Bootstrap current theory and experimental evidence

Abstract

A simple physical picture of the bootstrap current is presented and the classical and nonclassical theory of it is briefly discussed. The experimental evidence for the existence of this current in multipoles, stellarators and tokamaks is reviewed with the main emphasis being on its existence in tokamaks. Recent data from JET indicating the presence of large bootstrap currents ( approximately 1 MA) in H-mode plasma is presented. Finally the implications of the existence of this current in future high temperature tokamak experiments is discussed, with particular emphasis on its role in broadening the current profile and the stabilisation of sawteeth.