Abstract: Systems and methods for controlling traffic at an intersection are provided. A controller receives data from a vehicle detection device indicating a presence or non-presence of vehicles within a first area forward or adjacent to the stop sign. The controller receives data from a cross-traffic vehicle detection device indicating a presence or non-presence of vehicles within a second area rearward of the stop sign. Where data is received indicating the presence of at least one vehicle within the first area and the non-presence of any vehicles within the second area, the controller commands a traffic signaling device for the stop sign to temporarily cease providing the wait signal and instead provide the proceed signal.

Abstract: In the present invention, a pressure measurement device for determining the vacuum level within the evacuated housing of a vacuum electrode device is provided that includes an electrically conductive enclosure secured to an interior surface of the housing, an electrically conductive electrode extending through an aperture in the housing, the electrode having a tip at one end positioned within the interior of the housing inside the enclosure to define a gap between the tip and the enclosure and a conductive lead at a second end disposed outside of the housing, and a voltage source connected to the conductive lead to supply a voltage potential to the tip of the electrode. A voltage difference produced between the electrode and the enclosure ionizes gas within the enclosure causing a measurable current to flow between the electrode and the enclosure which can be used to determine the vacuum level in the housing.

Abstract: Devices and corresponding methods are provided to operate a hot cathode ionization pressure gauge (HCIG). A transistor circuit can be configured to pass the electron emission current with low input impedance and to control cathode bias voltage. Emission current and cathode bias voltage can be controlled independently of each other, without a servo settling time. HCIGs can be calibrated with respect to leakage current.

Abstract: In one example, this disclosure describes a circuit and techniques that may be used to measure the ion balance in an ionization balance device (10). The described circuit comprises a capacitor (22) that includes two conductors (23, 24), wherein a first one (23) of the conductors is exposed to the output of the ionization device, and the second one (24) of the conductors is shielded from the output of the ionization device. The first conductor may accumulate charge so as to quantify the output of the ionization balance device. A switch (29) may be used to discharge the first conductor at periodic intervals in order to measure the accumulated charge on the first conductor, and signal processing may be performed on this discharge measurement in order to generate feedback that can be used to control and adjust the output of an ion source.

Abstract: An air ionization monitoring device 200 and method is disclosed herein. In a described embodiment, the air ionization monitoring device 200 comprises an ion source 202 adapted to emit ions 204 and a capacitor 208 including a first conductor 210 arranged to be exposed to the ions 204 emitted by the ion source 202, and a second conductor 212 arranged to be shielded from the ions 204 emitted by the ion source 202. The monitoring device 200 further includes a commutation circuit 234 operable between a first configuration for charging the capacitor 208 to a first predefined voltage, and a second configuration for using the ions 204 emitted by the ion source 202 to discharge the capacitor 208 for a predefined time resulting in the capacitor 208 having a second voltage. The device 200 is configured to use the first and second voltages to determine an ionic current of the emitted ions.

Abstract: An ionization gauge that measures pressure has an electron source that emits electrons, and an anode that defines an ionization space. The gauge also includes a collector electrode to collect ions formed by an impact between the electrons and a gas and to measure pressure based on the collected ions. The electron source is dynamically varied in emission current between a plurality of emission levels dependent on pressure and a second parameter other than pressure. The ionization gauge may also vary various operating parameters of the gauge components according to parameters stored in a non-volatile memory and selected by a user.

Abstract: A neutron generator includes a sealed envelope providing a low pressure environment for a gas. One end of the envelope defines an ion source chamber. A target electrode is disposed at the other end of the envelope. An extracting electrode is spaced apart from the target electrode by an accelerating gap. The extracting electrode bounds the ion source chamber. A dispenser cathode electrode and grid electrode are disposed in the ion source chamber for inducing ionization in the ion source chamber. The dispenser cathode electrode, the grid electrode and the extracting electrode operate at a positive high voltage potential and the target electrode operates at or near ground potential. This configuration provides an electric field gradient that accelerates ions towards the target electrode to induce collisions of ions with target material, thereby causing fusion reactions that generate neutrons. High voltage power supply circuit means supplies a positive high voltage signal to the electrodes of the ion source.

