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Improved Pellet Charge Exchange Measurements in Large Helical Device

Tetsuo OZAKI, Naoki TAMURA, Tetsuo SEKI, Hiroshi KASAHARA, Shigeru SUDO, Pavel GONCHAROV¹⁾, High-Energy Particle Group, ICH Group and LHD Experimental Group

National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292, Japan

1)

Department of Plasma Physics, Saint Petersburg State Polytechnic University, 29 Polytechnicheskaya Street, 195251, Russia

(Received 30 November 2011 / Accepted 2 August 2012 / Published 15 October 2012)

Abstract

The pellet charge exchange technique (PCX), which is a combination of the compact neutral particle analyzer and an impurity pellet, is a unique method to observe the radial energetic particle distribution. There are not only charge exchange reactions between the hydrogen in the pellet and a proton, but also between the partially ionized carbon in the pellet and the proton. The neutralization factor from energetic ion to neutral particle could be deduced from the electron temperature and the electron density of the pellet cloud. The radial profiles of energetic particle distribution were measured and compared in various ion cyclotron resonance heating (ICH) plasmas. The energetic particle flux significantly increased at the resonance layer created by the ICH. PCX provides more precise information about the resonance layer than conventional neutral particle diagnostics.

Copyright (c) 2012 The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

PCX, LHD, TESPEL, pellet cloud, ICH, resonance layer, energetic particle, second harmonics

DOI: 10.1585/pfr.7.2402138

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This paper may be cited as follows:

Tetsuo OZAKI, Naoki TAMURA, Tetsuo SEKI, Hiroshi KASAHARA, Shigeru SUDO, Pavel GONCHAROV, High-Energy Particle Group, ICH Group and LHD Experimental Group, Plasma Fusion Res. 7, 2402138 (2012).