Measurement of Space Potential Fluctuations during MHD Activities in a Toroidal Helical Plasma with a Heavy Ion Beam Probe

Seishu Lee, Harukazu Iguchi, akihide fujisawa, Thomas P. Crowley, Yasuji Hamada, Mamoru Kojima, Ryuichi Akiyama, Keisuke Matsuoka, Shoichi Okamura, Chihiro Takahashi

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Abstract

A heavy ion beam probe (HIBP) is a unique diagnostic instrument which can measure local plasma potent and its fluctuations. However, in the presence of MHD activities, acceleration or deceleration of both primary and secondary beams are caused by the fluctuating vector potential ∂A/∂t along the beam trajectories (path integral effect). Such effect possibly induces a contamination to space potential measurement. We have evaluated those effects during a bursting MHD instability in the Compact Helical System (CHS), which is considered to be an m/n = 2/1 interchange instability. In this procedure, the vector potential profile is estimated both theoretically and experimentally. Contribution from path effect is found to be less than several percent o the measured space potential fluctuation. Then space potential fluctuation is found to be localized around q = 2 magnetic surface, which is consistent with a model for the interchange mode.

Original languageEnglish
Pages (from-to)3107-3113
Number of pages7
Journaljournal of the physical society of japan
Volume67
Issue number9
DOIs
Publication statusPublished - Jan 1 1998
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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    Lee, S., Iguchi, H., fujisawa, A., Crowley, T. P., Hamada, Y., Kojima, M., Akiyama, R., Matsuoka, K., Okamura, S., & Takahashi, C. (1998). Measurement of Space Potential Fluctuations during MHD Activities in a Toroidal Helical Plasma with a Heavy Ion Beam Probe. journal of the physical society of japan, 67(9), 3107-3113. https://doi.org/10.1143/JPSJ.67.3107