164 results about "Cold cathode" patented technology

The embodiment of the invention discloses a cold cathode flat plate X-ray source capable of coding light emitting and a coding light emitting method, the ray source comprises a vacuum sealing cavity, a cathode assembly and an anode assembly, the cathode assembly and the anode assembly are arranged in the vacuum sealing cavity in a sealing manner, and the cathode assembly and the anode assembly are oppositely arranged at an interval; a vacuum working space for electron acceleration and X-ray generation is formed; the cathode assembly comprises a cathode substrate and a nano cold cathode electron source array arranged on the cathode substrate; the anode assembly comprises an anode substrate and a transmission anode target arranged on the anode substrate; wherein at least one of the nanometer cold cathode electron source array and the transmission anode target is in a coding state: when the nanometer cold cathode electron source array is in the coding state, the nanometer cold cathode electron source array comprises a micro-unit electron source array capable of independently addressing, and a preset coding pattern is formed; and when the transmission anode target is in a coding state, a metal coating with a preset coding pattern is formed on the surface of the anode substrate through a micromachining process so as to integrate a coding function.

The invention belongs to the technical field of pipeline detection robots, and particularly relates to a cold cathode CT annular scanning walking nondestructive detection intelligent robot which comprises a supporting table and a controller installed on the side wall of the supporting table, and further comprises two carrier roller conveying assemblies which are installed on the two side walls of the supporting table correspondingly, the carrier roller conveying assembly is used for conveying polyethylene pipes. The movable table is arranged above the supporting table, the supporting table is provided with a driving mechanism, the driving mechanism is used for driving the movable table to move along the supporting table, and the end face of the movable table is provided with an X-ray source. According to the invention, nondestructive scanning detection can be automatically carried out on the annular hot melt interface of the polyethylene pipe, automatic defect identification and report generation of a welding seam are realized, multi-angle space imaging and reproduction display are carried out on defects, detection is efficient and accurate, and the interface can be heated to assist in accurate defect identification.

The invention discloses a novel electronic gun for a cyclotron wave protector, and relates to the technical field of vacuum electronic devices. The electron gun comprises a cathode assembly, an anode assembly, a supporting assembly and a permanent magnet system. Wherein the cathode assembly adopts a planar cold cathode structure; the anode assembly comprises an anode main body and an electron beam channel in the anode main body; the cathode and the anode are fixedly connected through a supporting assembly; the permanent magnet system provides a uniform magnetic field. The cold cathode is adopted to replace a traditional hot cathode to generate high-quality strip-shaped electron beams, and the device has the advantages of being simple in structure, easy to integrate, rapid to start, long-acting, reliable, low in consumption and energy-saving.

The invention discloses a cold cathode microfocus X-ray tube based on double electrostatic lenses, which belongs to the technical field of X-ray tubes, and comprises a shell, a window, an anode assembly and a cathode electron gun assembly, the anode assembly comprises an anode target; the cathode electron gun assembly comprises a cathode cylinder, and a cathode, a grid electrode, a first focusing electrode, a second focusing electrode, a third focusing electrode, an electrode core column, an electrode lead and a field emission material which are positioned in the cathode cylinder; the field emission material generates electrons under the action of field emission, the formed electron beams are converged for the first time under the action of the first electrostatic lens to form a first focus, are converged for the second time under the action of the second electrostatic lens to form a second focus, and finally bombard the anode target to generate X-rays. According to the X-ray tube, the convergence and compression capacity of electron beams is improved by forming the double electrostatic lenses, the size of a convergence focus is reduced under the condition that the emission area is not affected, and the resolution ratio of the X-ray tube is improved.

The present invention provides a multi-directional connection hub including a plurality of openings to which an anode adapter made of a metal material is connected through an insulation tube and an electron gun which emits electrons to the anode adapter to generate X-rays is connected, wherein the openings include a plurality of side openings to which the electron gun is connected and an upper opening through which the X-rays generated by the electrons, which are provided from the electron gun through the side opening and collide with the anode adapter, are emitted, and an emission direction of the X-rays is changed toward another side opening of the plurality of side openings or the upper opening according to a type of the anode adapter and a type or installation location of the electron gun.

