Showing papers on "Electric discharge published in 1976"

Xenon fluoride laser excitation by transverse electric discharge

Abstract: Stimulated emission has been produced in mixtures of He, NF3, and Xe at total pressures between 300 and 1000 Torr. Laser emission was on lines at 3511 and 3531 A which have been associated with the excited XeF molecule. Excitation of the gas mixture was by a transverse electric discharge which produced pulses with peak currents of approximately 104 A and rise times of 20 ns. A maximum laser energy of 7 mJ was obtained from a gas mixture with a ratio of He:Xe:NF3 of 98.0:1.5:0.5 at a total pressure of 300 Torr.

Discharge lamp ballast with resonant starting

Abstract: A circuit for operating an electric discharge lamp comprises an inductor in series with the lamp, a capacitor in parallel with the lamp, and a transistorized inverter circuit connected in series with the inductor and the lamp. The operating frequency of the inverter increases with increasing load. A harmonic of the inverter output frequency is initially established at the resonant frequency of the inductor and capacitor to produce a high open circuit lamp starting voltage. Upon establishment of an electrical discharge in the lamp, the inverter frequency increases to provide efficient, stable lamp operation.

CO Electric Discharge Lasers

Abstract: The history and status of CO electric discharge lasers are reviewed, and the directions of current research and development activity are discussed. (MHR)

Fluorescent lamp with superimposed luminescent layers

Abstract: Electric discharge lamp in which ultraviolet radiation is converted into light by means of two superposed luminescent layers. The two layers have about the same chromaticity point. The luminescent material in the layer more remote from the discharge is cheaper than that in the other layer.

Laser cavities with gas flow through the electrodes

Abstract: 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

Arc discharge sustaining circuit system for a discharge lamp

Abstract: It is the purpose of the present discharge lamp lighting system to provide reignition energy to a discharge lamp in each half cycle of the a.c. power source. The discharge lamp is connected to a conventional a.c. power source through ballast means and an oscillation booster circuit, which provides an intermittent oscillation output for the reignition operation of the discharge lamp. The operation period of the intermittent oscillation output is so controlled that the reignition operation period is included in each half cycle of the discharge lamp current. The lamp voltage and source voltage are established to agree as much as possible with each other for minimizing the terminal voltage of the ballast means, whereby a compact and economical device with a small inductance ballast means is achieved.

Method and apparatus for producing ozone

Abstract: Apparatus for producing ozone, wherein air or oxygen is passed through two high voltage electrodes mounted opposite each other in a housing and is converted into ozone by electrical discharge. The housing is constructed as a slender tube open at both ends and made from an electrically non-conductive material, while between the two electrodes, extending more or less over the entire inner length of the tube is mounted at least one bipolar electrode without an electrical input or output, which divides the inside of the tube into discharge channels. The bipolar electrode is formed by a surface, on which discharge points are mounted and directed at the earthed electrode. The discharge electrode, directed at the surface of the bipolar electrode, is similarly provided with a plurality of discharge points.

The Emission of Electrons from Glass Induced by a Strong Electric Field and the Mechanism of the Silent Electric Discharge

Abstract: Ordinary borosilicate (Pyrex) glass was found to emit electrons in vacuum when a sufficiently strong electric field was applied. Two distinct phenomena were observed. First, emission from the surface of a sharp glass tip occurred with a macroscopic field of about 5 × 10 9 V m -1 applied, but the electric stress was then great enough to shatter the glass in a short time. Second, emission from active sites on glass tubes occurred at macroscopic fields ( F ) of about 5 × 10 6 V m -1 . The number of emitting sites increased with applied field and was about 0.5 mm -2 with a field of 10 7 V m -1 . Emission from these sites was essentially the same under ordinary vacuum conditions and under ultra-high vacuum conditions. The current from active sites under vacuum conditions increased nearly exponentially with F ½ at constant temperature, and nearly exponentially with temperature at constant field. Active emitting sites on glass were very stable to chemical cleaning processes and to ion bombardment and electric discharges, in sharp contrast to emitting sites on thin metal wires. The sites on glass also emitted electrons in the presence of gases, but no emission of negative ions was noted in magnetic deflexion experiments. Current-voltage relations in the presence of gases were measured. With oxygen present, ozone was formed using glass tubes with either a. c. or d. c. applied. However, with a silica tubes ozonizer, ozone was formed with a. c. applied but not with d. c. applied. Ozone was also formed in an electric discharge between a thin metal wire (thin enough to act as a field emitter) and an outer metal cylinder. This ozonizer was compared with the glass ozonizer and energy efficiencies were measured. It is proposed that the external electric field causes emission of single electrons from isolated sites on glass and that the emitted electron interacts with the electron hole left behind at the surface. Equations are deduced for the case when the interaction is mainly between the electron and the electron hole rather than between the electron and its image. A model of field enhanced thermionic emission from sites with low work function (Schottky emission) is found to explain the results for emission from active centres on glass, and the field intensification factor β appears to be about unity. Although Schottky emission is considered more important than field emission for the fields used with glass tubes, calculations show that field emission becomes more important at higher electric fields. The emission of electrons is considered to be important in initiating the silent electric discharge.

