Abstract: A betatron, especially in X-ray testing apparatus is provided, that includes a rotationally symmetrical inner yoke having two interspaced parts, an outer yoke connecting the two inner yoke parts, at least one main field coil, a toroidal betatron tube arranged between the opposing front sides of the inner yoke parts, and at least one contraction and expansion coil. An individual CE coil is respectively arranged between the front side of the inner yoke part and the betatron tube, and the radius of the CE coil is essentially the same as the nominal orbital radius of the electrons in the betatron tube.

Abstract: Methods and related systems are described for gamma-ray detection. A gamma-ray detector is made depending on its properties and how those properties are affected by the data analysis. Desirable properties for a downhole detector include; high temperature operation, reliable/robust packaging, good resolution, high countrate capability, high density, high Z, low radioactive background, low neutron cross-section, high light output, single decay time, efficiency, linearity, size availability, etc. Since no single detector has the optimum of all these properties, a downhole tool design preferably picks the best combination of these in existing detectors, which will optimize the performance of the measurement in the required environment and live with the remaining non-optimum properties.

Abstract: A compact device for generating X-rays by scattering includes a means for producing a beam of electrons, which comprises a grid of wires arranged in a useful scattering cone, so that the beam of electrons encounters at least one of the wires of the wire grid.

Abstract: An X-ray source includes an electron-beam generating unit that generates an electron beam, and a transmission type target electrode to be irradiated with the electron beam to generate X-ray radiation. A plurality of convex portions each having an inclined surface with respect to an incident direction of the electron beam is formed on a surface of the transmission type target electrode.

Abstract: An embodiment of a gamma ray generator includes a neutron generator and a moderator. The moderator is coupled to the neutron generator. The moderator includes a neutron capture material. In operation, the neutron generator produces neutrons and the neutron capture material captures at least some of the neutrons to produces gamma rays. An application of the gamma ray generator is as a source of gamma rays for calibration of gamma ray detectors.

Abstract: An electron source has an electron emitter with an electron emission cathode, a high voltage unit provided for power supply of the electron emission cathode, and a low voltage unit provided to control the high voltage unit. Data are transmitted non-electrically (in particular optically) between the high voltage unit and the low voltage unit.

Abstract: A rotating anticathode X-ray generating apparatus which is configured such that an X-ray is generated by an irradiation of an electron beam emitted from a cathode includes a rotating anticathode with an electron beam irradiating portion to generate the X-ray through the irradiation of the electron beam so that a direction of the electron beam is set equal to a direction of a centrifugal force caused by a rotation of the rotating anticathode; and a film for covering at least the electron beam irradiating portion so as to prevent an evaporation of a material making the rotating anticathode.

Abstract: An apparatus providing a source of shortwave electromagnetic radiation utilizing a tape having a first side and a second side and a laser beam focused and impinging on the first side of the tape. The apparatus utilizes a tape storage unit which delivers or feeds tape from the same. A base supports a first projecting element which contacts the second side of the tape emanating from the storage unit. A second projecting element supported by the base contacts the first side of the tape being fed from the tape storage unit. The portion of the tape between the first and second projecting elements constantly lies in a plane during the feeding of the tape and provides a target surface for a focused laser beam which generates shortwave radiation.

Abstract: In a method and system for monitoring the power state of an x-ray emitter and/or an x-ray detector, the x-ray emitter is operated according to a set of test parameters, so as to emit x-rays that strike at least a portion of the detector region of the x-ray detector. At least one value characterizing the operation of the x-ray emitter and/or the x-ray detector is determined, and this detected parameter is compared with a comparable reference parameter value. The power state of the x-ray emitter and/or the x-ray detector is determined based on deviation of the detected parameter from the reference parameter.

Abstract: A system for producing at least one high flux photon beam is provided. The system includes two or more photon sources configured to produce photon beams, and at least one first stage optic device coupled to at least one of the photon sources and providing at least one focused photon beam through total internal reflection, wherein at least one of the photon beams and the focused photon beams are combined at a virtual focal spot.

