Abstract: The invention relates to an electrode for a discharge lamp, wherein the electrode has a base body having an electrode plateau providing an end face of the electrode, wherein the base body is delimited by the electrode plateau in a longitudinal extension direction of the electrode. Furthermore, the electrode has a coating, arranged in at least a first region of the base body that is different from the electrode plateau, to increase an emission of heat. In addition, the electrode has an at least partially contiguous free region of the base body extending at least partly in the longitudinal extension direction as far as the electrode plateau, in which the coating for increasing the emission of heat is not arranged, and wherein the first region adjoins at least one section of the free region in the circumferential direction of the electrode.

Abstract: A ring laser gyroscope comprises a laser block that includes a resonant internal cavity defined by a plurality of surfaces of an optical closed loop pathway, and a plurality of electrodes coupled to the laser block. The electrodes are configured to generate a pair of counter-propagating laser beams from a lasing gas in the optical closed loop pathway. The ring laser gyroscope also includes a field reducer shield comprising an electrically conductive material, with the field reducer shield located completely within the laser block. The field reducer shield is configured to modify an electric field generated by the plurality of electrodes to substantially prevent ions in the laser block from migrating toward the plurality of surfaces of the optical closed loop pathway.

Abstract: A beam ionization gauge (BIG) detector is disclosed for use in spectroscopy and configured to receive an analyte beam along a beam path. The BIG detector includes a filament configured to emit electrons and a grid. The grid is positioned substantially adjacent to the filament and configured to produce ions by directing the electrons to collide with the analyte beam along the beam path. A collector is positioned substantially adjacent to the grid to define the beam path therebetween and configured to detect the ions produced by the collisions of electrons with the analyte beam.

Abstract: The invention describes a method of manufacturing an electrode (1) for a gas-discharge lamp, which method comprises forming an electrode shaft (10); forming a coil (2) over a winding length (L W); arranging the coil (2) on the electrode shaft (10); and melting material of the coil (2) such that, when the melted coil material has re-solidified, the solidified material (30,31) comprises a one-piece shell (3), which one-piece shell (3) comprises a fused portion (30) over a fraction (L T) of the winding length (L W) and a mantle portion (31) over a remainder (L B) of the winding length (L W).

Abstract: A cathode for a discharge lamp in which an electron emitting section containing an easily electron emitting material at its end is provided that has simplified yet non-breakable structure and can reduce the manufacturing cost. A short arc discharge lamp includes an arc tube in which a cathode and an anode face each other and a xenon gas is enclosed. The cathode has an electron emitting section made from tungsten to which thorium is added as an easily electron emitting substance. The cathode also has an electrode body section made from tungsten to which no thorium is added. The electrode body section has a recess at a front end side. The electron emitting section has a circular truncated conical shape, a rear end side of the electron emitting section is received in the recess, and a front end side portion protrudes from the recess.

Abstract: Disclosed herein is a short arc discharge lamp which has a cathode electrode structure formed by solid-phase bonding a tip part made of thoriated tungsten to a body part made of tungsten. According to the present invention, the bonding strength between the body part and the tip part is increased to the same level as the mechanical strength of tungsten, thus preventing a breakage from being caused on a junction interface. For this, on a section of the cathode electrode taken along a line perpendicular to the junction interface, in an arbitrary portion of 500 ?m or more in length along the junction interface, when a length of the arbitrary portion along the junction interface is set to L0, and a sum of lengths of tungsten crystal grains, along the junction interface, that are present through the junction interface is set to L, (L/L0)?0.16 is satisfied.

Abstract: A flashtube of the present invention includes a glass tube, an anode-side electrode disposed at one end of the glass tube, and a cathode-side electrode disposed at the other end of the glass tube. The glass tube includes a first glass tube, and second glass tubes coupled to respective ends of the first glass tube via stage joint glass tubes. Each of the stage joint glass tube has a thermal expansion coefficient between the thermal expansion coefficient of the first glass tube and that of each of the second glass tube. A ratio of the outer diameter of the anode-side electrode to the inner diameter of the glass tube is 43.5% or higher.

Abstract: An electrically heated planar cathode for use in miniature x-ray tubes may be spiral design laser cut from a thin tantalum alloy ribbon foil (with grain stabilizing features). Bare ribbon is mounted to an aluminum nitride substrate in a manner that is puts the ribbon in minimal tension before it is machined into the spiral pattern. The spiral pattern can be optimized for electrical, thermal, and emission characteristics.