The embodiment of the invention provides a foil structure with a carbon nanotube and a preparation method thereof, a cold cathode and an X-ray tube, the foil structure comprises a metal substrate, the metal substrate is provided with a first surface and a first side surface, the first side surface is vertical to the first surface, and the first side surface is located at the edge of at least one side of the metal substrate; the bonding layer is located on the first surface of the metal substrate; the bonding layer is arranged on the first surface of the metal substrate, the multiple carbon nanotubes are located on the first surface of the metal substrate, the bonding layer is used for enhancing the bonding strength of the metal substrate and the multiple carbon nanotubes, the multiple carbon nanotubes comprise a carbon nanotube film and multiple discrete carbon nanotubes, the carbon nanotube film is located on the first surface, and the discrete carbon nanotubes are located on the second surface. The multiple discrete carbon nanotubes are located in the area, close to the first side face, of the first surface, at least the other part of the multiple discrete carbon nanotubes is located outside the carbon nanotube film, orthographic projections of the multiple discrete carbon nanotubes on the metal substrate are located outside the first surface, and the at least the other part of the multiple discrete carbon nanotubes protrude in the direction away from the metal substrate relative to the first side face.

The invention discloses a cold cathode ionization gauge driving acquisition circuit, relates to the field of vacuum measurement, and solves the problems of signal conversion nonlinearity and large ion flow when a gauge tube works at a lower vacuum degree in the existing cold cathode ionization gauge driving acquisition technology. Comprising an ion current logarithmic acquisition circuit used for converting the ion current of the cold cathode ionization gauge into a voltage signal, a current monitoring circuit used for generating a control signal according to the voltage signal, and a voltage-controlled high-voltage driving circuit used for driving the cold cathode ionization gauge according to the control signal. The nonlinear compensation operation conditioning circuit is used for performing nonlinear compensation on the voltage signal according to the control signal to obtain an operation acquisition voltage, and the operation acquisition voltage is used for being input into an acquisition system; the non-linear problem of signal conversion is solved through the non-linear compensation circuit, negative feedback loop control is carried out through the current monitoring circuit and the voltage-controlled high-voltage driving circuit, the driving voltage of a gauge tube is reduced, and the maximum ion current is limited at a low level.

The present invention belongs to the technical field of pipeline inspection robots, and in particular, relates to a cold cathode CT annular scanning walking nondestructive inspection intelligent robot, including a support platform and a controller installed on the side wall of the support platform, and also includes: two roller conveyor assemblies, the two roller conveyor assemblies are respectively installed on the two side walls of the support platform, and the roller conveyor assemblies are used to convey polyethylene pipes; a movable platform is arranged above the support platform, and the support platform is equipped with a driving mechanism, and the driving mechanism is used to drive the movable platform to move along the support platform, and the end face of the movable platform is equipped with an X-ray source. The present invention can automatically perform nondestructive scanning inspection on the annular hot-melt interface of polyethylene pipes, realize automatic defect recognition and report generation of welds, multi-angle spatial imaging and re-display of defects, and efficient and accurate detection, and can heat the interface to assist in accurate defect recognition.

The invention provides a cold cathode flat plate X-ray source and a control method, and relates to the technical field of X-rays. In the application, the cold cathode flat plate X-ray source comprises an anode substrate and a cathode substrate; the anode target material is arranged on the anode substrate; the cathode assembly is arranged on the cathode substrate and comprises a plurality of cathode blocks which are distributed in an array mode, each cathode block comprises a plurality of nanowire cold cathodes which are distributed in an array mode, and in the X-ray output process, the nanowire cold cathodes are arranged on each cathode block. And if at least one row of nanowire cold cathodes currently used for emitting electrons in the cathode block are abnormal, determining at least one row of nanowire cold cathodes without abnormality in the cathode block, and controlling the nanowire cold cathodes to emit electrons to the anode target material so as to generate X-rays. Based on the above content, the problem of low utilization rate of the cold cathode flat plate X-ray source in the prior art can be improved.

This invention provides a cobalt foam-carbon nanotube composite cathode material, its preparation method, and its applications, relating to the field of cathode material preparation technology. The composite cathode material of this invention is obtained by depositing a carbon nanotube array on a cobalt foam substrate. As a cold cathode material for field emission, this composite cathode material exhibits low turn-on and threshold electric fields, high current density, excellent field emission performance, and excellent current stability, meeting the performance requirements of field emission cathode materials. Furthermore, the preparation method of this composite cathode material is safe and simple. This invention provides a novel cathode material solution for high-performance, long-life vacuum electronic devices, with promising application prospects.

