Passive deconfinement of runaway electrons using an in-vessel helical coil
Abstract
A helical coil designed to passively generate non-axisymmetric fields during a plasma disruption is shown (via electromagnetic analysis, linear MHD modeling, and relativistic drift orbit tracing) to be effective at deconfining runaway electrons (REs) on a time scale significantly faster than the plasma current quench. Magnetic equilibria from DIII-D RE-producing scenarios are used to calculate the toroidal electric field generated during the current quench phase of a disruption, which in turn drives current in the proposed n = 1 in-vessel helical coil, without the need for any external power supplies or disruption detection or prediction techniques. Simulations of the plasma evolution using the TokSys GS Evolve code predict the inductive coupling of coil currents up to 12% of the pre-disruption plasma current into the helical coil. The coil geometry is parametrically varied to maximize both the non-resonant and resonant components of the 3D magnetic perturbation, resulting in δB/B ≈ 10–2 and a vacuumisland overlapwidth of up to 0.7ψN. The REORBIT module of the MARS-F code is used to model the full non-axisymmetric magnetic field and trace RE drift orbits to determine the effect on RE deconfinement, with up to 70% of the RE orbits lost after 0.2 ms. A two-stagemore »
- Authors:
-
[1];
[2];
[1];
- General Atomics, San Diego, CA (United States)
- General Atomics, San Diego, CA (United States); Columbia Univ., New York, NY (United States)
- Georgia Inst. of Technology, Atlanta, GA (United States)
- Publication Date:
- Research Org.:
- General Atomics, San Diego, CA (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES)
- OSTI Identifier:
- 1828581
- Grant/Contract Number:
- FC02-04ER54698
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Nuclear Fusion
- Additional Journal Information:
- Journal Volume: 61; Journal Issue: 10; Journal ID: ISSN 0029-5515
- Publisher:
- IOP Science
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; runaway electrons; disruption; magnetic perturbations; 3D coil
Citation Formats
Weisberg, David B., Paz-Soldan, C., Liu, Y. Q., Welander, A., and Dunn, C. Passive deconfinement of runaway electrons using an in-vessel helical coil. United States: N. p., 2021.
Web. doi:10.1088/1741-4326/ac2279.
Weisberg, David B., Paz-Soldan, C., Liu, Y. Q., Welander, A., & Dunn, C. Passive deconfinement of runaway electrons using an in-vessel helical coil. United States. https://doi.org/10.1088/1741-4326/ac2279
Weisberg, David B., Paz-Soldan, C., Liu, Y. Q., Welander, A., and Dunn, C. Thu .
"Passive deconfinement of runaway electrons using an in-vessel helical coil". United States. https://doi.org/10.1088/1741-4326/ac2279. https://www.osti.gov/servlets/purl/1828581.
@article{osti_1828581,
title = {Passive deconfinement of runaway electrons using an in-vessel helical coil},
author = {Weisberg, David B. and Paz-Soldan, C. and Liu, Y. Q. and Welander, A. and Dunn, C.},
abstractNote = {A helical coil designed to passively generate non-axisymmetric fields during a plasma disruption is shown (via electromagnetic analysis, linear MHD modeling, and relativistic drift orbit tracing) to be effective at deconfining runaway electrons (REs) on a time scale significantly faster than the plasma current quench. Magnetic equilibria from DIII-D RE-producing scenarios are used to calculate the toroidal electric field generated during the current quench phase of a disruption, which in turn drives current in the proposed n = 1 in-vessel helical coil, without the need for any external power supplies or disruption detection or prediction techniques. Simulations of the plasma evolution using the TokSys GS Evolve code predict the inductive coupling of coil currents up to 12% of the pre-disruption plasma current into the helical coil. The coil geometry is parametrically varied to maximize both the non-resonant and resonant components of the 3D magnetic perturbation, resulting in δB/B ≈ 10–2 and a vacuumisland overlapwidth of up to 0.7ψN. The REORBIT module of the MARS-F code is used to model the full non-axisymmetric magnetic field and trace RE drift orbits to determine the effect on RE deconfinement, with up to 70% of the RE orbits lost after 0.2 ms. A two-stage evolution of the RE orbit loss fraction is observed to be caused by resonant trapping between multiple magnetic island chains. Finally, electromagnetic and thermal stresses on the coil are calculated to be within operational limits for installation in DIII-D, and scale favorably to a reactor-size device. Furthermore, these findings motivate future experimental study of the helical coil concept in DIII-D or other tokamaks.},
doi = {10.1088/1741-4326/ac2279},
journal = {Nuclear Fusion},
number = 10,
volume = 61,
place = {United States},
year = {Thu Sep 23 00:00:00 EDT 2021},
month = {Thu Sep 23 00:00:00 EDT 2021}
}
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