Abstract: Disclosed herein is a short arc discharge lamp which has a cathode electrode structure formed by solid-phase bonding a tip part made of thoriated tungsten to a body part made of tungsten. In the present invention, thorium can be reliably diffused onto the surface of the cathode electrode over a long period of time without stagnation of reduction of thorium oxide in the tip part. Therefore, satisfactory emission characteristics can be provided, whereby the arc stability is more reliable. The cathode electrode of the present invention is characterized in that potassium concentration of the body part is higher than potassium concentration of the tip part.

Abstract: A discharge lamp (1) comprising a discharge vessel (4), at least one electrode (22, 24) arranged within the discharge vessel, wherein at least parts of the electrode (22) are provided with a particle composite coating (32) made up of a matrix layer and particles embedded in the matrix layer, wherein the extinction coefficient k of the material for the matrix layer is less than 0.1 in the spectral range between 600 nm and 2 ?m, and wherein the extinction coefficient k of the material for the particles is greater than 0.1 in the spectral range between 600 nm and 2 ?m.

Abstract: It is an object of the present invention to provide a metal halide lamp in which arc discharge in the initial stage of lamp lighting can be stabilized. A metal halide lamp includes a translucent outer tube with a base formed at one end thereof and a light-emitting portion disposed in the outer tube. This metal halide lamp is configured as a vertical mounting type such that the base thereof looks toward the upper side. The discharge tube has mercury and metal halides enclosed therein. Assuming that a lamp rated power is P [W], then a mercury concentration d(Hg) [?mol/cm3] in the discharge tube falls within a range of values of ±10% of a mercury concentration d(Hg) obtained by the following equation “d(Hg)=0.0007P2?0.4113P+99.557”.

Abstract: [Problems] Disclosed is a surge absorber which can absorb a surge having a long wave tail, wherein a stable sparkover voltage is obtained without applying a discharging aid to electrodes. [Means for Solving the Problems] The surge absorber is comprised of a pair of terminal electrode members (2) which are opposed to each other; and the insulation tube (3) on which the pair of terminal electrode members (2) are disposed on opposite ends thereof and that has a discharge control gas sealed therein. Bulging electrode elements (4) having an expanded center portion (4a) are formed on the inner surfaces of the terminal electrode members (2). The bulging electrode elements (4) contain metal which can emit more electrons than the terminal electrode members (2).

Abstract: An electrode structure configured to operate in a discharge lamp and a method to make such an electrode structure are described. The electrode structure includes an electrode head portion comprising a plurality of raised features arranged in a configuration such that an average pitch of the plurality of raised features is at least 105%. The method includes providing an electrode configured to operate in the discharge lamp and forming raised features on an electrode head portion of the electrode at an average pitch of at least 105%.

Abstract: Disclosed herein is a short arc discharge lamp which has a cathode electrode structure formed by solid-phase bonding a tip part made of thoriated tungsten to a body part made of tungsten. In the present invention, thorium can be reliably diffused onto the surface of the cathode electrode over a long period of time without stagnation of reduction of thorium oxide in the tip part. Therefore, satisfactory emission characteristics can be provided, whereby the arc stability is more reliable. The cathode electrode of the present invention is characterized in that potassium concentration of the body part is higher than potassium concentration of the tip part.

Abstract: Disclosed herein is a short arc discharge lamp which has a cathode electrode structure formed by solid-phase bonding a tip part made of thoriated tungsten to a body part made of tungsten. According to the present invention, the bonding strength between the body part and the tip part is increased to the same level as the mechanical strength of tungsten, thus preventing a breakage from being caused on a junction interface. For this, on a section of the cathode electrode taken along a line perpendicular to the junction interface, in an arbitrary portion of 500 ?m or more in length along the junction interface, when a length of the arbitrary portion along the junction interface is set to L0, and a sum of lengths of tungsten crystal grains, along the junction interface, that are present through the junction interface is set to L, (L/L0)?0.16 is satisfied.

Abstract: A hollow cathode lamp is described with an end cap, an anode, and a cathode. A data storage device is part of the end cap and communicates data to and from a computing device. The data communicated with the computing device may include identification information and usage information corresponding to the hollow cathode lamp. Additionally, a method is described that includes activating a power supply to a hollow cathode lamp and communicating data with a memory device located in the hollow cathode lamp. The data communicated with the memory device includes usage information about an amount of time the hollow cathode lamp has been in use.