This invention relates to a cold cathode X-ray inspection system and method with eddy current detection function, used for defect detection and evaluation of composite materials with conductive and magnetic panels and pure metal materials of a certain thickness. The inspection system includes a cold cathode X-ray instrument, a DR receiving panel, and a laptop computer. In addition to the cold cathode X-ray detection board, the mainboard of the cold cathode X-ray instrument also has an eddy current detection board. The eddy current detection board and the cold cathode X-ray detection board share the built-in power supply unit and operation unit of the cold cathode X-ray instrument. A transparent flexible panel is added to the photosensitive element layer of the DR receiving panel. A transparent detection coil made of metal coating technology with an array arrangement is set on the transparent flexible panel. During the inspection, the cold cathode X-ray image of the inspected workpiece and the eddy current detection signal on the surface of the inspected workpiece can be acquired simultaneously. By comparing, fusing, and analyzing the two image signals, a complete and accurate inspection result is obtained.

The invention relates to the technical field of vacuum microelectronic devices, in particular to a nano cold cathode electron source array and a preparation method thereof, and the nano cold cathode electron source array comprises a substrate; the bottom cathode electrode strips are arranged in parallel; the bottom gate electrode strips are arranged in parallel; the insulating layer covers and separates the bottom cathode electrode strip and the bottom gate electrode strip, and the insulating layer is located at the top of the substrate; a top cathode electrode and a top gate electrode which are manufactured at the top of the insulating layer are respectively connected with the bottom cathode electrode strip and the bottom gate electrode strip through the first etching through hole and the second etching through hole; and the composite cold cathode comprises a nano cold cathode manufactured at the top of the top cathode electrode and a surface film coating the nano cold cathode. According to the invention, the conductivity, thermal conductivity, work function and other characteristics of the composite cold cathode can be regulated and controlled through the surface film, the field emission characteristic of the nano cold cathode in a cold cathode electron source is improved, large-area preparation can be realized, and the application of the cold cathode electron source in a large-area flat X-ray source device is expanded.

The invention provides a carbon nanotube cold cathode, a preparation method thereof and an X-ray tube, and the preparation method of the carbon nanotube cold cathode comprises the following steps: carrying out ball milling on an agglomerated carbon nanotube to obtain carbon nanotube powder; mixing the carbon nanotube powder with a first solvent and an electrolyte solution, and performing ultrasonic oscillation to obtain a suspension; a metal substrate is placed in the suspension liquid for electrophoretic deposition, and the carbon nano tube thin film cold cathode is obtained; coating a curing agent on the carbon nano tube thin film cold cathode for cross-linking curing to obtain a cured carbon nano tube cold cathode; and enabling the carbon nano tube in the carbon nano tube cold cathode in the curing state to form a tip by utilizing a high-energy ion beam, and enabling the carbon nano tube to form an upright state by utilizing a high-strength electric field to obtain the carbon nano tube cold cathode in an activated state.

The invention relates to the technical field of ray detection, and particularly discloses a cold cathode ray machine digital control system based on high-frequency inversion and pulse modulation, which specifically comprises a master control and calculation module, a high-frequency high-voltage inversion and modulation module, a pulse driving and field emission control module and a precise sensing and acquisition module which are in communication connection with one another, a safety interlocking and state monitoring module; and a man-machine interface and communication module. According to the invention, a closed-loop control scheme of high-frequency inversion, pulse modulation and cathode state is provided for the first time, the problem of separation of independent operation of a power supply, a controller and an emitter of a traditional system is solved, and cross-module collaborative optimization is realized.

The application discloses a cold cathode ionization gauge driving and collecting circuit, and relates to the field of vacuum measurement, which solves the problems of signal conversion nonlinearity and excessive ion current when the gauge tube works at a lower vacuum degree in the existing cold cathode ionization gauge driving and collecting technology, and comprises the following parts: an ion current logarithmic collecting circuit, which is used for converting the ion current of the cold cathode ionization gauge into a voltage signal; a current monitoring circuit, which is used for generating a control signal according to the voltage signal; a voltage-controlled high-voltage driving circuit, which is used for driving the cold cathode ionization gauge according to the control signal; a nonlinear compensation operation conditioning circuit, which is used for performing nonlinear compensation on the voltage signal according to the control signal to obtain an operation collecting voltage; and the operation collecting voltage is used for inputting into a collecting system; the problem of signal conversion nonlinearity is overcome through the nonlinear compensation circuit, and the negative feedback loop control is performed through the current monitoring circuit and the voltage-controlled high-voltage driving circuit, so that the driving voltage of the gauge tube is reduced, and the maximum ion current is limited at a lower level.

