ARC disruption physics and strategy
Journal article, 2026
Commonwealth Fusion Systems (CFS) plans to operate a tokamak power plant called ARC in the early 2030s. Tokamak plasmas have stability limits that, if crossed, lead to a rapid termination of the plasma, referred to as a disruption. Disruptions pose a melt risk to the first wall resulting from thermal and non-thermal particle heat fluxes, and an electromagnetic loading risk on all metal components within the equilibrium coils. A comprehensive set of models is used herein to provide an assessment of both mitigated and unmitigated ARC disruption loads. A preliminary massive gas injection system is baselined and a runaway electron mitigation coil option is proposed to close possible gaps in the baseline. It is predicted that all ARC disruption loads are within a factor of 2 of the disruption loads in SPARC, a tokamak presently under construction by CFS, and therefore SPARC provides an opportunity to calibrate models, test solutions and inform the design of ARC. The goal for ARC is disruption-free operation, however, the pragmatic design target is to withstand one mitigated disruption per day, and to restart the plasma following mitigation in tens of seconds without interrupting the power output. Unmitigated disruptions must be rare, and experience with unmitigated disruption impacts in SPARC will better define what rare means. The implications of this strategy for plasma disruptivity and disruption prediction are discussed, and operating the ARC scenario on SPARC is expected to refine the ARC final design and operational plan.
runaway electrons
fusion plasma
plasma instabilities
Author
Ryan Sweeney
Commonwealth Fusion Systems
Valeria Riccardo
Commonwealth Fusion Systems
Anson Braun
Columbia University
Cesar Clauser
Massachusetts Institute of Technology (MIT)
Alexander J. Creely
Commonwealth Fusion Systems
Thomas Eich
Commonwealth Fusion Systems
Ida Ekmark
Chalmers, Physics, Subatomic, High Energy and Plasma Physics
Abigail Feyrer
Massachusetts Institute of Technology (MIT)
Christopher Hansen
Columbia University
Jon C. Hillesheim
Commonwealth Fusion Systems
Tom Looby
Commonwealth Fusion Systems
Svetlana Ratynskaia
Royal Institute of Technology (KTH)
Raphael Schramm
Max Planck Society
R. Alex Tinguely
Massachusetts Institute of Technology (MIT)
Hao Wu
Commonwealth Fusion Systems
John Boguski
Commonwealth Fusion Systems
Mark D. Boyer
Commonwealth Fusion Systems
Justin Carmichael
Commonwealth Fusion Systems
Austin Carter
Commonwealth Fusion Systems
Rishabh Datta
Massachusetts Institute of Technology (MIT)
Tünde-Maria Fülöp
Chalmers, Physics, Subatomic, High Energy and Plasma Physics
Robert Granetz
Massachusetts Institute of Technology (MIT)
Sophia Guizzo
Columbia University
Mathias Hoppe
Royal Institute of Technology (KTH)
Alexandra LeViness
Commonwealth Fusion Systems
Andrew O. Nelson
Columbia University
Konstantinos Paschalidis
Royal Institute of Technology (KTH)
Carlos Paz-Soldan
Columbia University
Istvan Pusztai
Chalmers, Physics, Subatomic, High Energy and Plasma Physics
Cristina Rea
Massachusetts Institute of Technology (MIT)
Tommaso Rizzi
Royal Institute of Technology (KTH)
Alex R. Saperstein
Massachusetts Institute of Technology (MIT)
Philip B. Snyder
Commonwealth Fusion Systems
Benjamin Stein-Lubrano
Massachusetts Institute of Technology (MIT)
Panagiotis Tolias
Royal Institute of Technology (KTH)
Journal of Plasma Physics
0022-3778 (ISSN) 1469-7807 (eISSN)
Vol. 92 3 E68Subject Categories (SSIF 2025)
Fusion, Plasma and Space Physics
DOI
10.1017/S0022377826101585