Power calculations for high flow CO electric discharge laser systems

Abstract: A self-consistent model for high-flow electric discharge CO laser systems with coincident optical and flow axes is presented. The model employed couples the kinetics of the electrons and heavy particles with the optical and fluid dynamic processes in the laser system. The resulting integrodifferential system of equations governing this multilevel system was solved by an exact numerical scheme. The effects of composition, total mass flow rate and inlet pressure and temperature on the intensities, and total power output were investigated. The results indicate that, for a given input power and N/sub 2/ fraction, the efficiency increases by reducing the inlet temperature and increasing the velocity and/or the fraction of CO. Moreover, transitions on the lower vibrational bands can be obtained at the expense of lower efficiencies by reducing the CO fraction.

Electric discharge gas dynamic laser

Abstract: An electric discharge gas dynamic laser in which excitation of one gas species is obtained in a plenum by use of a dc glow discharge. The gas present in the plenum is then accelerated through an array of supersonic nozzles where the laser species is injected and mixed with the primary flow. Energy transfer and lasing occur in the supersonic region of the flow. Brewster-angle windows which extend from 1 to 28 cm downstream from the nozzle exit plane enables a laser cavity or diagnostic apparatus to be positioned at a variable distance downstream from the injection point. The optics may be mounted on a motor-driven translation table so that continuous scans of the region downstream of the nozzle exit plane may be conveniently made. The present facility may easily be operated with a subsonic cavity, with an RF discharge to augment the dc plenum discharge, with all gases premixed, or with any combination of these configurations.

Solid state high energy electrical switch for under-sea-water electric discharge seismic generator

Abstract: An under-sea-water electric discharge generator includes a source of stored electrical energy connectable through solid state switch means to a cable extending to a number of pairs of electrodes to be towed under sea-water. The switch means comprises an inductor in series with five main branch circuits: a capacitor discharge branch includes a plurality of SCRs connected in series and a sub-branch of RC elements for gate control with one RC element across each but an end one of the SCRs; a reverse discharge branch includes a plurality of diode means, one across each SCR. Diodes across the gate-cathode circuit of each but said one SCR protect against reverse negative voltage during reverse discharge. Static, dynamic, and over voltage branches parallel the SCR branch with one element of each (resistor, RC element, thyrector) across each SCR.

Method of forming passivation film

Abstract: A method of forming a passivation film, wherein after circuit elements have been formed in the semiconductor substrate, a thin conductive film is formed on the entire surface of the substrate and then an insulating film is formed through electric discharge on the surface of the thin conductive film while the thin conductive film is kept at a constant potential.

Electric-discharge-pumped nitrogen ion laser

Abstract: A preionized transverse electric‐discharge‐pumped N+2 charge‐transfer laser oscillating on the (B2Σ+u−X2Σ+g) transition of N+2 is reported. Peak power of 180 kW in a 8‐nsec FWHM laser pulse has been obtained with a 0.1% mixture of N2 in helium at a total pressure of 3 atm. The most intense laser oscillation occurs on the (0,1) vibrational transition at 427.8 nm.

On the effect of the addition of SF 6 to a N 2 electrical discharge laser

Abstract: The electron distribution function has been calculated for simulated conditions of SF6-N2 gas mixtures under conditions typical of a N2 electrical discharge laser. The results indicate that the electron distribution function, transport quantities, and electronic excitation rates change only a few percent in the presence of SF6 provided E/N is unchanged. The enhancement in laser power output with the addition of SF6 is attributed to an increased operating value of E/N in the electrical discharge.

