Abstract

Systematic test particle tracing simulations for runaway electrons (REs) are performed for six post-thermal quench equilibria from DIII-D and ITER, where large scale, kink-like n = 1 (n is the toroidal mode number) magnetohydrodynamic (MHD) instabilities are found. The modeled particle guiding center orbits allow extraction of the effective diffusion–convection coefficients of REs in the presence of large three-dimensional (3D) perturbations up to 10% of the equilibrium toroidal field. With a fixed spatial distribution of the field perturbation, the RE transport coefficients along the plasma radial coordinate track reasonably well with the surface-averaged perturbation level. A substantial variation in the value of the transport coefficients—by three orders of magnitude in most cases, however, occurs with varying launching location of REs along the plasma radius. Large 3D perturbations almost always lead to comparable diffusion and convection processes, meaning that diffusion alone is insufficient to describe the particle motion. At lower (but still high) level of perturbation, the RE convection is found to be dominant over diffusion. A similar observation is made when the perturbation is too strong. In the presence of large perturbation, the dependence of the RE transport on the particle energy is sensitive to the spatial distribution of themore » perturbation. Based on numerically obtained RE transport coefficients, an analytic fitting model is proposed to quantify the particle diffusion and convection processes due to large MHD events in post-thermal quench plasmas. The model is shown to reasonably well reproduce the direct test particle tracing results for the RE loss fraction and can, thus, be useful for incorporating into other kinetic RE codes in order to simulate the RE beam evolution in the presence of large 3D perturbations.« less

Authors:

Liu, Yueqiang  ^[1];

• Search DOE PAGES for author "Liu, Yueqiang"
• Search DOE PAGES for ORCID "0000-0002-8192-8411"

Aleynikova, K.  ^[2];

• Search DOE PAGES for author "Aleynikova, K."
• Search DOE PAGES for ORCID "0000-0001-9606-7346"

Hollmann, E. M.  ^[3];

• Search DOE PAGES for author "Hollmann, E. M."
• Search DOE PAGES for ORCID "0000-0002-6267-6589"

Paz-Soldan, C.  ^[4];

• Search DOE PAGES for author "Paz-Soldan, C."
• Search DOE PAGES for ORCID "0000-0001-5069-4934"

Aleynikov, P.  ^[2];

• Search DOE PAGES for author "Aleynikov, P."
• Search DOE PAGES for ORCID "0009-0002-3037-3679"

Khayrutdinov, R. ^[5]; Lukash, V. ^[5]

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+ Show Author Affiliations

1. General Atomics, San Diego, CA (United States)
2. Max-Planck-Institut fur Plasmaphysik, Greifswald (Germany)
3. University of California, San Diego, La Jolla, CA (United States)
4. Columbia University, New York, NY (United States)
5. National Research Center Kurchatov Institute, Moscow (Russia)

Publication Date:

Thu Sep 07 00:00:00 EDT 2023

Research Org.:

General Atomics, San Diego, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Fusion Energy Sciences (FES)

OSTI Identifier:

2228283

Grant/Contract Number:  

SC0016452; FC02-04ER54698; FG02-95ER54309

Resource Type:

Accepted Manuscript

Journal Name:

Physics of Plasmas

Additional Journal Information:

Journal Volume: 30; Journal Issue: 9; 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; Relativistic corrections; Magnetohydrodynamics; Plasma instabilities; Runaway electrons; Tokamaks