Measurements of Hydrogen Atom Density in a Z-Discharge Plasma Using Intensities of Hα and Hβ Lines

Abstract
A study is presented on the time evolutions and radial profiles of the hydrogen atom density in a Z-discharge without pinched states. The time evolutions of the hydrogen atom density n H were experimentally determined from the ratio of the chord-averaged intensity of the Hα line to that of the Hβ line. The two line intensities were simultaneously measured by splitting a collimated radiation beam from the same position into two beams. The hydrogen atom density evaluated from the intensity ratio was sufficiently low under conditions of a high discharge current. For a pressure of 20 mTorr, the magnitude of the density reached 0.1×1014 cm-3 at a time 50 µs after the initiation of the Z-discharge. The radial profiles of n H, obtained from the chord-averaged intensities of Hα line, showed an annular-type distribution.