Magnetron, anode and cathode therefor

Abstract

It provides a magnetron with a higher output. [Solution] The magnetron 1 comprises an anode 10 having a cylindrical anode shell 11 and a plurality of vanes 12 arranged radially on the inner circumferential wall of the anode shell 11, a cathode 20 provided at the center of the anode 10 along the central axis of the anode shell 11, and a pair of pole pieces 31 and 32 provided opposite each other at both ends of the anode shell 11, and the anode 10 has a plurality of anode divisions 10a and 10b.

Description

Technical Field

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

Background Art

[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 toward 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.

Summary of the Invention

Problems to be Solved by the Invention

[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 an oscillator with a higher output is desired.

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

Means for Solving the Problems

[0005] In order to achieve the above object, a magnetron according to one aspect of the present invention includes an anode having a cylindrical anode shell and a plurality of vanes radially provided on an inner peripheral wall of the anode shell, a cathode provided at a central portion of the anode along a central axis of the anode shell, and a pair of pole pieces provided on both end sides of the anode shell so as to face each other, wherein the anode has a plurality of anode divided bodies.

[0006] Furthermore, in a magnetron according to one aspect of the present invention, the anode may be formed by joining together a plurality of anode divisions.

[0007] Furthermore, in a magnetron according to one aspect of the present invention, the multiple anode divisions may be those in which the anode is divided by a plane perpendicular to the central axis of the anode shell.

[0008] Furthermore, in a magnetron according to one aspect of the present invention, each of the vanes may have an internal flow passage through which a liquid refrigerant flows.

[0009] 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 every other vane.

[0010] Furthermore, in a magnetron according to one aspect of the present invention, the cathode may be arranged coaxially with the anode.

[0011] 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 plurality of anode segments.

[0012] Furthermore, a method for manufacturing a magnetron anode according to one aspect of the present invention includes the steps of manufacturing a plurality of 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 the plurality of anode divisions to manufacture an anode. [Effects of the Invention]

[0013] According to one aspect of the present invention, the anode can be made larger, and as a result, the output can be increased. [Brief explanation of the drawing]

[0014] [Figure 1]Cross-sectional perspective view showing the configuration of a magnetron according to an embodiment of the present invention. [Figure 2] Perspective view showing multiple anode divisions according to the same embodiment. [Figure 3] This figure shows the refrigerant flow path provided within the vane according to the same embodiment. [Figure 4] Perspective view showing the cathode according to the same embodiment. [Modes for carrying out the invention]

[0015] The magnetron according to the present invention will be described below using embodiments. 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. This embodiment describes a magnetron that has a directly heated cathode and generates a continuous wave, which is used in microwave heating devices and the like.

[0016] Figure 1 is a cross-sectional perspective view of the magnetron 1 according to this embodiment; Figure 2 is a perspective view showing multiple anode divisions 10a and 10b obtained by dividing the anode 10; Figure 3 is a diagram showing the flow passage 14 for the liquid coolant 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.

[0017] 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 referred to as the axial direction, the circumferential direction of the anode shell 11 is sometimes simply referred to as the circumferential direction, and the radial direction of the anode shell 11 is sometimes simply referred to as the radial direction.

[0018] 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.

[0019] Multiple vanes 12 arranged radially on the inner circumferential wall of the anode shell 11 may 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 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 so that a resonant cavity is formed according 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 vanes 12 may, as an example, be about 1 / 4 the wavelength of the generated microwave.

[0020] 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 positioned, for example, concentrically with the anode shell 11. The strap 13 may be connected, for example, to the top of the vanes 12, to the bottom of the vanes 12, or to the joints 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 the 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, respectively, 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.

[0021] 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 heat up. 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 inside of the vane 12 near the cathode 20, 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. 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 may further include, 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.

[0022] As shown in FIG. 2, the anode 10 according to the present embodiment may be formed by joining a plurality of anode segments 10a and 10b obtained by dividing the anode 10. That is, the anode 10 may have a plurality of anode segments 10a and 10b. In the present embodiment, the case where the number of divisions of the anode 10 is two will be mainly described, but the number of divisions may be three or more. From the viewpoint of facilitating the manufacture of the anode 10, it is preferable that the number of divisions is small. Further, in the present embodiment, the case where the plurality of anode segments 10a and 10b are formed by dividing the anode 10 by a plane perpendicular to the central axis of the anode shell 11 will be mainly described, but the plurality of anode segments may be formed by dividing the anode 10 at other positions.