Abstract: A system for regulating a pressure of a filled-in gas is presented. The system includes a reservoir that stores a reservoir gas adsorbed in a sorbent material at a storage temperature, a gas-filled tube containing the filled-in gas, a controller configured to determine a pressure change required in the filled-in gas based upon signals representative of a pressure of the filled-in gas inside the gas-filled tube and a required pressure threshold, determine an updated temperature of the sorbent material based upon the pressure change required in the filled-in gas, and regulate the pressure of the filled-in gas by controlling the reservoir to change the storage temperature of the sorbent material to reach the updated temperature of the sorbent material.

Abstract: A field emission device is configured as a heat engine. Different embodiments of the heat engine may have different configurations that may include a cathode, gate, suppressor, and anode arranged in different ways according to a particular embodiment. Different embodiments of the heat engine may also incorporate different materials in and/or proximate to the cathode, gate, suppressor, and anode.

Abstract: A field emission device is configured as a heat engine, wherein the configuration of the heat engine is variable as a function of time. A method corresponding to a field emission device comprises applying an anode electric potential to an anode region that is greater than a cathode electric potential of a cathode region, applying a gate electric potential to a gate region to release a set of electrons from the cathode region, passing the set of electrons from the gate region to a suppressor region, applying a suppressor electric potential to decelerate the set of electrons between the suppressor region and the anode region, binding the set of electrons in the anode region, and varying at least one of the anode electric potential, gate electric potential, and suppressor electric potential as a function of time.

Abstract: A suppressor grid is configured proximate to an anode to produce a suppressor electric field selected to provide a force on an electron in a direction pointing away from the anode, wherein the suppressor electric field is further selected to pass electrons from the suppressor grid to the anode.

Abstract: A field emission device is configured as a heat engine.

Abstract: In one embodiment, the trajectory of one or more electrons is controlled in a field emission device. In another embodiment, the field emission device is configured analogously to a klystron. In another embodiment, the field emission device is configured with electrical circuitry selected to control the input and output of the device.

Abstract: An arrangement for generating plasma, the arrangement comprising a primary plasma source (1) comprising a primary source chamber (15) and a first coil (4) for generating plasma in the primary source chamber, a secondary plasma source (25) comprising a secondary source chamber (16) and a second coil (26) for enhancing plasma generated by the primary plasma source and/or generating plasma in the secondary source chamber generating plasma in the primary source chamber, a hollow guiding body (11) arranged for guiding at least a portion of the plasma generated by the primary plasma source to the secondary plasma source, and an outlet (14) for emitting at least a portion of the plasma generated by the arrangement.

Abstract: The disclosed charged particle beam apparatus includes a field-emission electron source including <310> single crystal of tungsten; a vacuum chamber having the electron source therein; an exhausting system for exhausting the vacuum chamber; a filament connected to the electron source to let flow a current through the electron source and thereby heat the electron source; a power supply for letting a current flow through the filament; an ammeter for measuring a total current emitted from the electron source; and a controlling unit for exercising control to cause the power supply to let a current flow through the filament when the total current measured periodically has become a predetermined ratio or less as compared with a total current from the electron source found immediately after first electron beam emission, or a total current from the electron beam found immediately after a current is let flow through the filament.

Abstract: A field emission device is configured as a heat engine. Different embodiments of the heat engine may have different configurations that may include a cathode, gate, suppressor, and anode arranged in different ways according to a particular embodiment. Different embodiments of the heat engine may also incorporate different materials in and/or proximate to the cathode, gate, suppressor, and anode.

Abstract: An ionization gauge to measure pressure and to reduce sputtering yields includes at least one electron source that generates electrons. The ionization gauge also includes a collector electrode that collects ions formed by the collisions between the electrons and gas molecules. The ionization gauge also includes an anode. An anode bias voltage relative to a bias voltage of a collector electrode is configured to switch at a predetermined pressure to decrease a yield of sputtering collisions.

Abstract: A field emission device is configured as a heat engine.

Abstract: A ballast for fluorescent tubes and the use thereof for producing fluorescent tube lighting fixtures using a novel gas excitation mode in which light is generated by means of controlled pulses leading to an increased power efficiency, with a data collection and transmission functionality, are disclosed.

Abstract: A field emission device is configured as a heat engine.

Abstract: A gas delivery system for a cell-based mass spectrometer includes a mass flow controller having an input coupled to a gas source. A three-way valve includes an input coupled to an output of the mass flow controller, a first output coupled to a vacuum system, and a second output normally coupled to a reaction or collision cell. A cell is positioned inside a vacuum chamber of the mass spectrometer where the second output of the three-way valve is coupled to an inlet of the cell and the mass flow controller provides a gas to the cell that increases a pressure inside the cell relative to the pressure in the vacuum chamber.

