Experiments with Controllable Application of Radial Electric Fields in GDT Central Cell

Influence of the radial electric field on the MHD-stability was studied in the GDT using a set of biased end plates and limiters that provided a possibility to control radial profile of the plasma potential. It was shown that biasing of the limiters or peripheral end plate section to a potential of 250 - 300 V leads to considerable increase of the energy confinement time due to reduction of the electric field in the plasma volume. MHD-stability of the plasma was observed in this regime with the remote anchors not energized. The possible stabilization mechanism associated with radial electric field is discussed.