Abstract: An ionization device comprises: a plasma source configured to generate a plasma. The plasma comprises light, plasma ions and plasma electrons. The plasma source comprises an aperture disposed such that at least part of the light passes through the aperture and is incident on a gas sample. The ionization device further comprises an ionization region; and a plasma deflection device comprising a plurality of electrodes configured to establish an electric field, wherein the electric field substantially prevents the plasma ions from entering the ionization region.

Abstract: An atmospheric plasma apparatus and a method for manufacturing the same are disclosed. The atmospheric plasma apparatus includes an anode, a cathode, and an insulation medium disposed between the anode and the cathode. An ionizable gas is filled between the anode and the cathode. The cathode includes a plurality of plasma generating and removing units, each of which includes a plasma generating region and a plasma removing region. The plasma generating regions and the plasma removing regions are distributed uniformly and equal to each other in area. Any two plasma removing regions among every three plasma removing regions which are adjacent to each other have a same center-to-center distance. In this way, erosion caused by the plasma to the cathode and the insulation medium may be reduced to prolong the service life of the atmospheric plasma apparatus, and uniformity of cleaning of a substrate surface may be improved.

Abstract: A short arc type discharge lamp wherein a cathode and an anode are arranged opposite to each other in an interior of a light emitting tube and said cathode comprises a main part made from tungsten and a tip end part made from thoriated tungsten, wherein thorium oxide particles having been peripherally coated with thorium are contained in the tip end part of said cathode.

Abstract: An electrically heated planar cathode for use in miniature x-ray tubes may be spiral design laser cut from a thin tantalum alloy ribbon foil (with grain stabilizing features). Bare ribbon is mounted to an aluminum nitride substrate in a manner that is puts the ribbon in minimal tension before it is machined into the spiral pattern. The spiral pattern can be optimized for electrical, thermal, and emission characteristics.

Abstract: A flashtube of the present invention includes a glass tube, an anode-side electrode disposed at one end of the glass tube, and a cathode-side electrode disposed at the other end of the glass tube. The glass tube includes a first glass tube, and second glass tubes coupled to respective ends of the first glass tube via stage joint glass tubes. Each of the stage joint glass tube has a thermal expansion coefficient between the thermal expansion coefficient of the first glass tube and that of each of the second glass tube. A ratio of the outer diameter of the anode-side electrode to the inner diameter of the glass tube is 43.5% or higher.

Abstract: A short arc type discharge lamp that includes a body member a light permeable member a pair of an anode and a cathode. The pair of the anode and cathode is arranged with a gap at a focal position of the reflective face. The cathode has a cathode tip portion that is approximately conic and a cathode rod portion. The anode has an anode tip portion that has a tapering portion and a flat tip end portion. Further, an outer diameter of the tip of the anode flat tip end portion is smaller than the outer diameter of the cathode rod portion, and an outer diameter of a back end of the anode tip portion is larger than that of the cathode rod portion.

Abstract: A vehicular discharge lamp that emits light by a DC lighting system, the vehicular discharge lamp includes: an outer tube; a light emitting tube disposed in the outer tube and including a light emitting portion and fine tube portions connected to the light emitting portion; cathode-side and anode-side electrodes disposed in the light emitting tube; two lead wires connected to the electrodes; and a metal film or a metal oxide applied on an outer peripheral surface of the fine tube portion on an anode side of the light emitting tube, or the metal wire being wound on the outer peripheral surface. Inert gas having negative pressure is filled in a space outside the light emitting tube in the outer tube, and a negative high-voltage pulse is applied to the anode-side electrode at a time of start-up.

Abstract: A short arc type discharge lamp wherein a cathode and an anode are arranged opposite to each other in an interior of a light emitting tube and said cathode consists of a main body part with tungsten as the main constituent and an emitter part comprised of thoriated tungsten, wherein an oxygen content of the main body part of said cathode is lower than that of the emitter part, and band-shaped tungsten carbide is formed at the tip end face of the emitter part of said cathode.

