Observation of nonlinear coupling between small-poloidal wave-number potential fluctuations and turbulent potential fluctuations in ohmically heated plasmas in the JFT-2M tokamak

Y. Nagashima, K. Hoshino, A. Ejiri, K. Shinohara, Y. Takase, K. Tsuzuki, K. Uehara, H. Kawashima, H. Ogawa, T. Ido, Y. Kusama, Y. Miura

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Abstract

Two types of electrostatic modes with small-poloidal wave numbers (∼1 and 10-15kHz) are observed in the edge region of Ohmically heated plasmas in the JFT-2M tokamak. The envelope of the higher frequency coherent mode is modulated at the frequency of the lower frequency mode. A bispectral analysis revealed that a significant nonlinear coupling among the two types of fluctuations and the broadband background turbulent potential fluctuations occurs inside the last closed magnetic flux surface, suggesting that a nonlinear process such as the parametric-modulational instability is involved.

Original languageEnglish
Article number095002
JournalPhysical Review Letters
Volume95
Issue number9
DOIs
Publication statusPublished - Aug 26 2005
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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