Characteristics of radio-frequency-generated plasmas in static magnetic fields

When plasmas are immersed in static magnetic fields a number of plasma instabilities are likely to develop. In turns out that in many cases the type of instability which occurs is in some way related to the method used to generate the plasma. One of the easiest and most common ways of generating a plasma is to pass a radio-frequency current through it. On the other hand, very little is known about the behavior of such RF-generated plasmas when immersed it static magnetic fields. In this paper experiments dealing with the behavior of RF magnetoplasmas are reviewed. It is observed in many different RF experiments that once the static magnetic field exceeds a critical value, the rate at which plasma is transported across the magnetic field is enhanced. This phenomenon, which is known as anomalous diffusion, is accompanied by an onset of fluctuations it plasma density and potential. The characteristics of the experimental onset data are reviewed and compared with the onset conditions of a number of particularly applicable theories. On the basis of this comparison, it is concluded that the ion-acoustic instability comes closest to explaining the experimental behavior of high-frequency discharges in static magnetic fields.