Superconduction cryo-module

Abstract

To provide a superconduction cryo-module which can be downsized.SOLUTION: A superconduction cryo-module 1 according to the present disclosure includes: a superconduction acceleration hollow 12 having a cell unit 122 for accelerating an electron, a beam pipe unit 121A extending to an incidence side of the electron from the cell unit 122, and a discharge unit for discharging the electron accelerated by the cell unit 122; and an electronic gun 11 located in the beam pipe unit 121A of the superconduction acceleration hollow 12 and also on the same axis as a beam axis BA of the superconduction acceleration hollow 12, the electron gun discharging the electron to the cell unit 122.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a superconducting cryomodule. [Background technology]

[0002] A superconducting accelerator can operate at 4K by forming a superconducting thin film on the inner cavity wall of the superconducting accelerating cavity, and a large-scale cryogenic cooling system is not required. This makes it possible to reduce the introduction cost and miniaturize the device. For example, Patent Document 1 discloses a superconducting accelerating radio frequency cryomodule that employs a heat transfer cooling method in which the cooling stage of a Gifford-McMahon refrigerator and the superconducting accelerating cavity are connected with a heat transfer member for cooling. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2021-507544 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the superconducting acceleration radio frequency cryomodule described in Patent Document 1, the input beam tube and the output beam tube are provided outside the superconducting acceleration cavity, which increases the size of the superconducting acceleration radio frequency cryomodule. In view of the above problems, the present disclosure aims to provide a superconducting cryomodule that can be made compact. [Means for solving the problem]

[0005] In order to solve the above-mentioned problems and achieve the objectives, the superconducting cryomodule of the present disclosure comprises a superconducting acceleration cavity having a cell section for accelerating electrons, a beam pipe section extending from the cell section to the electron entrance side, and an emission section for emitting electrons accelerated in the cell section, and an electron gun located inside the beam pipe section of the superconducting acceleration cavity and coaxial with the beam axis of the superconducting acceleration cavity, and emitting electrons to the cell section. Effect of the Invention

[0006] According to the present disclosure, it is possible to provide a superconducting cryomodule that can be made compact. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is an overall view of a superconducting accelerating cavity of a superconducting cryomodule according to the present disclosure. [Diagram 2] FIG. 2 is a cross-sectional view of the superconducting accelerating cavity of the superconducting cryomodule according to the present disclosure taken along the line AA in FIG. [Diagram 3] FIG. 3 is a schematic diagram showing a configuration example of an electron gun of a superconducting cryomodule according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments described below.

[0009] (First embodiment) (Configuration of superconducting cryomodule) Fig. 1 is a schematic diagram showing a configuration example of a superconducting cryomodule according to the present disclosure. As shown in Fig. 1, the superconducting cryomodule 1 includes an electron gun 11, a superconducting acceleration cavity 12, a heat shield 13, a magnetic shield 14, a vacuum chamber 15, an RF (Radio Frequency) input coupler 16, a vacuum valve 17, and a refrigerator 18.

[0010] The electron gun 11 is located inside the beam pipe section 121 of the superconducting acceleration cavity 12, and is located coaxially with the beam axis BA of the superconducting acceleration cavity 12, and emits electrons to the cell section 122. In this embodiment, the beam axis BA is the central axis of the superconducting acceleration cavity 12. In the superconducting acceleration cavity 12, electrons move along the beam axis BA. In the superconducting cryomodule 1 according to the first embodiment, a thermionic emission type electron gun is used for the electron gun 11. The thermionic emission type electron gun emits free electrons from a metal forming a cathode by heating the cathode, and emits electrons by drawing out the emitted electrons by a potential applied to the anode. The configuration of the electron gun 11 will be described later.

[0011] The superconducting acceleration cavity 12 is a cavity formed of a material exhibiting superconductivity, and accelerates electrons by an electric field formed by applying high-frequency power. The superconducting acceleration cavity 12 is generally made of, for example, high-purity niobium. The energy of the electromagnetic field caused by the high-frequency power is consumed by resistance heating of the metal constituting the cavity wall of the superconducting acceleration cavity 12. Therefore, by making the metal constituting the cavity wall of the superconducting acceleration cavity 12 superconducting, it is possible to suppress the resistance heating and suppress the energy loss of the electromagnetic field. High-purity niobium is suitable as a material for the superconducting acceleration cavity 12 because it exhibits a superconducting state at 9.2 K.

