Magnetron, and anode and cathode therefor

Abstract

The present invention provides a magnetron having greater output. A magnetron 1 comprises: an anode 10 that has a cylindrical anode shell 11 and a plurality of vanes 12 provided in a radial configuration to the inner peripheral wall of the anode shell 11; a cathode 20 that is provided to a center portion of the anode 10 along the center axis of the anode shell 11; and a pair of pole pieces 31, 32 that are respectively provided to the two end sides of the anode shell 11 so as to face each other. The anode 10 has first and second anode split bodies 10a, 10b, and the plurality of vane split bodies in the first anode split body 10a and the plurality of vane split bodies in the second anode split body 10b are joined to each other.

Description

Magnetron, anode and cathode therefor

[0001] The present invention relates to a magnetron, an anode and a cathode therefor.

[0002] Conventionally, a magnetron has been used to generate microwaves. It is conceivable to use such microwaves as a means for electrifying a chemical plant aimed at achieving carbon neutrality. For example, taking a naphtha cracker as an example, in order to use microwaves as a heating means, an output of about several tens of MW in continuous wave is required. However, in currently commercially available oscillators, even with a large output, it is about 100 kW, and it is necessary to install oscillators on the order of 100 units.

[0003] If the output per unit can be increased, the number of required oscillators can be significantly reduced. Therefore, in order to use microwaves as a heating means, the development of oscillators with a higher output is desired.

[0004] The present invention has been made in view of such points, and the problem thereof is to provide a magnetron with a higher output or an anode or a cathode therefor.

[0005] In order to solve the above problems, a magnetron according to an aspect of the present invention includes an anode having a cylindrical anode shell and a plurality of vanes radially provided on the inner peripheral wall of the anode shell, a cathode provided along the central axis of the anode shell at the central portion of the anode, and a pair of pole pieces provided on both end sides of the anode shell so as to face each other. The anode has first and second anode split bodies, and a plurality of vane split bodies of the first anode split body and a plurality of vane split bodies of the second anode split body are joined together.

[0006] Further, in the magnetron according to an aspect of the present invention, the anode may have a third anode split body.

[0007] Further, in the magnetron according to an aspect of the present invention, the plurality of anode split bodies of the anode may be those obtained by splitting the anode in a plane perpendicular to the central axis of the anode shell.

[0008] Furthermore, in a magnetron according to one aspect of the present invention, at least some of the vanes may each have a cooling mechanism provided inside.

[0009] Furthermore, in a magnetron according to one aspect of the present invention, the cooling mechanism may cool the vicinity of the central axis of the vane on which the cooling mechanism is provided.

[0010] Furthermore, in a magnetron according to one aspect of the present invention, the cooling mechanism may be a flow passage through which a liquid coolant flows.

[0011] Furthermore, in a magnetron according to one aspect of the present invention, the cooling mechanism may be a porous metal body through which a liquid passes, and cooling may be performed by utilizing the latent heat of vaporization of the liquid passing through the porous body.

[0012] Furthermore, in a magnetron according to one aspect of the present invention, the anode may further have an annular strap that electrically connects a plurality of vanes alternately.

[0013] Furthermore, in a magnetron according to one aspect of the present invention, the cathode may be arranged coaxially with the anode.

[0014] Furthermore, the anode of a magnetron according to one aspect of the present invention has a cylindrical anode shell and a plurality of vanes arranged radially on the inner circumferential wall of the anode shell, and the anode has a first and a second anode segment, and the plurality of vane segments of the first anode segment and the plurality of vane segments of the second anode segment are joined together.

[0015] Furthermore, a method for manufacturing a magnetron anode according to one aspect of the present invention includes the steps of manufacturing first and second anode divisions, each of which an anode having a cylindrical anode shell and a plurality of vanes radially arranged on the inner circumferential wall of the anode shell is divided, and the steps of joining a plurality of vane divisions of the first anode division and a plurality of vane divisions of the second anode division to manufacture an anode.

[0016] According to one aspect of the present invention, the anode can be made larger, and as a result, the output can be increased.

