| Abstract: | Hollow Cathodes (HC) usually consists of a metal tube impregnated in its interior with a low work function (thermo-emitter) material. A voltage is applied between the HC and the anode which is located outside of the HC. Gas flowing along the HC is ionized by electron impact. Free electrons are always present, at least in very small proportions, before the plasma formation starts. Those free electrons gain energy from the applied electric field and ionize some molecules of the flowing gas. The repetition of the process leads to a cascade of ionizations which are largely compensated by recombination of the ions at the cathode wall and a steady state is reached. The plasma so formed is able to support large electron current densities.
In the seminar will be explained several theoretical models of the Hollow Cathode plasma that have been proposed in order to determine the spatial distribution of plasma parameters inside the HC. |
