Effect of collector potential on the beam-plasma formed by a forevacuum-pressure plasma-cathode electron beam source

摘要

We consider the beam-plasma formed by an energetic electron beam at fore-vacuum pressure, when the beam is terminated by an electron collector plate. We show that in the pressure range of 1-10 Pa, the dependence of beam-plasma density n on the electron beam collector potential phi has a maximum. The maximum plasma density n(m) at the optimum collector potential can be much greater than the plasma density when the collector is at ground or at floating potential. The nonmonotonic dependence n((phi) is found to be caused by the contribution of secondary electrons from the collector to plasma generation.