[0012] The superconducting acceleration cavity 12 has a cell section 122 that accelerates electrons, a beam pipe section 121A that extends from the cell section 122 to the electron entrance side, and an emitter section 121B that emits the electrons accelerated in the cell section 122. The beam pipe section 121A is connected to the cell section 122, and the electron gun 11 is arranged inside the cell section 121A coaxially with the beam axis BA. The beam pipe section 121A is tubular and serves as an inlet for electrons to the cell section 122. The shape of the cell section 122 is determined so that the energy loss of the high frequency power in the cavity wall of the superconducting acceleration cavity 12 is reduced. The cell section 122 may be formed, for example, in an elliptical shape. The emitter section 121B is connected to the cell section 122, into which the electrons accelerated in the cell section 122 flow, and emits the electrons that have flowed in to the outside. The emitter section 121B may be formed, for example, in a tubular shape.

[0013] The heat shield 13 blocks radiant heat radiated from the vacuum chamber 15 in a room temperature atmosphere to the superconducting accelerating cavity 12. The heat shield 13 may be made of oxygen-free copper. Oxygen-free copper has a high thermal conductivity of 391 W / mK. Therefore, if oxygen-free copper is used for the heat shield 13, it is possible to keep the temperature of the heat shield 13 low by the cooler 18 connected to the heat shield 13, even if the heat shield absorbs radiant heat.

[0014] The magnetic shield 14 is formed of a material that absorbs magnetic fields, and absorbs the environmental magnetic field present outside the superconducting acceleration cavity 12. The magnetic shield 14 may be formed, for example, so as to cover the outside of the thermal shield 13. The magnetic shield 14 attracts magnetic flux lines of a magnetic field that may become an environmental magnetic field, and plays a role in keeping unnecessary magnetic fields away from the low temperature portion. That is, the magnetic shield 14 forms a path for the magnetic field, thereby blocking magnetic fields such as geomagnetism from flowing into the inside of the magnetic shield 14 from the outside of the magnetic shield 14. The magnetic shield 14 is formed using a metal having high magnetic permeability. The magnetic shield 14 may be formed, for example, using permalloy, which is a nickel-iron alloy containing 35 to 85% nickel.

[0015] The vacuum chamber 15 is a vacuum vessel whose interior is kept in a vacuum state. Inside the vacuum chamber 15, the superconducting acceleration cavity 12, the heat shield 13, and the magnetic shield 14 are arranged in this order from the inside to the outside of the vacuum chamber 15. By keeping the inside of the vacuum chamber 15 in a vacuum state, it is possible to reduce radiant heat and conductive heat from the outside of the vacuum chamber 15 to these components inside the vacuum chamber 15.

[0016] The RF input coupler 16 is connected to an acceleration power supply source and supplies high frequency power from the acceleration power supply source to the superconducting acceleration cavity 12. The RF input coupler 16 includes a central portion 161 connected to the outermost shell (outer wall portion 117) of the electron gun 11 and an outer peripheral portion 162 connected to the beam pipe portion 121A. The RF input coupler 16 propagates high frequency power from the acceleration power supply source to the superconducting acceleration cavity 12 by a coaxial structure formed by the beam pipe portion 121A serving as an outer conductor and the outermost shell of the electron gun 11 serving as an inner conductor. The acceleration power supply source may be a high frequency power supply source that realizes amplification of high frequency power by vacuum tubes such as inductive output tubes (IOT) and klystron. The acceleration power supply source may also realize amplification of high frequency power by a semiconductor amplifier such as a field effect transistor (FET). The acceleration power supply source may also be connected to a low level radio frequency (LLRF) control system to control the frequency of the high frequency power. Also, a circulator to which a port is connected may be provided between the acceleration power supply source and the RF input coupler 16 so that the high-frequency power reflected from the superconducting accelerating cavity 12 does not return. That is, the RF input coupler 16, the acceleration power supply source, the LLRF control system, and the circulator constitute an acceleration power supply device.