[0017] A cross-sectional perspective view showing the configuration of a magnetron according to the first embodiment of the present invention. A perspective view showing a plurality of anode divisions according to the same embodiment. A diagram showing the refrigerant flow path provided in the vane according to the same embodiment. A perspective view showing the cathode according to the same embodiment. A diagram showing another example of the joint of the vane division according to the same embodiment. A diagram showing another example of the joint of the vane division according to the same embodiment. A diagram showing a cooling mechanism provided in the vane according to the second embodiment of the present invention. A cross-sectional view showing a cooling mechanism provided in the vane according to the third embodiment of the present invention.

[0018] (First Embodiment) The magnetron according to the present invention will be described below using the first embodiment. In the following embodiments, components denoted by the same reference numerals are the same or equivalent, and further explanation may be omitted. The magnetron according to this embodiment can achieve a higher output. In this embodiment, a magnetron having a direct-heated cathode and generating a continuous wave used in microwave heating devices and the like will be described.

[0019] Figure 1 is a cross-sectional perspective view of a magnetron 1 according to a first embodiment of the present invention; Figure 2 is a perspective view showing a plurality of anode divisions 10a, 10b obtained by dividing the anode 10; Figure 3 is a diagram showing a liquid coolant flow passage 14 provided inside the vane 12; and Figure 4 is a perspective view of the cathode 20. Note that Figure 3 is a view of one vane 12 from a direction perpendicular to the plane direction of the vane 12.

[0020] The magnetron 1 according to this embodiment comprises a cylindrical anode shell 11, an anode 10 having a plurality of vanes 12 radially arranged on the inner circumferential wall of the anode shell 11, a cathode 20 provided at the center of the anode 10, and a pair of pole pieces 31 and 32 provided opposite each other at both ends of the anode shell 11. It may also further include an output unit 40 that outputs microwaves generated in the resonant cavity of the anode 10 to the outside. In this embodiment, the direction of the central axis of the cylindrical anode shell 11 is sometimes simply called the axial direction, the circumferential direction of the anode shell 11 is sometimes simply called the circumferential direction, and the radial direction of the anode shell 11 is sometimes simply called the radial direction.

[0021] The frequency band of the microwaves generated by the magnetron 1 according to this embodiment may be, for example, around 433.92 MHz, 500 MHz, 915 MHz, 2.45 GHz, and 5.8 GHz, or it may be any other frequency band within the range of 300 MHz to 300 GHz. Furthermore, the output of the magnetron 1 is preferably 100 kW or more, more preferably 500 kW or more, even more preferably 1 MW or more, and even more preferably 10 MW or more. As an example, the output of the magnetron 1 may be 100 kW to 100 MW, 500 kW to 80 MW, 1 MW to 60 MW, or 10 MW to 50 MW.

[0022] The multiple vanes 12 arranged radially on the inner circumferential wall of the anode shell 11 may each extend radially so as to have a space in the center of the anode shell 11 where the cathode 20 can be placed. The vanes 12 may be, for example, flat. The number of vanes 12 on the anode 10 is not particularly limited as long as there are multiple vanes, but as will be described later, if they are connected by straps 13 every other vane, there may be an even number. The number of vanes 12 is preferably 8 or more, 10 or more, or 12 or more. When trying to obtain the same output, if the number is small, a high cooling capacity is required for the flow passage 14 that cools each vane 12. On the other hand, if the number increases, instability due to mode hopping increases, so it is preferable to have 16 or fewer, 14 or fewer, or 12 or fewer. The materials of the anode shell 11 and the vanes 12 may each be, for example, metals such as copper. In the anode 10, a resonant cavity is formed between adjacent vanes 12. The anode 10 is preferably designed to form a resonant cavity corresponding to a desired microwave frequency. The axial length of the resonant cavity may be, for example, less than or equal to half the wavelength of the generated microwave, and is typically about 0.1 to 0.2 times the wavelength. The radial length of the vane 12 may, for example, be about 1 / 4 the wavelength of the generated microwave.