High pressure sodium vapor lamp having low starting voltage

Abstract: The alumina arc tube of a high pressure sodium arc discharge lamp has a multiple turn wire starting aid wound therearound in order to reduce lamp starting voltage. The starting aid must extend longitudinally along the arc tube for a distance that is at least 10% of the arc length of the arc tube.

Electric discharge lamp with annular current conductor

Abstract: The current leadthrough for the auxiliary electrode of a discharge lamp with ceramic lamp vessel is constructed as a cylindrical tube concentric with the leadthrough of the main electrode. The cylindrical tube which serves as a current leadthrough can extend in the lamp vessel and serve itself as an auxiliary electrode. This construction avoids cracking of the lamp vessel. Niobium and tantalum, tungsten molybdenum, rhenium and alloys thereof may be used for the current leadthrough.

Acoustic waves and heating due to molecular energy transfer in an electric discharge CO laser

Abstract: This paper summarizes analytical studies and the interpretation of experimental results for the compression and rarefaction waves generated in the cavity of a pulsed CO electric discharge laser. A one-dimensional analysis of acoustic waves is applied to a transversely excited laser. The influences of heating in the cathode fall, heat transfer to the cathode, flow through both the anode and cathode, and bulk heating of the plasma are included. The analysis is used to relate the bulk heating rate to observable features of the pressure and density waves. Data obtained from interferograms and reported elsewhere are used to infer the bulk heating rates in a pulsed CO laser. Results are presented for CO/Ar, CO/N 2 , and N 2 plasmas. Comparison of the data with recent theoretical results for the heating due to electron/ neutral collisions and the anharmonic defect associated with V-V energy transfer shows substantial differences at lower values of total energy deposition. The change of heating With E/N is in fairly good agreement with predicted values.

Emission spectra of electrical discharges in Cs-rare gas mixtures

Abstract: Broad red and yellow bands have been observed in the emission spectrum of an electrical discharge containing caesium vapour mixed with rare gases at low pressures. By varying the discharge conditions, it is shown that these bands are correlated with well defined excited levels of the caesium atom. An afterglow study further reveals that at least a part of the red emission is from excimer states of the Cs-noble gas molecule.

High power gas transport laser

Abstract: Continuous wave (CW) output power from a gas transport laser is substantially increased without arcing by the use of a tubular cathode having a racetrack-shaped cross section and disposed in the main stream of gas flow through the laser channel transversely of the direction of flow and spaced above and upstream from a coextensive segmented anode in the opposite wall of the channel. The racetrack-shaped cross-sectional configuration of the cathode provides maximum electrode surface for generating a glow mode electric discharge and also induces turbulence at that surface so as to support high current densities without arcing. Continuous output power greater than 3.5 KW is achieved with improved efficiency with this electrode configuration.

Ionization detector utilizing electric discharge

Abstract: The invention relates to an ionization detector comprising a discharge section which generates ultraviolet rays and a detector section which collects ionic current caused or altered by the photoionization of a sample gas with the ultraviolet radiation. A container holds the two sections together and a pointed cathode is spaced at least several millimeters from an anode in order that the electric discharge may be executed as field-emission discharge.

Electric-discharge sintering of oxidized metal powders

Abstract: 1. An investigation into the effect of various methods of application of electric energy and mechanical load on some characteristics of materials produced by electric sintering has shown that, at a given level of energy consumption, EDS ensures the most homogeneous structure, the highest density, and the best mechanical properties. 2. Use of an alternating current leads to more effective sintering of peripheral regions. The reason for this is that sintering with an ac component is accompanied by the evolution of a large quantity of heat in the surface zone as a result of the skin effect. This heat counterbalances the heat lost from peripheral zones, thereby ensuring a more even temperature distribution over the specimen cross section. 3. It has been established that the variation of porosity as a function of prepressing pressure has a non-monotonic character. In particular, for an electrolytic nickel powder with a particle size of < 50μ and an oxygen content of 0.06% this function passes through a minimum at a prepressing pressure of 16–20 kg/cm2. 4. Experiments have shown that there exists a critical value of prepressing pressure above which uniform electric breakdown through interparticle gaps occurs in the whole volume of the compact.

