Abstract

It is known since many years that with a capacitively coupled transverse radio frequency (ccrf) discharge the same blue (441.6 nm), green (533.7 nm and 537.8 nm), and red (635.5 nm and 636 nm) lines can be excited in a He-Cd⁺ mixture as with a hollow cathode discharge. However, so far a quantitative specification of this laser is missing. Therefore it will be given here at least in parts. The discharge was operated between 400-mm-long and 4-mm-wide electrodes in a ceramic alumina oxide tube of 4 mm inner diameter and 400 mm length that was inserted into a fused silica tube ended off in Brewster windows. The Cd vapor was fed into the tube by an oven attached to the fused silica tube half way between the windows. A nearly homogeneous, controllable Cd vapor distribution could be achieved within the A1₂O₃ tube by this method. The discharge was maintained by a rf generator operating at 13.56 MHz with an output power up to 400 W. To obtain a uniform discharge between the two electrodes a special matching was used which symmetrizes the rf voltage.

© 1994 IEEE