Various kinds of plasma are used for industrial applications. Among those, low pressure gas discharge plasma has been recognized to be a most elegant and efficient means for dry processing, such as treatment and deposition of material, etching, oxidation and polymerization.
For this reason, special attention is directed toward low pressure gas discharge, which is driven by direct current (d.c.) or high frequency (h.f.) electric field. The plasma thus produced is a partially ionized one with low-temperature and low-density. Therefore, the properties of the discharge as well as the plasma are governed by various collision processes.
In this note, the initation and sustainment of the d.c. and h.f. discharges are considered. Also, the positive ion sheath formed around the electrode and the positive column with charge neutrality are separately discussed. Further, detailed descriptions are given to elucidate peculiar phenomena appearing in the h.f. discharge. These include the trapping of the charged particles, the sheath potential as affected by the asymmetrical electrode area and the self-bias voltage.
