Showing papers on "Electric discharge published in 1984"

Fractal Dimension of Dielectric Breakdown

Abstract: It is shown that the simplest nontrivial stochastic model for dielectric breakdown naturally leads to fractal structures for the discharge pattern. Planar discharges are studied in detail and the results are compared with properly designed experiments.

New theory of electrical discharge and breakdown in low‐mobility condensed insulators

Abstract: Electrical discharge and breakdown in low‐mobility insulating liquids and solids involve the creation of low‐density domains or channels in the bulk by carrier injection from electrical contacts and subsequently dissociative trapping and recombination as a necessary prelude. Internal discharge such as electrical treeing and breakdown are initiated by impact ionization within such low‐density domains or channels and then followed by an indefinite increase in carrier multiplication in the conduction level that extends the channels and finally destroys the material inside them.

Line shapes of atomic hydrogen in hollow-cathode discharges.

Abstract: Emission lines of atomic hydrogen produced in the hollow cathode of an electric glow discharge are found to have articulated line shapes indicating three quite different excitation mechanisms for the emitting atoms. Particularly striking is the extensive development of the far wings, which have Gaussian line shapes with FWHM values attaining 10 cm−1 or more. This corresponds to an atomic kinetic energy greater than 100 eV and suggests an origin for such energy in the cathode-fall region.

Hollow Cathode Discharges: Analytical Applications.

Abstract: The low pressure glow discharges considered in this paper are the hollow cathode (Paschen), and the flat cathode (Grimm). Both discharges have similar voltage-current characteristics which are responsible for their radiation stability. The analytical sample is supplied to the discharge through a sputtering mechanism which provides a stable and non-selective source of particles. Some of the fundamental properties of the glow discharge and sputtering phenomena will be discussed, including the relation between the geometry of the discharge, and the nature and pressure of sustaining gas, and current, on the emission characteristics of the discharges. These will he followed by a description of the conventional instrumentation developed for analytical purposes using the hollow cathode and flat discharge. A description of the hollow cathode developed at the National Bureau of Standards (NBS) will follow. The techniques used for the introduction of various conductive and nonconductive materials into the discharge will be discussed. The use of these discharges will be illustrated with examples taken from the literature and from the measurements performed at NBS. The paper will conclude with a discussion of possible future developments of low pressure glow discharges. A collection of references to works on low pressure glow discharges, containing 690 entries, concludes this work.

Electric discharge processing of thin films

Abstract: A deposited film is processed in a preselected pattern by discharging electric energy through the film across a gas dielectric. In a preferred embodiment, a voltage pulse chain is applied to a moving probe spaced a preselected distance from the film. The discharge either removes the film material over the pattern to expose underlying material, or produces a conductive path from the top to the bottom of the film.

Retrograde motion of a positive column of low pressure discharge

Abstract: The motion of a positive column of low pressure discharge passing through the annulus between coaxial glass tubes and subjected to a transverse magnetic field has been investigated. The positive column was photographed and measured optically, and was found to move in the retrograde direction. Variation in this retrograde motion with tube geometry, discharge current and gas pressure was measured and examined based on the ‘‘neutral drag instability theory’’ of Hoh and Simon.

Electric discharge machine

Abstract: PURPOSE:To normalize the condition of an interpole clearance by a method wherein the discrimination of a normal electric discharge and an abnormal electric discharge are effected by means of the sperctrum analysis of the frequency of the wave form of an interpole clearance electric discharge voltage upon generating the electric discharge to control a reference voltage utilized for the control of the interpole clearance between an electrode and a work piece. CONSTITUTION:In case a detecting signal SA is ''1'' or an abnormal condition, the output of an invertor 100 is ''0'', therefore, an analog switch 101 is put ON and the same switch 102 is put OFF. Accordingly, the input voltage ei of an integral circuit, consisting of an operational amplifier 103, a resistor R10 and a capacitor C10, becomes same as -e and the voltage Vr is expressed by the formula in the diagram. Here, V is the initial value of the voltage at t=0. Accordingly, the reference voltage Vr continues to increase as far as the signal SA is ''1'', the voltage Vs increases into negative in cooperating with the voltage Vr, and the interpoel clearance is increased into an expanding direction. Next, when the signal SA is ''0'' or none of an electric discharge concentration occurs, the input voltage ei becomes ''0'' and the voltage of an integral capacitor C10 is discharged. Accordingly, the voltage VR is decreased, the interpole clearance is controlled toward a narrowing direction, the relative frequency of the electric discharge is increased and the working speed may be increased.

