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Title: Resolving the fast ion distribution from imaging neutral particle analyzer measurements

Journal Article · · Nuclear Fusion
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [3]; ORCiD logo [4]; ORCiD logo [2];  [1]
  1. General Atomics, San Diego, CA (United States)
  2. Univ. of California, Irvine, CA (United States)
  3. Oak Ridge Associated Univ., Oak Ridge, TN (United States)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
+ Show Author Affiliations

A recently developed imaging neutral particle analyzer (INPA) on the DIII-D tokamak [X.D. Du et al., Nucl. Fusion 58, 082006 (2018)] enables fast ion velocity-space tomography of high fidelity at the interrogated phase space. To accomplish this, the spatial and energy depending fast (E<80keV) neutral flux towards the INPA stripping foils is calculated with FIDASIM and a newly developed code INPASIM simulates the INPA instrumental response to this neutral ux. Included in INPASIM is the neutral-foil interaction, the Larmor orbit tracing between the foil and the phosphor, the phosphor response to the incident ion flux as well as camera focusing. Bene ting from heavy, localized velocity-space weights and excellent signal to noise, computed tomography using the Ridge regression method is able to successfully reconstruct ne-scale velocity-space structures produced by multiple neutral beams separated by as small as ~3keV in tests. Applying the inversion method to a sawtooth crash event reveals a significant pro le flattening of confined passing particles across q = 1 flux surface, as well as a redistribution of fast ions into the trapped orbits at the plasma edge close to the last closed flux surface.

Research Organization:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); General Atomics, San Diego, CA (United States); Univ. of California, Irvine, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
Grant/Contract Number:
AC05-00OR22725; FC02-04ER54698; AC02-09CH11466; SC0015878; SC0020337
OSTI ID:
1651250
Alternate ID(s):
OSTI ID: 1737639; OSTI ID: 1782228
Journal Information:
Nuclear Fusion, Vol. 60, Issue 11; ISSN 0029-5515
Publisher:
IOP ScienceCopyright Statement
Country of Publication:
United States
Language:
English

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