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

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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

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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

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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)

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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)

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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

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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)

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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

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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

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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

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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

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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

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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

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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

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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

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Example: Astrophysical Models used for observations can be benchmarked by Laboratory

Understanding laboratory data helps understanding astrophysical objects

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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

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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

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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

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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

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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

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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

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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!