[0023] The anode 10 may further have, for example, an annular strap 13 that electrically connects a plurality of vanes 12 alternately. The annular strap 13 may be arranged, for example, concentrically with the anode shell 11. The strap 13 may be connected, for example, to the upper part of the vanes 12, to the lower part of the vanes 12, or to the joint of the vane divisions 12a and 12b, which will be described later. The strap 13 may also be electrically connected to the vanes 12 in a recess 15 provided in the vanes 12 as shown in Figure 3. By electrically connecting a plurality of vanes 12 alternately along the circumferential direction using the strap 13, the magnetron 1 will oscillate in π mode. As shown in Figure 2, if the anode 10 has 10 vanes 12 along the circumferential direction, i.e., the first to tenth vanes 12, the anode 10 may, for example, have a first strap 13a electrically connected to the first vane 12, the third vane 12, the fifth vane 12, the seventh vane 12, and the ninth vane 12, and a second strap 13b electrically connected to the second vane 12, the fourth vane 12, the sixth vane 12, the eighth vane 12, and the tenth vane 12, respectively.

[0024] Each of the multiple vanes 12 may have a flow passage 14 through which a liquid coolant flows, for example, as shown in Figures 1 and 3. The coolant may flow through the flow passage 14, for example, as indicated by the arrow in Figure 3. By flowing the coolant through the flow passage 14 in this way, the vanes 12 can be cooled more efficiently than when cooling fins are provided on the outer surface of the anode shell 11. Note that electrons emitted from the cathode 20 strike the end 12c of the vane 12 on the cathode 20 side, causing the end 12c of the vane 12 to be heated. Such heating becomes more pronounced as the output of the magnetron 1 increases. Therefore, in high-output magnetrons 1, it is preferable to cool the vanes 12 using a liquid coolant in order to cool the vanes 12 more efficiently than with cooling fins. Furthermore, since the cathode 20 side of the vane 12, i.e., the left side in Figure 3, is heated more by electrons emitted from the cathode 20, it is preferable that the flow passage 14 is provided to pass through the interior of the vane 12 near the cathode 20 or near the central axis of the anode shell 11, as shown in Figure 3. For this reason, the flow passage 14 may be formed across, for example, the vane segments 12a and 12b, which will be described later, as shown in Figure 3. If it does not span across them, the area near the joint of the vane segments 12a and 12b will not be cooled, leading to deterioration of the vane 12. The liquid refrigerant flowing through the flow passage 14 may be, for example, water, or any other liquid refrigerant. When the flow passage 14 is provided inside the vane 12, the magnetron 1 further includes, for example, a heat exchanger (not shown) for cooling the refrigerant discharged from the flow passage 14 of the vane 12, and a pump (not shown) for circulating the liquid refrigerant, and the refrigerant cooled by the heat exchanger may be returned to the flow passage 14 by the pump. The cooling mechanism only needs to be provided inside each vane 12 to sufficiently cool each vane 12 to the vicinity of the cathode 20 or the vicinity of the central axis of the anode shell 11, and is not limited to a flow passage 14 for circulating the coolant. Furthermore, it is not necessarily required to be provided in all vanes 12.

[0025] The anode 10 according to this embodiment may be formed by joining together a plurality of anode divisions 10a, 10b obtained by dividing the anode 10, as shown in Figure 2. That is, the anode 10 may have a plurality of anode divisions 10a, 10b. In this embodiment, the case in which the anode 10 is divided into two parts will be mainly described, but the number of divisions may be three or more. From the viewpoint of making the manufacturing of the anode 10 easier, it is preferable to have a small number of divisions. For example, the number of divisions is preferably five or less, and more preferably three or less. In addition, in this embodiment, the case in which the anode 10 is divided in a plane perpendicular to the central axis of the anode shell 11 will be mainly described, but the plurality of anode divisions may be formed by dividing the anode 10 at other positions.

[0026] In this way, by making the anode 10 composed of multiple anode divisions 10a and 10b, it becomes easier to increase the size of the anode 10. For example, there is a limit to the size of the anode 10 that can be manufactured by machining, but by manufacturing multiple anode divisions 10a and 10b separately and then joining them, it is possible to manufacture an anode 10 of a size that cannot be manufactured as a single piece. Using a larger anode 10 allows for a higher output of the magnetron 1. In a high-output magnetron 1, the temperature of the anode 10 tends to rise, but by increasing the size of the anode 10, the heat density can be reduced, making it easier to suppress the temperature rise of the anode 10. Also, when increasing the output of the magnetron 1, it is possible to reduce the microwave frequency, but in order to reduce the frequency, a larger anode 10 is required. Furthermore, by increasing the surface area of ​​the vane 12 facing the cathode, the heat density can be reduced accordingly, and the temperature rise of the vane 12 can be suppressed.