[0017] The vacuum valve 17 is a valve that maintains a vacuum state inside the superconducting accelerating cavity 12. A vacuum pump is connected to the vacuum valve 17, and the air inside the superconducting accelerating cavity 12 is removed by using the vacuum pump to evacuate the cavity, and then the vacuum valve 17 is closed to prevent air from entering from the outside and to maintain the pressure inside the superconducting accelerating cavity 12 at a predetermined pressure.

[0018] The refrigerator 18 is connected to the superconducting accelerating cavity 12 to cool the superconducting accelerating cavity 12. A mechanical refrigerator such as a Gifford-McMahon refrigerator can be used as the refrigerator 18. The Gifford-McMahon refrigerator achieves cooling by sending a refrigerant such as helium gas compressed by a compressor into a cylinder, and repeating adiabatic expansion of the refrigerant gas by the reciprocating motion of a displacer in the cylinder. In contrast, a liquefied helium refrigerator has a complex configuration including a helium liquefier and requires extremely large equipment. The Gifford-McMahon refrigerator can be made smaller by using a simple mechanical configuration including a compressor and a displacer.

[0019] Here, the connection portion between the refrigerator 18 and the superconducting accelerating cavity 12 will be described with reference to Fig. 2. Fig. 2 is an AA cross-sectional view of the superconducting accelerating cavity of the superconducting cryomodule according to the present disclosure. As shown in Fig. 2, the refrigerator 18 includes a first stage 181, a second stage 182, and a cold head 183. The first stage 181 refers to the stage of the refrigerator 18 that has a lower temperature, and the second stage 182 refers to the stage of the refrigerator 18 that has a higher temperature. The cold head 183 is a portion that obtains cooling by expansion of a refrigerant supplied from a compressor.

[0020] As shown in FIG. 2, a connection portion 19 is provided in the first stage 181 and is connected to the superconducting accelerating cavity 12 by the connection portion 19. Note that the connection portion 19 may be formed in a flange shape. As shown in FIG. 2, the cooler 18 is arranged such that the angle formed by the central axis CA of the cooler 18 and the beam axis BA of the superconducting accelerating cavity 12 is a right angle and in a twisted position. That is, the central axis CA of the cooler 18 and the beam axis BA of the superconducting accelerating cavity 12 are arranged at positions where they do not intersect. Thus, assuming that the cylindrical radius of the vacuum chamber 15 is R, the radius of the superconducting accelerating cavity 12 is r, and the distance between the connection portions of the first stage 181 and the second stage 182 of the cooler 18 is d, the cylindrical radius R of the vacuum chamber 15 can satisfy the following equation (1). R < r + d... Equation (1) Therefore, it is possible to reduce the size of the vacuum chamber 15.

[0021] (Configuration of Electron Gun) Next, the configuration of the electron gun 11 according to the present disclosure will be described with reference to FIG. 3. FIG. 3 is a diagram showing a first aspect of the electron gun of the superconducting cryomodule according to the present disclosure. As shown in FIG. 3, the electron gun 11 includes a cathode 111, an anode 112, a heat shield plate portion 113, a notch portion 114, and a power supply 115.

[0022] The cathode 111 is formed of a metal material and emits free electrons when heated. The metal material is composed of positive ions in a stable closed-shell state of atoms and outer shell electrons (free electrons) that can move freely between atoms. When the temperature of the metal material is increased, the energy of the free electrons increases, and the free electrons are emitted from the metal material over the potential barrier. The cathode 111 emits electrons using such a principle. Also, the tip of the cathode 111 is arranged at a position upstream in the electron movement direction from the inlet portion of the cell portion 122. Thereby, electrons can be appropriately introduced from the electron gun 11 into the cell portion 122.

[0023] The anode 112 extracts the electrons emitted from the cathode 111 by the electric potential and emits them outside the electron gun 11. A high-frequency electric field is generated between the anode 112 and the heat shielding plate 113 by the high-frequency power supplied from the RF input coupler 16, and the electrons emitted from the cathode 111 are accelerated.

