Collisionless drift instability and ion heating in a current-carrying inhomogeneous plasma

Abstract

Low-frequency collisionless drift waves grow intensively when electron currents parallel to a magnetic field are drawn in a single-ended Q machine. For a smaller electron drift velocity, the measured dispersion relations of the wave are consistent with the linear theory of the current-driven collisionless drift instability. The temperature of the ions is observed to increase anisotropically concomitant with the growth of the drift wave. The heating rate is found to be proportional to the wave energy estimated from the saturated frequency spectrum and its dependence on the electron drift is measured to be of the form (u/ve)4. A further increase in the electron drift results in the excitation of an ion acoustic wave and a flute-like instability.