Electrodeless discharge lamp with rapid light build-up

Abstract: An electrodeless fluorescent lamp having a core of magnetic material surrounded by a coil for producing a high-frequency magnetic field in a lamp vessel surrounding the core and coil. An amalgam holder is located in the vessel, in the region surrounding the core where the electric discharge is formed so that the amalgam is heated directly by the discharge. Substantially all the mercury contained in this amalgam is released quickly after the lamp is turned on, so that the light output rises rapidly.

Arc discharge lamp with ultraviolet enhanced starting circuit

Abstract: An apparatus and method for increasing the reliability of an arc discharge occurring in metal halide gas discharge lamps by providing UV radiation in the gas discharge path.

Fusion mass-splicing for optical fibers using electric discharges between two pairs of electrodes.

Abstract: A low loss fusion splicing method for ribbon units has been developed and evaluated. Five fibers are heated simultaneously by 50-Hz ac electric discharges. The heating conditions and fiber aligning techniques are discussed in this paper. By using two pairs of electrodes, a stable and uniform heating condition was attained. In the splicing experiment, an average splice loss of 0.11 dB was obtained for 50-μm core diam graded-index silica fibers.

High-pressure discharge lamp operating circuit

Abstract: A high pressure discharge lamp in which discharge between a pair of main electrodes in an arc tube of the discharge lamp is sustained by a D.C. or high frequency current. The circuit comprises discharge mode controller for controlling the discharge such that mainly a low-frequency discharge is produced between the main electrodes at least within a predetermined time from initiation of the discharge within the arc tube, and subsequently transferred to the D.C. or high-frequency discharge.

Wire-cut electric discharge machining apparatus

Abstract: A wire-cut electric discharge machining apparatus for cutting a workpiece by producing an electric discharge across the workpiece and a wire while a machining liquid is allowed to flow between the wire and the workpiece via machining liquid flow rate control apparatus. When machining speed is reduced and machining discharge energy diminishes at a corner-cut portion or at a portion which is to be cut into the shape of a circular arc, the machining liquid flow rate, namely the pressure of the liquid, is reduced to prevent wire oscillation.

Long-Term Statistical Study of the Corona Electric Field and Ion-Current Performance of a ±900-kV Bipolar HVDC Transmission Line Configuration

Abstract: The corona, electric field and ion- current performnance of a 6 x 406-cm conductor bundle, chosen for use on a ±900-kV bipolar HVDC transmission line, was studied on a test line for a period of over 18 months The results obtained provide a statistical evaluation of radio interference (RI), audible noise (AN), corona loss (CL), electric field and ozone generated by the line at the nominal voltage as well as furnishing data on the frequency spectra of AN and on the lateral profiles of RI, AN and ion-current density at ground level In addition, the results were analyzed to obtain the influence of atmospheric variables such as air density, humidity and wind velocity on the corona performance characteristics and to draw conclusions about the influence of the test duration on the statistical significance of the results

Hysteresis in a low‐pressure argon discharge

Abstract: Hysteresis in the discharge characteristics of a low pressure (p≂10−4 Torr), magnetized argon plasma column is reported. The hysteresis is associated with sudden jumps in plasma density and discharge current as either the discharge voltage or magnetic field strength is varied. A substantial change in the plasma density profile and the appearance of coherent plasma oscillations are also observed.

