Avco Everett Research Laboratory, Inc.

United States of America As Represented by the Secretary of the Air Force

Jack D Daugherty

George W Sutton

Joseph A Mangano

Jonah H Jacob

Oswald L Zappa

Marvel John Yoder

Howard A Hyman

Arthur R Kantrowitz

David R Ahouse

Sheldon L Glickler

Paul F Kellen

Siva A Mani

David Korff

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 high pressure, high power, continuous wave electro-dynamic laser having one of the electrodes (preferably the cathode) made of a porous conductive surface and a backing material capable of broad band acoustic absorption. Such an arrangement effectively absorbs acoustic disturbances which arises primarily from a linear instability within the resonant cavity of the electro-dynamic laser and thereby substantially reduces output flux modulations within the resonant cavity.

Electro-dynamic laser with acoustic absorbing electrode

This invention is directed towards a scalable X-ray laser comprising means for providing an active medium of lithium-like atoms or ions, means for producing in the active medium a population of low density ions in an excited intermediate metastable state and a visible or near infrared laser to stimulate X-ray lasing by resonant or non-resonant antistokes Raman process to the ground state of the ions. The irradiation of the ions by the laser provides phased or traveling wave excitation which produces the desired directivity. Production of the metastable state is provided by directing energy from a suitable source, such as a high power short pulse laser beam, onto a target material and causing it to radiate as a black body, filtering this radiation to derive radiation in the soft X-ray region, and directing this filtered radiation into the lithium-like vapor.

X-ray laser

Improved electron beam driven gas laser method and apparatus with the achievement of high single pulse energies therefore enabled by establishment of a magnetic field in a direction substantially parallel to the desired direction of electron beam propagation into a gas. The applied magnetic field is made substantially uniform and sized to exceed that of the self induced magnetic field of the current established by the electron beam, alone or in combination with a discharge current (optionally) established in the gas.

High energy electron beam driven laser

Apparatus for and method of operating a laser wherein a discharge is produced preferably in a high pressure lasing gaseous mixture comprising at least one suitable first gaseous species capable of providing an excited state which has a finite probability of being ionized and a molecular second gaseous species having a capability for attaching electrons to form negative ions. The gaseous mixture may, for example, comprise argon, neon, helium, xenon, krypton or a metal vapor such as mercury as the first species and, for example, hydrogen iodide, carbon tetrachloride, bromine, iodine or fluorine as the second species. A buffer gas such as, for example, argon, helium or neon may also be used. The discharge is produced by means of an electron beam and an electric field. The discharge resulting from the application of the electric field heats secondary electrons produced by the electron beam to an energy level sufficient to make excited states. Thus, for a mixture comprising argon, krypton and fluorine, for example, the heated secondary electrons pump at least some of the argon and the krypton to the metastable state. The excited argon transfers energy to the krypton to form additional excited krypton which, in turn, reacts with the fluorine to form excited krypton fluoride molecules. The krypton fluoride then dissociates or decays upon the emission of spontaneous or stimulated radiation. At power input levels where the electron density remains constant in time for a constant electric field, efficient discharge pumping of the excited states is provided when the fractional excited state population is kept small. Stable discharge operation is achieved when the lasing mixture contains an amount of the second species gas sufficient to provide an attachment rate n times the equilibrium ionization rate where n is the number of electron excitations which causes ionization of the first species.

Apparatus for and method of operating electron beam attachment

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Winchester, MA, United States of America

Jack D Daugherty