Abstract: A discharge lamp with excellent arc stability and excellent durability in which the use level of thoriated tungsten is restrained has an anode and a cathode in the interior of a discharge vessel, wherein said cathode is made up from a thoriated tungsten part with a tungsten filling ratio of at least 90 vol.-% and a main body part connected to said thoriated tungsten part and consisting of pure tungsten, wherein a ratio ST/S of a side surface area ST of said thoriated tungsten part and a side surface area S of said cathode is in a range of from 0.005 to 0.15, with the proviso that, in case the cathode has a length in the direction of the cathode axis which exceeds twice the maximum diameter of the cathode, a side surface area S is used for calculating the ratio ST/S which corresponds to the side surface area where the distance along the cathode axis from a tip end adjacent to the anode is twice the maximum diameter of the cathode.

Abstract: A short arc type discharge lamp that includes a body member a light permeable member a pair of an anode and a cathode. The pair of the anode and cathode is arranged with a gap at a focal position of the reflective face. The cathode has a cathode tip portion that is approximately conic and a cathode rod portion. The anode has an anode tip portion that has a tapering portion and a flat tip end portion. Further, an outer diameter of the tip of the anode flat tip end portion is smaller than the outer diameter of the cathode rod portion, and an outer diameter of a back end of the anode tip portion is larger than that of the cathode rod portion.

Abstract: An atmospheric plasma apparatus and a method for manufacturing the same are disclosed. The atmospheric plasma apparatus includes an anode, a cathode, and an insulation medium disposed between the anode and the cathode. An ionizable gas is filled between the anode and the cathode. The cathode includes a plurality of plasma generating and removing units, each of which includes a plasma generating region and a plasma removing region. The plasma generating regions and the plasma removing regions are distributed uniformly and equal to each other in area. Any two plasma removing regions among every three plasma removing regions which are adjacent to each other have a same center-to-center distance. In this way, erosion caused by the plasma to the cathode and the insulation medium may be reduced to prolong the service life of the atmospheric plasma apparatus, and uniformity of cleaning of a substrate surface may be improved.

Abstract: The invention relates to a discharge lamp with a floor plate and a roof plate designed for dielectrically impeded discharge, in which the minimum discharge distances are at least 10 mm.

Abstract: An extra-high pressure mercury lamp includes an arc tube made of quartz glass. The lamp includes an arc tube portion and sealing portions connected to the arc tube portion, and encloses 0.15 mg/mm3 or more of mercury. A pair of electrodes are disposed face to face in the arc tube. Each electrode has a rod portion and a base end portion. The base end portion of each electrode is embedded in one of the sealing portions. One of the pair of electrodes serves as a cathode and includes a head portion, which has a larger diameter than the rod portion. A cylinder portion is connected to a rear end portion of the head portion. The cylinder portion extends in the axis direction of the electrode and surrounds the rod portion. The cylinder portion has an inner surface separated from the rod portion.

Abstract: A short arc type discharge lamp wherein a cathode and an anode are arranged opposite to each other in an interior of a light emitting tube and said cathode consists of a main body part with tungsten as the main constituent and an emitter part comprised of thoriated tungsten, wherein an oxygen content of the main body part of said cathode is lower than that of the emitter part, and band-shaped tungsten carbide is formed at the tip end face of the emitter part of said cathode.

Abstract: A short arc type discharge lamp wherein a cathode and an anode are arranged opposite to each other in an interior of a light emitting tube and said cathode comprises a main part made from tungsten and a tip end part made from thoriated tungsten, wherein thorium oxide particles having been peripherally coated with thorium are contained in the tip end part of said cathode.

Abstract: A discharge lamp for a vehicle has an external tube attached to a socket, a light emitting tube disposed in the external tube and formed of ceramic, the light emitting tube including a light emitting portion and a pair of narrow tube portions linked to the light emitting portion at opposite sides with the light emitting portion interposed therebetween, a cathode side electrode and an anode side electrode which are disposed in the light emitting tube, and two lead wires connected to the cathode side electrode and the anode side electrode respectively and having at least a part disposed in the external tube respectively. A length of the narrow tube portion on the cathode side being set to be smaller than that of the narrow tube portion on the anode side. The cathode side electrode being disposed on an opposite side to the socket with the anode side electrode interposed therebetween.

Abstract: The invention relates to a high-pressure mercury discharge lamp for DC operation at a nominal wattage of more than 1.5 kW. Said high-pressure mercury discharge lamp comprises an anode, at least some areas of which are made of a material containing at least some tungsten, said material having a grain number of more than 200 grains per mm2 and a density of more than 19.05 g/cm3.