[0027] The cathode 20 is located in the center of the anode shell 11, along the central axis of the anode shell 11. Preferably, the cathode 20 is positioned such that its longitudinal direction aligns with the central axis of the anode shell 11. Thus, the cathode 20 may be positioned coaxially with the anode 10. To generate high-power, continuous-wave microwaves, a directly heated cathode 20 is usually used. As an example, the directly heated cathode 20 may have a filament 21, end hats 22 and 23, and a cathode lead 24, as shown in Figure 4. The directly heated cathode 20 is suitable for generating high-power, continuous-wave microwaves because it can use a filament 21 made of a metal with a high melting point and high thermal conductivity, thereby reducing the effects of backheat caused by electron backbombardment. The diameter of the cylindrical void near the central axis of the anode shell 11 in which the cathode 20 is housed may be, for example, about half the radial length of the vane 12. A larger diameter of this void would result in a higher applied voltage, which is undesirable. As mentioned above, a directly heated cathode 20 is usually used, but an indirectly heated cathode 20 may also be used. For example, a dispenser-type hot cathode made of porous tungsten impregnated with barium oxide or the like has some drawbacks, such as runaway electron emission due to back bombardment and poor temperature control responsiveness characteristic of indirectly heated cathodes. However, it can achieve high current at relatively low temperatures and increase current density to improve output, so it may be used as the cathode 20 in some cases. The cathode 20 or its components may be removable for replacement as consumables.

[0028] The filament 21 may be, for example, a metal wire wound spirally around a cathode lead 24 for power supply. Since the filament 21 becomes hot when microwaves are generated, the material of the filament 21 is preferably one that can withstand such high temperatures, such as tungsten or thorium tungsten. The cross-section perpendicular to the longitudinal direction of the wire may be circular, for example, as shown in Figure 1. End hats 22 and 23 may be provided at both ends of the filament 21 in the axial direction. At the end hat 23, for example, the filament 21 and the cathode lead 24 may be electrically connected. The cathode lead 24 may support the filament 21 and also apply voltage to the filament 21. At the end hat 22, for example, the filament 21 may be electrically connected to another lead for power supply. When microwaves are generated, a voltage is applied to both ends of the filament 21, heating it up. At the same time, a high voltage is applied between the filament 21 and the anode 10, causing thermionic electrons to be emitted from the high-temperature filament 21.

[0029] A pair of pole pieces 31 and 32 are provided opposite each other at both ends in the axial direction of the anode shell 11. A magnetic field is applied in the axial direction by this pair of pole pieces 31 and 32. For example, the pole pieces 31 and 32 may be disc-shaped. Also, one of the pole pieces, for example pole piece 31, may have a hole in the center of its disc shape through which the cathode lead 24 can pass, as shown in Figure 1. Furthermore, to prevent microwave leakage from between the hole in the pole piece 31 and the cathode lead 24, a microwave leakage prevention mechanism, such as a choke structure, may be provided. The material of the pole pieces 31 and 32 may be, for example, a magnet or a magnetic material. Also, in Figure 1, for example, electromagnets (not shown) may be placed on the upper surface of pole piece 31 and the lower surface of pole piece 32, respectively. An axial magnetic field may be formed by these electromagnets. The magnetic field between the pair of pole pieces 31 and 32, and the electric field between the anode 10 and the cathode 20, cause the electrons emitted from the filament 21 to perform swirling and orbital motions, inducing high-frequency vibrations that resonate in the resonant cavity of the anode 10. The interaction between these high-frequency vibrations and the electrons sustains strong high-frequency vibrations.

[0030] The output unit 40 may, for example, have an antenna 41 that radiates microwaves corresponding to high-frequency vibrations generated in the resonant cavity of the anode 10, and an antenna cap 42 surrounding the antenna 41, as shown in Figure 1. The antenna 41 may, for example, be connected to the vane 12, as shown in Figure 1.