Abstract: A gamma ray generator includes an ion source in a first chamber. A second chamber is configured co-axially around the first chamber at a lower second pressure. Co-axially arranged plasma apertures separate the two chambers and provide for restricted passage of ions and gas from the first to the second chamber. The second chamber is formed by a puller electrode having at least one long channel aperture to draw ions from the first chamber when the puller electrode is subject to an appropriate applied potential. A plurality of electrodes rings in the third chamber in third pressure co-axially surround the puller electrode and have at least one channel corresponding to the at least one puller electrode aperture and plasma aperture. The electrode rings increase the energy of the ions to a selected energy in stages in passing between successive pairs of the electrodes by application of an accelerating voltage to the successive pairs of accelerator electrodes.

Abstract: An electron beam detection device (34) is arranged on an electron beam passing path so that a beam delay time tB from a passing moment of an electron beam (1) to a moment when the beam reaches a predicted collision point (9a) is longer than a laser delay time tL from a moment when a command for generating laser light (3) is issued to the moment when the laser light reaches the predicted collision point (9a) by at least a predetermined delay time ?t. The device (34) may detect passing therethrough without affecting the electron beam and output a laser light generation command from a laser light command delay circuit (36) when the predetermined delay time ?t (=tB?tL) has elapsed after the detection.

Abstract: An apparatus and method for determining the density and other properties of a formation surrounding a borehole using a high voltage x-ray generator. One embodiment comprises a stable compact x-ray generator capable of providing radiation with energy of 250 keV and higher while operating at temperatures equal to or greater than 125° C. In another embodiment, radiation is passed from an x-ray generator into the formation; reflected radiation is detected by a short spaced radiation detector and a long spaced radiation detector. The output of these detectors is then used to determine the density of the formation. In one embodiment, a reference radiation detector monitors a filtered radiation signal. The output of this detector is used to control at least one of the acceleration voltage and beam current of the x-ray generator.

Abstract: Methods and systems for generating bremsstrahlung with enhanced photon flux in a narrow cone at forward angles utilize a thin target of a high-Z material such as gold as radiator, supported on a tube of a low-Z material such as titanium, which tube contains a circulating fluid such as water which acts as a coolant and also may absorb the incident electron beam.

Abstract: A method for generating radiation in a range of desired wavelengths in a direction of emission is provided. According to the method, initial radiation is produced by a radiation source, the wavelengths thereof including the desired range, and the initial radiation is filtered in such a way as to substantially eliminate the initial radiation beams having a wavelength outside the desired range. The inventive method is characterized in that the filtering is carried out by setting up a controlled distribution of the refractive index of the beams in a control region through which the initial radiation passes, in such a way as to selectively deviate the beams of the initial radiation according to the wavelength thereof and to recover the beams having desired wavelengths. The invention also relates to an associated device.

Abstract: A device for generating x-rays has an enclosing vessel having a structure suitable to provide an enclosed space at a predetermined fluid pressure, wherein the enclosing vessel has a window portion and a shielding portion in which the shielding portion is more optically dense to x-rays than the window portion; a mechanoluminescent component disposed at least partially within the enclosing vessel; and a mechanical assembly connected to the mechanoluminescent component. The mechanical assembly provides mechanical energy to the mechanoluminescent component while in operation, and at least some of the mechanical energy when provided to the mechanoluminescent component by the mechanical assembly is converted to x-rays.

Abstract: The present invention provides systems and methods for x-ray imaging. In some embodiments, an aperture, or a plurality thereof, are configured to have image transfer functions lacking a zero within a usable spatial frequency range. In further embodiments, the image transfer function is determined according to the shape of the aperture and the usable spatial frequency range is deter mined according to a usable signal to noise ratio.

Abstract: A multiple focal spot X-ray tube (100) comprising an electron source (105), which is adapted to generate an electron beam (106), an anode (110), which is arranged within the electron beam (106) and which comprises a first focal spot portion (120) and a second focal spot portion (130), whereby the second focal spot portion (130) is spatially separated from the first focal spot portion (120). The X-ray tube (100) further comprises a first electron beam manipulation unit (125), which is adapted to interact with the electron beam (106), when the electron beam (106) impinges onto the first focal spot portion (120), and a second electron beam manipulation unit (135), which is adapted to interact with the electron beam (106), when the electron beam (106) impinges onto the second focal spot portion (130).

Abstract: An x-ray tube disclosed here in includes an emitter arranged to emit electrons on to a focal spot on a rotatable anode. The x-ray tube also includes a hollow tube arranged to receive electromagnetic radiation from the focal spot at one end of the hollow tube and transmit it to another end. The x-ray tube also includes two or more sensors arranged to detect the electromagnetic radiation through the hollow tube.

