Improved beta (local beta > 1) and density in electron cyclotron resonance heating on the RT-1 magnetosphere plasma

M. Nishiura, Z. Yoshida, H. Saitoh, Y. Yano, Y. Kawazura, T. Nogami, M. Yamasaki, T. Mushiake, A. Kashyap

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)

Abstract

This study reports the recent progress in improved plasma parameters of the RT-1 device. Increased input power and the optimized polarization of electron cyclotron resonance heating (ECRH) with an 8.2 GHz klystron produce a significant increase in electron beta, which is evaluated by an equilibrium analysis of the Grad-Shafranov equation. The peak value of the local electron beta βe is found to exceed 1. In the high-beta and high-density regime, the density limit is observed for H, D and He plasmas. The line-averaged density is close to the cutoff density for 8.2 GHz ECRH. When the filling gas pressure is increased, the density limit still exists even in the low-beta region. This result indicates that the density limit is caused by the cutoff density rather than the beta limit. From the analysis of interferometer data, we found that inward diffusion causes a peaked density profile beyond the cutoff density.

Original languageEnglish
Article number053019
JournalNuclear Fusion
Volume55
Issue number5
DOIs
Publication statusPublished - 2015 May 1
Externally publishedYes

Keywords

  • dipole field
  • high beta
  • inward diffusion
  • magnetosphere plasmas
  • metric distortion

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Condensed Matter Physics

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