[0031] Furthermore, the magnetron 1 may further include an input section (not shown) that generates a voltage to heat the filament 21 and a high voltage to be applied between the anode 10 and the cathode 20. The input section may also supply power to electromagnets located near the pole pieces 31 and 32.

[0032] Next, a method for manufacturing the anode 10 will be described. The method for manufacturing the anode 10 may include, for example, a step of manufacturing a plurality of anode divisions 10a and 10b, and a step of joining the plurality of anode divisions 10a and 10b to manufacture the anode 10.

[0033] In the process of manufacturing multiple anode divisions 10a and 10b, the multiple anode divisions 10a and 10b may be manufactured, for example, by machining such as cutting a metal block, by cutting a metal block by wire cutting, by punching or punching in press working, or by other methods. From the viewpoint of manufacturing larger anode divisions, it is preferable to manufacture the anode divisions by machining or wire cutting.

[0034] The anode segment 10a may, for example, have an anode shell segment 11a obtained by dividing the anode shell 11, and a plurality of vane segments 12a obtained by dividing a plurality of vanes 12. Similarly, the anode segment 10b may have, for example, an anode shell segment 11b and a plurality of vane segments 12b. In the anode segment 10a, the anode shell segment 11a and the plurality of vane segments 12a may be formed integrally by, for example, machining or wire cutting. The same applies to the anode segment 10b.

[0035] In the process of manufacturing the anode 10, the anode 10 may be manufactured by joining multiple anode segments 10a and 10b, for example, by brazing. For example, it is preferable that multiple anode segments 10a and 10b are joined so that two anode shell segments 11a and 11b are joined to form one anode shell 11, and two vane segments 12a and 12b are joined to form one vane 12. When two anode segments 10a and 10b are joined, for example, the two anode shell segments 11a and 11b may be joined by brazing, and for each of the multiple vanes 12, two vane segments 12a and 12b may be joined by brazing. The same applies when the anode 10 is divided into three or more anode segments.

[0036] Furthermore, the method for manufacturing the anode 10 may further include, for example, a step of forming the flow passages 14 in the anode segments 10a and 10b before the step of manufacturing the anode 10. In the step of forming the flow passages 14, for example, the flow passages 14 may be formed in the anode shell segments 11a and 11b and the vane segments 12a and 12b by drilling or the like. When multiple anode segments 10a and 10b are joined together, it is preferable that the joining is performed such that the flow passages 14 of the two vane segments 12a and 12b being joined are connected for each of the multiple vanes 12. In addition, in order to prevent refrigerant leakage at the joints of the flow passages 14, for example, brazing or electron beam joining from the inside may be performed. Furthermore, if the anode shell segments 11a, 11b and vane segments 12a, 12b are made of copper, after drilling holes in them, copper pipes may be inserted into the holes, copper pieces may be filled into the gaps between the holes and the copper pipes, and then pressure-welded from the inside of the copper pipes, i.e., by explosive pressure welding, to form a flow passage 14 using copper pipes. By forming the flow passage 14 in this way, it is possible to prevent refrigerant leakage at the joints of the vane segments 12a, 12b, and also to increase the contact area between the refrigerant and the vane segments 12a, 12b. Although Figure 3 shows the case where the flow passage 14 is formed across the vane segments 12a, 12b, the flow passage 14 may be formed so as not to cross the vane segments 12a, 12b. That is, a first flow passage may be formed in the vane segment 12a and a second flow passage may be formed in the vane segment 12b, and the first and second flow passages may not be connected. In this way, when joining the anode divisions 10a and 10b, an additional step is not required to prevent refrigerant leakage at the joint between the two.

[0037] Next, a method for generating microwaves using the magnetron 1 according to this embodiment will be described. First, an axial magnetic field is generated by electromagnets positioned adjacent to the pole pieces 31 and 32. In addition, a voltage is applied to the filament 21 of the cathode 20 to heat the filament 21, and a high voltage is applied between the anode 10 and the cathode 20 to cause thermionic electrons to be emitted from the heated filament 21. The electrons emitted from the filament 21 undergo swirling and orbital motion due to the magnetic and electric fields, inducing high-frequency vibrations that resonate in the resonant cavity of the anode 10, and the interaction between these high-frequency vibrations and electrons sustains strong high-frequency vibrations. The microwaves corresponding to the high-frequency vibrations generated in the resonant cavity in this way are radiated through the antenna 41 of the output unit 40.

