Ion kinetic investigations are performed on a 27.12 MHz capacitively c
oupled parallel plate discharge configuration using argon and oxygen a
s the process gases. The incident ions on the grounded electrode are s
eparated, according to their mass and energy, and the influence of rf-
power density and fetal pressure on the ion mass spectra and, especial
ly, on the ion energy distribution are discussed. In the observed para
meter range, a transition from space charge-limited to mobility limite
d ion transport in the plasma sheath occurs. The ion sheath thickness
can be calculated from the change of the shape of the energy distribut
ion with pressure.