THE H-1 RADIO-FREQUENCY SYSTEM AND AN INITIAL STUDY OF PLASMA FORMATION

Eight commercial broadcast transmitters rated at 30 kW PEP 4-26 MHz ar e being commissioned for plasma formation and heating in H-1. These ma y be either excited separately or combined into two antennas by a set of six power combiners. In this paper we describe the various componen ts of the r.f, power transmission system. We present preliminary resul ts using this system for plasma formation in argon and hydrogen with m agnetic fields <2 kG and powers up to 30 kW at 4 and 7 MHz using a sin gle saddle coil loop antenna. We have been able to produce both hollow and centrally peaked plasmas in both gases and have demonstrated that the plasma centre of symmtry shifts with the magnetic field axis as e xpected. In argon, we have achieved a density in the order of 10(18) m (-3) peaked on axis.