Flute instability of plasma in a gas-dynamic trap
Abstract
The flute instability of a plasma confined in a gas-dynamic trap where the mean free path of the particles λ is small compared with the trap length L is examined. In analysing the instability the influence on the oscillations both of the energy and particle injection which maintains the system in steady state and also of the damping of perturbations which results from plasma flowing out through the mirrors is included. An expression is obtained for the growth rate of the flute instability which is used in formulating the necessary and sufficient criterion of stability. It is found that in certain conditions, even when the flute instability has been suppressed, an instability with a characteristic growth rate of the order of the reciprocal of the plasma life-time can still develop in the trap. The effects examined in the paper are also of interest for open traps with λ > L.