[0024] The heat shielding plate portion 113 includes a plurality of metal plates formed around the cathode 111 that emits electrons. The plurality of metal plates of the heat shielding plate portion 113 may be formed of at least two layers of metal plates. The number of metal plates constituting the heat shielding plate portion 113 is not limited to two layers, and may be set to any number. The heat shielding plate portion 113 is formed so as to cover, that is, to surround, the cathode 111. For example, when the cathode 111 has a cylindrical shape, the heat shielding plate portion 113 is formed in a cylindrical shape. In addition, the heat shielding plate portion 113 has a beam hole 113a through which electrons pass at its tip portion. The heat shielding plate portion 113 may be formed using a material that plays a role of shielding heat. For example, the heat shielding plate portion 113 may be formed using oxygen-free copper.

[0025] The cutout portion 114 is a portion obtained by cutting out a part of the outer wall portion 117 of the anode 112. The cutout portion 114 is provided at a position where acceleration power can be supplied at the timing when electrons pass through the beam hole 112a of the anode 112. The shape of the cutout portion 114 may be a hole or a cylindrical slit. This allows high-frequency power to be attracted to the inside of the electron gun 11 from the cutout portion 114. The attracted high-frequency power propagates through the coaxial structure formed between the inner wall of the anode 112 and the outermost layer of the heat shielding plate portion 113, and generates a high-frequency acceleration electric field in the space 113b between the beam hole 112a of the anode 112 and the beam hole 113a of the heat shielding plate portion 113. This allows the electrons E accelerated at the initial stage to be introduced into the cell portion 122.

[0026] The power supply 115 supplies a potential to the multiple metal plates constituting the heat shielding plate portion 113. The power supply 115 may be realized by, for example, a DC (Direct Current) power supply. The power supply 115 applies a positive or negative voltage to the multiple metal plates with respect to the potential of the cathode 111. This makes it possible to extract electrons emitted from the cathode 111 while converging them. In other words, the multiple metal plates constituting the heat shielding plate portion 113 serve as a Wehnelt electrode and an extraction grid.

[0027] The dielectric 116 is provided between the anode 112 and the metal plate constituting the heat shielding plate portion 113. The dielectric 116 may be made of, for example, a ceramic material, a glass material, a plastic material, or the like. The dielectric 116 may be formed in a ring shape so as to cover the outer periphery of the metal plate. The dielectric 116 functions as an insulator for direct current, but is conductive for high frequency power supplied from a high frequency power source. Furthermore, by providing the dielectric 116, it is possible to control the transmission time of the high frequency power that reaches the beam hole 112a.

[0028] The operation of the superconducting cryomodule 1 configured as above will be described. By heating the cathode 111 of the electron gun 11, electrons E (see FIG. 3) are emitted from the cathode 111. By applying a voltage between the cathode 111 and the metal plate by the power supply 115, the emitted electrons E are emitted from the electron gun 11. Since the heat shielding plate portion 113 surrounds the periphery of the cathode 111, the transfer of heat from the cathode 111 to the cell portion 122 is suppressed.

[0029] Electrons E emitted from electron gun 11 move along beam axis BA inside beam pipe section 121A toward cell section 122. Electrons E that reach cell section 122 are accelerated by high frequency power supplied from RF input coupler 16 in cell section 122, and are emitted from emission section 121B. A portion of the high frequency power supplied from RF input coupler 16 is attracted into electron gun 11 from notch section 114. As a result, electrons E emitted from cathode 111 are accelerated and drawn out of electron gun 11.

[0030] As described above, the superconducting cryomodule 1 of the first embodiment comprises a superconducting acceleration cavity 12 having a cell section 122 for accelerating electrons, a beam pipe section 121A extending from the cell section 122 to the electron entrance side, and an emission section 121B for emitting electrons accelerated in the cell section 122, and an electron gun 11 located inside the beam pipe section 121A of the superconducting acceleration cavity 12 and coaxially with the beam axis BA of the superconducting acceleration cavity 12 for emitting electrons to the cell section 122.

[0031] According to this configuration, the electron gun of the superconducting cryomodule 1 can be accommodated inside the beam pipe section 121A of the superconducting acceleration cavity 12. Therefore, it is not necessary to provide and connect the electron gun 11 outside the superconducting cryomodule 1, and it is possible to miniaturize the entire device.

