Propagation of a nonrelativistic electron beam in a plasma in a strong magnetic field has been studied using electrostatic one-dimensional particle simulation models. Electron beams of finite pulse length and of continuous injection are followed in time to study the effects of beam-plasma interact ion on the beam propagation. For the case of pulsed beam propagation, it is found that the beam distribution rapidly spreads in velocity space generating a plateaulike distribution with a high energy tail extending beyond the initial beam velocity. This rapid diffusion takes place within several amplification lengths of the beam plasma instability given by (f^b' V o where ""ni %> and V Q are the target plasma, beam plasma frequencies, and the beam drift speed, respectively. This plateaulike distribution, however, becomes unstable as the high energy tail electrons free-stream, generating a secondary beam. A

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

TJiU tttrk MM supported ty the U.S. OepertiMnc of Energy ttofl, publication, ute and disposal, in whole or in part, by or for tii* United States jovcrnmene '3 permitted.