Large amplitude striations in an RF discharge

Paired luminous rings separated by a narrow dark-gap are observed in a radio-frequency discharge. In the discharge, a 0.8 - 5 MHz radio-frequency field with an amplitude of ±0.5 - ±1.7 kV is applied to two 100 mm wide electrodes, separated by 20 - 100 mm each other, surrounding a 100 mm diameter pyrex glass tube containing hydrogen gas of 1 - 50 Torr. The number of paired rings, which are axially symmetric with respect to the midplane of two electrodes, increases with the hydrogen gas pressure. The time resolved light intensity measurements show that the outer rings near the electrodes start to appear early in time then the inner rings are produced later. (author)