Current Profile Control and Improved Confinement in JT-60 Tokamak Plasmas

Abstract

In a tokamak, one of toroidal shaped magnetic confinement systems, a large toroidal current induced in a high temperature plasma produces helical magnetic fields to confine the plasma itself. Therefore, the spatial structure of confining magnetic fields can be determined by measuring the profile of the plasma current. This can lead to the understanding of the transport and stability properties of the plasma. In this review, a novel technique using the motional Stark effect to measure the current profile in the JT-60 tokamak is shown. With the aid of this technique, a new operational mode of a tokamak, with which the plasma confinement can be substantially improved, has been discovered. Recent experimental results of confinement improvement with the current profile control are presented.