[0038] As described above, with the magnetron 1 according to this embodiment, by making the anode 10 composed of multiple anode divisions 10a and 10b, it becomes easy to enlarge the anode 10 of the magnetron 1. In this way, by being able to enlarge the anode 10, the output of the magnetron 1 can be increased.

[0039] Furthermore, by circulating a liquid coolant through the flow passage 14 provided inside the vane 12, the vane 12 can be cooled more efficiently, preventing the vane 12 from becoming overheated in a high-power magnetron 1. In addition, since the flow passage 14 is provided to pass through the inside of the vane 12 near the cathode 20, the area that is particularly susceptible to heating by electrons emitted from the cathode 20 can be cooled efficiently.

[0040] In this embodiment, the case in which the filament 21 is made of a single wire has been mainly described, but the filament 21 may also be made of a strand of multiple wires. In this case as well, for example, the filament 21 may be made by winding this strand of wire spirally along the cathode lead 24. In the case of the stranded wire, it is preferable that the multiple wires are twisted together so that they are not electrically connected. By making the filament 21 out of a strand of multiple wires in this way, the current flowing through each wire can be reduced.

[0041] Furthermore, in this embodiment, as shown in Figure 3, the case in which the direction in which the junction of the vane divisions 12a and 12b extends is radial and is the same as the direction of movement of electrons emitted from the cathode 20 and hitting the end 12c of the vane 12 has been described, but this is not required. For example, as shown in Figures 5A and 5B, the junction 16 of the vane divisions 12a and 12b may be bent in part. The junction 16 may be bent near the cathode 20 or near the central axis of the anode shell 11, as an example. Figure 5A shows an example in which the direction in which the junction 16 extends on the cathode 20 side of the bend is different from the left-right direction in the figure, which is the direction of movement of electrons hitting the end 12c of the vane 12. Figure 5B shows an example in which the direction in which the junction 16 extends on the cathode 20 side of the bend coincides with the direction of movement of electrons, but its length is shorter compared to other parts of the junction 16. As shown in Figures 5A and 5B, the joint 16 is bent near the cathode 20 or near the central axis of the anode shell 11. This reduces the area over which electrons emitted from the cathode 20 strike the brazing material used to braze the joint 16, thus preventing the brazing material from being heated by electrons and weakening the joint between the vane segments 12a and 12b.

[0042] (Second Embodiment) The magnetron according to the present invention will be described using the second embodiment. The magnetron according to this embodiment is the same as that of the first embodiment except that the cooling mechanism of the vane 12 is a flow path capable of causing a liquid refrigerant to flow in a turbulent flow, and redundant descriptions will be omitted.

[0043] FIG. 6 is a diagram showing a flow path 51 of a liquid refrigerant provided inside the vane 12. The flow path 51 is a flow path capable of causing a liquid refrigerant to flow in a turbulent flow. By using the flow path 51 capable of causing a liquid refrigerant to flow in a turbulent flow instead of the linear flow path 14, it is possible to avoid the liquid flowing through the flow path 51 from becoming a laminar flow, and the heat exchange efficiency in the flow path 51 can be further increased. When the flow velocity of the liquid refrigerant flowing through the flow path 51 is low, the inside of the flow path 51 becomes a laminar flow, and the liquid on the central side does not contribute to heat exchange. Therefore, it is preferable to set the flow velocity of the liquid refrigerant flowing through the flow path 51 to a predetermined value or more so that a turbulent flow occurs in the flow path 51. The flow path 51 is preferably provided so as to pass through the inside of the vane 12 near the cathode 20 or near the central axis of the anode shell 11.

