Plasma flute oscillation stabilization by means of a feedback system

Considered in this paper is the possibility of stabilizing flute oscillations of plasma in right traps with the aid of a feedback system involving measurement of the radial component of a disturbed electric field. It is assumed that the plasma is confined along the Z axis, while transducers and suppressing electrodes may be arranged at different distances from the axis of the system. For the flute oscillation equation in which the finite length of the plasma along the magnetic field is taken into account, an eigenvalue problem is examined with boundary conditions simulating the feedback system. It is assumed that the transfer factor is independent of frequency and that the azimuthal modes are separated. Numerical methods are used to study effects of the longitudinal dimensions of plasma, magnetic field gradient and vacuum region size on stability. Oscillation stability boundaries have been derived, depending on the feedback factor values and the transducer location