Radiation asymmetry and MHD destabilization during the thermal quench after impurity shattered pellet injection

JET Contributors, JOREK team, D. Hu (Corresponding author)

Research output: Contribution to journalArticleAcademicpeer-review

40 Citations (Scopus)

Abstract

The radiation response and the MHD destabilization during the thermal quench after a mixed species shattered pellet injection with impurity species neon and argon are investigated via 3D non-linear MHD simulation using the JOREK code. Both the n = 0 global current profile contraction and the local helical cooling at each rational surface caused by the pellet fragments are found to be responsible for MHD destabilization after the injection. Significant current driven mode growth is observed as the fragments cross low order rational surfaces, resulting in rapidly inward propagating stochastic magnetic field, ultimately causing the core temperature collapse. The thermal quench (TQ) is triggered as the fragments arrive on the q = 1 or q = 2 surface depending on the exact q profile and thus mode structure.When injecting from a single toroidal location, strong radiation asymmetry is found before and during the TQ as a result of the unrelaxed impurity density profile along the field line and asymmetric outward heat flux. Such asymmetry gradually relaxes over the course of the TQ, and is entirely eliminated by the end of it. Simulation results indicate that the aforementioned asymmetric radiation behavior could be significantly mitigated by injection from toroidally opposite locations, provided that the time delay between the two injectors is shorter than 1 ms. It is also found that the MHD response are sensitive to the relative timing and injection configuration in these multiple injection cases.

Original languageEnglish
Article number026015
Number of pages23
JournalNuclear Fusion
Volume61
Issue number2
DOIs
Publication statusPublished - Feb 2021

Bibliographical note

Funding Information:
The authors thank L. Baylor, P. Parks, L.E. Zakharov, R. Sweeney, D. Bonfiglio, B.C. Lyons and C.C. Kim for fruitful discussion. ITER is the Nuclear Facility INB No. 174. The views and opinions expressed herein do not necessarily reflect those of the ITER Organization. This publication is provided for scientific purposes only. Its contents should not be considered as commitments from the ITER Organization as a nuclear operator in the frame of the licensing process. Part of this work is supported by the National Natural Science Foundation of China under Grant No. 11905004. Part of this work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training program 2014–2018 and 2019–2020 under Grant agreement No. 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. This work is carried out partly on the supercomputer MARCONI operated by Cineca, and also partly on Tianhe-3 prototype operated by NSCC-TJ.

Funding

The authors thank L. Baylor, P. Parks, L.E. Zakharov, R. Sweeney, D. Bonfiglio, B.C. Lyons and C.C. Kim for fruitful discussion. ITER is the Nuclear Facility INB No. 174. The views and opinions expressed herein do not necessarily reflect those of the ITER Organization. This publication is provided for scientific purposes only. Its contents should not be considered as commitments from the ITER Organization as a nuclear operator in the frame of the licensing process. Part of this work is supported by the National Natural Science Foundation of China under Grant No. 11905004. Part of this work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training program 2014–2018 and 2019–2020 under Grant agreement No. 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. This work is carried out partly on the supercomputer MARCONI operated by Cineca, and also partly on Tianhe-3 prototype operated by NSCC-TJ.

FundersFunder number
Horizon 2020 Framework Programme
H2020 Euratom633053
National Natural Science Foundation of China11905004

    Keywords

    • Disruption
    • Disruption mitigation
    • Impurity radiation
    • Magneto-hydrodynamics
    • Shattered pellet injection
    • Thermal quench

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