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Two Dimensional Li Beam Imaging to Study the Magnetic Field Configuration Effects on Plasma Confinement in Spherical Tokamak CPD

R. BHATTACHARYAY, H. ZUSHI¹⁾, T. MORISAKI²⁾, K. KIKUKAWA, S. WATANABE, Y. INADA, M. HASEGAWA¹⁾, H. TSUCHIYA³⁾, K. N. SATO¹⁾, K. NAKAMURA¹⁾, M. SAKAMOTO¹⁾, H. IDEI¹⁾, K. SASAKI, H. XU, F. WANG, S. KAWASAKI¹⁾, H. NAKASHIMA¹⁾ and A. HIGASHIJIMA¹⁾

Interdisciplinary Graduate school of Engineering Science, Kyushu University, Kasuga, Fukuoka, 816-8580, Japan

1)

Research Institute of Applied Mechanics, Kyushu University, Kasuga, Fukuoka, 816-8580, Japan

2)

National Institute for Fusion Science, Toki 509-5292, Japan

3)

Graduate Universty for Advanced Studies, National Institute for Fusion Science, Toki 509-5292, Japan

(Received 4 December 2006 / Accepted 21 April 2007 / Published 20 November 2007)

Abstract

Two dimensional lithium beam imaging technique has been applied in the spherical tokamak, CPD (Compact Plasma wall interaction experimental Device), to study the effects of various magnetic field configurations on RF plasma confinement topology. The performance of the lithium sheet beam is absolutely calibrated by a quartz crystal monitor. Experimental results show that plasma initiation takes place at the electron cyclotron resonance layer in a simple torus configuration and then it expands quickly to the low magnetic field side. Different magnetic field configurations critically affect the RF plasma confinement topology. A sharp lower boundary exists for the RF plasma in magnetic null configuration. Magnetic connection length plays the key role in defining plasma boundary and the critical value of connection length for plasma to exist in CPD is found to be ∼ 5-6 meter for a given pressure condition.

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

Keywords

lithium beam, spherical tokamak, plasma confinement, plasma boundary, magnetic field configurations, connection length, decay index

DOI: 10.1585/pfr.2.S1103

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References

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This paper may be cited as follows:

R. BHATTACHARYAY, H. ZUSHI, T. MORISAKI, K. KIKUKAWA, S. WATANABE, Y. INADA, M. HASEGAWA, H. TSUCHIYA, K. N. SATO, K. NAKAMURA, M. SAKAMOTO, H. IDEI, K. SASAKI, H. XU, F. WANG, S. KAWASAKI, H. NAKASHIMA and A. HIGASHIJIMA, Plasma Fusion Res. 2, S1103 (2007).