STABILIZATION OF FLUTE INSTABILITY BY MEANS OF HIGH FREQUENCY FIELD

Abstract

Flute instability is studied theoretically from the point of view of non-linear particle interaction under inhomogeneous high frequency field whose electric field component is parallel to confining magnetic. field. At first, kinetic equations with nonlinear term are solved by neglecting the non-linear term, i.e. by linear approximation. Using the linear solution, a first order non-linear solution is obtained and similarly a second order non-linear equation is solved. These solutions of the kinetic equations are utilized for induction of the dispersion relation of Flute instability. The interaction of the high frequency field with the instability are supposed to scour as a result of the additional induced particle motions paraller to the wave number Vector of the instability. Effects of the field on the instability are considered from the two points of view; one is attributed to the electron drifts and the other is owing to the periodic displacement of ions or electrons oscillating with the various inherent frequencies. The instability can be stabilized by the electron drifts whose velocities are larger than those of the ions drifted by the driving force of the instability and moreover may be easily stabilized by the additional periodic displacements of ions or electrons, superimposed on the above electron drifts. These displacement are owing to the high frequency field whose frequency is more resonant to half the ion or electron cyclotron frequency.