Acoustic instabilities and plasma heating resulting from energetic ion beam injection

Electrostatic instabilities excited by an energetic ion beam are examined as a possible plasma heating mechanism. The dielectric properties of electrostatic waves in a uniform magnetized plasma are studied for a warm ion beam propagating at an arbitrary angle with respect to the magnetic field. The instability threshold and growth rate are calculated for the resonant ion-beam and ion- acoustic modes. The quasi-linear moment equations are used to follow the self-consistent evolution of the macroscopic plasma properties. A comparison is made with the collisional slowing-down rate of the beam. For the fastest growing modes it is found that the quasi-linear slowing-down time is significantly shorter than the coffisional slowing-down time.