z> consistent for large and small scale hohlraums
FLYCHK gives an estimate of Gold
Charge state distributions and L-shell spectra
FLYCHK Gold ionization balance
FLYCHK gives an estimate of <Z> for a wide range of plasma conditions, which is suitable for experimental design and analysis
Spectroscopic data and calculation
IAEA
Example: Cu K radiation measured by single hit CCD spectrometer and 2-D imager for Te diagnostics
Single Hit CCD K yield is higher than
that of 2-D imager for smaller target
volumes :
An experimental evidence of shifting
and broadening of Kα emission lines in
small targets with high temperatures
Kα yield (photons/Sr/J)
At 8.048 keV
Target volume ( )
500x500x30
100x100x20
100x100x5
100x100x1
IAEA
Shifts and Broadening of Kemission as a function of electron thermal temperature
Target volume ( )
FLYCHK simulations
Average Te(eV) of targets
500x500x30
100x100x20
100x100x5
100x100x1
2d spacinguncertainty
IAEA
Example: Astrophysical Models used for observations can be benchmarked by Laboratory
Understanding laboratory data helps understanding astrophysical objects
IAEA
The ionization parameter characterizes X-ray photoionized plasmas
Correct interpretation of X-ray astronomy data relies on atomic modeling of the complex processes in radiation dominated, NLTE regime
IAEA
Application to photoionized plasmas compares reasonably well with astrophysical models
The agreement between measured and calculated CSDs is reasonable at Te = 150 eV:
• Cloudy: Astrophysics code
• Galaxy: NLTE kinetics code• FLYCHK: NLTE kinetics code
=20-25 ergs-cm/s
Z-pinch
IAEA
Example: XFEL provides an opportunity for HEDS plasma spectroscopy• Source for hollow ion experiment
0.1 µm CH
25 µm Mg
Visiblelaser
t = 0 laser irradiates CH with Mg dot
• Photoionization of multiple ion species: KxLyMz+hXFELKx-1LyMz+e (x=1,2; y=1-8; z=1,2)
• Auger Decay of multiple ion species: KxLyMz+hXFEL Kx-1LyMz+e KxLy-2Mz+e
• Sequential multi-photon ionization: KxLyMz+hXFEL Kx-1LyMz+e+hXFELK0LyMz+e+hXFEL K0Ly-1Mz+2e +hXFEL … KxLyMz+hXFEL Kx-1LyMz+e+hXFEL Kx-1Ly-2Mz+2e
• Direct multi-photon ionization: KxLyMz+2hXFEL K0LyMz +2e
XFEL
spectrometer
t > 1 ps XFEL pumps Mg
plasma
IAEA
In Warm Dense Matter regime the hollow ions provide time-resolved diagnostic information
• XFEL forms unique states and provides in situ diagnostics with ~100 fs res.
• 5x1010 1.85 keV photons in 30 µm spot into a ne=1023 cm-2 plasma
• Strong coupling parameter, ii = Potential/Kinetic Energy ~ 10
• Steady-state Spectra at various Te • At high ne emisson lasts ~100 fs
IAEA
Example: Radiative loss rates are important as an energy loss mechanism of high-Z plasmas
0
1x10-7
2x10-7
3x10-7
4x10-7
1 1.5 2 2.5 3 3.5 4 4.5 5
Ne=1E16Ne=1E18Ne=1E20Ne=1E22Ne=1E24
Te(keV)
Calculated Kr radiative cooling rates per Ne
[eV/s/atom/cm-3]
coronal
Ion HULLAC+DHS
1 3049
2 27095
3 30078
4 404328
5 3058002
6 5882192
7 7808014
8 6202123
9 5544814
10 1050919
11 841094
Sum 30,851,708
# of radiative transitions using HULK code
IAEA
FLYCHK radiative loss rates give quick estimates over a wide range of conditions
0
1 x 10-7
2 x 10-7
3 x 10-7
4 x 10-7
1 1.5 2 2.5 3 3.5 4 4.5 5
H:1E16H:1E18H:1E20H:1E22H:1E24F:1E16F:1E18F:1E20F:1E22F:1E24
Te(keV)
Radiative cooling rates per Ne
Ion HULLAC+DHS FLYCHK
1 3049 45
2 27095 107
3 30078 89
4 404328 140
5 3058002 140
6 5882192 140
7 7808014 140
8 6202123 140
9 5544814 140
10 1050919 131
11 841094 122
sum 30,851,708 1334
Time ~2 days ~mins
# of radiative transitions
Max~30%
Better agreement for higher Ne
IAEA
Activities at IAEA AMD Unit : http://www-amdis.iaea.org
• Databases on Atomic and Molecular Data for Fusion. ALADDIN The atomic and molecular, plasma-surface interaction database
AMBDAS The bibliographical database GENIE A search engine on different databases on the web OPEN-ADAS A joint development between the ADAS Project and IAEA
• Online Computing Heavy Particles collisions Cross sections for excitation and charge transfer for collisions
Los Alamos atomic physics codes An interface to run several Los Alamos atomic physics codes Average Approximation An average approximation cross sections Rate coefficients collisional radiative calculations with the Los Alamos modeling codes to obtain total radiated power, average ion charge, and relative ionization populations FLYCHK Charge state distributions over a wide range of plasma conditions up to Z=79
• Coordinated Research Projects Light Element Atom, Molecule and Radical Behaviour in the Divertor and Edge Plasma Regions
Characterization of Size, Composition and Origins of Dust in Fusion Devices Data for Surface Composition Dynamics Relevant to Erosion ProcessesSpectroscopic and Collisional Data for Tungsten from 1 eV to 20 keV
NEW KNOWLEDGE BASE LAUNCHED!