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Title: Design calculations for a xenon plasma x-ray shield to protect the NIF optical Thomson scattering diagnostic

Abstract

An Optical Thomson Scattering (OTS) diagnostic is currently being developed for the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. This diagnostic is designed to make measurements of the hohlraum plasma parameters, such as the electron temperature and the density, during inertial confinement fusion (ICF) experiments. NIF ICF experiments present a very challenging environment for optical measurements; by their very nature, hohlraums produce intense soft x-ray emission, which can cause “blanking” (radiation induced opacity) of the radiation facing optical components. The soft x-ray fluence at the surface of the OTS blast shield, 60 cm from the hohlraum, is estimated to be ∼8 J cm{sup −2}. This is significantly above the expected threshold for the onset of “blanking” effects. A novel xenon plasma x-ray shield is proposed to protect the blast shield from x-rays and mitigate “blanking.” Estimates suggest that an areal density of 10{sup 19} cm{sup −2} Xe atoms will be sufficient to absorb 99.5% of the soft x-ray flux. Two potential designs for this shield are presented.

Authors:
; ; ; ; ; ;  [1]
  1. Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
Publication Date:
OSTI Identifier:
22596597
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 87; Journal Issue: 11; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ATOMS; DESIGN; DIAGNOSTIC TECHNIQUES; ELECTRON DENSITY; ELECTRON TEMPERATURE; ELECTRONS; EXPLOSIONS; IGNITION; INERTIAL CONFINEMENT; LAWRENCE LIVERMORE NATIONAL LABORATORY; PLASMA; SHIELDS; SOFT X RADIATION; SURFACES; THOMSON SCATTERING; US NATIONAL IGNITION FACILITY; XENON

Citation Formats

Swadling, G. F., Ross, J. S., Datte, P., Moody, J., Divol, L., Jones, O., and Landen, O. Design calculations for a xenon plasma x-ray shield to protect the NIF optical Thomson scattering diagnostic. United States: N. p., 2016. Web. doi:10.1063/1.4958913.
Swadling, G. F., Ross, J. S., Datte, P., Moody, J., Divol, L., Jones, O., & Landen, O. Design calculations for a xenon plasma x-ray shield to protect the NIF optical Thomson scattering diagnostic. United States. doi:10.1063/1.4958913.
Swadling, G. F., Ross, J. S., Datte, P., Moody, J., Divol, L., Jones, O., and Landen, O. Tue . "Design calculations for a xenon plasma x-ray shield to protect the NIF optical Thomson scattering diagnostic". United States. doi:10.1063/1.4958913.
@article{osti_22596597,
title = {Design calculations for a xenon plasma x-ray shield to protect the NIF optical Thomson scattering diagnostic},
author = {Swadling, G. F. and Ross, J. S. and Datte, P. and Moody, J. and Divol, L. and Jones, O. and Landen, O.},
abstractNote = {An Optical Thomson Scattering (OTS) diagnostic is currently being developed for the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. This diagnostic is designed to make measurements of the hohlraum plasma parameters, such as the electron temperature and the density, during inertial confinement fusion (ICF) experiments. NIF ICF experiments present a very challenging environment for optical measurements; by their very nature, hohlraums produce intense soft x-ray emission, which can cause “blanking” (radiation induced opacity) of the radiation facing optical components. The soft x-ray fluence at the surface of the OTS blast shield, 60 cm from the hohlraum, is estimated to be ∼8 J cm{sup −2}. This is significantly above the expected threshold for the onset of “blanking” effects. A novel xenon plasma x-ray shield is proposed to protect the blast shield from x-rays and mitigate “blanking.” Estimates suggest that an areal density of 10{sup 19} cm{sup −2} Xe atoms will be sufficient to absorb 99.5% of the soft x-ray flux. Two potential designs for this shield are presented.},
doi = {10.1063/1.4958913},
journal = {Review of Scientific Instruments},
number = 11,
volume = 87,
place = {United States},
year = {Tue Nov 15 00:00:00 EST 2016},
month = {Tue Nov 15 00:00:00 EST 2016}
}