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Title: Simulations of stand-off runaway electron beam termination by tungsten particulates for tokamak disruption mitigation

Journal Article · · Nuclear Fusion
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [1]; ORCiD logo [1]
  1. Los Alamos National Laboratory (LANL), Los Alamos, NM (United States). Theoretical Division
  2. Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
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Stand-off runaway electron termination by injected tungsten particulates offers a plausible option in the toolbox of disruption mitigation. Tungsten is an attractive material choice for this application due to large electron stopping power and high melting point. To assess the feasibility of this scheme, we simulate runaway collisions with tungsten particulates using the MCNP program for incident runaway energies ranging from 1 to 10 MeV. We assess runaway termination from energetics and collisional kinematics perspectives. Energetically, the simulations show that 99% of runaway beam energy is removed by tungsten particulates on a timescale of 4–9 µs. Kinematically, the simulations show that 99% of runaways are terminated by absorption or backscattering on a timescale of 3–4 µs. By either metric, the runaway beam is effectively terminated before the onset of particulate melting. Furthermore, the simulations show that secondary radiation emission by tungsten particulates does not significantly impact the runaway termination efficacy of this scheme. Secondary radiation is emitted at lower particle energies than the incident runaways and with a broad angular distribution such that the majority of secondary electrons emitted will not experience efficient runaway re-acceleration. Overall, the stand-off runaway termination scheme is a promising concept as a last line of defense against runaway damage in ITER, SPARC, and other future burning-plasma tokamaks.

Research Organization:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
Grant/Contract Number:
89233218CNA000001
OSTI ID:
2329251
Alternate ID(s):
OSTI ID: 2326091; OSTI ID: 2329330
Report Number(s):
LA-UR--23-28143
Journal Information:
Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 5 Vol. 64; ISSN 0029-5515
Publisher:
IOP ScienceCopyright Statement
Country of Publication:
United States
Language:
English

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
magnetic fusion energy
runaway electrons
tungsten particulates
disruption mitigation
Monte Carlo