Stability of thermal ions confined by rigid-rotor electron clouds in Penning fusion systems

In the Penning fusion device, a spherical cloud of electrons, confined in a Penning-type trap, creates the ion-confining electrostatic well. Calculati ons performed with a bounce-averaged Fokker-Planck model have suggested tha t highest fusion energy gains in Penning fusion systems occur when the ion population is predominantly Maxwellian. However, the question arises about the stability of the electron cloud in the presence of thermal ions. Here, a stability analysis of rigid-rotor electrons confining thermal ions is per formed. The results indicate that such configuration is absolutely stable t o electrostatic perturbations for arbitrary rigid-rotor electron distributi ons. (C) 2000 American Institute of Physics. [S1070-664X(00)02711-7].