Abstract: A display panel includes a first plurality of scan lines, a second plurality of scan lines, and a cell section that includes first and second electrode layers that cross form a plurality of display cells. Each cell includes a light-emitting layer which is formed between the first and second electrode layers. The panel also includes a plurality of contacts, each of which electrically couples at least one of the first or second scan lines to a corresponding one of the second electrode layers. One or more of the contacts have a dimension which is different from a dimension of one of the display cells.

Abstract: A discharge lamp has an electrode comprising a base portion having a base portion side flange portion, and a lid portion having a lid portion side flange portion. In a sealed space of the electrode, heat conductive member is enclosed. At time of lighting, the electrode is not damaged, and the discharge lamp can be stably operated. In the electrode, the diameter direction width of a welding portion of a base portion side flat portion and a lid portion side flat portion is 0.8 to 3.0. Further, an angle formed by the base portion side flat portion and a base side slope portion is 30 degrees or less and an angle formed by the lid portion side flat portion and a lid side slope portion is 30 degrees or less. The sum total of these angle is 160 degrees or less.

Abstract: For stably supplying an electron emitting substance and preventing illuminance fluctuations, a cathode is provided made from a tungsten material containing an electron emitting substance and having a taper part a diameter of which becomes smaller towards a tip end, a tip end face formed at the tip end side of said taper part, and a fine hole extending from said tip end face in an interior of said cathode, wherein said fine hole is formed at said tip end face such that it extends over at least two tungsten crystal grains. The invention also relates to a short arc type discharge lamp comprising said cathode.

Abstract: The invention relates to an electrode having a nano-hollow array on the surface thereof, the nano-hollow array comprising a plurality of nano-pores or nano-balls, each pore having a diameter of less than 500 nm, formed by a process comprising depositing a uniform metal film on the electrode structure surface at a rate of 2 ? per second or less, annealing the metal film under rapid anneal conditions at a temperature within about 100 degrees of the melting point of the metal film and without subjecting the metal film to a temperature ramp-up to create metal droplets, and anodizing and over-anodizing the metal droplets in the presence of an anodization agent for the metal at from 20 to 200 volts at 0.1 to 2 amps to create nano-pores in the metal droplets or nano-balls to, creating increased surface area and increased electric field around the electrode which enhances speed of fill gas ionization.

Abstract: A discharge lamp in which fluctuation of the arc when the lamp starts and in which devitrification and damage of the arc tube are prevented, so that light intensity can be kept uniform over a long time is achieved by the cathode having a tapering part with a diameter which decreases in the direction to the tip that is formed with an area with different diameters extending around the tapering part in the peripheral direction which has concave-convex parts with groups of convex parts which are located next to one another in the axial direction of the cathode, the concave-convex parts in longitudinal cross section being arranged such that corner points of each convex part are located inside of an edge line of the tapering part, and an envelope curve which connects the corner points is convex with respect to the center line of the cathode.

Abstract: A discharge lamp having a cathode containing lanthanum oxide (La2O3) as an electron emission material, to provide a discharge lamp where reduction of lanthanum oxide (La2O3) is accelerated; a supply amount of lanthanum (La); and its lifespan is long has an anode (4) and a cathode (5) arranged within a discharge vessel (1) so as to face toward each other in a tube axis direction of the discharge vessel (1), and the cathode (5) is made from a material containing a metal oxide of lanthanum (La2O3) and a metal oxide of zirconium (ZrO2) in a tungsten metal (W) substrate with carbon present as a solid solution in the tungsten metal (W) substrate forming the cathode (5).

Abstract: A cathode for a discharge lamp contains emitter material, wherein a carbide layer is formed on an outer surface of the cathode, the carbide layer is formed on an area extending from a tip portion of the cathode, and two or more grooves extending toward the tip portion of the cathode are formed on the area where the carbide layer is formed.

Abstract: Broadband radiation may be generated by supplying a gas mixture containing hydrogen and/or deuterium and/or helium and/or neon to an enclosure, generating a plasma inside the enclosure with the gas mixture. Broadband radiation generated as a result of the plasma discharge to a substrate may be optically coupled to a substrate located outside the enclosure.

