Title: Continuum electromagnetic gyrokinetic simulations of turbulence in the tokamak scrape-off layer and laboratory devices

Abstract

Here, we present algorithms and results from Gkeyll, a full-f continuum, electromagnetic gyrokinetic code, designed to study turbulence in the edge region of fusion devices. The edge is computationally very challenging, requiring robust algorithms that can handle large-amplitude fluctuations and stable interactions with plasma sheaths. We present an energy-conserving high-order discontinuous Galerkin scheme that solves gyrokinetic equations in Hamiltonian form. Efficiency is improved by a careful choice of basis functions and automatically generated computation kernels. Previous verification tests were performed in the straight-field-line large plasma device [Shi et al., J. Plasma Phys. 83, 905830304 (2017)] and the Texas Helimak, a simple magnetized torus [Bernard et al., Phys. Plasmas 26, 042301 (2019)], including the effect of end-plate biasing on turbulence. Results for the scrape-off layer for NSTX parameters with a model helical magnetic geometry with bad curvature have been obtained [Shi et al., Phys. Plasmas 26, 012307 (2019)]. In this paper, we present algorithms for the two formulations of electromagnetic gyrokinetics: the Hamiltonian and the symplectic. We describe each formulation and show results of benchmark tests. Although our scheme works for the Hamiltonian formulation, the presence of spurious numerical modes for high-β and large $$k^2_⊥ρ^2_s$$ regimes shows that the symplectic formulation is more robust. We then review our recent algorithm for the symplectic formulation [Mandell et al., J. Plasma Phys. 86, 905860109 (2020)], along with example application of this new capability. Maintaining positivity of the distribution function can be challenging, and we describe a new and novel exponential recovery based algorithm to address this.

Authors:

Hakim, Ammar H.  ^[1];

• Search DOE PAGES for author "Hakim, Ammar H."
• Search DOE PAGES for ORCID "0000-0001-6603-8595"

Mandell, Noah R.  ^[2];

• Search DOE PAGES for author "Mandell, Noah R."
• Search DOE PAGES for ORCID "0000-0003-1446-5397"

Bernard, T. N.  ^[3];

• Search DOE PAGES for author "Bernard, T. N."
• Search DOE PAGES for ORCID "0000-0002-7331-9704"

Francisquez, M.  ^[4];

• Search DOE PAGES for author "Francisquez, M."
• Search DOE PAGES for ORCID "0000-0002-8247-3770"

Hammett, G. W.  ^[1];

• Search DOE PAGES for author "Hammett, G. W."
• Search DOE PAGES for ORCID "0000-0003-1495-6647"

Shi, E. L.  ^[5]

• Search DOE PAGES for author "Shi, E. L."
• Search DOE PAGES for ORCID "0000-0002-8506-7890"

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+ Show Author Affiliations

1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
2. Princeton Univ., NJ (United States)
3. General Atomics, San Diego, CA (United States); Univ. of Texas, Austin, TX (United States)
4. MIT Plasma Science and Fusion Center, Cambridge, MA (United States); Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
5. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Publication Date:

Tue Apr 07 00:00:00 EDT 2020

Research Org.:

Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1668050

Alternate Identifier(s):

OSTI ID: 1608504

Grant/Contract Number:  

FG02-97ER25308; FG02-95ER54309; FG02-04ER-54742; AC02-09CH11466; FC02-08ER54966

Resource Type:

Accepted Manuscript

Journal Name:

Physics of Plasmas

Additional Journal Information:

Journal Volume: 27; Journal Issue: 4; Journal ID: ISSN 1070-664X

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

70 PLASMA PHYSICS AND FUSION TECHNOLOGY