A model of giant ELMs

Sanae I. Itoh, Kimitaka Itoh, Atsushi Fukuyama, Masatoshi Yagi

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

A theoretical model of giant ELMs (type-I ELMs) is developed. The theory of the self-sustained turbulence of the current-diffusive ballooning mode (CDBM) is developed in the presence of a steep pressure gradient and a radial electric field shear. Multifold states for the L-mode, H-mode and the third state with magnetic braiding are obtained. Transition to the state with magnetic braiding is found to occur if the pressure gradient becomes high enough. At this critical point, nonlinear excitation of the magnetic perturbation takes place, the growth time of which is of the order of the poloidal Alfven time. This event can cause catastrophic enhancement of the transport coefficient by a factor of almost 10. The avalanche of the transport catastrophe is also analysed, showing a very rapid radial propagation velocity. The magnetic braiding terminates if the pressure gradient becomes small, leading to a back transition to the H- (L-) mode. Under a constant power supply these processes can repeat themselves, causing periodic bursts. The period becomes shorter as the average power flux increases.

Original languageEnglish
Pages (from-to)527-549
Number of pages23
JournalPlasma Physics and Controlled Fusion
Volume38
Issue number4
DOIs
Publication statusPublished - Dec 1 1996

All Science Journal Classification (ASJC) codes

  • Nuclear Energy and Engineering
  • Condensed Matter Physics

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