The invention is suitable for the field of hot cathode ionization vacuum gauge filament life prediction and monitoring, and provides a novel ionization vacuum gauge hot cathode filament damage state monitoring device and method, and the device comprises a damage device and a state monitoring device. The damage device comprises a hand-cranking digital display sliding table, a first flange nut, a second flange nut, a third flange nut, a fourth flange nut, a short pressing plate, a first screw rod, a second screw rod, an iridium-yttrium oxide lamp filament, a cross-shaped sliding table, a long pressing plate, a bread board, a nut and a cutter fixing clamp. The state monitoring device comprises a molecular pump set, a vacuum valve, a cold cathode ionization vacuum gauge, a vacuum chamber, a hot cathode ionization vacuum gauge, a controller, an upper computer and a high-speed camera. The operation process of the damage system provided by the invention completely meets the requirement for damage to the coating width and the depth of the lamp filament, and the precision is relatively accurate. Moreover, the change of the surface of the lamp filament in the working process of the lamp filament can be observed, and real-time damage detection can be carried out on the lamp filament on the basis of processing image information in the experiment process.

The invention provides a double-layer field emission cold cathode electron source and a manufacturing method thereof, and relates to the technical field of nano electronics, and the double-layer field emission cold cathode electron source comprises a first cathode, an insulating layer, a second cathode and a grid electrode which are sequentially connected from bottom to top; the first cathode comprises a conductive substrate and a first layer of field emitter, and the first layer of field emitter is arranged on the upper surface of the conductive substrate; the second cathode comprises a conductive grid and a second layer of field emitter, the second layer of field emitter is arranged on the upper surface of the conductive grid, and the field emission current and the current density are improved by increasing the effective emission area of the cold cathode emitter; the manufacturing method is simple, the universality is high, the repeatability is high, current increasing of the field emission electron source is facilitated, and a feasible scheme is provided for promoting application of a large-current electron source in a vacuum microelectronic device.

The application belongs to the technical field of cold cathode trigger tube, and discloses a cold cathode trigger tube circuit simulation SPICE design method, which comprises the following steps: main gap channel design; trigger gap channel design; control module design; cold cathode trigger tube characteristic parameter verification and problem analysis; cold cathode trigger tube SPICE model improvement based on gas discharge theory and characteristic parameter verification; improved cold cathode trigger tube application simulation and result analysis. The cold cathode trigger tube SPICE model provided by the application meets the functions of the modern cold cathode trigger tube, and is verified by simulation; and different parameters of the model can be modified to meet the requirements of different scenes.

The embodiment of the present application provides a backscatter detection device and imaging method, equipment and storage medium. The method includes: using a cold cathode X-ray source to work in pulse mode, and modulating the pulsed rays into a fan-shaped ray beam through a front collimator component to solve the contradiction between scanning speed and image quality, and constraining the receiving range of the backscatter detector component to the backscatter photons through the collimation channel formed by the backscatter collimator component, and then the backscatter detector component receives the target backscatter photons passing through the collimation channel, and generates a backscatter electrical signal based on the target backscatter photons and transmits it to the processor, and the processor generates a backscatter image of the inspected object based on the backscatter electrical signal. It avoids the single-frame backscatter data from being affected by the jitter or movement of the detection device, and realizes instant scanning and high-quality dynamic imaging.

This invention discloses a novel welding machine, comprising: a welding frame, the welding frame including a support frame, a sealed door on the front of the support frame, a welding chamber at the upper end of the inner cavity of the support frame, and a welding table at the bottom of the inner cavity of the welding chamber. This invention belongs to the field of welding machine technology. The purpose of this invention is to solve the problems of traditional hot cathode electron beam welding machines in the prior art, where the hot cathode requires continuous preheating, has a long start-up time, and still needs to maintain a high temperature in standby mode. The technical effect achieved is: using a directional carbon nanotube array microbeam emitter as a cold cathode, utilizing the field emission principle of carbon nanotubes, an electric field is applied between the grid and the cathode to allow electrons to escape from the tip of the carbon nanotube through quantum tunneling effect, without heating the cathode to a high temperature, achieving millisecond-level instantaneous start-up, solving the drawback of traditional welding machines requiring 5-10 minutes of preheating, and significantly improving work efficiency and equipment response speed.

