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Title: Simulation study of 3–5 keV x-ray conversion efficiency from Ar K-shell vs. Ag L-shell targets on the National Ignition Facility laser

Abstract

Tailored, high-flux, multi-keV x-ray sources are desirable for studying x-ray interactions with matter for various civilian, space and military applications. For this study, we focus on designing an efficient laser-driven non-local thermodynamic equilibrium 3–5 keV x-ray source from photon-energy-matched Ar K-shell and Ag L-shell targets at sub-critical densities (∼n{sub c}/10) to ensure supersonic, volumetric laser heating with minimal losses to kinetic energy, thermal x rays and laser-plasma instabilities. Using HYDRA, a multi-dimensional, arbitrary Lagrangian-Eulerian, radiation-hydrodynamics code, we performed a parameter study by varying initial target density and laser parameters for each material using conditions readily achievable on the National Ignition Facility (NIF) laser. We employ a model, benchmarked against Kr data collected on the NIF, that uses flux-limited Lee-More thermal conductivity and multi-group implicit Monte-Carlo photonics with non-local thermodynamic equilibrium, detailed super-configuration accounting opacities from CRETIN, an atomic-kinetics code. While the highest power laser configurations produced the largest x-ray yields, we report that the peak simulated laser to 3–5 keV x-ray conversion efficiencies of 17.7% and 36.4% for Ar and Ag, respectively, occurred at lower powers between ∼100–150 TW. For identical initial target densities and laser illumination, the Ag L-shell is observed to have ≳10× higher emissivity per ion per deposited lasermore » energy than the Ar K-shell. Although such low-density Ag targets have not yet been demonstrated, simulations of targets fabricated using atomic layer deposition of Ag on silica aerogels (∼20% by atomic fraction) suggest similar performance to atomically pure metal foams and that either fabrication technique may be worth pursuing for an efficient 3–5 keV x-ray source on NIF.« less

Authors:
; ; ; ; ; ; ;  [1]
  1. Lawrence Livermore National Laboratory, Livermore, California 94550-9698 (United States)
Publication Date:
OSTI Identifier:
22410337
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 22; Journal Issue: 5; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ARGON; COMPUTERIZED SIMULATION; K SHELL; KEV RANGE 01-10; KINETIC ENERGY; KRYPTON; L SHELL; LAGRANGIAN FUNCTION; LASER-PRODUCED PLASMA; LASER-RADIATION HEATING; LTE; MONTE CARLO METHOD; PLASMA INSTABILITY; SILICA; SILVER; TEV RANGE 100-1000; THERMAL CONDUCTIVITY; US NATIONAL IGNITION FACILITY; X-RAY SOURCES

Citation Formats

Kemp, G. E., E-mail: kemp10@llnl.gov, Colvin, J. D., Fournier, K. B., May, M. J., Barrios, M. A., Patel, M. V., Scott, H. A., and Marinak, M. M. Simulation study of 3–5 keV x-ray conversion efficiency from Ar K-shell vs. Ag L-shell targets on the National Ignition Facility laser. United States: N. p., 2015. Web. doi:10.1063/1.4921250.
Kemp, G. E., E-mail: kemp10@llnl.gov, Colvin, J. D., Fournier, K. B., May, M. J., Barrios, M. A., Patel, M. V., Scott, H. A., & Marinak, M. M. Simulation study of 3–5 keV x-ray conversion efficiency from Ar K-shell vs. Ag L-shell targets on the National Ignition Facility laser. United States. doi:10.1063/1.4921250.
Kemp, G. E., E-mail: kemp10@llnl.gov, Colvin, J. D., Fournier, K. B., May, M. J., Barrios, M. A., Patel, M. V., Scott, H. A., and Marinak, M. M. Fri . "Simulation study of 3–5 keV x-ray conversion efficiency from Ar K-shell vs. Ag L-shell targets on the National Ignition Facility laser". United States. doi:10.1063/1.4921250.
@article{osti_22410337,
title = {Simulation study of 3–5 keV x-ray conversion efficiency from Ar K-shell vs. Ag L-shell targets on the National Ignition Facility laser},
author = {Kemp, G. E., E-mail: kemp10@llnl.gov and Colvin, J. D. and Fournier, K. B. and May, M. J. and Barrios, M. A. and Patel, M. V. and Scott, H. A. and Marinak, M. M.},
abstractNote = {Tailored, high-flux, multi-keV x-ray sources are desirable for studying x-ray interactions with matter for various civilian, space and military applications. For this study, we focus on designing an efficient laser-driven non-local thermodynamic equilibrium 3–5 keV x-ray source from photon-energy-matched Ar K-shell and Ag L-shell targets at sub-critical densities (∼n{sub c}/10) to ensure supersonic, volumetric laser heating with minimal losses to kinetic energy, thermal x rays and laser-plasma instabilities. Using HYDRA, a multi-dimensional, arbitrary Lagrangian-Eulerian, radiation-hydrodynamics code, we performed a parameter study by varying initial target density and laser parameters for each material using conditions readily achievable on the National Ignition Facility (NIF) laser. We employ a model, benchmarked against Kr data collected on the NIF, that uses flux-limited Lee-More thermal conductivity and multi-group implicit Monte-Carlo photonics with non-local thermodynamic equilibrium, detailed super-configuration accounting opacities from CRETIN, an atomic-kinetics code. While the highest power laser configurations produced the largest x-ray yields, we report that the peak simulated laser to 3–5 keV x-ray conversion efficiencies of 17.7% and 36.4% for Ar and Ag, respectively, occurred at lower powers between ∼100–150 TW. For identical initial target densities and laser illumination, the Ag L-shell is observed to have ≳10× higher emissivity per ion per deposited laser energy than the Ar K-shell. Although such low-density Ag targets have not yet been demonstrated, simulations of targets fabricated using atomic layer deposition of Ag on silica aerogels (∼20% by atomic fraction) suggest similar performance to atomically pure metal foams and that either fabrication technique may be worth pursuing for an efficient 3–5 keV x-ray source on NIF.},
doi = {10.1063/1.4921250},
journal = {Physics of Plasmas},
issn = {1070-664X},
number = 5,
volume = 22,
place = {United States},
year = {2015},
month = {5}
}