Abstract: Methods for the plasma-based generation of X-radiation are described with the steps: provision of a target material (50) in the form of a free flow structural formation (51) in a vacuum chamber (20), and irradiation of the target material (50) in order to produce a plasma condition in which the X-radiation is radiated therefrom, the flow structural formation (51) being formed in such a way that the target material has, at least at the location of the irradiation, a surface (52) with a local curvature minimum. Devices for the imple mentation of the methods and, in particular, X-ray sources for the plasma-based generation of X-radiation are also described.

Abstract: A microminiature X-ray tube with a triode structure using a nano emitter is provided, which can increase a field emission region as much as possible by means of nano emitters fine-patterned in a cathode to not only increase an emission current per unit area as much as possible but secure high electrical characteristics, reliability, and structural stability by means of a cover and a bonding material. In addition, gate holes having a macro structure can be formed in the gate to promote electron beam focusing by means of the gate without using a separate focusing electrode and to prevent a leakage current from occurring on the gate. Further, an auxiliary electrode can be formed on a top or an inner surface of a cover applied for structural stability to further promote the electron beam focusing and to control the output amounts per individual X-ray tubes output according to current switching to be equal to each other.

Abstract: An HF frequency tuning device includes a resonance cavity in which an HF is introduced, a phase detecting section which generates a sign data representing a sign of a phase difference between a traveling wave and a reflected wave included in the HF in the resonance cavity. The frequency of the HF is repeatedly shifted by a first pitch. The direction of the shift is determined by the sign data for reducing the phase difference. When the sign is inverted, the frequency of the HF is repeatedly shifted to the opposite direction by a second pitch smaller than the first pitch until the sign is inverted again. By this tuning process, the fine tuning of HF can by achieved in a short time.

Abstract: An x-ray metrology tool having only one x-ray source. The x-ray source includes a liquid metal source for heating and melting at least one metal and producing a liquid metal jet, a liquid metal collector for acquiring the liquid metal jet, a liquid metal circulation system for returning liquid metal from the liquid metal collector to the liquid metal source, and an electron beam source for directing an electron beam at the liquid metal jet anode, thereby producing an incident x-ray beam that is directable towards a sample. A detector receives emissions from the sample in response to the incident x-ray beam, and produces signals indicative of properties of the sample. A controller controls the x-ray source, acquires the signals from the detector, and determines the properties of the sample based at least in part on the signals.

Abstract: An enhancement cavity includes a plurality of focusing mirrors, at least one of which defines a central aperture having a diameter greater than 1 mm. The mirrors are configured to form an optical pathway for closed reflection and transmission of the optical pulse within the enhancement cavity. Ring-shaped optical pulses having a peak intensity at a radius greater than 0.5 mm from a central axis are directed into the enhancement cavity. Accordingly, the peak intensity of the optical pulse is distributed so as to circumscribe the central apertures in the apertured mirrors, and the mirrors are structured to focus the pulse about the aperture toward a central spot area where the pulse is focused to a high intensity.

Abstract: A liquid target producing device to which multiple capillary tubes are mountable includes a capillary tube for injecting a liquid target in a jet form; a gas storage tank connected to the capillary tube through a gas line to store a gas to be supplied to the capillary tube; a metal jacket positioned at an outer circumference of the capillary tube such that a plurality of capillary tubes are installable thereto, the metal jacket liquefying the gas supplied through the gas line; a cryo-cooler connected to the metal jacket through a thermal conductive wire to cool the metal jacket; and a moving means for moving the metal jacket so as to set an initial position of the capillary tube.

Abstract: A method and apparatus for downhole generation of non-radioactive, ionized radiation arranged so as to be able to generate reverberation, particularly X-ray and/or gamma radiation, from the surroundings of a borehole, wherein the method includes the steps of: exciting laser light in a multistage laser light booster by means of a pump-type laser light source so as to form a pulsed laser light, the incoming light energy being concentrated in restricted laser light pulses representing a higher amount of light energy than that of a continuous flux of laser light; forming a concentration of dissociated electrons in a vacuum chamber; focusing the pulsed laser light at a point in the concentration of dissociated electrons so as to form a field (wakefield) of pulsed electrons which, upon generation of Bremsstrahlung, emit ionized radiation to the surroundings, thereby forming a high-energy reverberation in the gamma and/or X-ray frequency range from the surroundings.

