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arXiv · 2202.00811

Kinetic modeling of neutral transport for a continuum gyrokinetic code

T. N. Bernard·F. D. Halpern·M. Francisquez·N. R. Mandell·J. Juno·G. W. Hammett·A. Hakim·G. Wilkie·J. Guterl
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Abstract

We present the first-of-its-kind coupling of a continuum full-f gyrokinetic turbulence model with a 6D continuum model for kinetic neutrals, carried out using the Gkeyll code. Our objective is to improve the first-principles understanding of the role of neutrals in plasma fueling, detachment, and their interaction with edge plasma profiles and turbulence statistics. Our model includes only atomic hydrogen and incorporates electron-impact ionization, charge exchange, and wall recycling. These features have been successfully verified with analytical predictions and benchmarked with the DEGAS2 Monte Carlo neutral code. We carry out simulations for a scrape-off layer (SOL) with simplified geometry and NSTX parameters. We compare these results to a baseline simulation without neutrals and find that neutral interactions reduce the normalized density fluctuation levels and associated skewness and kurtosis, while increasing auto-correlation times. A flatter density profile is also observed, similar to the SOL density shoulder formation in experimental scenarios with high fueling.

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T. N. Bernard, F. D. Halpern, M. Francisquez, N. R. Mandell, J. Juno, G. W. Hammett, A. Hakim, G. Wilkie, J. Guterl. 2022-02-01. Kinetic modeling of neutral transport for a continuum gyrokinetic code. https://doi.org/10.1063/5.0087131

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