Abstract: A plasma light source system includes a plurality of plasma light source 10 that periodically emits plasma light 8 from respective predetermined light emitting points 1a and a light collecting device 40 that collects the plasma light emitted from the plurality of light emitting points of the plasma light sources to a single light collecting point 9.

Abstract: The present invention provides a charged particle beam system which can perform evacuation on an electron gun chamber or an ion-gun chamber having a non-evaporable getter pump in a short time and can maintain the ultra-high vacuum for a long time, and a technology of evacuation therefor.

Abstract: A method and apparatus for operating a multi-hot-cathode ionization gauge is provided to increase the operational lifetime of the ionization gauge in gaseous process environments. In example embodiments, the life of a spare cathode is extended by heating the spare cathode to a temperature that is insufficient to emit electrons but that is sufficient to decrease the amount of material that deposits on its surface or is optimized to decrease the chemical interaction between a process gas and a material of the at least one spare cathode. The spare cathode may be constantly or periodically heated. In other embodiments, after a process pressure passes a given pressure threshold, plural cathodes may be heated to a non-emitting temperature, plural cathodes may be heated to a lower emitting temperature, or an emitting cathode may be heated to a temperature that decreases the electron emission current.

Abstract: A method and apparatus for operating a multi-hot-cathode ionization gauge is provided to increase the operational lifetime of the ionization gauge in gaseous process environments. In example embodiments, the life of a spare cathode is extended by heating the spare cathode to a temperature that is insufficient to emit electrons but that is sufficient to decrease the amount of material that deposits on its surface or is optimized to decrease the chemical interaction between a process gas and a material of the at least one spare cathode. The spare cathode may be constantly or periodically heated. In other embodiments, after a process pressure passes a given pressure threshold, plural cathodes may be heated to a non-emitting temperature, plural cathodes may be heated to a lower emitting temperature, or an emitting cathode may be heated to a temperature that decreases the electron emission current.

Abstract: A method of stabilizing an arc between electrode tips in a high pressure arc discharge lamp is provided comprising initially creating an arc between the pair of electrodes during a start-up phase of the lamp by supplying power to the lamp for a first period. The method then transitions the arc to attach itself between the tips of the electrodes by removing the power supplied to the lamp for a second period and then resupplying power to the lamp after completion of the second period. The first and second periods for respectively initially supplying and removing power are preferably selected based on either an elapsed period of time, the measured operating lamp voltage, or the measured lamp pressure. Once the arc becomes attached to the tips of the electrodes in this manner, the arc will remain stabilized between the electrode tips during operation of the discharge lamp.

Abstract: The invention generates high-energy particles, or quantum energy, from a quantum macro object. The method used comprises: (a) isolating a gaseous substance within a bounded area; (b) energizing the gaseous substance, causing the gaseous substance to transition into a glow discharge plasma state; (c) increasing the gas pressure within the bounded area to transition the glow discharge plasma to a quantum macro object comprising a positively charged nucleus surrounded by an electron cloud; (d) inducing an active impact upon the quantum macro object such that the potential energy existing within the quantum macro object is converted and released in the form of quantum energy in a continuous and inexhaustible manner. The bounded area is typically created by a dielectric of various sorts, such as within a dielectric container or properly charged air.

Abstract: A system is disclosed for speeding workpiece thoughput in low pressure, high temperature semiconductor processing reactor. The system includes apparatus for loading a workpiece into a chamber at atmospheric pressure, bringing the chamber down to an intermediate pressure, and heating the wafer while under the intermediate pressure. The chamber is then pumped down to the operating pressure. The preferred embodiments involve single wafer plasma ashers, where a wafer is loaded onto lift pins at a position above a wafer chuck, the pressure is rapidly pumped down to about 40 Torr by rapidly opening and closing an isolation valve, and the wafer is simultaneously lowered to the heated chuck. Alternatively, the wafer can be pre-processed to remove an implanted photoresist crust at a first temperature and the chamber then backfilled to about 40 Torr for further heating to close to the chuck temperature.

