Structure of short-wavelength drift modes and transport in a toroidal plasma

Abstract

Short-wavelength fluctuations, such as electron and ion drift waves, may be one cause of anomalous transport in toroidal plasmas. The purpose of this paper is to establish the radial structure of these modes and to clarify some discrepancies in the literature. The conventional form of toroidal drift modes can occur only at isolated plasma radii and are unlikely to be the source of a universal transport. However, a more recently described class of electron and ion drift modes can occur at all plasma radii. They have a structure consistent with an anomalous transport exhibiting the Bohm scaling with magnetic field and decreasing with plasma rotation.