Starting and operating device for a high pressure discharge lamp

Abstract: The invention relates to a starting and operating device, including an intance in the ignition circuit, for a high pressure discharge lamp, especially for a high pressure mercury vapor discharge lamp with metal halide additive, having at least one starting electrode positioned near one of the main electrodes within the discharge vessel. The starting electrode and the main electrode remote from the starting electrode are bridged by an electric circuit externally of the discharge vessel which comprises a current-interrupting and/or current-limiting electrical component. This arrangement of an auxiliary electrode within the discharge vessel of a high pressure discharge lamp brings about a reduction of the supply voltage required for initiation of the discharge which is particularly desirous in the case of high pressure mercury vapor discharge lamps containing metal halides.

Electric-discharge laser initiated in the active medium

Abstract: An investigation was made of an electric-discharge CO2 laser initiated directly in the active medium. An energy output of 52 Jliter–1atm–1 was obtained when the efficiency was 25%. The maximum energy output recorded in these experiments was 62 Jliter–1atm–1. A preliminary discharge was initiated by fast electrons accelerated in a dense gas medium. The geometry of the excitation system could be varied and it could be employed to pump a laser with a different gas mixture.

The application of low-pressure experimental data to the calculation of electrical discharge thresholds in compressed gases

Abstract: Low-pressure experimental data concerning fundamental gas discharge parameters may be used in compressed gases provided the gas compressibility factor is taken into consideration and that this has a significant effect on the interpretation of breakdown in sulphur hexafluoride at pressures greater than about 100 kPa (1 bar). A modified relationship giving values of the effective ionization coefficient for SF6 at high pressures is presented.

Method of driving a flat discharge panel

Abstract: In a flat discharge panel having a cathode adapted to perform a discharge in cooperation with an anode through a main discharge space, being applied with a discharge voltage, and adapted to perform another discharge in cooperation with an auxiliary anode through an auxiliary discharge space, being applied with an auxiliary discharge voltage, said cathode being connected in series to a resistor, a method of driving the flat discharge panel characterized in that a memory function or characteristics is imparted to a matrix panel consisting of the flat discharge panel by shifting the discharge from the auxiliary discharge space to the main discharge space through raising the voltage applied to the main discharge space while lowering the voltage applied to the auxiliary discharge space, and by shifting the discharge from the main discharge space to the auxiliary discharge space by raising the voltage applied to the auxiliary discharge space while lowering the voltage applied to the main discharge space.

Relation of electric discharge parameters to short-pulse CO2 laser efficiency

Abstract: A study is reported of the choice of the discharge and gas mixture parameters of an electron-beamsustained nanosecond CO2 laser with the aim of achieving maximum efficiency. An analysis is made of the dependence of the efficiency of such a CO2 laser on the composition and pressure of the gas mixture, properties and parameters of the discharge, electron and ion recombination coefficients, energy transfer between CO2, N2, and He levels, etc.

Dielectric gas mixtures containing sulfur hexafluoride

Abstract: Electrically insulating gaseous media of unexpectedly high dielectric strength comprised of mixtures of two or more dielectric gases are disclosed wherein the dielectric strength of at least one gas in each mixture increases at less than a linear rate with increasing pressure and the mixture gases are present in such proportions that the sum of their electrical discharge voltages at their respective partial pressures exceeds the electrical discharge voltage of each individual gas at the same temperature and pressure as that of the mixture.

Potential Efficiencies of Open- and Closed-Cycle CO, Supersonic, Electric-Discharge Lasers

Abstract: Computed open- and closed-cycle system efficiencies (laser power output divided by electrical power input) are presented for a CW carbon monoxide, supersonic, electric-discharge laser. Closed-system results include the compressor power required to overcome stagnation pressure losses due to supersonic heat addition and a supersonic diffuser. The paper shows the effect on the system efficiencies of varying several important parameters. These parameters include: gas mixture, gas temperature, gas total temperature, gas density, total discharge energy loading, discharge efficiency, saturated gain coefficient, optical cavity size and location with respect to the discharge, and supersonic diffuser efficiency. Maximum open-cycle efficiency of 80-90% is predicted; the best closed-cycle result is 60-70%.