Influence of Radial Electric Field on High-Beta Plasma Confinement in the Gas Dynamic Trap

One of the most important subjects of the GDT research program is MHD-stability and transversal transport of high pressure two-component plasma. Positive influence of radial electric field on the plasma confinement was demonstrated in previous experiments on the GDT in regimes without any special MHD stabilizers. In recent experiments it was observed that stable plasma confinement always corresponds to intermittent distribution of biasing potential on limiters and plasma dumps. It was shown that enhancement of plasma confinement time corresponds to the radial electric field in the range of 15-40 V/cm and one induces the sheared plasma rotation. Regime with grounding of all radial electrodes was typically unstable with plasma confinement time two times lower than gas dynamic flow time. Therefore sheared rotation can stabilize MHD modes of high two-component plasma in the GDT experiment. It is also shown that contact between plasma and radial electrodes is essential but can not completely provide MHD stability in GDT.

Measurements using special combined probe were carried out to study fluctuation induced transversal transport and allowed to conclude that cross field transport is negligible and does not play essential role in regimes with sheared plasma rotation.