skip to main content
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Shadowing effects in simulated Alcator C-Mod gas puff imaging data

Abstract

A synthetic gas puff imaging (GPI) diagnostic is applied to a gyrokinetic turbulence simulation of Alcator C-Mod with the objective of assessing the impact of turbulent plasma fluctuations on the GPI neutral density field. We find that these effects are significant for much of the run, resulting in qualitatively different light emission patterns relative to the idealized limit of a fixed neutral profile. Spatial and temporal variations in the local neutral density within the GPI gas cloud are shown to be comparable in magnitude to those in the plasma, which would affect the interpretation of plasma fluctuations made using GPI. Assessing the experimental implications of these results will require additional study using validated turbulence simulations. Here, our findings are compatible with previous theoretical investigations concluding that GPI may unreliably diagnose plasma turbulence more than one neutral mean free path away from the gas source. Although we used a comprehensive, time dependent simulation to arrive at these results, our analysis shows that a frozen-plasma treatment of the neutrals is adequate in this case. That is, we can assume that the neutral transport is too fast to be affected by temporal fluctuations in the turbulent plasma structures.

Authors:
ORCiD logo [1]; ORCiD logo [1];  [1];  [1];  [1]; ORCiD logo [2]
  1. Princeton Univ., Princeton, NJ (United States)
  2. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1498790
Grant/Contract Number:  
AC02-09CH11466; FC02-99ER54512; AC02-05CH11231
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Materials and Energy
Additional Journal Information:
Journal Volume: 19; Journal Issue: C; Journal ID: ISSN 2352-1791
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Synthetic diagnostic; Gas puff imaging; Neutral transport simulation; Plasma turbulence simulation; Alcator C-Mod

Citation Formats

Stotler, D. P., Ku, S., Zweben, S. J., Chang, C. S., Churchill, R. M., and Terry, J. L.. Shadowing effects in simulated Alcator C-Mod gas puff imaging data. United States: N. p., 2019. Web. doi:10.1016/j.nme.2019.02.008.
Stotler, D. P., Ku, S., Zweben, S. J., Chang, C. S., Churchill, R. M., & Terry, J. L.. Shadowing effects in simulated Alcator C-Mod gas puff imaging data. United States. doi:10.1016/j.nme.2019.02.008.
Stotler, D. P., Ku, S., Zweben, S. J., Chang, C. S., Churchill, R. M., and Terry, J. L.. Mon . "Shadowing effects in simulated Alcator C-Mod gas puff imaging data". United States. doi:10.1016/j.nme.2019.02.008. https://www.osti.gov/servlets/purl/1498790.
@article{osti_1498790,
title = {Shadowing effects in simulated Alcator C-Mod gas puff imaging data},
author = {Stotler, D. P. and Ku, S. and Zweben, S. J. and Chang, C. S. and Churchill, R. M. and Terry, J. L.},
abstractNote = {A synthetic gas puff imaging (GPI) diagnostic is applied to a gyrokinetic turbulence simulation of Alcator C-Mod with the objective of assessing the impact of turbulent plasma fluctuations on the GPI neutral density field. We find that these effects are significant for much of the run, resulting in qualitatively different light emission patterns relative to the idealized limit of a fixed neutral profile. Spatial and temporal variations in the local neutral density within the GPI gas cloud are shown to be comparable in magnitude to those in the plasma, which would affect the interpretation of plasma fluctuations made using GPI. Assessing the experimental implications of these results will require additional study using validated turbulence simulations. Here, our findings are compatible with previous theoretical investigations concluding that GPI may unreliably diagnose plasma turbulence more than one neutral mean free path away from the gas source. Although we used a comprehensive, time dependent simulation to arrive at these results, our analysis shows that a frozen-plasma treatment of the neutrals is adequate in this case. That is, we can assume that the neutral transport is too fast to be affected by temporal fluctuations in the turbulent plasma structures.},
doi = {10.1016/j.nme.2019.02.008},
journal = {Nuclear Materials and Energy},
number = C,
volume = 19,
place = {United States},
year = {2019},
month = {2}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Save / Share: