JP6663290B2 - Coaxial magnetron - Google Patents

Description

  The present invention relates to a structure of a magnetron that oscillates microwaves, and more particularly, to a structure of a coaxial magnetron having an external cavity outside an anode resonance cavity.

  2. Description of the Related Art Conventionally, magnetrons have been used for various applications and devices because they can efficiently oscillate high-power microwaves with a simple structure. Among them, it is necessary to tune the oscillation frequency precisely.For example, in order to avoid interference, a radar that changes the frequency precisely to detect and a narrow-band resonator with high Q characteristics are used precisely. Linac and the like apply a tuned microwave and apply an accelerating electric field to electrons. Magnetrons used in such applications and devices need to have a mechanism capable of mechanically varying the frequency, and a coaxial magnetron has been put to practical use as one of the mechanisms.

  FIG. 7 shows an example of a coaxial magnetron capable of obtaining a large output. In this example, vanes 2 radially arranged as an anode (anode) around a cathode (cathode) 1 arranged at the center are shown. And an anode cylinder 3 to which the vane 2 is bonded is provided, and the anode resonance cavity 50 is formed by the vane 2 and the anode cylinder 3. A slot 4 is provided in the anode cylinder 3, and the outer cylinder 6 is arranged around the anode cylinder 3, thereby forming an external cavity 60 coaxial with the anode resonance cavity 50.

  Further, pole pieces 7 a and 7 b are arranged above and below the cathode 1, a tuning piston 8 is mounted in the outer cavity 60, and a cooling liquid is supplied to the input side structure 10 joined to the input section 9. A cooling passage 11 is provided. The pole piece 7b is attached as a part of the upper structure 12, and the upper structure 12 is joined to the outer cylinder 6 to assemble a magnetron. 10, but not joined to the upper structure 12, it is in a cantilevered state.

  According to such a configuration, the resonance frequency and the oscillation frequency of the magnetron can be adjusted by externally moving the position of the tuning piston 8 and changing the reactance of the external cavity 60. As a result, it becomes possible to precisely vary the oscillation frequency of the magnetron and tune it to the frequency required by the application, device, or the like. According to this magnetron, a high-output microwave can be oscillated, and a design can be obtained to obtain a high output with a peak output of several MW and an average output of several kW.

  By the way, in such a magnetron having a very high output, although high oscillation efficiency can be obtained, a cooling design for heat generated by anode loss is important. In addition, since the above-mentioned vane 2 is densely manufactured from a thin metal, when overheating occurs, the vane 2 may be deformed and affect oscillation characteristics, or may be melted and deformed to impair the function as a magnetron. Was. For this reason, in a high-power magnetron, a design has been proposed in which a liquid for water cooling is caused to flow close to the anode structure to cool it. Even in the case of FIG. 7, a cooling passage 11 is provided near the anode cylinder 3. , Cooling the magnetron.

  Patent Literature 1 (Japanese Patent Application Laid-Open No. 2004-134160) discloses a cooling liquid that is not a coaxial magnetron but uses a cooling liquid. In this example, the outer wall surface of an anode cylinder to which vanes are joined is described. A cooling jacket is provided along the circumferential direction, and a cooling liquid flows through the cooling jacket. According to such a structure, heat due to anode loss generated around the vane can be efficiently exchanged with the liquid, and the temperature of the anode including the vane can be reduced.

JP 2004-134160 A JP-A-10-269953 JP-A-10-302655 JP 2014-132536 A

  However, as can be seen from the structures of Patent Document 2 (Japanese Patent Application Laid-Open No. 10-302655) and Patent Document 3 (Japanese Patent Application Laid-Open No. 10-302655), in the coaxial magnetron shown in FIG. Since the external cavity 60 is provided on the outside and the tuning piston 8 is moved up and down, it is impossible to adopt the structure of the cooling jacket as in Patent Document 1, and the magnetron can be cooled efficiently. There is a problem that can not be.

  On the other hand, in the coaxial magnetron, as described above, there is a problem that the anode cylinder 3 is in a cantilever state joined only to the input-side structure 10, and the heat cannot be radiated from the anode cylinder 3 to the outside. Generally, in a magnetron, the length of the anode cylinder 3 which causes an error is set to be short as shown in FIG. 7 in order to strictly observe the dimension of the gap (gap) Lb between the opposing pole pieces 7a and 7b. Only the upper structure 12 is designed to be free and the other end on the upper structure 12 side is free. In assembling, the upper structure 12 is joined to the outer cylinder 6 while the distance La between the upper structure 12 and the input-side structure 10 is exactly equal to a specified value, whereby the distance between the pole pieces 7a and 7b is increased. The interval Lb is adjusted to a predetermined size. For this reason, the anode cylinder 3 becomes cantilevered on the input side structure 10, and the upper structure 12 side becomes free. As a result, heat radiation from the anode cylinder 3 is not promoted, and the cooling efficiency cannot be increased. Was.

  In the figures shown in Patent Document 2 and the like, the anode cylinder is in contact with the upper and lower pole pieces. However, when the gap between the pole pieces is precisely set, as described above, the anode cylinder is in contact with the other pole pieces. Preferably, the ends are free.

  As described above with reference to FIG. 7, it has been proposed to provide a cooling passage 11 at the base of the anode cylinder 3 on the side of the input side structure 10 and cool by flowing a cooling liquid. There is.

  On the other hand, a structure disclosed in Patent Document 4 (Japanese Patent Application Laid-Open No. 2014-132536) has also been proposed. In this example, the upper and lower ends of the anode cylinder 3 are joined (brazed) and generated around the tip of the vane 2. By diffusing the heat through both ends of the anode cylinder 3, the temperature rise of the vane 2 can be suppressed, and the cooling can be performed efficiently.

  However, in this example, by joining the upper and lower sides of the anode cylinder 3, it is difficult to confirm the state after joining in the manufacturing process, and there is a problem that simplification of the assembling process cannot be promoted. That is, each member needs to be accurately positioned at the interval Lb between the pole pieces 7a and 7b, including the positioning (centering) of the cathode 1 at the center of the anode cylinder 3, and the position of each member. Although the assembly is performed while checking the dimensions between the members, the structure of joining the upper and lower parts of the anode cylinder 3 makes it difficult or difficult to check the state of each member.

  In addition, when the magnetron is not cooled well when used, the anode cylinder 3 and the like expand and deform due to overheating of the anode part and its surroundings, the gap Lb between the pole pieces 7a and 7b changes, and the oscillation characteristics Has the disadvantage of affecting

  The present invention has been made in view of the above problems, and its object is to promote heat radiation from the anode portion, improve the overall cooling efficiency, increase the maximum oscillation output, and improve the anode cylinder and the like. An object of the present invention is to provide a coaxial magnetron capable of eliminating the influence of expansion and deformation.

In order to achieve the above object, a coaxial magnetron according to the first aspect of the present invention has an anode vane arranged so as to surround a cathode, and an anode cylinder having the anode vane fixed inside and an anode cylinder outside the anode cylinder. In a coaxial magnetron having an external cavity disposed therein, one end of the anode cylinder is fixed to one side of the main body, and the other end is slidably contacted and arranged on the other side of the main body. I do.
According to a second aspect of the present invention, a step for arranging the anode cylinder is provided on the other side of the main body, and one of the inner surface and the outer surface of the anode cylinder slides on a vertical surface (vertical surface) of the step. The contact is made in a movable state.
The invention according to claim 3 is characterized in that a surface of the other end of the anode cylinder that is slidable, which is not in contact with the step on the other side of the main body, is shaved.
The invention according to claim 4 is characterized in that a groove for arranging the anode cylinder is provided on the other side of the main body, and the inner surface and the outer surface of the anode cylinder are brought into contact with both sides of the groove.
The invention according to claim 5 is characterized in that both contact surfaces where the other end of the anode cylinder and the other side of the main body contact each other are formed into an irregular shape (including a wavy shape) which can be fitted and slidable with each other. And
The invention according to claim 6 is characterized in that a corner of the tip of the contact surface at the other end of the anode cylinder that contacts the other side of the main body is chamfered.

  According to the above configuration, for example, one of the cathode and the pole piece (other than the outer cylinder) is fixed to the input-side structure (lid-like structure) on one side of the main body. One end of the anode cylinder is fixed, and an upper structure (lid-shaped structure) on the other side of the main body is attached to the input side structure, so that one end of the anode cylinder is slidable. It is placed in contact with the body.

