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Title: Dual-pass upgrade to the Thomson scattering diagnostic on the Prototype-Material Plasma Exposure eXperiment (Proto-MPEX)

Abstract

The Thomson scattering (TS) diagnostic on the Prototype-Material Plasma Exposure eXperiment has been upgraded to measure electron temperature (T e) and density (n e) simultaneously at two axial locations. After the first pass through the vacuum vessel, the exiting laser beamline is re-collimated in the atmosphere and rerouted into the vacuum vessel for the second pass. The upgrade will help diagnose axial T e and n e gradients between the “central chamber” and the target region which are located 1 m and 2.5 m, respectively, downstream from the Helicon radio-frequency source. The TS measurements have given T e ≈ 4–15 eV and n e ≈ 2–4 × 10 19 m -3 at the central chamber and T e ≈ 1–2 eV and n e ≈ 1–2 × 10 19 m -3 at the target region. The upgrade also increases the number of sampling points at the target region from 3 fibers to 5 fibers, measuring 3 cm radially across the plasma column, and 25 fibers in the central chamber, radially spanning 8 cm. The intensified CCD camera is double triggered for each laser pulse in order to measure (1) the TS and laser stray light and (2) the plasma backgroundmore » light that contains nuisance emission lines and bremsstrahlung. Subtracting the background light from the TS photons improves the temperature and density measurements. Details of the diagnostic setup, axial and radial measurements, and areas for further optimization are discussed.« less

Authors:
ORCiD logo [1]; ORCiD logo [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1607299
DOE Contract Number:  
AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Journal Volume: 89; Journal Issue: 10; Conference: 22nd Topical Conference on High Temperature Plasma Diagnostics (HTPD 2018) - San Diego, California, United States of America - 4/16/2018 12:00:00 PM-4/19/2018 4:00:00 AM
Country of Publication:
United States
Language:
English
Subject:
Linear device; dual-pass Thomson Scattering; electron temperature; electron density

Citation Formats

Kafle, Nischal, Biewer, Theodore, and Donovan, David C. Dual-pass upgrade to the Thomson scattering diagnostic on the Prototype-Material Plasma Exposure eXperiment (Proto-MPEX). United States: N. p., 2018. Web. doi:10.1063/1.5039370.
Kafle, Nischal, Biewer, Theodore, & Donovan, David C. Dual-pass upgrade to the Thomson scattering diagnostic on the Prototype-Material Plasma Exposure eXperiment (Proto-MPEX). United States. doi:10.1063/1.5039370.
Kafle, Nischal, Biewer, Theodore, and Donovan, David C. Mon . "Dual-pass upgrade to the Thomson scattering diagnostic on the Prototype-Material Plasma Exposure eXperiment (Proto-MPEX)". United States. doi:10.1063/1.5039370. https://www.osti.gov/servlets/purl/1607299.
@article{osti_1607299,
title = {Dual-pass upgrade to the Thomson scattering diagnostic on the Prototype-Material Plasma Exposure eXperiment (Proto-MPEX)},
author = {Kafle, Nischal and Biewer, Theodore and Donovan, David C.},
abstractNote = {The Thomson scattering (TS) diagnostic on the Prototype-Material Plasma Exposure eXperiment has been upgraded to measure electron temperature (Te) and density (ne) simultaneously at two axial locations. After the first pass through the vacuum vessel, the exiting laser beamline is re-collimated in the atmosphere and rerouted into the vacuum vessel for the second pass. The upgrade will help diagnose axial Te and ne gradients between the “central chamber” and the target region which are located 1 m and 2.5 m, respectively, downstream from the Helicon radio-frequency source. The TS measurements have given Te ≈ 4–15 eV and ne ≈ 2–4 × 1019 m-3 at the central chamber and Te ≈ 1–2 eV and ne ≈ 1–2 × 1019 m-3 at the target region. The upgrade also increases the number of sampling points at the target region from 3 fibers to 5 fibers, measuring 3 cm radially across the plasma column, and 25 fibers in the central chamber, radially spanning 8 cm. The intensified CCD camera is double triggered for each laser pulse in order to measure (1) the TS and laser stray light and (2) the plasma background light that contains nuisance emission lines and bremsstrahlung. Subtracting the background light from the TS photons improves the temperature and density measurements. Details of the diagnostic setup, axial and radial measurements, and areas for further optimization are discussed.},
doi = {10.1063/1.5039370},
journal = {},
issn = {0034--6748},
number = 10,
volume = 89,
place = {United States},
year = {2018},
month = {10}
}

Conference:
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