English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The fragment ablation rate plays significant roles in the mitigationefficiency of Shattered Pellet Injection (SPI) as a Disruption MitigationSystem (DMS). Current mainstream 3D MHD codes modelling SPIs mostly assumeinstantaneous thermalization between the previously hot ambient electrons andthe newly released cold electrons, which results in underestimation of theablation rate if the hot electron thermalization time is comparable or evenlonger than the fragment flying time. To resolve this doubt, we herebyinvestigate the thermalization dynamics and the overall hot-electron impact.The finite-time collisional thermalization of hot-tail electrons in a rapidlycooling plasma, as well as the so-called ``self-limiting'' effect areconsidered. The former effect tends to deplete the colder population within ahot-tail species, while the latter is found to preferentially deplete thehigher energy population. The combined result is found to cause an almostself-similar decay of the hot electron distribution function, while its shapedoes not deviate much from that of Maxwellian distribution and the mean energydoes not change much during the thermalization process. Based on thisobservation, axisymmetric JOREK D2 SPI simulations were carried out withadditional hot-tail contribution to evaluate their overall impact onto theinjection assimilation and penetration. It is found that the hot-tail effectindeed causes enhanced assimilation and shallower penetration, although theoverall effect depends on the exact injection configuration, with the slowinjection showing negligible hot-tail effect while the fast singlenon-shattered pellet case shows drastic hot-tail ablation enhancement. ForITER-like SPI parameters, there is no significant deviation in the totalassimilation, but some deviation in the injection penetration is observed forthe fast injection velocity cases.

Hot-tail electrons' impact on assimilation and injection penetration of D2 Shattered Pellet Injections