According to the coaxial magnetron of the present invention, even when the external cavity for tuning is provided outside the anode resonance cavity, the cooling efficiency is improved by promoting heat radiation from the upper and lower ends of the anode cylinder. As a result, the maximum oscillation output can be increased.
Also, since the other end of the anode cylinder is not joined by brazing or the like, the assembly process of the magnetron having a structure that ensures good heat radiation performance is simplified, and the mounting state of each member after assembly can be checked well. Further, there is an effect that the anode cylinder or the like expands and deforms and does not change the interval between the pole pieces and does not affect the oscillation characteristics and the like.
Furthermore, if the surface that does not contact the step on the other side of the main body is shaved at the other slidable end of the anode cylinder, the stress caused by thermal expansion is absorbed in the thinned portion, and the anode cylinder and the other side of the main body are cut off. There is an advantage that the slidability can be ensured even when the gap between both contact surfaces becomes small.

1 is a cross-sectional view illustrating a configuration of a coaxial magnetron according to a first embodiment of the present invention. FIG. 4 is a cross-sectional view illustrating a configuration of a coaxial magnetron according to a second embodiment. FIG. 9 is a cross-sectional view illustrating a configuration of a coaxial magnetron according to a third embodiment. It is a sectional view showing the composition of the coaxial magnetron of a 4th example. It is a figure which shows the example of two structures which provided the unevenness | corrugation in the contact surface of an anode cylinder and an upper structure in an Example. It is an expanded sectional view which shows the contact part of an anode cylinder and an upper structure in an Example. It is a sectional view showing the composition of the conventional coaxial magnetron.

  FIG. 1 shows the configuration (excluding the output and the magnetic circuit) of the coaxial magnetron of the first embodiment. In this magnetron, a cathode (cathode) 1 is arranged at the center, and an anode ( By providing a radial vane (anode vane) 2 and an anode cylinder 14 to which the vane 2 is joined as an anode, an anode resonance cavity 50 is formed. The anode cylinder 14 is provided with a slot 4 for high-frequency coupling. An external cavity 60 coaxial with the anode resonance cavity 50 is formed between the anode cylinder 14 and the outer cylinder (body) 6. You. The input-side structure (one of the main body) 10 and the upper structure (the other of the main body) 16 that are joined to the input unit 9 are arranged above and below the anode resonance cavity 50 and the external cavity 60, respectively. Pole pieces 7 a and 7 b are arranged above and below the cathode 1, a tuning piston 8 is mounted in the external cavity 60, and a cooling passage 11 is provided in the input-side structure 10.

  In the embodiment, as shown in FIG. 1, the upper end of the anode cylinder 14 is formed to be long, and the anode cylinder 14 is formed on the inner surface of the upper structure 16 (annular member outside the pole piece 7 b). An annular concave portion 17 for arranging the upper end portion is formed, and the concave portion 17 is arranged such that the inner surface of the anode cylinder 14 is in contact with the inner surface of the concave portion 17 (the inner step vertical surface). The concave portion 17 is formed at a depth having a gap G between the upper end surface of the anode cylinder 14 and the bottom surface of the concave portion 17 when the anode cylinder 14 is arranged and assembled.

  That is, in the coaxial magnetron, since the external cavity 60 is surrounded by the input-side structure 10 and the upper structure 16, if the distance (distance) La between the input-side structure 10 and the upper structure 16 changes, the external cavity 60 changes. If the resonance frequency of the cavity 60 shifts and the distance Lb between the two pole pieces 7a and 7b changes, the withstand voltage of the cathode 1 decreases and the magnetic flux density distribution between the pole pieces 7a and 7b changes. Therefore, it is important to accurately set the intervals La and Lb.

  In the assembling of the embodiment, for example, the lower end of the anode cylinder 14 is fixed to the input structure 10 and the outer cylinder 6 and the like are also joined together to assemble, and the assembly is covered with the upper structure 16 as a lid. At this time, by moving the upper end side of the anode cylinder 14 in the cylindrical axis direction inside the concave portion 17, the inner surface of the anode cylinder 14 comes into contact with the inner surface of the upper structure concave portion 17 (the inner step vertical surface). Placed in a state. At this time, the upper end of the anode cylinder 14 and the bottom surface of the concave portion 17 do not come into contact with each other due to the gap G. Can be precisely maintained at a specified value.

