Some results from a systematic study on the impedance matching conditions and on the longitudinal power distributions in planar rf discharges forCO2lasers, are given. They show that both plasma impedance and voltage distribution are different in cw and pulsed discharge modes revealing the importance of parameters such as the interelectrode temperature distribution and the local gas density and composition. These parameters have to be taken into account when designing matching networks and voltage smoothing schemes. ©1997 American Institute of Physics.