A study of high energy flash rubes and their application to ruby lasers

Abstract

The design of 6½” arc length, xenon filled flash tubes capable of withstanding energy inputs up to 10000 joules is described. The lamp performance is investigated as a function of filling pressure, bore size of lamp between 10 mm and 15 mm, operating voltage, energy input and circuit parameters. The lamp life has been related to input energy, flash duration and the inner wall area of the lamp. Above a given lamp wall loading, the lamp is likely to shatter in the first few discharges. Lamp efficiency, measurements show that for a fixed capacitor bank, operating voltage variation between 1.0 and 2.4 kV does not change the efficiency and that the efficiency is lower when a lamp is lightly loaded. Flash duration is almost independent of bank voltage and tube bore. The peak light intensity is increased and the flash duration decreased by a factor 2 when the lamp series inductance is changed from 450 μH to100 μH. Design aspects of a laser system using ruby rods 6½” long x ½" diameter are studied and the output characteristics of six ruby rods of varying optical quality measured. The laser performance does not necessarily depend on the rod optical quality. Measurements of the variation of laser performance with lamp operating parameters show a linear relationship between output energy and input energy above laser threshold. For maximum efficiency, the lamp should be operated with a low bank capacity, a high bank voltage and short flash duration provided the lamp wall loading limit is not exceeded. The 10 mm bore lamp gives the highest efficiency. Measurement of the output beam divergence shows that the ruby rods giving the lowest beam divergence are of the best optical quality.