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Destabilization of ellipticity-induced Alfvén eigenmodes during ICRF heating and stabilization by negative-ion-based neutral beam injection in JT-60U

  • Y. Kusama
  • , G. Y. Fu
  • , G. J. Kramer
  • , M. Saigusa
  • , T. Oikawa
  • , T. Ozeki
  • , S. Moriyama
  • , F. V. Tchernychev
  • , M. Nemoto
  • , T. Kondoh
  • , T. Hatae
  • , K. Tobita
  • , M. Kuriyama
  • , C. Z. Cheng
  • , H. Kimura

Research output: Contribution to journalArticlepeer-review

Abstract

High-frequency modes in the 525-550 kHz range with toroidal mode numbers n = 3-7 were excited after the sawtooth crash during ion cyclotron range of frequency (ICRF) heating. Based on the stability analysis using the NOVA-K code, these modes were found to be consistent with ellipticity-induced Alfvén eigenmodes (EAEs) excited in the EAE gap located at the q = 1 surface. A change in the safety factor after the sawtooth crash was essential for the excitation of EAEs in the core region of the plasma. The high-frequency modes were stabilized by the neutral beam injection at 350 keV using negative-ion-based neutral beam (NNB) injectors. Stability analysis using the NOVA-K code has shown that NNB-injected ions enhance the damping of the EAEs and tend to stabilize them.

Original languageEnglish (US)
Pages (from-to)1167-1177
Number of pages11
JournalPlasma Physics and Controlled Fusion
Volume41
Issue number9
DOIs
StatePublished - Sep 1999
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Nuclear Energy and Engineering
  • Condensed Matter Physics

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