[0044] As shown in FIG. 6, the flow path 51 may be, for example, a spiral flow path. A flow path 52 for supplying a liquid refrigerant from the anode shell 11 side to the flow path 51 is connected to the upstream end of the spiral flow path 51, and a flow path 53 for discharging the liquid refrigerant from the flow path 51 to the anode shell side 11 may be connected to the downstream end of the spiral flow path 51. The refrigerant discharged from the flow path 53 may be cooled and supplied to the flow path 52, for example. The flow paths 52 and 53 may each be linear flow paths provided inside the vane 12 and extending in the radial direction of the anode shell 11. The inner diameter of the spiral flow path 51 may be, for example, about 1 mm to 3 mm. Further, as another example, the flow path 51 capable of causing the passing liquid to flow in a turbulent flow may be a meandering flow path or a flow path in which a baffle plate is arranged in a linear flow path. For example, a meandering flow path 51 may be formed by alternately arranging baffle plates on the opposing inner surfaces of the linear flow path.

[0045] The flow channels 51 may be formed, for example, by metal additive manufacturing such as a metal 3D printer. After fabricating the metal body with the flow channels 51 formed by metal additive manufacturing, internal defects may be removed and mechanical strength improved by performing, for example, HIP (Hot Isostatic Pressing). Alternatively, the metal body with the flow channels 51 formed may be joined to the anode shell 11 side member of the vane divisions 12a and 12b by brazing or the like to manufacture the vane divisions 12a and 12b having the flow channels 51. When multiple anode divisions 10a and 10b are joined, the method of joining so that the flow channels 51 of the two vane divisions 12a and 12b to be joined are connected may be the same as, for example, the method of joining so that the flow passages 14 of the two vane divisions 12a and 12b to be joined are connected.

[0046] If the amount of heat exchanged with the liquid refrigerant flowing through the channel 51 is large, some of the refrigerant may vaporize. However, even if some of the refrigerant vaporizes, turbulence is generated in the channel 51, allowing the liquid refrigerant to remain in contact with the inner surface of the channel 51, thus maintaining the cooling capacity. If there is a possibility of some of the refrigerant vaporizing downstream of the channel 51, the channel 51 may be divided into multiple sections, and liquid refrigerant may be supplied to each of the divided sections.

[0047] (Third Embodiment) The magnetron according to the present invention will now be described using a third embodiment. The magnetron according to this embodiment is the same as the first embodiment except that the cooling mechanism of the vane 12 is a porous metal body through which liquid passes, and cooling is performed by utilizing the latent heat of vaporization of the liquid passing through the porous body, so redundant explanations will be omitted.

[0048] FIG. 7 is a longitudinal sectional view showing the internal structure of the vane 12. A porous body 61 of metal may be disposed near the cathode 20 inside the vane 12 or near the central axis of the anode shell 11. The porous body 61 may be divided, for example, into a porous divided body 61a on the vane divided body 12a side and a porous divided body 61b on the vane divided body 12b side. When joining the vane divided bodies 12a and 12b, the porous divided bodies 61a and 61b may simply have their joining surfaces in contact. Even in this case, liquid and vapor can flow between the porous divided bodies 61a and 61b through the joining surface. The porous body 61 may be a porous body of a metal such as copper, a copper alloy, tungsten, or the like. Porous bodies of metals are already known, and a detailed description thereof will be omitted.

[0049] Liquid may be supplied to the porous body 61 through the flow path 63. This liquid may be, for example, water. The liquid supplied to the porous body 61 through the flow path 63 may evaporate when passing through the porous body 61 from the bottom to the top in the figure, and the vane 12 may be cooled by the latent heat of evaporation. Thus, the porous body 61 may function as a heat exchanger that cools the vane 12 by the latent heat of evaporation of the liquid. The liquid and vapor that have passed through the porous body 61 may be discharged through the flow path 64. Further, an auxiliary flow path 65 is provided in the vane 12, and liquid may also be supplied to the auxiliary flow path 65 as indicated by the dashed arrow. This liquid may be, for example, the same as the liquid supplied to the porous body 61 through the flow path 63. Liquid may also be supplied to the porous body 61 from the auxiliary flow path 65. For example, the surface of the porous body 61 on the anode shell 11 side is in contact with the auxiliary flow path 65, and liquid may be supplied to the porous body 61 from the auxiliary flow path 65 through that surface. The liquid supplied to the porous body 61 by the flow path 63 and the auxiliary flow path 65 may be pressurized by, for example, a pump or the like.

