Large ELM-like events triggered by core MHD in JET advanced tokamak plasmas: impact on plasmas profiles, plasma-facing components and heating systems

TitleLarge ELM-like events triggered by core MHD in JET advanced tokamak plasmas: impact on plasmas profiles, plasma-facing components and heating systems
Publication TypeJournal Article
Year of Publication2012
AuthorsY.F Baranov, C.D Challis, J. Ongena, B. Alper, G. Arnoux, P. Buratti, T. Gerbaud, D. Keeling, V. Kiptily, J. Mailloux, M.L Mayoral, I. Monakhov, V. Parail, G. Sergienko, S. Sharapov
Corporate AuthorsJET-EFDA Contributors
JournalNuclear Fusion
Volume52
Issue2
Pagination023018
Abstract

Large and infrequent collapse events have been observed in high β N advanced tokamak (AT) plasmas in JET. Although they have features similar to large ELMs, they were triggered by core MHD. They caused a considerable loss of the plasma thermal and fast particle energy ( 10% of the total stored energy), but the heat load in the divertor due to these collapse events was small as a fraction of the plasma energy loss compared with regular type-I ELMs. Instead, significant heating of the main chamber wall was observed. A large, toroidally asymmetric, increase in the neutral gas pressure outside the plasma was observed after such events, which caused arcs in the lower hybrid (LH) and ion cyclotron (IC) heating systems and increased reionization in the neutral beam (NB) injectors. The collapses resulted in a reduction in the electron and ion temperatures and toroidal rotation of the whole plasma, a rise in Z eff ; and a sufficiently large increase in the peripheral electron density to completely black-out the ECE emission from the plasma core. These features have been modelled to gain an understanding of the plasma behaviour associated with these collapse events and the implication for the operation of AT plasma scenarios with high additional heating power will be discussed.

URLhttp://www.euro-fusionscipub.org/wp-content/uploads/2014/11/EFDP10055.pdf
DOI10.1088/0029-5515/52/2/023018
Division

FP

Department

PDG

PID

c376153b3a1ad9595ea8043c3eb4bc86

Alternate TitleNucl. Fusion
LabelOA

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