Magnetic Configuration in the Helical Device and Formation of the X-point in Helical Plasmas upon Injection of High Energy Particles

M.YAKOVLEV, O.MOTOJIMA1), S.INAGAKI1), A.SHISHKIN2), A.Komori1)

Department of Fusion Science, The Graduate University for Advanced Studies, 322-6,Oroshi-cho, Toki-city, 509-5292 Japan
1) National Institute for Fusion Science, Toki-city, Gifu 509-5292, Japan
2) Institute of Plasma Physics, National Science Center "Kharkov Institute of Physics and Technology",Kharkov-108, UKRAINE
and
Department of Physics and Technology, Kharkov "V.N.Karazin" National University, Kharkov-77, UKRAINE

It is necessary to improve plasma confinement for fusion reactor. The radial electric field and its shear can suppress the plasma turbulence, and thus the control of electric field is now very important issue. One of the candidates to control the electric field in plasma is injection of the charged particles proposed in [1, 2]. In this paper, additional configuration effect of injection of high energy charged particles in plasma is presented. The injected high energy charged particles drive the localized currents in plasma, and thereby they can modify the magnetic field structure, particularly can form the X-point. The helical magnetic configurations with X-points, which can be realized on LHD are proposed.
The analytical description of X-point due to the localized current is presented on the base of magnetic surfaces function with analysis. The helical filament current is used to calculate the magnetic flux surfaces. The formation of large ∇n/n region in magnetic configuration with the X-point by localized current is predicted. The bifurcation of the electric field is expected by change in ∇n/n [3].

References

[1] O.Motojima, A.A.Shishkin, S.Inagaki, K.Y.Watanabe, Nucl. Fusion 40 (2000) 833

[2] S.Inagaki, O.Motojima, A.Shishkin, J. Plasma Fusion Res. SERIES 3 (2000) 485

[3] K.Itoh and S.Itoh, Plasma Phys. Controlled Fusion 38 (1998) 1