[0050] As shown in Figure 7, a flow path 62 through which liquid can flow may be present on the cathode 20 side of the porous body 61. The flow path 62 may be narrower than the other flow paths 63, etc. For example, the flow path 62 may have a gap of about 1 mm. Liquid may be supplied to this flow path 62, for example, from the flow path 63, or liquid may be supplied from the porous body 61 by capillary action. Liquid passing through the flow path 62 from bottom to top in the figure will also evaporate, and the latent heat of vaporization may cool the cathode 20 side of the vane 12. The vapor generated in the flow path 62 may be discharged from the vane 12 via the porous body 61 and flow paths 64 and 65. The liquid and vapor discharged from flow paths 64 and 65 may, for example, be cooled and supplied again to flow paths 63 and 65, or they may be discarded. In the latter case, new liquid may be supplied to flow paths 63 and 65.

[0051] Furthermore, if it is sufficient to supply liquid to the porous body 61 via the flow path 63, an auxiliary flow path 65 does not need to be provided inside the vane 12. In this case, the surface of the porous body 61 facing the anode shell 11 may be sealed to prevent liquid and vapor from leaking from the porous body 61.

[0052] Thus, because the cooling mechanism of the vane 12 is a porous body 61, the vane 12 can be cooled using the latent heat of vaporization of the liquid passing through the porous body 61 and the flow path 62 on the cathode 20 side of the porous body 61, thereby achieving highly efficient cooling.

[0053] Furthermore, the embodiments described above are illustrative examples for specifically carrying out the present invention and do not limit the technical scope of the present invention. The technical scope of the present invention is indicated by the claims rather than by the description of the embodiments, and modifications within the literal scope and equivalent meaning of the claims are intended.

[0054] 1 Magnetron 10 Anodes 10a, 10b Anode split 11 Anode shell 12 Vane 13 Strap 14 Flow channel 20 Cathode 31, 32 Pole piece 51 Flow channel 61 Porous material

Claims

1. A magnetron comprising: an anode having a cylindrical anode shell and a plurality of vanes radially arranged on the inner circumferential wall of the anode shell; a cathode provided at the center of the anode along the central axis of the anode shell; and a pair of pole pieces provided opposite each other at both ends of the anode shell, wherein the anode has a first and a second anode segment, and the plurality of vane segments of the first anode segment and the plurality of vane segments of the second anode segment are joined together.

2. The magnetron according to claim 1, wherein the anode has a third anode segment.

3. A magnetron according to claim 1 or 2, wherein the plurality of anode divisions of the anode are obtained by dividing the anode in a plane perpendicular to the central axis of the anode shell.

4. A magnetron according to any one of claims 1 to 3, wherein at least a portion of the plurality of vanes each has a cooling mechanism provided inside.

5. The magnetron according to claim 4, wherein the cooling mechanism cools the vicinity of the central axis of the vane on which the cooling mechanism is provided.

6. The magnetron according to claim 4 or 5, wherein the cooling mechanism is a flow passage through which a liquid coolant flows.

7. A magnetron according to claim 4 or 5, wherein the cooling mechanism is a porous metal body through which a liquid passes, and cooling is performed by utilizing the latent heat of vaporization of the liquid passing through the porous body.

8. A magnetron according to any one of claims 1 to 7, wherein the anode further comprises an annular strap that electrically connects the plurality of vanes every other vane.

9. A magnetron according to any one of claims 1 to 8, wherein the cathode is arranged coaxially with the anode.

10. An anode for a magnetron, comprising a cylindrical anode shell and a plurality of vanes arranged radially on the inner circumferential wall of the anode shell, wherein the anode has first and second anode divisions, and the plurality of vane divisions of the first anode division and the plurality of vane divisions of the second anode division are joined together.

11. A method for manufacturing an anode of a magnetron, comprising the steps of: manufacturing first and second anode divisions, each of which an anode having a cylindrical anode shell and a plurality of vanes radially arranged on the inner circumferential wall of the anode shell is divided; and manufacturing the anode by joining a plurality of vane divisions having a first anode division and a plurality of vane divisions having a second anode division.

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