PLASMA-OSCILLATIONS INDUCED BY TANGENTIALLY INJECTED NEUTRAL BEAMS

A stability analysis is carried out for the m = 1, n = 1 internal kink mode, in the presence of energetic circulating particles. It is found that, including the effect of finite radial particle-orbit excursion, the energetic particles that cross the q < 1 region can resonantly interact with the mode and destabilize it. For typical tokamak parameters, the growth, rate of the instability is comparable to the one of the corresponding trapped-particle induced instability [6]. Such an instability could explain the experimental observations of ''fishbone'' oscillations during tangential neutral beam injection [2].