[0032] Second embodiment Next, the superconducting cryomodule 1 according to the second embodiment will be described. The superconducting cryomodule 1 according to the second embodiment has the same configuration as the superconducting cryomodule 1 according to the first embodiment, except for the configuration of the electron gun 11. Therefore, of the configuration of the superconducting cryomodule 1 according to the second embodiment, the configuration of the electron gun 11, which is different from that of the superconducting cryomodule 1 according to the first embodiment, will be described.

[0033] The electron gun 11 is a field emission type electron gun that includes an emitter, an extraction electrode, and an acceleration electrode. Electrons emitted from the emitter are extracted by an extraction voltage, and the electrons are accelerated by an acceleration voltage applied by the acceleration electrode. A field emission type electron gun emits electrons by utilizing the field emission phenomenon that occurs when a high electric field is applied to a metal surface. Specifically, when a voltage of several kV is applied to the extraction electrode placed opposite the emitter, electrons are emitted from the emitter due to the tunnel effect. Then, the electrons that pass through a hole formed in the center of the extraction electrode can be emitted with a predetermined energy by applying an acceleration voltage to the acceleration electrode.

[0034] According to this configuration, since the electron gun 11 can be provided inside the superconducting accelerating cavity 12, the superconducting cryomodule 1 can be made compact.

[0035] Third embodiment Next, the superconducting cryomodule 1 according to the third embodiment will be described. The superconducting cryomodule 1 according to the third embodiment has the same configuration as the superconducting cryomodule 1 according to the first embodiment, except for the configuration of the electron gun 11. Therefore, of the configuration of the superconducting cryomodule 1 according to the third embodiment, the configuration of the electron gun 11, which is different from that of the superconducting cryomodule 1 according to the first embodiment, will be described.

[0036] The electron gun 11 is a photoemission type electron gun, which irradiates a cathode with laser light and emits electrons by utilizing the photoelectric effect. The photoelectric effect is a phenomenon in which a material absorbs photons and emits electrons. For example, when a metal is irradiated with a short-wavelength laser light, electrons are emitted from the metal surface. For the cathode of a photoemission type electron gun, a material with high quantum efficiency, which means the efficiency of conversion of photons and electrons due to the photoelectric effect, can be used.

[0037] According to this configuration, since the electron gun 11 can be provided inside the superconducting accelerating cavity 12, the superconducting cryomodule 1 can be made compact.

[0038] (Composition and Effects) The superconducting cryomodule according to the first aspect of the present disclosure is a superconducting cryomodule 1 including a superconducting acceleration cavity 12 having a cell section 122 for accelerating electrons, a beam pipe section 121A extending from the cell section 122 to the electron entrance side, and an emission section 121B for emitting electrons accelerated in the cell section 122, and an electron gun 11 located inside the beam pipe section 121A of the superconducting acceleration cavity 12 and coaxially with the beam axis BA of the superconducting acceleration cavity 12 for emitting electrons to the cell section 122.

[0039] According to this configuration, the electron gun of the superconducting cryomodule 1 can be accommodated inside the beam pipe section 121A of the superconducting acceleration cavity 12. Therefore, it is not necessary to provide and connect the electron gun 11 outside the superconducting cryomodule 1, and it is possible to miniaturize the entire device.

[0040] A superconducting cryomodule according to a second aspect of the present disclosure is a superconducting cryomodule 1 according to the first aspect, in which the electron gun 11 is a thermionic emission type electron gun, beam holes through which the electrons pass are formed around the cathode that emits electrons, and a heat shielding plate portion 113 including a plurality of metal plates formed surrounding the cathode is provided.

[0041] This configuration makes it possible to prevent radiant heat from the cathode of the thermionic emission electron gun from being transmitted to the superconducting accelerating cavity 12. Therefore, it becomes possible to maintain the temperature of the superconducting accelerating cavity 12 at a low temperature, which makes it possible to maintain the superconducting accelerating cavity 12 in a superconducting state, thereby enabling stable operation of the superconducting cryomodule 1.

