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(TH/P2-11) Profile Relaxation and Tilt Instability in a Field-Reversed Configuration

H. Ohtani1), R. Horiuchi1), T. Sato2)
1) National Institute for Fusion Science, Toki, Japan
2) Japan Marine Science and Technology Center, Yokohama, Japan

Abstract.  We perform two dimensional electromagnetic particle simulation to investigate the profile relaxation from an MHD equilibrium to a kinetic one and to clarify the physical property of the kinetic equilibrium in the field-reversed configuration. The radial oscillation is excited in order to relax an excess energy in the MHD equilibrium. After this profile oscillation, the system spontaneously relaxes toward a kinetic equilibrium, in which the electron current profile becomes hollow as a result of the combined effects of the gradient B drift near the null point and the ExB drift generated by the ion finite Larmor radius effect near the magnetic separatrix. On the other hand, the ion current profile becomes peaked due to the effect of the ion meandering orbit near the null point. We also study the stability of the obtained kinetic equilibrium against the tilt mode by means of three dimensional full electromagnetic particle simulation. It is found that the growth rate of the tilt instability in the case of the hollow current profile is smaller than that in the case of the peaked current profile.

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IAEA 2003