Abstract: Methods and apparatus are described for irradiating living tissue via a cavity or lumen, using an inflatable balloon applicator. In a preferred embodiment the applicator balloon has a balloon skin with x-ray contrast material in relatively low concentration, so that an outline of the balloon will appear sharply when imaged externally. In another preferred embodiment the balloon catheter has a drain for withdrawing liquids from the cavity, which may include channels or texture on the exterior of the balloon. Methods are described for using a switchable miniature x-ray tube, variable as to voltage and current, to achieve accuracy in an isodose profile.

Abstract: A method for the production of X-ray bunches tunable in both time and energy level by generating multiple photon, X-ray, beams through the use of Thomson scattering. The method of the present invention simultaneously produces two X-ray pulses that are tunable in energy and/or time.

Abstract: The present invention is made to provide an extreme ultraviolet light source target or an X-ray source target having a good operationality. An extreme ultraviolet light source target in accordance with an aspect of the present invention is obtained by including a heavy metal such as tin into a matrix made of a polymeric material such as hydroxylpropylcellulose (HPC). The target can be manufactured by mixing the heavy metal and the polymeric material with a solvent, and evaporating the solvent. Since the target uses the polymeric material as a matrix, the target can be easily deformed to have a desired shape. For this reason, the target can be easily attached to a target holder irrespective of the shape of the holder, resulting in a good operationality of the target. Furthermore, an emission efficiency can be improved by including the heavy metal at a low density.

Abstract: An X-ray waveform is generated by validating detection data corresponding to when an X-ray (4) is generated at a collision point (9) among X-ray detection data and invalidating other data. For example, when laser light (3) is pulse laser light and an electron beam (1) is a continuous electron beam or a pulse-like electron beam having a pulse width equal to or greater than that of the pulse laser light, the X-ray waveform is generated by detecting the laser light (3) and multiplying the X-ray detection data by laser light detection data after making time axes coincident with respect to the collision point (9).

Abstract: An X-ray generating device includes an electron-beam generator, a target assembly group, and an electron-beam focusing unit. The electron-beam generator generates electron beams. The target assembly group includes a plurality of target assemblies that are arranged along a straight line in a direction in which X-rays are output; each of the target assemblies includes a target and a supporting member; the target generates X-rays from one of the electron beams generated by the electron-beam generator; and the supporting member supports the target by being disposed adjacent thereto. The electron-beam focusing unit focuses the electron beams onto the targets included in the target assembly group so that X-rays are generated in each of the target assemblies and output along the straight line after passing through the target assemblies.

Abstract: A method and apparatus for measuring a structure. An x-ray system and the structure are positioned relative to each other. The x-ray system comprises a gas source configured to provide a gas, a laser system configured to emit a laser beam, a steering system, and a detector. The steering system is configured to direct a first portion of the laser beam into the gas such that an electron beam is generated by the laser beam interacting with the gas and is configured to direct a second portion of the laser beam into the electron beam such that a collimated x-ray beam is formed. The detector is configured to detect the collimated x-ray beam. The collimated x-ray beam is emitted with the structure positioned relative to the x-ray system.

Abstract: An X-ray photoelectron spectroscopy analysis system for analysing an insulating sample 20, and a method of XPS analysis. The system comprises an X-ray generating means 30 having an exit opening 32 and being arranged to generate primary X-rays 46,56 which pass out of the exit opening in a sample direction towards a sample surface 22 for irradiation thereof. It has been found that the X-ray generating means in use additionally generates unwanted electrons 258 which may pass out of the exit opening substantially in the sample direction and cause undesirable sample charging effects. The system further comprises an electron deflection field generating means 380,480,580 arranged to generate a deflection field upstream of the sample surface. The deflection field is configured to deflect the unwanted electrons away from the sample direction, such that the unwanted electrons are prevented from reaching the sample surface.