[0023] By configuring the anode 10 from a plurality of anode segments 10a and 10b in this way, it becomes easier to increase the size of the anode 10. For example, although there is a limit to the size of the anode 10 that can be manufactured by machining or the like, by manufacturing the plurality of anode segments 10a and 10b respectively and then joining them, an anode 10 of a size that cannot be manufactured integrally can be manufactured. By using a larger anode 10, the output of the magnetron 1 can be increased. 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 temperature rise of the anode 10 can be easily suppressed. Further, when increasing the output of the magnetron 1, it is also conceivable to reduce the frequency of the microwave, but in order to reduce the frequency, it is necessary to use a larger anode 10.

[0024] The cathode 20 is provided along the central axis of the anode shell 11 at the center of the anode shell 11. It is preferable that the cathode 20 is arranged such that the longitudinal direction of the cathode 20 is along the central axis of the anode shell 11. Thus, the cathode 20 may be arranged on the same axis as the anode 10. In order to generate high-power and continuous-wave microwaves, usually, a directly heated cathode 20 is used. As an example, the directly heated cathode 20 may have a filament 21, end caps 22, 23, and a cathode lead 24, as shown in FIG. 4. Since the directly heated cathode 20 can use a filament 21 made of a metal with a high melting point and high thermal conductivity, it is possible to reduce the influence of backheating caused by electron back bombardment, and it is suitable for generating high-power and continuous-wave microwaves. The diameter of the cylindrical gap near the central axis of the anode shell 11 in which the cathode 20 is accommodated may be, for example, about 1 / 2 of the radial length of the vane 12. If the diameter of this gap is large, the applied voltage will be high, which is not preferable. As described above, usually, a directly heated cathode 20 is used, but it is also conceivable to use an indirectly heated cathode 20. As an example, a dispenser-type hot cathode impregnated with barium oxide or the like in porous tungsten has some difficult-to-handle aspects such as the runaway of electron emission due to back bombardment and the low responsiveness of temperature control peculiar to the indirectly heated type, but it can be made to have a relatively low temperature and a large current, and the current density can be increased to improve the output. Therefore, in some cases, it may be adopted as the cathode 20.

[0025] The filament 21 may be, for example, a metal wire spirally wound 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, respectively. Also, at the position of 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. Also, at the position of 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.

[0026] 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 side of pole piece 31 and the lower side 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 electrons emitted from the filament 21 to undergo swirling and orbital motion, 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.

[0027] 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.

[0028] 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.

[0029] 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 segments 10a and 10b, and a step of joining the plurality of anode segments 10a and 10b to manufacture the anode 10.

[0030] 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.

[0031] 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 as a single unit by, for example, machining or wire cutting. The same applies to the anode segment 10b.

[0032] 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. The same applies when the anode 10 is divided into three or more anode segments.

[0033] 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 and 11b and the vane segments 12a and 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 and 12b, and also to increase the contact area between the refrigerant and the vane segments 12a and 12b. Although Figure 3 shows the case where the flow passage 14 is formed across the vane segments 12a and 12b, the flow passage 14 may be formed so as not to cross the vane segments 12a and 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. This eliminates the need for additional steps to prevent refrigerant leakage at the joint when joining the anode segments 10a and 10b.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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. [Explanation of symbols]

[0039] 1 Magnetron 10 anodes 10a, 10b Anode splitter 11 Anode Shells 12 Bane 13 straps 14 Distribution path 20 Cathode 31, 32 pole pieces

Claims

1. An anode having a cylindrical anode shell and a plurality of vanes arranged radially on the inner circumferential wall of the anode shell, A cathode is provided at the center of the anode, along the central axis of the anode shell, A pair of pole pieces are provided opposite each other on both ends of the anode shell. A magnetron equipped with, The anode has a plurality of anode dividers.

2. A magnetron according to claim 1, The anode is formed by joining together the multiple anode divisions.

3. A magnetron according to claim 1, The anode further comprises a ring-shaped strap that electrically connects the plurality of vanes alternately.

4. A magnetron according to claim 1, The cathode is located on the same axis as the anode.

5. The anode of a magnetron, A cylindrical anode shell, Multiple vanes are provided radially on the inner circumferential wall of the anode shell and It has, The anode has a plurality of anode dividers.

6. A method for manufacturing the anode of a magnetron, A process for manufacturing a plurality of anode divisions, each having a cylindrical anode shell and a plurality of vanes arranged radially on the inner circumferential wall of the anode shell, A step of manufacturing the anode by joining together the plurality of anode divisions. Includes.

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