[0042] The superconducting cryomodule 1 according to the third aspect of the present disclosure is the superconducting cryomodule according to the first or second aspect, and further comprises an RF input coupler that supplies high frequency power to the superconducting acceleration cavity 12. The RF input coupler 16 comprises a central portion 161 connected to the outermost shell of the electron gun 11 and an outer peripheral portion 162 connected to the beam pipe portion 121A, and transmits high frequency power to the superconducting acceleration cavity 12 via a coaxial structure formed by the beam pipe portion 121A as the outer conductor and the outermost shell of the electron gun 11 as the inner conductor.

[0043] According to this configuration, high frequency power can be supplied from RF input coupler 16 to a coaxial structure in which beam pipe section 121A is the outer conductor and the outermost shell of electron gun 11 is the inner conductor. Therefore, it becomes possible to accelerate electrons emitted from electron gun 11 by the high frequency power and introduce them into cell section 122.

[0044] A superconducting cryomodule according to a fourth aspect of the present disclosure is the superconducting cryomodule 1 according to the third aspect, further comprising an electron gun 11 having a cutout portion 114 formed by cutting out a portion of the anode, and high-frequency power is supplied via the cutout portion 114 to impart an electric field to electrons emitted from the cathode of the electron gun 11, and by controlling the high-frequency power, the extraction and acceleration of electrons emitted from the cathode of the electron gun 11 are controlled.

[0045] According to this configuration, high frequency power is supplied from the notch 114, so that it is possible to control the beam by applying an electric field to the electrons emitted from the cathode of the electron gun 11.

[0046] A superconducting cryomodule according to a fifth aspect of the present disclosure is a superconducting cryomodule 1 according to any one of the second to fourth aspects, in which the electron gun 11 has a dielectric 116 between the anode 112 and the metal plate that constitutes the heat shielding plate portion 113.

[0047] According to this configuration, it becomes possible to control the transmission time of the high frequency power by the dielectric 116. Therefore, it becomes possible to emit electrons from the electron gun 11 to the superconducting accelerating cavity 12 at an appropriate timing in accordance with the periodic fluctuation of the high frequency power of the superconducting accelerating cavity 12.

[0048] A superconducting cryomodule according to a sixth aspect of the present disclosure is the superconducting cryomodule 1 according to the first aspect, in which the electron gun 11 is a field emission type electron gun and includes an emitter, an extraction electrode, and an acceleration electrode, and electrons emitted from the emitter are extracted by an extraction voltage and accelerated by an acceleration voltage applied by the acceleration electrode.

[0049] According to this configuration, the electron gun 11 of the superconducting cryomodule 1 can be accommodated inside the beam pipe portion 121 of the superconducting acceleration cavity 12. Therefore, it is not necessary to provide and connect the electron gun 11 outside the superconducting cryomodule 1, and it is possible to miniaturize the entire device.

[0050] A superconducting cryomodule 1 according to a seventh aspect of the present disclosure is the superconducting cryomodule 1 according to the first aspect, in which the electron gun 11 is a photoemission type electron gun that irradiates the cathode with laser light and emits electrons by utilizing the photoelectric effect.

[0051] According to this configuration, the electron gun 11 of the superconducting cryomodule 1 can be accommodated inside the beam pipe portion 121 of the superconducting acceleration cavity 12. Therefore, it is not necessary to provide and connect the electron gun 11 outside the superconducting cryomodule 1, and it is possible to miniaturize the entire device.

[0052] A superconducting cryomodule according to an eighth aspect of the present disclosure is a superconducting cryomodule 1 according to the first aspect, in which the tip of the cathode of the electron gun 11 is positioned upstream in the direction of electron movement away from the entrance portion of the cell section 122.

[0053] According to this configuration, electrons emitted from the electron gun 11 can be introduced into the cell section 122, making it possible to appropriately accelerate the electrons emitted from the electron gun 11 in the cell section 122 to which high-frequency power is applied.

[0054] The superconducting cryomodule 1 of the ninth aspect of the present disclosure is the superconducting cryomodule 1 of the first aspect, further comprising a cooling device 18 connected to the superconducting accelerating cavity 12 and cooling the superconducting accelerating cavity 12, the cooling device 18 having a connection portion 19 connecting to the superconducting accelerating cavity 12, and the cooling device 18 being arranged in a twisted position such that the angle between the central axis CA of the cooling device 18 and the beam axis BA of the superconducting accelerating cavity 12 is perpendicular.

