S. I. Krasheninnikov

Helium transport in the edge plasma of a tokamak reactor

A simple linear diffusive/convective model is proposed for helium transport in the edge plasma of a tokamak reactor. Kinetic effects related to weak collisionality of the plasma are assessed. Results of two-dimensional numerical modelling of helium transport in the edge plasma are presented. Issues of ITER divertor optimization with respect to helium exhaust are considered, with a realistic geometry of the divertor plates taken into account.

Kinetic effects and reversal flows in the tokamak edge plasma

Preliminary results of the edge tokamak plasma simulation in the frame of 3D kinetic Vlasov-Fokker-Planck equations are presented. Currently two versions of the code are developed: one of them is based on a stochastic modeling method, another uses a finite difference approach via split techniques. In both versions, the self-consistent electric field may be calculated from the quasi-neutrality condition, while the sheath potential is obtained from the ambipolarity of plasma flux towards the neutralizing plate. Simplified equations, describing the dense SOL plasma parameters distributions and allowing the analytical solutions are obtained. It is shown, that for the high particle recycling in SOL, the radial scales of the temperature Δ T and densities Δ n are close to each other. The reversal flow is formed within a narrow layer near the separatrix magnetic surface.