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Development of Collective Thomson Scattering for Alpha-Particle Diagnostic in Burning Plasmas

Takashi KONDOH, Toshimitsu HAYASHI, Yasunori KAWANO, Yoshinori KUSAMA and Tatsuo SUGIE

Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan

(Received 4 December 2006 / Accepted 8 May 2007 / Published 20 November 2007)

Abstract

A collective Thomson scattering (CTS) diagnostic using carbon dioxide (CO₂) laser is being developed to establish a diagnostic method of confined α-particles in burning plasmas. To realize the CTS diagnostic, a transversely excited atmospheric CO₂ laser has been developed. To obtain single-mode output, which is needed for the CTS diagnostic, seed laser is injected to the cavity with an unstable resonator. Using this technique, output energy of 17 J at a repetition rate of 15 Hz has been achieved. This result gives a prospect for the CTS diagnostic on International Thermonuclear Experimental Reactor (ITER). Proof-of-principle test of the CTS diagnostic is being performed with the new laser system on JT-60U. A method to improve spatial and spectral resolutions, which is subject to be resolved for the CO₂ laser CTS, is proposed using a resonance at the lower hybrid frequency. Calculation results show that the scattering power increases more than a factor of 10, and spatial and spectral resolution improve about 30% if the scattered wave vector is nearly perpendicular to the magnetic field.

Copyright (c) 2007 The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

collective Thomson scattering, burning plasma, carbon-dioxide laser, international thermonuclear experimental reactor, JT-60U

DOI: 10.1585/pfr.2.S1111

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This paper may be cited as follows:

Takashi KONDOH, Toshimitsu HAYASHI, Yasunori KAWANO, Yoshinori KUSAMA and Tatsuo SUGIE, Plasma Fusion Res. 2, S1111 (2007).