Reconstruction of NSTX Midplane Neutral Density Profiles from Visible Imaging Data
Authors: D.P. Stotler, F. Scotti, R.E. Bell, B.P. LeBlanc, R. Raman
Abstract: The experimental determination of neurtral densities in tokamak plasmas from line radiation is only accurate in the narrow region in which both the excitation rate and neutral density are significant. We describe an alternaitve procedure using the DEGAS 2 Monte Carlo neutral transport code to invert light emission data obtained from a tangetially viewing camera, yielding absolute radial profiles of deuterium atoms and molecules at midplane. That the neutral source in these simulations can be adequately characterized as a uniform flux at the vacuum vessel wall is demonstrated by the similarity of the shapes of the simulated and observed brightness profiles. A second test is obtained by comparing the resulting neutral pressures at the vessel walls with data from midplane micro-ion gauges. We also show that the simulated camera image is insensitive to variations in the spatial distribution of the neutral source.
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Presented at: The 21st International Conference on Plasma Surface Interactions 2014, Ongaku-do, Kanazawa Ishikawa, Japan, 26-30 May 2014 (P3-098)
Accepted for publication in: Journal of Nuclear Materials (2014)
doi: http://dx.doi.org/10.1016/j.jnucmat.2014.11.097
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