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Atomic Processes Modeling In the IFE studies

This paper discusses the modeling of atomic processes in non-local thermodynamic equilibrium (NLTE) kinetics and its applications in high energy density physics, such as in the field of inertial fusion energy (IFE) studies.

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Atomic Processes Modeling In the IFE studies

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  1. Atomic Processes Modeling In the IFE studies H. K. Chung Atomic and Molecular Data Unit Nuclear Data Section March 22, 2010

  2. 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

  3. Outline • Motivation • Atomic Processes Modeling NLTE (non-local thermodynamic equilibrium) Kinetics • Applications of NLTE Kinetics Modeling in High Energy Density Physics relevant ICF. • IAEA Atomic and Molecular Unit Activities

  4. XFEL Advances in plasma generation access new regimes of matter USP: Ultra short pulse laser(RAL, LULI, Titan, Texas) NIF (National Ignition Facility) Hotter and denser matter Transient states of matter XFEL: X-ray free electron lasers (SLAC, DESY, Spring-8) Pulse Power: X-Pinches, Z-Pinches... (Sandia, Cornell, UNR) Warm dense matter Astronomical X-ray applications

  5. A new state of matterachieved experimentally requires new theories and modeling capabilities Hydrogen phase diagram • 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 •  the strong coupling parameter is ratio of the interaction energy to the kinetic energy • µ is the degeneracy parameter (R.W. Lee)

  6. Modeling capabilities essential for high energy density physics • Radiation-Hydrodynamics simulationsare 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)

  7. 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- Space-resolved time-integrated spectra are collected at the back side to measure non-uniform thermal electron Te distributions Schematic diagram Ti-K Time resolved x-ray spectrometer t Thin Al Ti K- Al-He Thick Ti E Al K-shell emission Example of Spectroscopic Diagnostics : 5J 500 fs COMET laser on Al/Ti targets Electron spectrometer at the back side measures non-equilibrium electrontemperatures Electron energy [keV]

  8. Experiments require integrated simulations:Rad-Hydro, Electron transport, and NLTE Kinetics Determines charge state distribution Provides estimate of pre-plasma to PIC Feedback? PIC Experimental Laser/Target conditions Hydro Code NLTE-Kinetics Code LSP PIC sends back hot electron estimates to Hydro. Rad. Transport Hydro provides estimate of background electron temperature to NLTE-kinetics codes Predicted Spectrum (S. Wilks)

  9. Non-LTE kinetics is essential to predict charge state distributions, level populations, radiation intensity Energy levels of an atom BOUND-BOUND TRANSITIONS A1A2+hv2Spontaneous emission A1+hv1A2+ hv1+hv2Photo-absorption or emission A1+e1A2+e2Collisional excitation or deexcitation BOUND-FREE TRANSITIONS B1+eA2+hv3Radiative recombination B1+e A2+hv3Photoionization / stimulatedrecombination B1+e1 A2+e2+e3Collisional ionization / recombination B1+e1 A3 A2+hv3Autoionization / electron capture A3 Continuum B1 Ground state of ion Z+1 A1 A2 Ground state of ion Z 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.

  10. FLYCHK Model : simple, but complete HULLAC / FAC / MCDF FLYCHK • 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) (detailed-term) (nl) (nlj) (n)

  11. 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

  12. Applications to Plasma Research Time-dependent Ti K emissivities • 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 SiO2-Ti foam exp Tin charge state distributions 32eV 36eV 28eV

  13. Example: Gold ionization balance in high temperature hohlraum (HTH) experiments • High-T hohlraum reach temperatures: ~ 10 keV • Spectrum from ne ~ 4x1021 cm-3, Te ~ 7-10 keV measured for first time LASNEX simulation (D. Hinkel) L-shell gold spectra (K. Widmann) Ne/Ncr Line of sight Te Line of sight

  14. Lower Te than the peak simulated Te: <Z> consistent for large and small scale hohlraums FLYCHK Gold ionization balance Spectroscopic data and calculation HTH FLYCHK gives an estimate of Gold Charge state distributions and L-shell spectra FLYCHK gives an estimate of <Z> for a wide range of plasma conditions, which is suitable for experimental design and analysis

  15. Example: Cu K radiation measured by single hit CCD spectrometer and 2-D imager for Te diagnostics At 8.048 keV 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) 500x500x30 100x100x20 100x100x5 100x100x1 Target volume (m3 )

  16. Shifts and Broadening of Kemission as a function of electron thermal temperature FLYCHK simulations Average Te(eV) of targets 100x100x1 100x100x5 100x100x20 500x500x30 2d spacing uncertainty Target volume (m3 )

  17. Example: Astrophysical Models used for observations can be benchmarked by Laboratory Understanding laboratory data helps understanding astrophysical objects

  18. 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

  19. Application to photoionized plasmas compares reasonably well with astrophysical models Z-pinch =20-25 ergs-cm/s • 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. t = 0 laser irradiates CH with Mg dot XFEL Visiblelaser 0.1 µm CH 25 µm Mg spectrometer Example: XFELprovides an opportunity for HEDS plasma spectroscopy • Source for hollow ion experiment t > 1 ps XFEL pumps Mg plasma • Photoionization of multiple ion species: KxLyMz+hXFELKx-1LyMz+e (x=1,2; y=1-8; z=1,2) • Auger Decay of multiple ion species: KxLyMz+hXFELKx-1LyMz+e KxLy-2Mz+e • Sequential multi-photon ionization: KxLyMz+hXFEL Kx-1LyMz+e+hXFELK0LyMz+e+hXFEL K0Ly-1Mz+2e +hXFEL … KxLyMz+hXFEL Kx-1LyMz+e+hXFEL Kx-1Ly-2Mz+2e • Direct multi-photon ionization: KxLyMz+2h XFEL K0LyMz +2e

  21. 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 keVphotons in 30 µm spot into a ne=1023cm-2 plasma • Strong coupling parameter, ii = Potential/Kinetic Energy ~ 10 • Steady-state Spectra at various Te • At high ne emisson lasts ~100 fs

  22. Example: Radiative loss rates are important as an energy loss mechanism of high-Z plasmas # of radiative transitions using HULK code Calculated Kr radiative cooling rates per Ne [eV/s/atom/cm-3] coronal

  23. FLYCHK radiative loss rates give quick estimates over a wide range of conditions Radiative cooling rates per Ne # of radiative transitions Max~30% Better agreement for higher Ne

  24. 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 Processes Spectroscopic and Collisional Data for Tungsten from 1 eV to 20 keV NEW KNOWLEDGE BASE LAUNCHED!

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