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Author(s):
Y. Matsumoto, S.-I. Oikawa and T. Watanabe
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Title:
Field Line and Particle Orbit Analysis in the Periphery of the Large Helical Device
Date of publication:
Sep. 2001
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Key words:
LHD, peripheral plasma, chaotic field line, particle orbit, potential control
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Abstract:
Magnetic field lines and particle orbits are analyzed in the periphery of the Large Helical Device (LHD), which is called chaotic field line region. The inner and outer borders of the chaotic field line region are determined precisely. It is found that the particles confined in the chaotic field line region are classified into two groups that are passing particles and reflected particles. Passing particles have long lifetime, because of the long connection length of the chaotic field line. Reflected particles are confined because they are trapped by the magnetic mirror in the chaotic field line region due to the strong adiabaticity. There exist the exceptional particles among the reflected particles. The mechanisms of the exceptional particles are described by the analysis of the magnetic structure in the chaotic field line region. The precise comparison between R_{ax} = 3.75m and R_{ax} = 3.6m magnetic configuration is carried out.
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