Sorokovyj E. Transport processes in the boundary plasma of the Uragan-3M torsatron

Physical processes have been studied, which are responsible for plasma transport near the boundary of the confinement region and in the divertor region of the Uragan-3M torsatron. Near the boundary, the perpendicular particle transport is largely caused by small-scale low-frequency fluctuations of plasma density and electric field. A considerable part of the total turbulent particle flux is contained in rare short bursts of large amplitude. The spatial distribution of plasma flow in this region is distinguished with a strong up-down asymmetry, where the larger ambipolar flow occurs on the ion toroidal drift side with any magnetic field direction, and the ions dominate in the corresponding non-ambipolar flow. It has been shown that the asymmetry is related to convective loss of fast ions, which are trapped into magnetic field non-uniformities.