CONFINEMENT OF NONNEUTRAL SPHEROIDAL PLASMAS IN MULTIRING ELECTRODE TRAPS

A nonneutral spheroidal plasma can be settled in a rigid rotor equilib rium inside a closed conducting cell independently of induced image ch arges on the cell wall if the electrostatic potential distribution on the wall surface is set equal to the sum of the external hyperbolic po tential (r(2) - 2z(2)) and the self-potential produced by the plasma. A confinement system equipped with a train of properly biased ring ele ctrodes can approximately generate any axisymmetric potential, includi ng the above field. Experiments on confinement of electron spheroids i n such a system showed that the confinement time became the longest wh en the condition to diminish the image charge effects was satisfied. T he observed frequency of the centre-of-mass harmonic oscillation of th e plasma in this configuration was in good agreement with the estimate d one.