MHD stability of a hot rotating plasma: A brief review of PSP-2 experiments

The paper presents a review of theoretical and experimental studies of plasma stability in systems with a rotating plasma (devices with crossed E×B fields) carried out in 1975–1985 at the Institute of Nuclear Physics, Siberian Branch of the Russian Academy of Sciences. The first group of studies involves numerical simulations based on the classical work by M. Rosenbluth and A. Simon. The conditions in which the centrifugal flute instability in the plasma of such devices is absent were investigated. It is shown that, in order for this instability to be suppressed, it is necessary that the following two requirements be satisfied simultaneously: azimuthal plasma rotation should be sheared and the longitudinal electric current should be strong enough (the so-called line-tying effect). The second group of studies involves experiments in the PSP-02 and PSP-2 devices. The main experiments were carried out in PSP-2 at proton energies of 15–20 keV (30–40 keV in the laboratory frame) and electron energies of a few kiloelectronvolts, the plasma potential being up to 0.4 MV. The possibility of completely suppressing centrifugal flute instability was demonstrated experimentally for the first time. In the stable (classical) regime, the only processes are ionization and proton charge exchange. When centrifugal instability is suppressed, no other types of MHD plasma activity are observed.