Operating characteristics, absorptivity/reflectivity measurements, and pulse system design of the NPS Hydrogen Fluoride/Deuterium Fluoride Laser.

Abstract

The Hydrogen Fluoride/Deuterium Fluoride Laser is a fast flow electrical discharge operated chemical laser. Refitting of the subsystems of the laser was completed and lasing was observed utilizing a 100 percent reflectance mirror and a 95 percent reflectance output coupling mirror. The maximum multiline output power obtained was 2.6 watts at 19.0 kV and 475 mA. The data obtained was in general agreement with previously reported data. However, an increase in power output from 1.6 to 2.6 watts was obtained by utilization of a Hipotronics power supply that enabled usage of higher input voltages for SF₆ dissociation. Measurements were also taken over a variation of the He, SF, H, and O flow rates resulting in the change of the optimum flow rates for the above listed gases. The new flows were found to be (1) SF₆ = .7167 grams/second (2) H₂ = .0220 grams/second (3) O₂ = .22 grams/second and (4) He = .05 grams/second. Target reflectivity/absorptivity measurements were taken and a dependence on incidence angle with the laser beam was found. For the P-doped Silicon wafer used, the power absorbed decreased over the range of 25 to 60 degrees. At the 25 degree angle approximately 95 percent of the incident power was absorbed. The reflected power was found to increase with the increase in target angle with approximately 95 percent of the incident power being reflected at 60 degrees. The results of these measurements are in general agreement with previously reported measurements. A design for reconfiguring the HF/DF laser system into a pulsed system was also formulated but was not tested. The design criterion was to utilize a capacitor bank to drop a high voltage pulse across the anodes of the laser.