Westinghouse Electric Corporation

Owen Farish

Richard L Hundstad

John L Pack

Henry Riemersma

A glow discharge device positioned upstream in a flow laser gas system supplies a continuous flow of electrons to a laser discharge region defined between planar laser electrodes to develop sufficient background electron density to permit CW or quasi CW laser operation.

Technique for CW or quasi CW operation of planar electrode laser

An improved gas-type circuit-interrupter is provided utilizing a mixture of helium and sulfur-hexafluoride (SF.sub.6) gases, with the percentage concentration of sulfur-hexafluoride (SF.sub.6) gas being 10%, or less, by volume. The improved gas-type circuit-interrupter of the present invention may be utilized to advantage as a 'puffer-type' circuit-interrupter, in which relative movement between a piston and operating cylinder takes place for forcing the compressed gas to flow through a suitably-located orifice, or nozzle member, and into intimate engagement with the established arc disposed therein to effect its extinction. Another form of the gas-type circuit-interrupter of the present invention may include a pressurized gas-reservoir chamber containing the aforesaid admixture of the helium and sulfur-hexafluoride gases in the proper concentration, that is 10%, or less, by volume, of sulfur-hexafluoride (SF.sub.6) gas with the remaining being made up substantially entirely of helium.

Gas-type circuit-interrupters having admixtures of helium with small

A trigger circuit which operates independently of the main discharge circuit can be used to initiate glow discharge useful for gas laser excitation. By utilizing independent trigger means, such as auxiliary dielectric electrodes, the main discharge can be controlled by modulating only a small part of the total energy input to the laser cavity. The main discharge gap of the laser is prestressed to a voltage below the spark breakdown voltage threshold of the electrode assembly under static conditions but above the glow discharge voltage of the electrode assembly. When the trigger means is pulsed to supply free electrons to the discharge gap the glow discharge is initiated between the electrodes independent of the need for modulating the main power to the gap.

Independent initiation technique of glow discharge production in

A gas laser system with moderate speed gas glow through the optical cavity to facilitate D.C. excitation of the gas to lasing levels. An electrode assembly is positioned so as to provide a glow discharge transverse to the optical axis within the optical cavity when a high D.C. voltage is applied thereto. By maintaining the high rate of flow of gas through the cavity, the glow discharge is stabilized while the gas medium is maintained at high pressure. Proper choice of electrode geometry and flow rate of the gas through the optical cavity allows the laser system to operate at pressures from a few Torr to atmospheric pressure and above thereby producing a high power CW output.

D.C. Excitation of high pressure gas lasers

A uniform field electrode arrangement for exciting a laser gas in a high pressure pulsed gas laser apparatus so constructed to facilitate discharge initiation and smooth laminar gas flow. The geometry of the electrode assembly provides for laminar gas flow through the discharge volume providing an optically homogeneous lasing medium. Discharge initiation for pulsed operation is achieved using, for example, ultraviolet irradiation of the electrode assembly, corona discharge devices and radioisotope irradiation of the electrode assembly. Independent of the type of initiatory discharge device used, the geometry of the assembly allows for efficient supply of initiating electrons to the discharge gap without interference with smooth gas flow through the optical cavity. Mesh electrodes can be used to facilitate gas flow in a direction parallel with the direction of electrical discharge.

Laser cavities with gas flow through the electrodes

A gas laser tube apparatus for producing a high-current glow, arc or spark which generates initiatory electrons and charged particles for establishing excitation of gas molecules in a separate region of the tube. Separate regions of ionization and excitation are established so that uniformity of excitation, optimization of the ratio of electric field intensity to electron density (E/N) and uniform intensity of excitation can be obtained in a high pressure gas laser system independent of ionization or initiation of discharge which also may need to be optimized. The separate fields are achieved by proper configuring of the electrodes with appropriate voltages applied thereto.

Generation of corona for laser excitation

A molecular gas laser capable of operating at or near atmospheric pressure in which electrical energy is coupled into an active molecular gas medium comprising molecules having vibrational rotational energy levels by means of an electric field transverse to the lasing axis. By applying an impulse voltage to the electrode configuration, high current glow discharges can be created. The pulse discharge takes place between electrodes having parallel planar surfaces facing each other. The lateral edges of these faces are suitably profiled to avoid field concentrations and thus provide a diffused glow discharge in a uniform electric field transverse to the lasing axis. Initiatory electrons required to produce the high current diffused glow are provided by generating an intense burst of corona in the gap between spacer members having very high dielectric constants which are interposed between the electrodes. Specifically, when a voltage pulse is applied to the gap between the spacer elements a very high field appears at the interface and generates an intense burst of corona which provides ultraviolet irradiation of the cathode resulting in the emission of electrons.

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Bearsden Glasgow, United Kingdom

Owen Farish