Confinement of Plasma in a Magnetic Cusp Field Combined with an Electrostatic Field

Abstract

The confinement of a plasma in a magnetic cusp field combined with an electrostatic field was studied. Theoretical analysis shows that the cusp loss can be suppressed with the use of an adequate electrostatic field. The macroscopic stability of a plasma in such combined fields was also theoretically examined and it was concluded that there is a region in which the plasma is stable against the interchange instability. An apparatus was constructed and preliminary experiments were carried out. The electric field was successfully applied to the plasma, which rotated around the symmetric axis with a uniform angular velocity. When the electric field of a proper strength was applied, the light emitted from the plasma decayed more slowly than in the case of no electric field. It is conjectured to be due to the reduction of the cusp loss of plasma particles.