Characteristics of edge-localized modes in the experimental advanced superconducting tokamak (EAST)

M. Jiang, G.S. Xu, C. Xiao, H. Y. Guo, B. N. Wan, H. Q. Wang, L. Wang, L. Zhang, Volker Naulin, K. F. Gan, D. S. Wang, Y. M. Duan, Ning Yan, P. Liu, S. Y. Ding, W. Zhang, S. C. Liu

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Edge-localized modes (ELMs) are the focus of tokamak edge physics studies because the large heat loads associated with ELMs have great impact on the divertor design of future reactor-grade tokamaks such as ITER. In the experimental advanced superconducting tokamak (EAST), the first ELMy high confinement modes (H-modes) were obtained with 1 MW lower hybrid wave power in conjunction with wall conditioning by lithium (Li) evaporation and real-time Li powder injection. The ELMs in EAST at this heating power are mostly type-III ELMs. They were observed close to the H-mode threshold power and produced small energy dumps (1-2% of the stored energy). Type-III ELMs produced a time-averaged peak heat flux of about 2 MW m(-2) on the target plate, a value which is similar to 10 times larger than that of ELM-free phases. A few isolated and large type-I-like ELM events were also observed in EAST with an energy loss of up to 5% of the stored energy. Statistically, the ELM frequencies are several hundred hertz and the frequency appears to decrease with q(95), the safety factor at 95% of the flux surface. When an ion cyclotron resonance frequency wave was injected during the H-mode phases, the ELM repetition frequency increased immediately. The frequency and amplitude of type-III ELMs can be effectively influenced by puffing impurity argon gas.
Original languageEnglish
JournalPlasma Physics and Controlled Fusion
Volume54
Issue number9
Pages (from-to)095003
ISSN0741-3335
DOIs
Publication statusPublished - 2012

Keywords

  • PHYSICS,
  • ELMY H-MODES
  • DIII-D
  • ASDEX UPGRADE
  • I ELMS
  • COLLISIONALITY REGIME
  • FREQUENCY CONTROL
  • PELLET INJECTION
  • HIGH-DENSITY
  • PEDESTAL
  • PLASMA

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