3D non-linear MHD simulation of the MHD response and density increase as a result of shattered pellet injection

The MHD response and the penetration of a deuterium shattered pellet into a JET plasma is investigated via the non-linear reduced MHD code JOREK with the neutral gas shielding (NGS) ablation model. The dominant MHD destabilizing mechanism by the injection is identified as the local helical cooling a...

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Bibliographic Details
Published in:Nuclear fusion 2018-10, Vol.58 (12), p.126025
Main Authors: Hu, D., Nardon, E., Lehnen, M., Huijsmans, G.T.A., van Vugt, D.C.
Format: Article
Language:English
Subjects:
disruption mitigation
JOREK
MHD instability
reduced MHD
shattered pellet injection
simulation
tokamak
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Summary:The MHD response and the penetration of a deuterium shattered pellet into a JET plasma is investigated via the non-linear reduced MHD code JOREK with the neutral gas shielding (NGS) ablation model. The dominant MHD destabilizing mechanism by the injection is identified as the local helical cooling at each rational surface, as opposed to the global current profile contraction. Thus the injected fragments destabilize each rational surface as they pass through them. The injection penetration is found to be much better compared to MGI, with the convective transport caused by core MHD instabilities (e.g. 1/1 kink) contributing significantly to the core penetration. Moreover, the injection with realistic JET SPI system configurations is simulated in order to provide some insights into future operations, and the impact on the total assimilation and penetration depth of varying injection parameters such as the injection velocity or fineness of shattering is assessed. Further, the effect of changing the target equilibrium temperature or q profile on the assimilation and penetration is also investigated. Such analysis will form the basis of further investigation into a desirable configuration for the future SPI system in ITER.
ISSN:0029-5515
1741-4326
1741-4326
DOI:10.1088/1741-4326/aae614