Further, in the magnetron after assembly, the inner surface of the anode cylinder 14 and the inner surface of the upper structure recess 17 come into contact with each other, so that heat from the anode cylinder 14 is transmitted to the upper structure 16 and the periphery of the vane 2 Can efficiently dissipate the heat generated in the above.
On the other hand, during the heat transfer, the temperature of the anode cylinder 14 also rises, so that thermal expansion occurs. At this time, the upper end portion of the anode cylinder 14 slides while contacting the upper structure concave portion 17, so that heat dissipation is performed. It is possible to release the stress due to the thermal expansion generated in the anode cylinder 14 while securing the distance, without changing the distance Lb between the pole pieces 7a and 7b.

  The first embodiment has a configuration in which the inner surface of the anode cylinder 14 contacts (inscribes) the inner surface (vertical surface perpendicular to the step) of the concave portion 17, and when the anode cylinder 14 thermally expands, the gap between both contact surfaces is increased. Therefore, a design that does not increase the gap between both contact surfaces so that heat transfer cannot be performed is required.

  FIG. 2 shows the configuration of the coaxial magnetron of the second embodiment. In this magnetron, an annular step 19 is formed on the inner surface of the upper structure 16 (annular member outside the pole piece 7b). The anode cylinder 14 is arranged so that the outer surface of the anode cylinder 14 contacts the vertical surface of the step portion 19. When the anode cylinder 14 is disposed, the step 19 is formed at a depth having a gap G between the upper end surface of the anode cylinder 14 and the bottom surface of the step 19.

In the magnetron of the second embodiment as well, as in the first embodiment, the anode cylinder 14 (outer surface) and the vertical surface of the upper structure step 19 come into contact with each other. Is transmitted to the upper structure 16, and the heat generated around the vane 2 can be efficiently radiated.
In addition, the temperature of the anode cylinder 14 also rises during the heat transfer, so that thermal expansion occurs. However, in this case, the upper end of the anode cylinder 14 slides while contacting the step 19 of the upper structure, so that heat is released. The stress caused by the thermal expansion generated in the anode cylinder 14 can be released while securing the distance, and the distance Lb between the pole pieces 7a and 7b does not change.

  In the second embodiment, the outer surface of the anode cylinder 14 is configured to contact (circumscribe) the vertical surface of the step portion 19 of the upper structure. When the anode cylinder 14 thermally expands, the gap between both contact surfaces is closed. It is necessary to design in consideration of this.

FIG. 3 shows the configuration of the third embodiment, and FIG. 4 shows the configuration of the fourth embodiment. In these embodiments, the surface other than the contact surface of the upper end of the anode cylinder 14 is cut off. is there.
In the third embodiment shown in FIG. 3, the outer surface 14a at the upper end of the anode cylinder 14 is formed in a tapered shape in which the tip end side becomes thinner in the same configuration as the first embodiment shown in FIG.
In the fourth embodiment of FIG. 4, in the same configuration as the second embodiment of FIG. 2, the inner surface 14b of the upper end portion of the anode cylinder 14 is formed to have a shape whose inner diameter increases toward the tip and the tip side becomes thinner.

  According to the third and fourth embodiments, the shaved upper end of the anode cylinder 14 absorbs the stress caused by thermal expansion (the anode cylinder is easily bent), and the anode cylinder 14 and the upper structure recess 17 are bent. Even if the gap between the two contact surfaces or the gap between both the contact surfaces of the anode cylinder 14 and the upper structure step 19 is small, there is an advantage that the slidability can be ensured.

FIG. 5 shows an example of providing irregularities on the contact surface between the anode cylinder and the upper structure. FIGS. 5A and 5B show the outer surface of the anode cylinder 14 (14-A) and the upper structure. Sinusoidal irregularities are formed on the inner surface of the body 16 (16-A) so that the respective surfaces come into contact and fit.
In FIG. 5C, rectangular corrugations are formed on the outer surface of the anode cylinder 14 (14-B) and the inner surface of the upper structure 16 (16-B) so that the respective surfaces come into contact with each other and fit. Things.

  With such an uneven shape, the contact area between the anode cylinder 14 and the upper structure 16 is increased, and the heat radiation effect can be enhanced. Further, in the configuration of FIG. 5C, since the side surface of the rectangular waveform coincides with the radial line d centered on the center O of the anode cylinder 14, the direction of thermal expansion of the anode cylinder 14 also coincides, and Even if the thermal expansion is such that a gap between the outer surface of the upper structure 16 and the inner surface of the upper structure 16 is opened, good heat transfer is ensured by maintaining the contact between the side surfaces of the rectangular waveform.

