Air suction thin-wall part, preparation method, vacuum chamber assembly and vacuum regulation and control method

Abstract

The invention discloses an air suction thin-wall part and a preparation method thereof, a vacuum chamber assembly and a vacuum regulation and control method, the air suction thin-wall part is used for being detachably installed in a vacuum chamber of a cyclotron, and the air suction thin-wall part can be activated and adsorb air in a vacuum chamber body; the air suction thin-wall part is used for surrounding the position close to the inner side wall of the vacuum chamber body. The air suction thin-wall part is provided with a plurality of open holes, and the surface area of the inner wall of each open hole is at least two times larger than the area of the cross section of the corresponding open hole. The technical problems that in the prior art, due to the fact that a compact cyclotron is small in size and small in available space, it is difficult to maintain the long-time high-vacuum state in the vacuum chamber by installing a plurality of low-temperature cold plates or additionally arranging a plurality of vacuum pumps are solved. The auxiliary device assists an existing vacuum pump to jointly maintain a long-time high-vacuum state in the vacuum chamber, so that the requirement for the pumping speed of the vacuum pump is lowered, and the pumping speed of an existing common vacuum pump can meet the requirement.

Description

Technical Field

[0001] The invention relates to the field of cyclotron accelerators, and in particular to an air-intake thin-walled component and a preparation method thereof, a vacuum chamber component and a vacuum control method. Background Art

[0002] In a cyclotron, an electric field is used to accelerate the accelerated particles, and a magnetic field is used to deflect the accelerated particles along a circular orbit. The magnetic field is generated by two magnetic poles, and the direction of the magnetic field is usually perpendicular to the cross-section of the vacuum chamber. The charged particles are accelerated by the electric field and move in a circular motion under the action of the magnetic field. The motion plane of the particles is perpendicular to the direction of the magnetic field. When the particles reach the required energy, they are output from the side wall of the vacuum chamber through a deflection device. The output beam direction is usually horizontal and perpendicular to the direction of the magnetic field. Particles accelerated by a cyclotron can be used in cancer treatment, isotope production, medical diagnosis and other fields.

[0003] In order to control beam loss during particle acceleration, the vacuum degree during particle acceleration needs to be kept within a relatively high range (about 10 -4 ~10 -6 Pa), usually located in a vacuum chamber. However, the large gas load in the vacuum chamber means that a very high pumping speed is required to reach about 10 -5 Pa working vacuum degree. In order to maintain a high vacuum state in the vacuum chamber, for large cyclotron accelerators, conventional means include installing multiple low-temperature cold plates in the vacuum chamber to increase the pumping speed or adding multiple vacuum pumps for vacuuming.

[0004] Although these two technical means can maintain a high vacuum state in the vacuum chamber for a long time, they are difficult to apply when facing a compact cyclotron, because installing multiple cryogenic cold plates or adding multiple vacuum pumps requires a large amount of space inside or outside the vacuum chamber, and the compact cyclotron is small in size, and the volume and external dimensions of the vacuum chamber are not enough to install multiple cryogenic cold plates or add multiple vacuum pumps.

[0005] Compact cyclotrons are widely used in nuclear physics, atomic physics, solid-state physics, isotope production, PET diagnosis, proton therapy and other fields due to their small size and low cost. Therefore, there is an urgent need to improve compact cyclotrons in order to maintain a high vacuum state in the vacuum chamber for a long time under the premise that there is insufficient indoor or outdoor space in the vacuum chamber, so as to obtain a method or device that can maintain a high vacuum state in the vacuum chamber for a long time without occupying too much indoor or outdoor space in the vacuum chamber. Summary of the invention

[0006] The purpose of the present invention is to provide an air-absorbing thin-walled part and a preparation method, a vacuum chamber assembly and a vacuum control method, so as to solve the technical problem in the prior art that the compact cyclotron itself has a small size and thus a small available space, making it difficult to maintain a high vacuum state in the vacuum chamber for a long time by installing multiple low-temperature cold plates or adding multiple vacuum pumps.

[0007] In order to achieve the above-mentioned objectives and solve the corresponding technical problems, the present invention provides an air-intake thin-walled component structure, which can assist the vacuum pump to maintain a high vacuum state in the vacuum chamber for a long time, and can reduce the parameter requirements on the vacuum pump pumping speed. The built-in baking function is more conducive to obtaining a high vacuum degree in the vacuum chamber. The air-intake thin-walled component structure occupies a small space and does not require an additional vacuum pump or multiple low-temperature cold plates. The air-intake thin-walled component structure is in the vacuum chamber, and can also reduce the radioactivity generated by the activation of the main vacuum chamber wall due to beam loss.

[0008] In addition, the present invention also provides a vacuum control method for a cyclotron vacuum chamber equipped with the air-intake thin-walled member, which can effectively maintain the vacuum degree of the vacuum chamber for a long time without adding an additional vacuum pump, and can also reduce the operating frequency and energy consumption of the existing vacuum pump.

