Electric-discharge ultraviolet-preionized HgBr laser with an active volume of 1 liter, an output pulse energy of 1.4 J, and an efficiency of 0.7%

A report is given of the construction of an electric-discharge HgBr laser having a ~ 1-liter (3 X 4 X 900-cm) active volume and preionized through a grid electrode by ultraviolet radiation from a spark array. The laser chamber was filled with neon containing 2% of nitrogen to a total pressure of 3 atm; it was then heated to 150–170 °C. The density of the HgBr vapor was 5 X 10¹⁶ cm ^{– 3}. An output pulse energy of 1.4 J was a record value for an HgBr laser preionized by ultraviolet radiation and characterized by an efficiency of 0.7%. This was achieved, firstly, by ensuring that the spark gaps of the ultraviolet radiation source were closely spaced (more than 2 gaps per square centimeter) in the immediate vicinity of the grid electrode (1 cm) and, secondly, by using a system for exciting the gas mixture with a high-voltage pulse (prepulse) applied to the laser electrodes 0.5–1 μs before the start of the main discharge.