Abstract: An electric lamp is provided which includes a sealed thin-walled outer envelope containing a fill gas having a high thermal conductivity. A lamp capsule is contained within the outer envelope and is in series with an oxidizable fuse also contained within the outer envelope. The fill gas serves to reduce the temperature of the fuse during normal operation of the lamp thereby reducing the power loss in the fuse, increasing overall lamp efficacy and eliminating glow of the fuse. The lamp capsule is quickly extinguished if the outer envelope is broken and the fuse exposed to air. In one embodiment, an incandescent lamp is provided wherein the lamp capsule is a tungsten halogen capsule, the fuse is a tungsten coil wire and the fill gas is helium.

Abstract: In a spark gap switch 12 of a pulse generating circuit 2 of a plasma generator T, an intermediate electrode 15, which is not connected to any electrical source, is disposed at a nearly middle position between a first spherical electrode 13 and a second spherical electrode 15 so as to hold respective spark gaps to the both spherical electrodes 13, 14. Further, in the spark gap switch 12, switching operation is performed between the both spherical electrodes 13, 14 by causing two-stage spark discharge in the first spark gap between the first spherical electrode 13 and the intermediate electrode 15, and in the second spark gap between the intermediate electrode 15 and the second spherical electrode 14. Thus, in the spark gap switch 12, pulse voltage of high voltage and high frequency is stably generated for a long time, and further the spark gap switch 12 may be made compact.

Abstract: A plasma processing chamber is provided which provides improved wafer area pressure control. The plasma processing chamber is a vacuum chamber with a device connected for generating and sustaining a plasma. Part of this device would be an etchant gas source and an exhaust port. A confinement ring defines an area above a wafer. The wafer area pressure is dependent on the pressure drop across the confinement ring. The confinement ring is part of a confinement device that provides wafer area pressure control greater than 40%. Such a confinement device may be a fixed vertical restriction ring in addition to the confinement ring, where the confinement ring is adjustable. In the alternative, three adjustable confinement rings may be used to provide the desired wafer area pressure control.

Abstract: A low pressure mercury vapor discharge lamp comprising a fluorescent tube having an amalgam container containing amalgam to control mercury vapor pressure at a steady lighting, a holder holding both ends of the fluorescent tube, a lighting circuit to light the fluorescent tube, a case accommodating the lighting circuit, and a base provided to the case, wherein the amalgam container and the base are connected with each other by a heat conductive component, so that the amalgam temperature is controlled at a proper value and the luminous efficiency is improved.

Abstract: An illumination control system comprises a source of a lighting intensity control signal, the source having an intensity control signal output. The system also includes at least one first lighting element coupled for direct intensity control by the lighting intensity control signal. Further, the system comprises at least one second lighting element. Additionally, the system comprises a low-pass filter having a filter input and a filter output, the filter input coupled in electrical communication with the intensity control signal output. Also, the system includes a transistor responsively coupled to the filter output and intensity-controllingly coupled to the at least one second lighting element.

Abstract: A luminosity control system (10) for a fluorescent lamp (12) that has a glass enclosure (18) and a pair of lead wires (14) at each end of the glass enclosure is provided. A filament (16) is electrically coupled to each pair of lead wires. An amalgam (22) is located adjacent each filament. The amalgam releases mercury into the glass enclosure upon activation of the fluorescent lamp. A wrapped wire heater (24) is in thermal contact with a first portion of the exterior surface of the glass enclosure. The heater and a thermoelectric cooler (36) raise the temperature of the fluorescent lamp to a level above the temperature at which the fluorescent lamp produces maximum visible light as determined by mercury pressure within the glass enclosure while the amalgam releases mercury into the fluorescent lamp. Thereafter, the thermoelectric cooler (36) maintains a portion of the glass enclosure at this temperature.

Abstract: A device for starting and maintaining a discharge which is placed within an enclosure. The enclosure contains a discharge zone confined by an electromagnetic field. The device has a microtip electron source located in the vicinity of the discharge zone. The electron source is polarized in such a way that it emits electrons to the discharge zone in order to start and maintain the discharge. The device can be used in a cold cathode vacuum gauge.

Abstract: Low pressure sodium lamp color output is shifted from yellow to a fuller spectral range of visible light (white) by effective simultaneous excitation of sodium and a mercury additive. This is made possible principally by controlling the vapor constituents and the excitation arrangement.

