RF Experiments on the PLT Tokamak

In previous RF experiments on the PLT tokamak, both efficient ion heating with fast magnetosonic waves and current drive with lower hybrid waves have been demonstrated. Recent experiments are concentrating on gaining a more thorough understanding of the physics through changes in the wave launching structures. A pair of quarter-turn, center-fed outside ICRF antennae has been installed in order to make comparisons with the present end-fed, half-turn loops. Three of the half-turn outside antennae have been modified to have carbon Faraday shields. The lower hybrid wave launcher has been changed to an eight waveguide grill with individual guides of half the width of the previous grill. This change permits the launching of a slower wave spectrum. The new coupler also has tuned dummy waveguide sections on each end in an attempt to reduce reflections in the outer most driven guides