Avco Everett Research Laboratory, Inc.

Arthur R Kantrowitz

George W Sutton

Oswald L Zappa

Jack D Daugherty

Armando Federico

George A Herzlinger

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. Cooling of the recirculating gas is accomplished, at least in part and preferably in large measure, by injection of make-up gas of the lasable gas composition under cooling conditions.

Laser operation with closed gas and tuned duct pulsing

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 to

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Cambridge, MA, United States of America

Arthur R Kantrowitz