Spatial Emission Properties of a Microwave-Induced Plasma

Abstract: The spatial dependence of emission from a microwave-induced plasma in argon has been studied A graphite furnace atomizer was used as a means of sample introduction Emission from metallic elements is localized to a few cm near the inlet of the discharge, but the exact position of the emission profile is element-dependent For non-metals, such as I, a broad profile centered about the resonant cavity is found This difference in behavior is shown to be due to the deposition of metals upon the walls of the discharge tube used to confine the plasma The removal of analyte atoms is explained by a mechanism which involves ionization of the analyte and then radial acceleration of these ions under the influence of the inhomogeneous microwave field This hypothesis accounts for the observed decrease in emission intensity as microwave power is increased

Wire-cut, electric discharge machining method

Abstract: When cutting workpiece into a desired number of closed loop configurations by means of a wire-cut, electric discharge machine provided with an automatic wire feed mechanism, electric discharge machining is started from a machining start hole made in the workpiece corresponding to each closed loop configuration and is performed to a point where the electric discharge machining operation is stopped, thus a part of the closed loop configuration is left uncut. After fixing at least one portion of each closed loop configuration to the workpiece and inserting the wire electrode into the machining start hole by the automatic wire feed mechanism, the electric discharge machining operation is resumed to cut off the remaining uncut part. In the case of the wire electrode breaking during the electric discharge machining operation, the wire electrode is inserted by the automatic wire feed mechanism into the machining start hole and is moved to the position where it breaks along the route where the machining operation has already been performed, and then the electric discharge machining operation is resumed.

Optical display with excimer fluorescence

Abstract: A display device employs an electric discharge passing through a mixture of gases to form an excimer that fluoresces in the blue/green region of the optical spectrum.

Operating circuit for electric discharge lamp

Abstract: There is disclosed an operating circuit for an electric discharge lamp in which a first DC operating circuit for starting an electric discharge lamp, a second DC operating circuit for making the electric discharge lamp operative by a voltage near a rated lamp voltage and by a current near a rated lamp current, and a third DC operating circuit for supplying a relatively large current to the electric discharge lamp immediately after the electric discharge lamp is started and for stabilizing the lamp luminous flux in a short time, are connected in parallel. A switching circuit for cutting off the first DC operating circuit after the electric discharge lamp is started is provided at the output terminal of the first DC operating circuit. In addition, reverse current preventing circuits for preventing the currents from reversely flowing from the operating circuits at higher voltages are provided at the output terminals of the second and third DC operating circuits.

Conductivity and transport in neon deuterium discharges in the plt tokamak.

Abstract: Introduction of large amounts of neon into Ohmically heated deuterium discharges in the PLT tokamakl results in higher central electron temperature (Te(0) 3 keV) and values of electron energy containment time that are larger than in regular discharges at the same electron density (τEe = 44 ms at e = 2 × 1019 m−3). For steady-state discharges with high effective Z (~ 5–8) the conductance is larger than that predicted by neoclassical theory by as much as a factor of two. Transport rates of hydrogen-like and helium-like ions can be fairly well approximated by assuming a diffusion constant of between 0.4 and 1 m2s−1. Within experimental uncertainties the diffusion of hydrogen-like neon is the same for co- and counter-directed high-power neutral beams.

Temperature and Electron Density Measurements in a DC Glow Discharge

Abstract: Data on the glow discharge have been accumulated by photographic detection with an echelle spectrometer. Intensity, excitation temperature, and electron density results are reported for the cathode dark space, negative glow, and Faraday dark space regions of the plasma for three values of discharge current and five values of fill gas pressure. It is concluded that neither excitation temperature nor electron density is a useful descriptor of excitation conditions in low pressure plasmas. Excitation is interpreted in terms of an ionization-radiative recombination model, and intensity of argon atomic emission is shown to be correlated with the product of discharge current and argon ionization cross section.