Abstract: A high brightness X-ray generator and a high brightness X-ray generating method are provided which are able to promote an increase in X-ray brightness (i.e., an increase in an X-ray output) while suppressing an excessive increase in the cost of optical elements such as a laser unit, a mirror, and a lens. A high brightness X-ray generator generates an X-ray by inverse Compton scattering by colliding an electron beam with pulse laser light. There are provided a plurality of pulse laser units (32A, 32B) which emits a plurality of pulse laser lights (3a, 3b) in predetermined periods, an optical-path matching unit (34) which matches optical paths of the plurality of pulse laser lights, and a timing control unit (40) which controls timings of the optical-path matching unit and the pulse laser units, wherein the plurality of pulse laser lights is emitted from the same optical path at different timings.

Abstract: A source (19) for multiple energy X-ray generation in particular by field emitting carbon nanotubes (1, 2) is presented. In order to achieve a spatial overlap of the trajectories of the X-ray beams coming from different emitters, a focusing unit (7, 9) is supplied to the emitted electrons (28, 29). A fast switching between the emission of the different carbon nanotubes allows multiple kilovolt imaging. Independent determination of multiple focal spot parameters by the focusing unit leads to the possibilities of fast switching between different spot geometries and spatial resolutions. This might be seen in FIG. 1.

Abstract: A Coulomb force oscillator comprising a power supply having a closed primary winding circuit and an open secondary winding that produces charge differential within the secondary winding to separate positive charges and negative charges therein, and which effects charge separation in an external body coupled to the secondary winding. Switching the power source off causes a collapse of the magnetic field in the primary winding which causes the secondary winding to return to a steady state condition, which causes charge recombination in the external body effecting release of energy. Methods of generating electromagnetic energy are also disclosed.

Abstract: An apparatus and method for determining the density and other properties of a formation surrounding a borehole using a high voltage x-ray generator. One embodiment comprises a stable compact x-ray generator capable of providing radiation with energy of 250 keV and higher while operating at temperatures equal to or greater than 125° C. In another embodiment, radiation is passed from an x-ray generator into the formation; reflected radiation is detected by a short spaced radiation detector and a long spaced radiation detector. The output of these detectors is then used to determine the density of the formation. In one embodiment, a reference radiation detector monitors a filtered radiation signal. The output of this detector is used to control at least one of the acceleration voltage and beam current of the x-ray generator.

Abstract: X-ray radiation is generated at a target that emits x-ray radiation in response to being struck by accelerated electrons, the electrons being emitted by a cathode that emits electrons in response to being illuminated by electromagnetic radiation from a source, and the x-ray radiation is moved by orienting a surface that directs the electromagnetic radiation from the source toward the cathode.

Abstract: Grazing incidence collectors (GICs) for extreme ultraviolet (EUV) and X-ray radiation sources, such as laser produced plasma (LPP) sources, are disclosed. Source-collector systems comprising GICs and LPP sources are also disclosed. A laser beam is directed along the collector axis to a fuel target to form the LPP source, and the collector is arranged to collect the radiation and reflect it to an intermediate focus. The collector may include one or more grazing-incidence mirrors, and these mirrors may be electroformed. lithography systems that employ the source-collector systems as disclosed herein.

Abstract: A pulse source generates both terahertz radiation (T-rays) and X-rays consecutively at high peak intensity using the same electron beam generated in an RF photoinjector and two different extractors/radiators for the T- and X-rays.

Abstract: The present invention relates to a method of increasing the operation lifetime of an optical collector unit (33)) arranged in an irradiation device. The irradiation device at least comprises a radiation source (1) emitting optical radiation, in particular extreme ultraviolet radiation or soft X-rays, said radiation source (1) generating substances and/or particles colliding with optical surfaces of the optical collector unit (33), which forms a radiation beam of a portion of said radiation emitted by said radiation source (1), and a debris mitigation unit (37) arranged between the radiation source (1) and said optical collector unit (33). In the proposed method the optical collector unit (33) is moved during operation and/or in operation pauses of the device such that deposits or degradation effects caused by collision of said substances and/or particles with said optical surfaces of the collector unit (33) are distributed more homogeneously on said optical surfaces than without such a movement.

Abstract: A photoneutron-x ray source includes a photoneutron conversion target, which outputs both photoneutrons and x-rays simultaneously. The photoneutron-x ray source includes an x-ray generator for generating an x-ray main beam that is applied to the photoneutron conversion target. The photoneutron conversion target generates photoneutrons upon the application of the x-ray main beam to the photoneutron conversion target. The photoneutron conversion target has a body that defines a passageway extending through the body and that is structured such that a first x-ray beam of the x-ray main beam can pass through the passageway without any reaction with the body, while a second x-ray beam of the x-ray main beam can enter the body and react with the body to emit the photoneutrons.