Abstract: The mercury vapor pressure in a low pressure mercury discharge lamp is thermostatically controlled. A low pressure mercury discharge lamp includes electrodes and a source of mercury vapor sealed in a lamp envelope. A heater and a thermal switching device are in thermal contact with the source of mercury vapor. The heater is energized when the source of mercury vapor is below a predetermined temperature during operation of the lamp. The heater is preferably a resistance heater electrically connected in series with one of the lamp electrodes. The thermal switching device can be a bimetal thermostatic switch. The source of mercury vapor is typically an amalgam selected to have an optimum mercury vapor pressure at the maximum operating temperature of the lamp. The heater and the thermal switching device can be located external to the lamp envelope or can be located within the lamp envelope.

Abstract: A spark gap switch system is disclosed which is capable of operating at a high pulse rate comprising an insulated switch housing having a purging gas entrance port and a gas exit port, a pair of spaced apart electrodes each having one end thereof within the housing and defining a spark gap therebetween, an easily condensable and preferably low molecular weight insulating gas flowing through the switch housing from the housing, a heat exchanger/condenser for condensing the insulating gas after it exits from the housing, a pump for recirculating the condensed insulating gas as a liquid back to the housing, and a heater exchanger/evaporator to vaporize at least a portion of the condensed insulating gas back into a vapor prior to flowing the insulating gas back into the housing.

Abstract: In a fluorescent lamp device, a discharge tube is made by arranging electrodes at the ends of a glass tube, sealing mercury and a rare gas into the glass tube and coating the inner surface of the glass tube with a phosphor, and an amalgam forming material is disposed close to one or the other of the ends of the discharge tube. This fluorescent lamp is operated with a d.c. current using as the anode the electrode arranged on the discharge tube end side where the amalgam forming material is located.

Abstract: A spark gap switch apparatus is disclosed which is capable of operating at a high pulse rate which comprises an insulated housing; a pair of spaced apart electrodes each having one end thereof within a first bore formed in the housing and defining a spark gap therebetween; a pressure wave reflector in the first bore in the housing and spaced from the spark gap and capable of admitting purge flow; and a second enlarged bore contiguous with the first bore and spaced from the opposite side of the spark gap; whereby pressure waves generated during discharge of a spark across the spark gap will reflect off the wave reflector and back from the enlarged bore to the spark gap to clear from the spark gap hot gases residues generated during the discharge and simultaneously restore the gas density and pressure in the spark gap to its initial value.

Abstract: A fluorescent lamp having a multi-U-bent tubular envelope of convoluted configuration is combined with circuit means, a translucent protective cover and a base module to provide an efficient lamp unit of high brightness and long life that is compact enough to be used as a replacement for incandescent lamps in fixtures designed for residential and commerical lighting installations. Various spatial arrangements for including the ballast and starter components of the energizing circuit as integral parts of the compact lamp unit, despite the stringent space limitations, and also venting the cover and base module to provide convection cooling of the convoluted fluorescent lamp and the other electrical components are also disclosed. Tubulations provided on U-bent portions of the lamp envelope serve as phosphor-drainage means during lamp manufacture and are subsequently tipped off to form mercury-condensation chambers within the finished lamp that regulate the mercury-vapor pressure during lamp operation.

Abstract: A plasma processing apparatus wherein a means is provided to apply the proper negative DC voltage through a filter circuit to an electrode for generating the low-temperature plasma through the feed of the high-frequency power. When the high-frequency power has been fed in the higher high-frequency power density to the electrode for generating the low temperature plasma, the sparks (abnormal discharge) easy to be generated are prevented from being caused to generate the stable low-temperature plasma for better plasma processing.

Abstract: An improved high pressure sodium vapor lamp is described having resistance heater means contained within a tubular light-transmitting ceramic envelope that further contains a reservoir of sodium-mercury amalgam in excess of the quantity vaporized during lamp operation and which are supplied by electric current other than the lamp current responsive to a rise in the lamp operating voltage to reduce the quantity of amalgam being vaporized during lamp operation to help maintain said lamp operation at a relatively constant voltage. In a preferred embodiment, said resistance heater means comprises a refractory metal coil wound around the tungsten shank at one thermionic electrode and electrically insulated therefrom, with said thermionic electrode including a tubular metal inlead serving as the amalgam reservoir, and with the electric current being supplied at a lower value to said refractory metal coil than being supplied to said thermionic electrode.

