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Title: Measurement and simulation of passive fast-ion D-alpha emission from the DIII-D tokamak

Spectra of passive fast-ion D-alpha (FIDA) light from beam ions that charge exchange with background neutrals are measured and simulated. The fast ions come from three sources: ions that pass through the diagnostic sightlines on their first full orbit, an axisymmetric confined population, and ions that are expelled into the edge region by instabilities. A passive FIDA simulation (P-FIDASIM) is developed as a forward model for the spectra of the first-orbit fast ions and consists of an experimentally-validated beam deposition model, an ion orbit-following code, a collisional-radiative model, and a synthetic spectrometer. Model validation consists of the simulation of 86 experimental spectra that are obtained using 6 different neutral beam fast-ion sources and 13 different lines of sight. Calibrated spectra are used to estimate the neutral density throughout the cross-section of the tokamak. The resulting 2D neutral density shows the expected increase toward each X-point with average neutral densities of 8 X 10 9 cm -3 at the plasma boundary and 1 X 10 11 cm -3 near the wall. Here, fast ions that are on passing orbits are expelled by the sawtooth instability more readily than trapped ions. In a sample discharge, approximately 1% of the fast-ion population ismore » ejected into the high neutral density region per sawtooth crash.« less
 [1] ;  [1] ;  [2] ;  [2] ;  [2]
  1. Univ. of California, Irvine, CA (United States)
  2. General Atomics, San Diego, CA (United States)
Publication Date:
Grant/Contract Number:
FC02-04ER54698; FG03-94ER54271
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 56; Journal Issue: 11; Journal ID: ISSN 0029-5515
IOP Science
Research Org:
General Atomics, San Diego, CA (United States)
Sponsoring Org:
USDOE Office of Nuclear Energy (NE), Nuclear Facility Operations (NE-3)
Country of Publication:
United States
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; passive FIDA; edge light; neutral density; FIDASIM; FIDA; sawtooth crash; fast ion losses
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1324334; OSTI ID: 1399485