Abstract
Previous investigations on JET suggest half or less of plasma stored thermal energy W t h is radiated ( f rad , t h ≲ 0.5 ) using either massive gas injection (MGI) or shattered pellet injection (SPI) disruption mitigation. We investigate whether the apparent incomplete f rad , t h is explained by radiation peaking near the injection plume. High toroidal peaking throughout the pre-thermal quench is found in argon-deuterium MGI on JET, with typically >3× higher radiation near the injector than toroidally distant. Previously unexplained toroidal bolometry measurements in neon-deuterium SPI are reproduced with similar peaking using the Emis3D radiation analysis code. These observations align with results from Alcator C-Mod and KSTAR. This peaking is not captured by previous JET studies that found poor thermal mitigation. Two sets of neon-deuterium SPI and two sets of argon-deuterium MGI are analyzed using Emis3D. In SPI, f rad , t h rises from no-plume estimates of 0.31 and 0.66 to lower bounds of 0.84 and 0.92, respectively, and f rad , t h ∼ 1 is possible. In MGI, the toroidal spread of the peaking feature is poorly constrained. f rad , t h up to 0.85 and 0.65 are possible using the largest possible spread, increasing from 0.42 and 0.28, although f rad , t h ∼ 1 does not appear to be reached. Revised mitigation estimates on JET suggest a lower melt risk to the divertor in mitigated disruptions on ITER and SPARC than previously thought. However, peaking near injectors could increase flash melting risk on nearby plasma facing components.
| Original language | English |
|---|---|
| Article number | 042510 |
| Journal | Physics of Plasmas |
| Volume | 32 |
| Issue number | 4 |
| DOIs | |
| State | Published - Apr 1 2025 |
Funding
This work has been carried out within the framework of the EUROfusion consortium, partially funded by the European Union via the Euratom Research and Training Programme (Grant Agreement No. 101052200\u2014EUROfusion). The Swiss contribution to this work has been funded by the Swiss State Secretariat for Education, Research and Innovation (SERI). Views and opinions expressed are, however, those of the author(s) only and do not necessarily reflect those of the European Union, the European Commission, or SERI. Neither the European Union nor the European Commission nor SERI can be held responsible for them. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences, under Award No. DE-SC0014264. The views and opinions expressed herein do not necessarily reflect those of the Department of Energy.