10 kV/150 mA current regulated power supply for helium cadmium ion laser (Paper No. CP 32)

The design and fabrication of a current regulated power supply that is being used for the He-Cd Laser at Nuclear Physics Division is reported. This laser is about 250 Cms. long and produces output power at 4416A in excess of 100 mW. The presence of cadmium vapour alters the net impedence of the tube and hence also the current through the tube. The current variation can be inhibited by employing a constant current power supply. The initial striking voltage to start discharge is 10.0 kV. while for sustaining the discharge a voltage of 6 kV. is adequate. Further in the presence of cadmium vapour the discharge voltage drops to 4.5 kV. It is clear that pre regulation of voltage is necessary. This is achieved by semiconductor rectifiers connected back to back in series with primary of transformer. (author). 2 figs