Turbulent transport in magnetic confinement: how to avoid it

Abstract

From recent tokamak research, there is considerable experimental evidence that superthermal ions slow down and diffuse classically in the presence of turbulent fluctuations that cause anomalous transport of thermal ions. Further more, research on field-reversed configurations at Los Alamos is consistent with the view that kinetic effects suppress instability growth when the ratio of plasma radius to ion orbital radius is small; turbulence is enhanced and confinement degrades when this ratio increases. Motivated by these experiments, we consider a plasma consisting of large-orbit non-adiabatic ions and adiabatic electrons. For such a plasma, it is possible that the anomalous transport characteristic of tokamaks can be avoided and a compact reactor design becomes viable.