The present invention relates to the field of radiation imaging technology, and particularly to a multi-modal imaging device based on a cold cathode, including: an X-ray source module, a CT detection module, an ultrasonic detection module, an imaging module, a storage module, a control module, and a data analysis module. The data analysis module analyzes the initial image to obtain a sharpness comparison difference, determines the sharpness level of the initial image according to the sharpness comparison difference, and determines whether to perform a secondary scan on the ultrasonic detection module according to the sharpness level; based on performing the secondary scan, determines whether to adjust the power of the ultrasonic detection module according to the secondary scan result; determines whether to perform a region analysis according to the similarity level of the secondary image; determines the region similarity ratio based on the region analysis result, and adjusts the power of the X-ray source module according to the region similarity ratio. The present invention adjusts the scanning parameters according to the sharpness of different images to obtain a complete and clear scanning image.

The invention relates to the technical field of radiation imaging, in particular to a multi-mode imaging device based on a cold cathode, which comprises an X-ray source module, a CT detection module, an ultrasonic detection module, an imaging module, a storage module, a control module and a data analysis module, determining the image definition grade of the initial image according to the definition comparison difference value, and judging whether to carry out secondary scanning on the ultrasonic detection module or not according to the definition grade; on the basis of secondary scanning, whether the power of the ultrasonic detection module is adjusted or not is judged according to a secondary scanning result; judging whether to carry out regional analysis or not according to the image similarity grade of the secondary image; and determining a region similarity ratio based on the region analysis result, and adjusting the power of the X-ray source module according to the region similarity ratio. According to the invention, the scanning parameters are adjusted through different image definitions so as to obtain a complete and clear scanning image.

A production method for producing an anode for a cold cathode X-ray source, including the following steps: producing an element referred to as target from a first material adapted to generating X-rays from the absorption of an electron beam, the first material having a first thermal expansion coefficient Ce,1(Tu) at a predetermined temperature Tu of use of the anode in the X-ray source, producing an element referred to as target support from a second material having a second thermal expansion coefficient Ce,2(Tu) at the predetermined temperature Tu, joining the target to the target support by hard soldering using a solder material at a soldering temperature higher than the predetermined temperature Tu and higher than a melting point of the solder material, so as to form a film of solder interposed between the target and the target support.

The invention discloses a gate structure composite nanometer cold cathode electron source and a manufacturing method thereof, the cold cathode electron source is sequentially provided with an electrode layer on a substrate, the electrode layer comprises a plurality of first electrodes and a plurality of second electrodes, and the first electrodes and the second electrodes are alternately arranged in parallel; the pre-growth layer thin film is arranged on the plurality of first electrodes and the plurality of second electrodes; and a composite nanometer cold cathode, wherein the composite nanometer cold cathode is arranged on the pre-growth layer thin film. The composite nanometer cold cathode electron source has the addressing driving capacity, by applying specific driving voltage to the electrode strips, grid cathode multiplexing can be achieved, and the service life of a device is prolonged. Meanwhile, the device structure has the self-alignment characteristic, the process is simple, and the device has important application prospects in the fields of addressable panel X-ray sources and the like.

The present invention provides a technology that can contribute to facilitating the reduction of the beam diameter and focal spot size of an electron beam and making it easier for a field emission device to exhibit the desired functions. [Solution] In a cold cathode 1 having a columnar electrode substrate 11 arranged with one end of its axis facing an anode 2, the radial dimension of the anode-side facing surface 12 is set to 0.1 mm to 1 mm, and an electron emission section 4 made of a carbon nanostructure is formed on the anode-side facing surface 12. The surface of the carbon nanostructure is formed such that granular sections 40 protruding from the surface are distributed in islands on the surface, forming an island structure. The granular sections 40 are formed so that the dimension in the protruding direction is 10 μm or more, and the radial dimension at the maximum diameter part of the granular sections is 10 μm or more.

