Power limitations of the cw He-Hg laser

The variation of output power with discharge current in the hollow-cathode cw He-Hg laser has been investigated. In strong contrast to the comparable data for the positive-column discharge, the 6150 Å transition shows no turnover in output power with increasing current. Laser powers approaching 100 mW (cw) have been achieved at 6150 Å using a 3mm-bore, 50cm-long tube. Investigation of the excitation mechanisms for the 6150 and 7945 Å transitions confirms both are excited by thermal energy charge transfer reactions.