April 15-17

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Abstracts

Author: Gregory W Hammett
Requested Type: Poster
Submitted: 2019-02-23 17:21:08

Co-authors: E. L. Shi (LLNL), T. Bernard (U. Texas), A. Hakim, N. R. Mandell, T. Stoltzfus-Dueck

Contact Info:
Princeton Plasma Physics Laboratory
100 Stellarator Road
Princeton, NJ   08540
United States

Abstract Text:
The Gkeyll code is used to carry out full-F gyrokinetic simulations of turbulence in a helical field model of a tokamak scrap-off-layer (SOL) plasma[1,2,3]. Parameters for a case from the National Spherical Torus Experiment (NSTX) are used. This simplified helical magnetic field still retains the important effects of the bad-curvature instability drive. Conducting sheath boundary conditions are used. The formation and radial transport of plasma blobs is observed. By reducing the strength of the poloidal magnetic field, the profile of the heat flux to the divertor plate is observed to broaden. One of the challenges of simulating turbulence in the edge regions of tokamaks is handling the large amplitude fluctuations that can occur and avoiding negative density overshoots, which might cause various problems. One of the attractive features of discontinuous Galerkin (DG) algorithms is that they can conserve particles and energy exactly for Hamiltonian systems even with limiters. To preserve the realizability of the solution within a cell, there are situations where it is actually necessary to enhance the boundary flux, not limit it. We show a new method that accomplishes this with exponential reconstructions, while still preserving exact particle and energy conservation. Exponential reconstructions are also helpful for handling the infinite velocity domain. We demonstrate the algorithm in 1D with a series of tests, and show some tests in multiple dimensions.

Supported by the MGK and HBPS SciDAC projects and DOE Contract DE-AC02-09CH11466

[1] E.L. Shi et al., Phys. Plasmas 26, 012307 (2019) https://doi.org/10.1063/1.5074179
[2] E. L. Shi, Ph.D. Dissertation, Princeton (2017) https://arxiv.org/abs/1708.07283
[3] J. Juno, A. Hakim, et al., J. Comp. Phys. (2018) https://doi.org/10.1016/j.jcp.2017.10.009

Comments:
Group the Gkeyll-related presentations together:

1. Ammar Hakim
2. Noah Mandell
3. Manaure Francisquez
4. Tess Bernard
5. Greg Hammett
6. James Juno
7. Valentin Skoutnev