DE85 005352 Parasitic excitation of ion Bernstein waves is observed from a Faraday shielded fast wave loop antenna in the ion cyclotron frequency range. Local analysis of the Vlasov-Maxwell equations demonstrates the role of plasma density gradient in the coupling process. The effects of plasma density and of parallel wave number on the excitation process are investigated. DrSCLAIMER This report was prepared as an account or work sr.inrorcd by an agency of the United Stales Government. Neither the United Stales Government nor any agency therccr.

Fast wave current drive is demonstrated in the Princeton BCT-I toroid.»X device. The fast Alfven wave, in the range of high ion-cyclotron harmonics, produced 40 A of current from 1 kw of rf power coupled into the plasma by a fast wave loop antenna. This wave excites a steady current by damping on the energetic tail of the electron distribution function in the same way as lower-hybrid current drive, except that fast wave current drive is appropriate for higher plasma densities. PPPL-2238 DE85 015307 Process rfijcioto, "•*• "MPfelMBs, or uJT ** °r "*"mcs ajiv I V? ' " 0r ™V of H~,v

Ion Bernstein wave heating (IBWH) has been investigated on PLT with up to 650 kW of rf power coupled to the plasma, exceeding the ohmic power of 550 kW. Plasma antenna loading of 2 a has been observed, resulting in 80-90? of the rf power being coupled to the plasma. An ion heating efficiency of AT^OJn /P f = 6 x 10'3 eV cnT-VkW, without high energy tail ions, has been observed up to the maximum rf power. The deuterium particle confinement during high, power IBWH increases significantly (as much as 300%). Associated with it, a longer injected impurity confinement time, reduced drift wave turbulence activity, frequency shifts of drift wave turbulence, and development of a large negative edge potential were observed. The energy confinement time, however, shows some degradation from the ohmic value, which can be attributed to the enhanced radiation loss observed during IBWH. The ion heating and energy confinement time are relatively independent of plasma current.