Process and apparatus for the production of a polymerised coating on a substrate

Abstract: 1. A process for forming a polymerized coating on a substrate, wherein the surface of a substrate to be coated is contacted with a confined atmosphere containing a dispersed monomer or prepolymer which is to be transformed into the coating polymer and a cold plasma is generated by electric discharge in the confined atmosphere for creating reactive species which result into the polymerized coating, characterized in that the electric discharge is a Corona A.C. discharge under a pressure close to atmospheric pressure between an electrode (28) having a low curvature ratio and an electrode (26) which carries the substrate, in an atmosphere which contains the monomer or prepolymer as a vapor or dispersed phase.

Toward a fundamental model for steady point‐plane corona discharges

Abstract: A mathematical model expressed in prolate spheroidal coordinates is developed from fundamental equations for steady state corona discharges from needle‐to‐plane electrodes. The bases of the theory are the Poisson and current continuity equations coupled with a mobility model for the transport of the charge carriers. The potential and field are constrained to be consistent with boundary conditions at the plane electrode, the surface boundary of the glow discharge, and the surface delineating the finite bound of the distribution of space charge. In the fully developed corona glow the steady state current is assumed to be limited by space‐charge fields at the glow boundary surface and a potential V0 across the glow region is required to sustain the discharge. An additional requirement is that the space‐charge region must satisfy a power‐balance equation. Utilizing current vector potential methods results in a current density exactly yielding Warburg’s law at the plane electrode. A current‐potential character...

Lighting apparatus for an electric discharge lamp

Abstract: A lighting apparatus for an electric discharge lamp includes a lighting ballast capacitor connected in series to an electric dicharge lamp for stabilizing a lighting current to the lamp; a preheating ballast capacitor connected in parallel to the lamp for supplying a preheating electric power to the lamp; electric power supply including an output transformer for supplying an electric power to the lighting ballast capacitor; a control electric power supply circuit for obtaining a control electric power through the lighting ballast capacitor and discharge lamp or the preheating ballast capacitor without adding a stepdown transformer or a resistive element for voltage drop; and an oscillator which receives the control electric power from the control power supply circuit and controls the electric power supply. With this lighting apparatus, the electric power loss is made small and the miniaturization of the apparatus can be realized.

Transversely excited gas laser

Abstract: A transversely excited gas laser, includes: an elongated gas-filled discharge chamber having an optical axis; a main cathode electrode and a main anode electrode extended along the optical axis in the discharge chamber defining a main discharge space between the main cathode and the main anode electrodes through which the optical axis extends, the main electrodes bordering two sides of the main discharge space leaving two other sides open; two pairs of auxiliary electrodes each being extended parallel to the optical axis in vicinity of a respective one of the open sides of the main discharge space and mutually spaced apart by a given distance, each of the auxiliary electrodes including a conductor and a dielectric shell surrounding the conductor, each of the auxiliary electrodes being spaced from all of the other electrodes by a set breakdown distance; and a driving unit connected to the electrodes, the driving unit supplying different potentials to the main cathode and main anode electrodes producing a main electric discharge therebetween during operation of the gas laser, and the driving unit supplying different potentials to the pairs of auxiliary electrodes causing a corona discharge preionizing the gas in the main discharge space to take place therebetween across the given distance during operation of the gas laser.

Minimum Potential of Charged Insulator to Cause Incendiary Discharges

Abstract: Incendiary discharges can occur when a grounded metal sphere approaches a charged insulator, but there are few studies on its electrostatic potential causing ignition. The aim of this research is to determine the minimum potential required for ignition of flammable gases and vapors mixed with air. Discharges between a charged plastic film and grounded metal spheres are experimentally investigated, and an equation for estimating the discharge energy is presented. Then the minimum potential to produce the incendiary discharge is considered from this equation and compared with the experiments. It becomes clear that the minimum potential is determined by the diameter of the grounded metal sphere, the potential of the charged plastic film, and its apparent capacitance. The results obtained with hydrogen-air and propane-air mixture are reported.