Abstract: In a pulsed gas laser, pulses of electrical or other energy are desirably converted in part into pulses of quantum mechanical pumping of the lasable gas, and unavoidably converted in part into pulses of heating of the lasable gas. According to this invention, efficiency and economy of operation are enhanced by exploiting the pulses of heating to propel and recirculate the gas through cooling means to freshen it thermally for further cycles of lasing, utilizing a structure comprising an acoustically tuned duct and an acoustic diode to establish proper phasing and direction of the pulsed and recirculating operation. The invention, although applicable to other gas lasers, is particularly applicable to electron beam ionized, electrical current sustained lasers. The invention reduces if not eliminates the cost, bulk and other disadvantages of a mechanical pump or other conventional recirculation equipment.

Abstract: In a laser, a gaseous mixture is suitably heated to a first temperature and at a first pressure to provide a large energy content. The gaseous mixture comprises a polyatomic gas such as carbon dioxide having an upper level, ground state, and intermediate level. It also comprises at least one auxiliary gas such as nitrogen, having an energy level substantially resonant with one of the above-mentioned levels and a relaxation time operative to increase the ratio of the relaxation time of the upper level to that of the lower level. A chamber receives the mixture via a supersonic nozzle proportioned to provide a flow time short compared to the relaxation time of the upper level and long compared to the relaxation time of the lower level and the gas is throttled to a relative low second gas temperature and pressure, whereby population inversion exists in the chamber. An optical resonator defines a light path beam through the gaseous medium in the chamber.

Abstract: A cardiac output monitor. The monitor receives signals representing radial arterial pressure, balloon pressure, balloon drive and balloon volume from an intra-aortic balloon pumping system. These signals are processed to define balloon depletion pressure (P.sub.1), ventricle ejection pressure (P.sub.2), balloon volume (BV) and heart rate (HR). The monitor displays the cardiac output according toCardiac output = (P.sub.2 /P.sub.1) (BV) (HR)the monitor also indicates certain improper pumping system operations and can provide a continuous display.

Abstract: Lasing action is electrically induced in a supersonic flow of nitrogen gas, resulting in an increase in pulse repetition rate to a new order.