[0009] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0010] On the one hand, the present invention provides an air-intake thin-walled component for detachably installing in the vacuum chamber of a cyclotron, wherein the air-intake thin-walled component can be activated and adsorb the gas in the vacuum chamber body; the air-intake thin-walled component is used to surround a position close to the inner wall of the vacuum chamber body; and a hole is opened on the air-intake thin-walled component for beam extraction.

[0011] This solution aims to improve the technical problem in the prior art that it is difficult to maintain a high vacuum state in the vacuum chamber for a long time by installing multiple low-temperature cold plates or adding multiple vacuum pumps due to the small size and small available space of the compact cyclotron. By adding an air-inhaling thin-walled part in the vacuum chamber to assist the existing vacuum pump, the high vacuum state in the vacuum chamber can be maintained for a long time, thereby reducing the requirements for the vacuum pump's own pumping speed, so that the pumping speed of the existing commonly used vacuum pump can meet the requirements. At the same time, the presence of the through hole does not affect the movement of the gas itself.

[0012] The air-intake thin-walled member is installed around the inner wall of the vacuum chamber body, and can protect the inner wall of the vacuum chamber. Because when the vacuum chamber is working, the beam will be lost, and the lost beam will hit the inner wall of the vacuum chamber, thereby activating the inner wall of the vacuum chamber and generating radioactivity. At this time, the air-intake thin-walled member can help intercept part of the lost beam, thereby reducing the possibility of generating radioactivity due to the activation of the inner wall of the vacuum chamber by the beam loss.

[0013] Preferably, the air-intake thin-walled member comprises a tubular frame, the air-intake thin-walled member has a plurality of openings, the surface area of ​​the inner wall of each opening is greater than at least twice the cross-sectional area of ​​the corresponding opening; each opening is evenly arranged on the tubular frame, the inner and outer surfaces of the tubular frame and the inner wall surface of each opening are covered with a getter film, and the getter film can adsorb the gas in the vacuum chamber body. The plurality of openings increase the surface area of ​​the air-intake thin-walled member, thereby improving the air-intake efficiency of the air-intake thin-walled member; the use of the getter film structure can increase the getter area on the surface of the air-intake thin-walled member as much as possible, the surface of the air-intake thin-walled member contacts the gas molecules first, and the use of the surface film structure can enable the air-intake thin-walled member to quickly adsorb the gas molecules when working, and at the same time, the inner and outer surfaces and the inner wall surface of the opening are covered with a getter film, which can increase the adsorption amount of the gas and enhance the air-intake effect, so that the high vacuum state in the vacuum chamber can be maintained more easily.

[0014] Preferably, the getter film is a titanium-based film. The titanium-based film can provide uniform surface coverage, which helps to improve the getter efficiency. The titanium-based film has a lower infrared emissivity, which helps to reduce thermal radiation loss, promote uniform temperature distribution in the vacuum chamber, and improve the operating stability of the cyclotron.

[0015] Preferably, a resistance heater is provided on the periphery of the air intake thin-walled component, and the resistance heater is electrically connected to an external power supply. The resistance heater can generate heat when powered on and heat the air intake thin-walled component to an air intake activation temperature, and the air intake activation temperature is used to activate the air intake thin-walled component to make it inhale air. The resistance heater can generate heat when powered on, and transfer the temperature to the air intake thin-walled component so that the air intake thin-walled component is heated synchronously, and the heating temperature is gradually increased to the air intake activation temperature, thereby making the air intake thin-walled component start to work. If it is necessary to stop the air intake work of the air intake thin-walled component, it is only necessary to turn off the power of the resistance heater. In addition, the temperature of the resistance heater in the heating stage before it rises to the temperature that activates the air intake thin-walled component also has a baking effect on the vacuum chamber, which can reduce the probability of the gas in the vacuum chamber adhering to the inner wall of the vacuum chamber, so that the gas in the vacuum chamber can be drawn away as much as possible or adsorbed by the air intake thin-walled component.

[0016] Preferably, the air-intake thin-walled member is a tubular structure with a circular cross-section, and the resistance heater is an annular resistance heater, which surrounds the radially outer middle of the air-intake thin-walled member. Correspondingly, this solution is suitable for a vacuum chamber whose side wall is also a circular tubular structure, and can better adapt to the shape of the vacuum chamber side wall, and can help intercept part of the lost beam as much as possible, and reduce the possibility of radioactivity generated by activation of the inner wall of the vacuum chamber due to beam loss. Fixing the annular resistance heater to the radially outer middle of the tubular structure can make the resistance heater heat the air-intake thin-walled member more uniformly, and can make the getter film activated at the same time as much as possible to enter the air-intake state.

