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

An Optical Thomson Scattering (OTS) diagnostic is currently being developed for the National Ignition Facility (NIF) at Lawrence Livermore National Labs (LLNL). This diagnostic is designed to make measurements of hohlraum plasma parameters, such as the electron temperature and 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 -2. This is then significantly above the expected threshold for the onset of “blanking” effects. A novel Xenon Plasma X-ray Shield (XPXS) has been proposed to protect the blast shield from x-rays and mitigate “blanking”. Finally, these estimates suggest that an areal density of 10 19 cm -2 Xe atoms will be sufficient to absorb 99.5% the soft x-ray flux. Two potential designs for this shield are presented.
Authors:
ORCiD logo [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ; ORCiD logo [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
OSTI Identifier:
1258507
Report Number(s):
LLNL-CONF-693137
Journal ID: ISSN 0034-6748; RSINAK
Grant/Contract Number:
AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 87; Journal Issue: 11; Conference: Presented at: High Temperature Plasma Diagnostics, Madiso, WI, United States, Jun 05 - Jun 09, 2016; Journal ID: ISSN 0034-6748
Publisher:
American Institute of Physics (AIP)
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION; 42 ENGINEERING; x-ray plasma diagnostics; soft x-rays; hohlram; experiment design; x-ray scattering