[Table of Contents]

Plasma and Fusion Research

Volume 2, S1071 (2007)

Regular Articles

Current Profile Estimation in Full LHCD Plasmas using Hard X-Ray Measurement along the Top and Bottom Identical Line of Sight on TRIAM-1M
Kazuaki HANADA, Keisuke SASAKI1), Makoto HASEGAWA, Hiroshi IDEI, Hideki ZUSHI, Kazuo NAKAMURA, Mizuki SAKAMOTO, Konosuke SATO, Shoji KAWASAKI, Hisatoshi NAKASHIMA, Aki HIGASHIJIMA and TRIAM group
RIAM, Kyushu University, Kasuga, Fukuoka, 816-8580, Japan
1)
Interdisciplinary Graduate School of Engineering Science Kyushu Univ., Fukuoka, Japan
(Received 2 December 2006 / Accepted 18 April 2007 / Published 20 November 2007)

Abstract

A new technique to measure the current profile in plasmas with asymmetric distribution function such as lower hybrid current drive (LHCD) by using hard X-ray (HXR) energy spectrum measurement along the top and bottom identical line of sights (ILOS) is proposed and is applied to the full and partially LHCD plasmas on the TRIAM-1M tokamak at the first time in the world. The pitch angles were measured at R - R0 = ±2.5 cm, where R, R0 mean the major radii of the ILOS and the magnetic axis, respectively. The measured pitch angle of the magnetic field inverted at the magnetic axis estimated magnetic measurement in partially LHCD plasmas. This indicates that the difference of the measured pitch angles is caused by the plasma current in the plasma and this new method is available in detecting the current profile in tokamaks. In full LHCD plasma, no difference between the HXR signals along the top and bottom ILOS appear. This indicates that the current density around the magnetic axis was reduced compared with that in partially LHCD plasmas. This observation is no contradiction with power deposition of LHCD.

Keywords

lower hybrid current drive, current profile measurement, hard X-ray, tokamak, TRIAM-1M

DOI: 10.1585/pfr.2.S1071

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This paper may be cited as follows:

Kazuaki HANADA, Keisuke SASAKI, Makoto HASEGAWA, Hiroshi IDEI, Hideki ZUSHI, Kazuo NAKAMURA, Mizuki SAKAMOTO, Konosuke SATO, Shoji KAWASAKI, Hisatoshi NAKASHIMA, Aki HIGASHIJIMA and TRIAM group, Plasma Fusion Res. 2, S1071 (2007).