[Table of Contents]

Plasma and Fusion Research

Volume 4, 014 (2009)

Rapid Communications

Geodesic Acoustic Mode Spectroscopy II
Sanae-I. ITOH, Seiya NISHIMURA1), Kimitaka ITOH1), Akihide FUJISAWA1), Yoshihiko NAGASHIMA2) and Shigeru INAGAKI
Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan
1)
National Institute for Fusion Science, Toki 509-5292, Japan
2)
Graduate School of Frontier Science, The University of Tokyo, Kashiwa 277-8561, Japan
(Received 16 January 2009 / Accepted 16 February 2009 / Published 7 May 2009)

Abstract

An extension of geodesic acoustic mode (GAM) spectroscopy [Plasma Phys. Control. Fusion 49, L7 (2007)] is proposed. The ratio between the lowest frequency of the co-existing ion acoustic mode (IAM) and the frequency of GAM enables us to identify the safety factor of toroidal plasmas. The lowest frequency can be detected by bispectrum analysis when both GAM and IAM are excited. The possibility of measuring the safety factor is discussed.

Keywords

geodesic acoustic mode, ion acoustic mode, toroidal plasma, safety factor, new diagnostics, bicoherence

DOI: 10.1585/pfr.4.014

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This paper may be cited as follows:

Sanae-I. ITOH, Seiya NISHIMURA, Kimitaka ITOH, Akihide FUJISAWA, Yoshihiko NAGASHIMA and Shigeru INAGAKI, Plasma Fusion Res. 4, 014 (2009).