Theoretical study of prepulse-main discharge XeCl lasers

To achieve high energy deposition efficiency of discharge pumped XeCl lasers, the energy storage capacitor should be charged to a voltage about two times of the self-sustained voltage of the laser system. Unfortunately, this voltage is too low to initiate a uniform glow discharge. To speed up the avalanche process, prepulse-main discharge technique was proposed in which, a high voltage breakdown pulse and a sustaining pulse are provided by separate circuits. In this paper, the discharge characteristics of prepulse-main discharge XeCl lasers and the effects of prepulse circuit parameters are investigated by means of a kinetic code. The modeling shows that an appropriately designed prepulse circuit could speed up the breakdown process effectively. The key point for this technique is to design a prepulse circuit which multiplies the electron density from its initial value to about 10 exp 14/cu cm in a reasonably short time during which the main discharge circuit is disconnected from the electrodes. Optimum values of capacitance, charge voltage of the prepulse circuit, delay time between prepulse and main discharge for energy deposition efficiency, XeCl* formation efficiency and laser performance have been investigated in the present work.