Abstract: A transverse flow uniform droplet generator and method for its use. The droplet generator, such as is used with a gas laser system, produces singlet oxygen from a flow of droplets of liquid basic hydrogen peroxide (BHP) reacting with a transverse a flow of He/Cl.sub.2 gas mixture. The resulting flow of singlet oxygen travels in the same direction as the He/Cl.sub.2 gas mixture and the unreacted BHP is collected on the opposite of the reaction volume from which it enters. Very uniformly-size BEP droplets are formed by an injector which specific mechanical resonance characteristics and the flow of the BHP and the gas mixture in the generator volume is also carefully controlled.

Abstract: The uniform droplet injector assembly is a rigid, low mass injector having a plurality of nozzles therein attached to a manifold. The manifold vibrates by piezoelectric actuators and springs in combination. The droplet injector array allows the process stream to flow through the injector assembly with the droplets uniformly dispersed into this stream. The moving parts such as the injector assembly, springs, and actuators are structurally resonant at a frequency near the droplet formation frequency. The colinear, spring/actuator configuration minimizes internal stresses due to manufacturing tolerances, preloading requirements, temperature changes, and cyclic operation in a large area generator. The linear spring/actuator configuration has low stiffness in the vibration direction and high stiffness in transverse direction to eliminate motions which would cause nonuniformly sized droplets.

Abstract: A very compact flow loop for circulating gas through a pulsed laser or other pulsed discharge device is disclosed. An apparatus, having greater resistance to flow and shock wave propagation in the upstream direction, preferentially converts energy from the pulsed discharge residue into flow energy and causes flow through the discharge region in the desired downstream direction. The large available work in the discharge residue lets the efficiency of the conversion apparatus be very low and yet still provide sufficient flow power to circulate gas for purging a conventional flow loop without using a separate input of power to drive the purge flow. Moderate conversion efficiency provides sufficient flow power to allow compact, high loss components to be used for a very compact flow loop with no external flow circulation power and no rotating components.

Abstract: A spark gap switch system is disclosed which is capable of operating at a high pulse rate comprising an insulated switch housing having a purging gas entrance port and a gas exit port, a pair of spaced apart electrodes each having one end thereof within the housing and defining a spark gap therebetween, an easily condensable and preferably low molecular weight insulating gas flowing through the switch housing from the housing, a heat exchanger/condenser for condensing the insulating gas after it exits from the housing, a pump for recirculating the condensed insulating gas as a liquid back to the housing, and a heater exchanger/evaporator to vaporize at least a portion of the condensed insulating gas back into a vapor prior to flowing the insulating gas back into the housing.

Abstract: A spark channel purge system for high pulse repetition frequency spark gap switches. A purge fluid having a liquid state and a gaseous state is caused to flow through a spark gap channel, at least a portion of the purge fluid passing through the spark channel being in the gaseous state. The purge fluid is supplied in its liquid state by a purge fluid source. In some embodiments, the purge fluid source is a recirculating flow loop which includes a heat exchanger, while in another embodiment, the purge fluid source is a low-pressure liquid storage vessel. The heat exchanger transfers waste heat from the spark gap switch via the purge fluid flowing from the spark channel into the purge fluid supplied by the purge fluid source. This causes at least a portion of the liquid purge fluid to change to the gaseous state. In some embodiments, the spark channel purge system is suitable for a closed loop system, while other embodiments are suitable for an open loop system.

Abstract: A spark gap switch apparatus is disclosed which is capable of operating at a high pulse rate which comprises an insulated housing; a pair of spaced apart electrodes each having one end thereof within a first bore formed in the housing and defining a spark gap therebetween; a pressure wave reflector in the first bore in the housing and spaced from the spark gap and capable of admitting purge flow; and a second enlarged bore contiguous with the first bore and spaced from the opposite side of the spark gap; whereby pressure waves generated during discharge of a spark across the spark gap will reflect off the wave reflector and back from the enlarged bore to the spark gap to clear from the spark gap hot gases residues generated during the discharge and simultaneously restore the gas density and pressure in the spark gap to its initial value.

Abstract: A spark gap chamber to promote mixing and/or translation of hot residue gases into the surrounding gases in an unpurged spark gap chamber. The shock (and expansion) waves are reflected from walls and other structures within the spark gap chamber to cause the hot residue gases formed by a spark between the electrodes in the spark channel to mix with the unheated gases found elsewhere in the spark gap chamber. The spark gap chamber walls can be symmetric and shaped to cause the reflected shock wave to converge simultaneously on the spark channel or to focus on different portions of the spark channel at different appropriate times. Alternatively, the spark gap chamber walls can be asymmetric with respect to the spark channel and can force the hot residue gases away from the spark channel.

Abstract: A method and apparatus for tailoring the concentration profiles of reactant and diluent species in the gas stream of a pulsed chemical laser provide a substantially uniform initial chemical reaction rate and index of refraction across the laser cavity. In the preferred embodiment, a gas stream is composed of the two reactant species, molecular hydrogen (or deuterium) and molecular fluorine, diluent species argon and helium, and a trace of oxygen as a preinitiation inhibitor. A substantially uniform initial chemical reaction rate within the laser cavity is obtained by tailoring the concentration profile of the fluorine across the cavity to compensate for the variation in absorption of UV initiation radiation across the cavity along the axis of initiation.