Abstract: A cold cathode discharge lamp includes: a transparent hollow housing; a fluorescent film formed on inner surfaces of the hollow housing; a pair of cold cathodes that are located in the hollow housing; and a discharge gas that contains hydrogen gas sealed within the hollow housing. Each of the cold cathodes includes: a supporting body that has conductivity; an insulating diamond film formed on the supporting body; and an insulating layer that insulates the supporting body from the insulating diamond film.

Abstract: The invention describes a light burner (1) comprising a discharge chamber (2) containing a gas sealed in the discharge chamber (2) by a seal (4, 5) and a pair of electrode shafts (6, 7), each of which partially intrudes from the seal (4, 5) into the discharge chamber (2) whereby a wrapping (8, 9), at least partially contained in the seal (4, 5), is freely wound around at least one of the electrode shafts (6, 7) and constrained in its motion by a number of containment elements (P1, P2, P3, P4) positioned along the longitudinal axis of the electrode shaft (6, 7).

Abstract: A high-pressure discharge lamp has a pressure chamber with two opposite end regions and delimited by a cylindrical envelope made of glass. An electrode is provided at each of the two end regions, the electrodes projecting into the pressure chamber and being arranged in the pressure chamber as anode and cathode. A discharge chamber is formed between the electrodes. The two end regions of the pressure chamber are designed differently at least outside of the discharge chamber.

Abstract: A method of making cathodes includes forming a first intermediate assembly having a current wire in juxtaposition with an outer mandrel wire and a basket wire wound around the first two wires. The first intermediate assembly is wound around a central mandrel to form a second intermediate assembly. Pulses of energy are used to produce an alloy solder joint between the current wire and the basket wire at selected locations. The second intermediate assembly is cut into segments, and the mandrels are removed. This results in a cathode having a coiled current wire and a basket wire wound around the current wire, with the basket wire being bonded to the current wire by the alloy solder joints. The cathode includes a central bore that is substantially free of the alloy solder joint.

Abstract: A cold cathode for a discharge lamp includes a metal plate that has bending portions; a diamond film that is formed on a face of the metal plate, except for the bending portions; and a metal member that is mounted on the metal plate.

Abstract: A high pressure discharge lamp in which the cathode has a cylindrical body part and a conical part which is doped with thorium dioxide (ThO2), and with a diameter which decreases in a direction from the body part toward the tip area of the conical part by at least one light receiving surface area being formed between the body part and the tip area of the cone in a base part of the conical part. The light receiving area lies at an angle with respect to the center axis of the conical part and the body part, said angle which is measured from the side of the body part being greater than the angle of inclination which is formed between the outer periphery of the conical part in the tip area of the cone and the center axis.

Abstract: Cathode unit for installation in a fluorescent tube body (3) belonging to a fluorescent tube (1), which cathode unit (5) comprises a cathode screen (15a, 15, 15?-15??) which partially surrounds an electrode (9) which is electrically insulated from the said cathode screen (15), a power supply device (11) arranged to make an electrical connection between the said electrode (9) and a contact (13), the said cathode screen (15a, 15 , 15?-15??) comprising a first end (19) facing towards the discharge, which first end (19) comprises a central opening (21), and a second end (39) facing towards the said contact (13). The first end (19) of the cathode screen (15a, 15, 15?-15??) is designed with a rounded-off part (25) in order to facilitate the insertion of the cathode unit (5) in the said fluorescent tube body (3).

Abstract: According to the present invention, a short arc lamp comprises a lamp main body having a reflective surface therein, a first opening on an optical axis thereof, and a second openings, a window member provided so as to close the second opening and to define a discharge space between the lamp main body and the opening, a first electrode and a second electrode that are arranged so as to face each other, wherein a tip portion of each of the electrodes extends into the discharge space, and a base disposed approximately at a back end portion of the lamp main body, wherein a hole is formed in the base, the first electrode is held in a burying portion of the base, and a diameter of the first electrode in the burying portion is larger than that of the tip portion of the first electrode.

Abstract: In a gas discharge tube, a first discharge path-induction portion is arranged between a first discharge path-limit portion and a second discharge path-limit portion. A voltage is applied to the first discharge path-induction portion from the outside. As a result, an active starting discharge capable of passing through a first opening of the first discharge path-limit portion is produced between a cathode portion and the first discharge path-induction portion. As a consequence, there is facilitated the discharge at a starting time to pass through a second opening. As a consequence, there is achieved a rapid starting of discharge between the cathode portion and an anode portion.