Abstract:

A theoretical analysis is made of the Kelvin-Helmholtz instability in a collisionless, low beta plasma, with Te>>Ti, in the regime of frequencies corresponding to electrostatic ion-sound and ion cyclotron oscillations. The dielectric tensor for linear oscillations of a plane parallel flow with velocity gradients is obtained from a simple ion fluid and electron in Boltzmann equilibrium, model. The relationship between radiation of waves from a tangential discontinuity surface and the instabilities of the system is brought in evidence through energetic considerations. Stability diagrams are given with the Mach number (defined with the Bohm velocity) as a parameter. An interpretation of the experiments of D'Angelo and Von Goeler with the Q3 machine is attempted and some suggestive concordances are pointed out.