Time evolution of the space-charge sheath in an rf hollow cathode

We have earlier shown that the inclusion of secondary and fast electrons, in addition to slow, thermalised electrons, give a wider space-charge sheath than with just slow electrons in an atmospheric pressure radio frequency hollow cathode. In this work we extend the previous work by including collisions between ions and neutrals by considering the motion of the ions to be mobility limited. To account for the slow and the fast electrons observed in hollow cathodes, we include two groups of Boltzmann dristributed electrons with different temperatures. In addition, we include secondary electrons created at the electrode surface. We look at the time evolution of the potential in the sheath and we also compare the sheath structures for atmospheric and low gas pressures.