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Title: MARS-F modeling of post-disruption runaway beam loss by magnetohydrodynamic instabilities in DIII-D

Abstract

A drift orbit model for relativistic test electrons has been incorporated into the MARS-F code, in order to study the runaway electron (RE) behavior in the presence of magneto-hydrodynamic perturbations computed by MARS-F. By implementing the model directly into the MARS-F curve-linear magnetic coordinates, maximal accuracy in representing the full field perturbation is preserved. The updated code is utilized to study the high current RE beam loss in a post-disruption DIII-D plasma, revealing that a fast growing, n = 1 ( n is the toroidal mode number) resistive kink instability, at ~100 Gauss level, can induce significant fraction of RE loss, largely by perturbing drift orbits of REs. A 103 Gauss perturbation fully terminates the RE beam, as found in both experiment and modeling. The 3-D field induced loss increases with the perturbation amplitude but decreases with the particle energy. The loss fraction is generally not sensitive to the initial particle pitch angle. The particle velocity change, due to electric field acceleration/deceleration, small pitch angle scattering, synchrotron radiation and Bremsstrahlung, further perturbs the RE trajectory but plays a minor role in prompt RE loss within microseconds time scale. Therefore, the dominant dependencies are simply the RE energy and instability strength.more » For comparison, a resonant magnetic perturbation field, generated by 4 kAt n = 3 even parity I-coil currents in DIII-D and with the plasma response field included, is found to induce almost no loss for the same RE beam.« less

Authors:
 [1];  [1]; ORCiD logo [1];  [2];  [1]
  1. General Atomics, San Diego, CA (United States)
  2. SLS2 Consulting, San Diego, CA (United States)
Publication Date:
Research Org.:
U.S. Dept. of Energy (USDOE), Washington D.C. (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
OSTI Identifier:
1568765
Grant/Contract Number:  
FG02-95ER54309
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 59; Journal Issue: 12; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; runaway electrons; MHD instabilities; MHD; RE loss; disruption; orbit loss

Citation Formats

Liu, Y. Q., Parks, P. B., Paz-Soldan, C., Kim, C., and Lao, L. L. MARS-F modeling of post-disruption runaway beam loss by magnetohydrodynamic instabilities in DIII-D. United States: N. p., 2019. Web. doi:10.1088/1741-4326/ab3f87.
Liu, Y. Q., Parks, P. B., Paz-Soldan, C., Kim, C., & Lao, L. L. MARS-F modeling of post-disruption runaway beam loss by magnetohydrodynamic instabilities in DIII-D. United States. doi:10.1088/1741-4326/ab3f87.
Liu, Y. Q., Parks, P. B., Paz-Soldan, C., Kim, C., and Lao, L. L. Fri . "MARS-F modeling of post-disruption runaway beam loss by magnetohydrodynamic instabilities in DIII-D". United States. doi:10.1088/1741-4326/ab3f87.
@article{osti_1568765,
title = {MARS-F modeling of post-disruption runaway beam loss by magnetohydrodynamic instabilities in DIII-D},
author = {Liu, Y. Q. and Parks, P. B. and Paz-Soldan, C. and Kim, C. and Lao, L. L.},
abstractNote = {A drift orbit model for relativistic test electrons has been incorporated into the MARS-F code, in order to study the runaway electron (RE) behavior in the presence of magneto-hydrodynamic perturbations computed by MARS-F. By implementing the model directly into the MARS-F curve-linear magnetic coordinates, maximal accuracy in representing the full field perturbation is preserved. The updated code is utilized to study the high current RE beam loss in a post-disruption DIII-D plasma, revealing that a fast growing, n = 1 (n is the toroidal mode number) resistive kink instability, at ~100 Gauss level, can induce significant fraction of RE loss, largely by perturbing drift orbits of REs. A 103 Gauss perturbation fully terminates the RE beam, as found in both experiment and modeling. The 3-D field induced loss increases with the perturbation amplitude but decreases with the particle energy. The loss fraction is generally not sensitive to the initial particle pitch angle. The particle velocity change, due to electric field acceleration/deceleration, small pitch angle scattering, synchrotron radiation and Bremsstrahlung, further perturbs the RE trajectory but plays a minor role in prompt RE loss within microseconds time scale. Therefore, the dominant dependencies are simply the RE energy and instability strength. For comparison, a resonant magnetic perturbation field, generated by 4 kAt n = 3 even parity I-coil currents in DIII-D and with the plasma response field included, is found to induce almost no loss for the same RE beam.},
doi = {10.1088/1741-4326/ab3f87},
journal = {Nuclear Fusion},
number = 12,
volume = 59,
place = {United States},
year = {2019},
month = {10}
}

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This content will become publicly available on October 11, 2020
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