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Title: Advances in neutral tungsten ultraviolet spectroscopy for the potential benefit to gross erosion diagnosis

Journal Article · · Plasma Physics and Controlled Fusion
ORCiD logo [1];  [1];  [1];  [1];  [1];  [2];  [2];  [2];  [3]; ORCiD logo [4];  [5]
  1. Auburn Univ., AL (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  3. General Atomics, San Diego, CA (United States)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  5. Queen's Univ., Belfast, Northern Ireland (United Kingdom)

A spectral survey of tungsten emission in the ultraviolet region has been completed in the DIII-D tokamak and the CTH torsatron to assess the potential benefit of UV emission for the diagnosis of gross W erosion. Here, a total of 29 W I spectral lines are observed from the two experiments using survey spectrometers between 200 and 400 nm with level identifications provided based on a structure calculation for many of the excited states that produce strong emission lines. Of the 29 observed lines, 20 have not previously been reported in fusion relevant plasmas, including an intense line at 265.65 nm which could be important for benchmarking the frequently exploited line at 400.88 nm. Nearly all of the observed spectral lines decay down to one of the six lowest energy levels for neutral W, which are likely to be long-lived metastable states. The impact of metastable level populations on the W I emission spectrum and any erosion measurement utilizing a spectroscopic technique is potentially significant. Yet, the high density of W I emission in the UV region allows for the possibly of determining the relative metastable fractions and plasma parameters local to the erosion region. Additionally, the lines observed in this work could be used to perform multiple independent gross erosion measurements, leading to more accurate diagnosis of gross tungsten erosion.

Research Organization:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Auburn Univ., AL (United States); Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
Grant/Contract Number:
FC02-04ER54698; SC0015877; AC52-07NA27344; AC05-00OR22725; FG02-00ER54610
OSTI ID:
1569476
Alternate ID(s):
OSTI ID: 1561607; OSTI ID: 1874104
Report Number(s):
LLNL-JRNL-779519; TRN: US2100322
Journal Information:
Plasma Physics and Controlled Fusion, Vol. 61, Issue 9; ISSN 0741-3335
Publisher:
IOP ScienceCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 8 works
Citation information provided by
Web of Science

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Cited By (1)


Figures / Tables (7)