Observation of sheath structure near a rf electrode in a magnetized afterglow plasma

The sheath structure near a rf electrode has been observed by measuring the spatial profiles of the potential and density in a magnetized afterglow plasma. Dependence of the structure on the rf frequency (10–40 MHz) and elapsed time during the afterglow in a periodic, pulsed rf discharge operation are obtained by a time resolved measuring method. The potential close to the electrode is found to increase with increasing frequency and with elapsed afterglow time, without much change of the density profile. In addition, a slight decrease of the electron temperature has been observed during the afterglow time, although the density is roughly constant.