[0055] According to this configuration, it is possible to reduce the height and width of the vacuum chamber 15 that houses the superconducting accelerating cavity 12 and the like, and therefore it is possible to reduce the size of the superconducting cryomodule 1.

[0056] Although the embodiment of the present invention has been described above, the embodiment is not limited to the contents of this embodiment. The above-mentioned components include those that a person skilled in the art can easily imagine, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the above-mentioned components can be appropriately combined. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the gist of the above-mentioned embodiment. [Explanation of symbols]

[0057] 1. Superconducting cryomodule 11 Electron gun 111 Cathode 112 Anode 113 Heat shield part 114 Cutout 115 Power supply 12 Superconducting Accelerating Cavity 13 Heat Shield 14 Magnetic Shielding 15 Vacuum chamber 16 RF Input Coupler 17 Vacuum valve 18 Cooler 181 1st Stage 182 Second Stage 183 Cold Head 19 Connection BA Beam axis CA center axis

Claims

1. A superconducting accelerating cavity having a cell section for accelerating electrons, a beam pipe section extending from the cell section to the electron incident side, and an emission section for emitting the electrons accelerated in the cell section; An electron gun located inside the beam pipe section of the superconducting accelerating cavity and coaxial with the beam axis of the superconducting accelerating cavity, for emitting electrons to the cell section; The electron gun includes a heat shielding plate section including a plurality of metal plates formed around the cathode for emitting electrons, and a beam hole through which electrons pass is formed around the cathode; A superconducting cryomodule.

2. The electron gun is a thermionic emission type electron gun; The superconducting cryomodule according to Claim 1.

3. The superconducting accelerating cavity further includes an RF input coupler for supplying high-frequency power thereto; The RF input coupler; A central section connected to the outermost shell of the electron gun; An outer peripheral section connected to the beam pipe section; High-frequency power is propagated to the superconducting accelerating cavity by a coaxial structure formed by the beam pipe section serving as an outer conductor and the outermost shell of the electron gun serving as an inner conductor; The superconducting cryomodule according to Claim 1 or 2.

4. The electron gun further includes a notch section with a part cut out from the anode; High-frequency power for applying an electric field to the electrons emitted from the cathode of the electron gun is supplied through the notch section; By controlling the high-frequency power, the extraction and acceleration of the electrons emitted from the cathode of the electron gun are controlled; The superconducting cryomodule according to Claim 3.

5. The electron gun includes a dielectric between the anode and the metal plates constituting the heat shielding plate section; The superconducting cryomodule according to Claim 2.

6. The electron gun includes a dielectric between the anode and the metal plates constituting the heat shielding plate section; The superconducting cryomodule according to Claim 3.

7. The electron gun is a field emission type electron gun; Comprising an emitter, an extraction electrode, and an acceleration electrode, the electrons emitted from the emitter are extracted by an extraction voltage and accelerated by an acceleration voltage applied by the acceleration electrode; The superconducting cryomodule according to Claim 1.

8. The electron gun is a photoelectron emission type electron gun; The cathode is irradiated with laser light, and electrons are emitted by utilizing the photoelectric effect; The superconducting cryomodule according to Claim 1.

9. The electron gun is arranged such that the tip of the cathode is located upstream of the inlet portion of the cell portion in the electron movement direction and separated therefrom. The superconducting cryomodule according to claim 1. **Claim 10**: A superconducting accelerating cavity having a cell portion for accelerating electrons, a beam pipe portion extending from the cell portion to the electron incident side, and an emission portion for emitting the electrons accelerated in the cell portion. An electron gun located inside the beam pipe portion of the superconducting accelerating cavity and coaxial with the beam axis of the superconducting accelerating cavity, which emits electrons to the cell portion. A cooler connected to the superconducting accelerating cavity for cooling the superconducting accelerating cavity. The cooler has a connection portion connected to the superconducting accelerating cavity. The cooler is arranged such that the angle formed by the central axis of the cooler and the beam axis of the superconducting accelerating cavity is a right angle and in a twisted position. A superconducting cryomodule.

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