Abstract: An apparatus and method for determining the density and other properties of a formation surrounding a borehole using a high voltage x-ray generator. One embodiment comprises a stable compact x-ray generator capable of providing radiation with energy of 250 keV and higher while operating at temperatures equal to or greater than 125° C. In another embodiment, radiation is passed from an x-ray generator into the formation; reflected radiation is detected by a short spaced radiation detector and a long spaced radiation detector. The output of these detectors is then used to determine the density of the formation. In one embodiment, a reference radiation detector monitors a filtered radiation signal. The output of this detector is used to control at least one of the acceleration voltage and beam current of the x-ray generator.

Abstract: A discretely addressable large-area X-ray system is provided. The large-area X-ray system can output a uniform flux of X-rays over a large area using discrete addressing operation of transistors connected to cathodes of electron emitters. Thus, when applied to a medical device, the system can minimize damage inflicted upon the human body because it enables effective imaging of only a desired specific portion of the body. Furthermore, the large-area X-ray system can be simply implemented by current switching using transistors. Thus, the system can be very easily applied to other applications.

Abstract: A method of generating in particular EUV radiation (12) and/or soft X-ray radiation (12a) emitted by a plasma (26) is described. The plasma (26) is formed by an operating gas (22) in a discharge space (14) which comprises at least one radiation emission window (16) and an electrode system with at least one anode (18) and at least one cathode (20). This electrode system transmits electrical energy to the plasma (26) by means of charge carriers (24) introduced into the discharge space (14). It is suggested for obtaining a reliable ignition of the plasma (26) at high repetition frequencies that a radiation (30) generated by at least one radiation source (28) is introduced into the discharge space (14) for making available the discharge carriers (24).

Abstract: A system and method for limiting emittance growth in an electron beam is disclosed. The system includes an emitter element configured to generate an electron beam and an extraction electrode positioned adjacent to the emitter element to extract the electron beam out therefrom, the extraction electrode including an opening therethrough. The system also includes a meshed grid disposed in the opening of the extraction electrode to enhance intensity and uniformity of an electric field at a surface of the emitter element and an emittance compensation electrode (ECE) positioned adjacent to the meshed grid on the side of the meshed grid opposite that of the emitter element and configured to control emittance growth of the electron beam.

Abstract: An electron source has an electron emitter, an anode, a voltage source connected between the electron emitter and the anode, as well as a switch connected with the electron emitter. The switch is fashioned as a optoelectronic switching element.

Abstract: Methods and apparatus are described for irradiating living tissue via a cavity or lumen, using an inflatable balloon applicator. In a preferred embodiment the applicator balloon has a balloon skin with x-ray contrast material in relatively low concentration, so that an outline of the balloon will appear sharply when imaged externally. In another preferred embodiment the balloon catheter has a drain for withdrawing liquids from the cavity, which may include channels or texture on the exterior of the balloon. Methods are described for using a switchable miniature x-ray tube, variable as to voltage and current, to achieve accuracy in an isodose profile.

Abstract: A method of manufacturing a radiation source in one example comprises selecting at least one of a target, a collimator, or target shielding consisting essentially of at least one isotope having a neutron production threshold greater than a peak acceleration energy of the source, and assembling the source including the selected material. A simulation may be used to assist in design a radiation source meeting neutron production requirements and optionally other requirements.

Abstract: In an X-ray source 1 and an X-ray tube 4, there is formed a shield portion 42 adapted to shield the portion W where a target support body 18 and an opening portion 34 on the other end side of a valve 20 are fixed to each other when viewed from the one end side of the valve 20. Therefore, the generation of discharge between the one end side of the valve 20 and the fixation portion W can be suppressed. Also, the other end portion of the valve 20 is formed as a narrowed portion 37 and the opening portion 34 on the other end side of the valve 20 is fixed to the target support body 18, whereby the shapes of the valve 20 and the shield portion 42 can be made simpler than in conventional X-ray tubes in which an inner cylindrical portion is formed in a valve. Such a simple structure can improve the stability of an electric field in the valve 20 when generating X-rays and thereby achieve an effective suppression of the generation of discharge in the valve 20.