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Title: First results from the Thomson scattering diagnostic on proto-MPEX

Abstract

A Thomson scattering (TS) diagnostic has been successfully implemented on the prototype Material Plasma Exposure eXperiment (Proto-MPEX) at Oak Ridge National Laboratory. The diagnostic collects the light scattered by plasma electrons and spectroscopically resolves the Doppler shift imparted to the light by the velocity of the electrons. The spread in velocities is proportional to the electron temperature, while the total number of photons is proportional to the electron density. TS is a technique used on many devices to measure the electron temperature (T{sub e}) and electron density (n{sub e}) of the plasma. A challenging aspect of the technique is to discriminate the small number of Thomson scattered photons against the large peak of background photons from the high-power laser used to probe the plasma. A variety of methods are used to mitigate the background photons in Proto-MPEX, including Brewster angled windows, viewing dumps, and light baffles. With these methods, first results were measured from argon plasmas in Proto-MPEX, indicating T{sub e} ∼ 2 eV and n{sub e} ∼ 1 × 10{sup 19} m{sup −3}. The configuration of the Proto-MPEX TS diagnostic will be described and plans for improvement will be given.

Authors:
;  [1]; ;  [2]
  1. Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)
  2. Bredesen Center, University of Tennessee, Knoxville, Tennessee 37996 (United States)
Publication Date:
OSTI Identifier:
22596551
Resource Type:
Journal Article
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 87; Journal Issue: 11; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0034-6748
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ARGON; BAFFLES; CONFIGURATION; DOPPLER EFFECT; ELECTRON DENSITY; ELECTRON TEMPERATURE; ELECTRONS; LASERS; ORNL; PHOTONS; PLASMA; THOMSON SCATTERING; VELOCITY; WINDOWS

Citation Formats

Biewer, T. M., E-mail: biewertm@ornl.gov, Meitner, S., Rapp, J., Ray, H., and Shaw, G. First results from the Thomson scattering diagnostic on proto-MPEX. United States: N. p., 2016. Web. doi:10.1063/1.4959163.
Biewer, T. M., E-mail: biewertm@ornl.gov, Meitner, S., Rapp, J., Ray, H., & Shaw, G. First results from the Thomson scattering diagnostic on proto-MPEX. United States. doi:10.1063/1.4959163.
Biewer, T. M., E-mail: biewertm@ornl.gov, Meitner, S., Rapp, J., Ray, H., and Shaw, G. Tue . "First results from the Thomson scattering diagnostic on proto-MPEX". United States. doi:10.1063/1.4959163.
@article{osti_22596551,
title = {First results from the Thomson scattering diagnostic on proto-MPEX},
author = {Biewer, T. M., E-mail: biewertm@ornl.gov and Meitner, S. and Rapp, J. and Ray, H. and Shaw, G.},
abstractNote = {A Thomson scattering (TS) diagnostic has been successfully implemented on the prototype Material Plasma Exposure eXperiment (Proto-MPEX) at Oak Ridge National Laboratory. The diagnostic collects the light scattered by plasma electrons and spectroscopically resolves the Doppler shift imparted to the light by the velocity of the electrons. The spread in velocities is proportional to the electron temperature, while the total number of photons is proportional to the electron density. TS is a technique used on many devices to measure the electron temperature (T{sub e}) and electron density (n{sub e}) of the plasma. A challenging aspect of the technique is to discriminate the small number of Thomson scattered photons against the large peak of background photons from the high-power laser used to probe the plasma. A variety of methods are used to mitigate the background photons in Proto-MPEX, including Brewster angled windows, viewing dumps, and light baffles. With these methods, first results were measured from argon plasmas in Proto-MPEX, indicating T{sub e} ∼ 2 eV and n{sub e} ∼ 1 × 10{sup 19} m{sup −3}. The configuration of the Proto-MPEX TS diagnostic will be described and plans for improvement will be given.},
doi = {10.1063/1.4959163},
journal = {Review of Scientific Instruments},
issn = {0034-6748},
number = 11,
volume = 87,
place = {United States},
year = {2016},
month = {11}
}