  FIG. 6 is an enlarged view of a contact portion between the anode cylinder 14 and the upper structure 16 according to the first embodiment. As shown in FIG. It may be chamfered by processing into an R surface or a C surface (or a tapered shape). According to this, the clearance at the entrance when the upper end portion of the anode cylinder 14 and the upper structure 16 are aligned is increased, and assembly (insertion / connection) is facilitated.

  In the case of the configuration of the above embodiment, it is easier to confirm the state in the manufacturing process as compared with the case where the upper and lower ends of the anode cylinder are joined by brazing as in Patent Document 4 (Japanese Patent Application Laid-Open No. 2014-132536). The assembly process is simplified. For example, the cathode 1 and the anode cylinder 14 are connected to the input-side structure 10, the position of the cathode 1 with respect to the anode cylinder 14 is checked, and then the upper structure 16 is connected so as to cover it as a lid, thereby facilitating assembly. Can be done.

  Further, according to the coaxial magnetron described above, the cooling efficiency is improved, and the deformation and melting due to overheating of the anode portion mainly of the vane 2 at the time of high output can be prevented. You can get the output. For applications and devices that use microwaves, such as radar and Linac, a large effect is obtained by high output, and it is not necessary to design a large magnetron for high cooling and high output.

  Furthermore, in the case of a high-frequency coaxial magnetron, the size of the cavity is reduced in accordance with the wavelength, but in this case, the anode component is downsized, the heat capacity is reduced, and the thermal resistance is increased. Is more disadvantageous. However, according to the present invention, in which an efficient cooling effect can be obtained, there is an advantage that a high-output coaxial magnetron can be designed with a high output.

In each of the above embodiments, the anode cylinder 14 is slidable on the upper structure 16 side. However, a step (a concave portion or the like) for disposing the anode cylinder is provided on the input side structure 10 side, and the anode cylinder 14 is provided on the input side structure 10 side. The anode cylinder 14 may be slidable.
In addition, the recess 17 and the step 19 are formed in the upper structure 16 for disposing the anode cylinder. Instead, grooves for disposing the anode cylinder are provided, and the inner surface and the outer surface of the anode cylinder 14 are formed on both sides of the groove. You may make both surfaces contact.

  It can be applied to applications and devices utilizing microwaves, such as radar and Linac, and can be applied to high frequency, high output coaxial magnetrons.

1 ... cathode (cathode), 2 ... vane (anode vane),
3, 14, 14-A, 14-B ... Anode (anode) cylinder,
4 ... slot, 6 ... outer cylinder (body),
7a, 7b: pole piece, 8: tuning piston,
10 ... input side structure (lid-like structure),
12, 16, 16-A, 16-B: Upper structure (lid-like structure),
14a: outer surface of the upper end of the anode cylinder, 14b: inner surface of the upper end of the anode cylinder,
14c: Corner of upper end of anode cylinder,
17: concave portion of upper structure, 19: step portion of upper structure,
50: Anode resonance cavity, 60: External cavity.

Claims (6)

In a coaxial magnetron having an anode vane disposed so as to surround a cathode, and an anode cylinder having the anode vane fixed inside, and an external cavity disposed outside the anode cylinder,
A coaxial magnetron wherein one end of the anode cylinder is fixed to one side of the main body, and the other end is slidably contacted and arranged on the other side of the main body.   A step for arranging the anode cylinder is provided on the other side of the main body, and one of the inner surface and the outer surface of the anode cylinder is slidably contacted with a vertical surface of the step. The coaxial magnetron according to claim 1.   The coaxial magnetron according to claim 2, wherein a surface of the other end of the anode cylinder that is slidable, which is not in contact with a step on the other side of the main body, is shaved.   The coaxial magnetron according to claim 1, wherein a groove for disposing the anode cylinder is provided on the other side of the main body, and inner and outer surfaces of the anode cylinder are brought into contact with both sides of the groove. Described in the above anode cylinder to the other end and both of the contact surfaces the other side of the body is in contact, either one of claims 1 to 4, characterized in that it has an uneven shape which is slidable fitted to each other Coaxial magnetron. The coaxial magnetron according to any one of claims 1 to 5 , wherein a corner of a tip of a contact surface at the other end of the anode cylinder that contacts the other side of the main body is chamfered.

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