Possibility of electric field bifurcation and internal transport barrier formation in LHD plasma

Theoretical analysis of the electric field bifurcation is made for the LHD plasma. For given shapes of plasma profiles, a region of bifurcation is obtained in a space of the plasma parameters. In this region of plasma parameters, the electric field domain interface is predicted to appear in the plasma column. The reduction of turbulent transport is expected to occur in the vicinity of the interface, inducing internal transport barrier. Within the present simple model, the electric field bifurcation associated with the internal transport barrier is predicted to be realized for the parameter of T_e(O) ≃ 2 keV and n(0) ≃ 10¹⁸(m^-3). The boundary of the region of multiple solution is characterized by a scaling T_e(0) ∼ [n(0)^0.4.