Transition from classical to vortex diffusion in the Wisconsin levitated octupole

Abstract

The transition between the anomalous diffusion previously reported in pulsed multipoles and classical diffusion has been observed at low poloidal magnetic fields, B≲100 G. The helium plasma parameters were ne =1010–1011 cm−3, Ti∼Te∼0.2 eV. The anomalous diffusion seen at higher magnetic fields scaled like vortex diffusion, but the transition point corresponds to a nonthermal vortex spectrum with effective temperature, T*∼106 eV. Transition from anomalous to classical regime is observed on a classical viscous damping time scale.