Observation of the self-generated toroidal magnetic field in rotamak

An experimental study of the self-generated toroidal magnetic field in rotamak field-reversed configuration plasmas is performed in the case of high input power (200 kW), long-duration (40 ms) discharges. In one round of experiments, the polarity of the toroidal field in the poloidal cross section is different not only from one hemisphere to another but also in radial direction. In another round of experiments, the toroidal field is seen to reverse its sign in the course of a shot. The data for the field are fitted with the vector spherical harmonic functions. The poloidally swirling currents associated with the self-generated toroidal field are shown to contribute to the formation of the two-peak structure of the toroidal plasma current. (c) 2005 American Institute of Physics.