ABSTRACT
The electron energy distribution function (EEDF) has been measured at different phases of the rf cycle in a high frequency electrodeless Ar-Hg discharge at frequencies f = 25-250 kHz. In this frequency range, the driving frequency co = 27f is much larger than the inverse of the ambipolar diffusion time, so the plasma density remains constant during an rf period. On the other hand, co is comparable to the characteristic frequency of electron energy change w=2QI3T, (where Q is the electron energy loss rate per electron) allowing modulation of the electron temperature T during an rf cycle. The strong dependence of the electron momentum transfer and impact excitation cross-sections on electron energy (temperature) can lead to significant differences in the time averaged rates of elastic and inelastic processes compared to those calculated in the dc (timeaveraged) approximation.