The invention discloses a carbon nanotube cold cathode-based miniature vacuum relay and a pulse driving control method thereof, and belongs to the technical field of vacuum relays. The problem that the performance and the application range of an existing method are limited is solved, current, voltage, temperature and vacuum degree data are obtained in real time, deep analysis is conducted on the collected data through a neural network model, and optimal pulse parameters are accurately predicted; the output of the pulse generator is dynamically adjusted according to the predicted pulse parameters, so that the carbon nanotube cold cathode can stably and efficiently emit electrons, the performance of the relay is optimized, and the response speed and reliability of the relay are improved; meanwhile, the circuit state is monitored in real time, once abnormal conditions such as over-current, over-voltage or short circuit are detected, a protection mechanism is triggered immediately, a power supply is cut off or current / voltage is limited, an operator is reminded through an alarm signal, circuit damage is effectively prevented, and safe operation of the system is guaranteed.

The invention relates to an electron gun device of a radio frequency excitation gas discharge cold cathode electron beam coaxial fuse. Comprising a funnel-like anode internally provided with a water cooling channel, a cathode internally provided with an annular water cooling channel and connected with a high-voltage power supply, a wire feeding system, a gun top cover, a wire guide pipe and a radio frequency excitation gas discharge unit, the cathode is arranged in a transparent discharge chamber of the radio frequency excitation gas discharge unit, an annular discharge convex edge is arranged at the upper end of the anode, and the radio frequency excitation gas discharge unit excites gas ionization between the lower edge of the cathode in the discharge chamber and the annular discharge convex edge of the anode through a radio frequency antenna outside the discharge chamber; the gas ionization degree is adjusted by controlling the power of the radio frequency power supply, and the working pressure in the discharge chamber is reduced. According to the invention, the limitation that the stable output of the beam of the traditional beam coaxial cold cathode electron gun has strong dependence on air pressure and low working voltage is solved, and the process controllability and engineering application potential of electron beam fuse additive manufacturing are remarkably improved.

The application discloses a double-wire additive gun body based on cold cathode electron beam internal wire melting additive manufacturing, which comprises an anode, an insulator, an internal cathode, an external cathode, a ring-shaped wire nozzle, a discharge cavity, an upper joint plate, a wire guide pipe, a pipe for cooling the cathode and a high-voltage power supply; the anode is internally provided with the insulator, the lower middle part of the insulator is provided with the internal cathode, the external cathode is annular and connected with the lower part of the insulator; the insulator is internally provided with through holes for the two wire guide pipes, a water cooling channel, a gas feeding channel and a high-voltage power supply channel, the ring-shaped wire nozzle arranged at the lower end of the insulator is a conical tubular with a wide upper part and a narrow lower part, the pipe wall surface of the ring-shaped wire nozzle is provided with a wire feeding channel communicated with the wire guide pipe, the wire feeding double channels in the ring-shaped wire nozzle make the wire passing through point to the annular electron beam focal point, and the discharge cavity is formed between the internal cathode, the external cathode, the ring-shaped wire nozzle and the lower part of the anode shell. The application realizes multiple special functions of parts and adopts double wires to carry out internal wire melting additive manufacturing.

The present invention discloses a power device, comprising at least one vacuum-encapsulated unit structure; wherein the unit structure comprises: a silicon substrate and an emitter, a light modulator and a collector formed on the silicon substrate. On the one hand, since the entire device is prepared using a unified silicon-based process, the problem of inconsistency in the process preparation of the emitter of the traditional cold cathode field emission is solved, the internal precision and consistency of the device are improved, and the reliability of the device is enhanced; on the other hand, based on the silicon-based process, a light modulator formed on the silicon substrate is introduced, the field emission efficiency of the emitter is enhanced, the inconsistency between the emitter tip and the collector caused by the emitter non-uniformity is offset, and the process redundancy of the cold cathode emission electrode is increased, so that the device does not need to rely entirely on the field emission principle to generate electrons, the load of field emission is reduced, and the reliability of the device is further enhanced.

The outer peripheral side of a columnar electrode base (11) of a cold cathode (1) oriented to face an anode (2) is surrounded by a focusing electrode (3) having a cylindrical electrode base (31; cylindrical part (30)) arranged coaxially with the axis of the columnar electrode base (11). The cylindrical electrode base (31) has: a cylindrical part (30) that is arranged coaxially with the cold cathode axis and surrounds the outer peripheral side of the columnar electrode base (11); an annular base diameter reduction part (33) that protrudes from an end (32) of the cylindrical part (30) on the anode (2) side to the cold cathode axis side and overlaps a peripheral edge part (41) of an electron emission part (4) in the extension direction of the cold cathode axis; and an electron beam passing hole (34) that penetrates in the extension direction on the inner peripheral side of the base diameter reduction part (33).