Abstract: An improved high pressure sodium vapor lamp is described having resistance heater means contained within a tubular light-transmitting ceramic envelope that further contains a reservoir of sodium-mercury amalgam in excess of the quantity vaporized during lamp operation in order to increase the quantity of amalgam being vaporized during lamp operation and thereby help maintain the desired lamp color temperature. In a preferred embodiment, said resistance heater means comprises a refractory metal coil wound around the tungsten shank of one thermionic electrode and electrically insulated therefrom with said thermionic electrode including a tubular metal inlead serving as the amalgam reservoir.

Abstract: A method for breaking direct current, whereby an initial gas pressure, corresponding to the working conditions of a stationary current channel, is set in a gas discharge device, whereafter direct current is passed through the gas discharge device, and the density of the gas filling said gas discharge device is simultaneously reduced over the entire volume of the gas discharge device to a critical value which causes a breaking of the direct current. The d.c. breaker for effecting this method is built around a gas discharge device comprising an anode, a cathode, and intermediate electrodes interposed between said anode and cathode. The cathode is formed by an end emitter, a cone-shaped reflector with the cone's apex facing the end emitter, and two coaxial cylinders encompassing the end emitter and reflector.

Abstract: The invention relates to a device for operating a low-pressure sodium vapor discharge lamp without a stabilizing ballast.The lamp is provided with a discharge tube having first and second main electrodes opposing a third main electrode. An automatically operating change-over switch occasionally switches the lamp current to either the first or second electrodes. A reservoir of liquid sodium near the first electrode affects sodium vapor pressure in the discharge tube by the switching action.

Abstract: In the ion gauge system disclosed herein, the ion current obtained from an ion gauge tube is directly converted to a signal having a frequency proportional to the ion current so that a digital measurement of vacuum may be obtained. The ion current charges an integrating capacitor which is periodically discharged after reaching a preselected threshold. Preferably, the threshold is adjusted in proportion to the ion gauge emission current so that automatic compensation for variation in the emission current is obtained, the output frequency being proportional to the ratio of the ion current to the emission current. The variable frequency output signal generated by the integration and discharge process is counted by a scaling circuit which automatically changes the timing interval to provide the desired number of significant figures while incrementing the exponent value in a scientific notation display in keeping with the active time base.

Abstract: The mercury-vapor pressure within a fluorescent lamp is controlled by a metal (indium or an alloy of indium and tin, for example) that wets glass, combines with the mercury within the lamp to form an amalgam and is divided into segments which are fused directly to one or both of the glass stems at spaced locations. The amalgamative-metal segments are of such shape and mass that they inherently remain in place on the stem when they are heat-softened and pressed onto the glass surface. Segments of larger size and mass are retained in place by an overlying porous layer of inert material that adheres to the glass or by an embedded wire mesh member and an exterior porous coating of inert material. The amalgamative metal can also be combined with a fusible binder to form a composite which is divided into small pellets that are pressed onto the glass stem and held in place by the adhesive action of the binder when the latter is fused during the bulb-lehring operation required to fabricate the lamp.

Abstract: A technique is disclosed herein for the enhancement of efficiency, and uniformity of light emission from a DC-operated fluorescent lamp. It involves the correlation of mercury vapor pressure within the lamp (which is dependent upon the temperature of liquid mercury within the lamp) with the magnitude and polarity orientation of the DC current applied to the lamp, and an optimization of these parameters along with lamp tube diameter.

Abstract: Apparatus for generating ultraviolet radiation of high spectral radiance whereby the radiation is produced in a discharge tube having a thermoemissive cathode and a discharge space and filled with mercury/argon by means of a wall-stabilized direct-current gas discharge at a mercury pressure p.sub.Hg of between 5 .times. 10.sup.-.sup.3 and 5 .times. 10.sup.-.sup.1 Torr and a current density j of the discharge current I of between 1 and 25 A/cm.sup.2. The discharge tube incorporates a pressure-equalizing space connecting the cathode space to the anode space whereby the sum of the volumes of the cathode space, anode space and pressure-equalizing space is greater than the volume of the discharge space. The pressure of the argon is maintained between 0.01 and 10 Torr. A first control element is provided which regulates the current density j of the discharge current I to a constant value j.sub.O between 1 and 25 A/cm.sup.2. A second control element is provided which regulates the pressure p.sub.