[0017] On the other hand, the present invention also provides a method for preparing an air-intake thin-walled member, which is used to prepare the air-intake thin-walled member as described above, comprising the following steps:

[0018] S1. Prepare two flat plate frames, and evenly open a plurality of openings on the flat plate frames;

[0019] S2, forging the two flat plate frames obtained in step S1 into semi-cylindrical structures respectively, and welding the two ends of the two semi-cylindrical structures respectively to form a tubular frame with a circular cross section;

[0020] S3, annealing the tubular frame obtained in step S2, and cleaning and drying it;

[0021] S4. Put the cleaned and dried tubular frame into a vacuum environment. When the vacuum environment reaches a preset vacuum degree, introduce an inert gas into the vacuum environment. Use a getter material as a raw material to evenly coat a getter film on the surface of the tubular frame. After coating, continue to heat at a constant temperature for a preset time to obtain the getter thin-walled component.

[0022] In actual application, the thickness of the air-intake thin-walled part is about 10 mm. Therefore, a flat frame is prepared first, and then a semi-cylindrical structure is forged. Finally, the two semi-cylindrical structures are welded to obtain an air-intake thin-walled part with a relatively precise preset shape. This preparation method can make the air-intake agent film evenly plated on the outer and inner surfaces of the tubular frame, including the inner wall surfaces of each opening, to ensure that the obtained air-intake thin-walled part can achieve good air-intake function on the basis of structural integrity.

[0023] On the other hand, the present invention also provides a vacuum chamber assembly for use in a cyclotron accelerator, including a vacuum chamber body, wherein the vacuum chamber body is installed with the above-mentioned air-intake thin-walled member; the vacuum chamber body is enclosed by a first magnet, a second magnet and a bushing structure, wherein the first magnet and the second magnet are respectively sealed and installed at the two ends of the bushing structure; the air-intake thin-walled member is installed around the position close to the inner wall of the bushing; the bushing has a beam outlet, and a through-hole is opened at a corresponding position on the air-intake thin-walled member, and the beam can pass through the through-hole and be led out from the beam outlet. This solution installs a small-volume air-intake thin-walled member in the vacuum chamber, utilizing the narrow space between the magnet in the vacuum chamber and the inner wall of the vacuum chamber, thereby improving the space utilization rate, while not occupying the space of other functional components in the vacuum chamber, nor occupying additional space outside the vacuum chamber, and no additional vacuum pump is required, thereby achieving the technical effect of maintaining a high vacuum state in the vacuum chamber for a long time.

[0024] Preferably, the first magnet and the second magnet have a plurality of first protrusions and a plurality of second protrusions on the opposite side thereof, respectively, and there is an acceleration space between the opposite sides of each of the first protrusions and each of the second protrusions; there is a first annular gap between the outer peripheral side of each of the first protrusions and the inner wall of the bushing, and there is a second annular gap between the outer peripheral side of each of the second protrusions and the inner wall of the bushing; a first annular slot is fixed on the first magnet in the first annular gap, and a second annular slot is fixed on the second magnet in the second annular gap, and the notches of the first annular slot and the second annular slot are opposite, and the first annular slot and the second annular slot are respectively used to plug the two ends of the air-intake thin-walled member, so that the acceleration space is located within the surrounding range of the air-intake thin-walled member. The air-intake thin-walled member is arranged between the first annular gap and the second annular gap, so that the air-intake thin-walled member can be as close to the inner wall of the bushing as possible, and the acceleration space is located within the surrounding range of the air-intake thin-walled member, which can ensure that the lost beam can be intercepted by the air-intake thin-walled member as much as possible, and can reduce the possibility of radioactivity generated by the activation of the inner wall of the vacuum chamber due to beam loss. In addition, the plug-in form makes the installation, removal and replacement of the air intake thin-walled parts very convenient. If the air intake performance of the air intake thin-walled parts is found to be reduced or disappeared, it can be directly taken out and replaced with the same part to work normally.

[0025] Preferably, a molecular pump and a first cryopump are installed on the first magnet, and correspondingly, the pump outlets of the molecular pump and the first cryopump are respectively connected to the interior of the vacuum chamber body; the pump outlet of the molecular pump is provided with a fourth valve, and the pump outlet of the first cryopump is provided with a first valve; the second magnet is provided with a second cryopump and a third cryopump, and correspondingly, the pump outlets of the second cryopump and the third cryopump are respectively connected to the interior of the vacuum chamber body; the pump outlet of the second cryopump is provided with a second valve; the pump outlet of the third cryopump is provided with a third valve. When in use, first use the molecular pump to quickly evacuate the vacuum, and when the vacuum degree reaches the vacuum degree of the getter, activate the air-intake thin-walled component to maintain the high vacuum degree of the main vacuum chamber, and at this time, use the air-intake thin-walled component and each cryopump to cooperate to maintain the vacuum state, and when the air-intake performance of the air-intake thin-walled component reaches the limit, it is only necessary to reduce the vacuum degree to the vacuum atmospheric pressure, open the vacuum chamber, and replace the new air-intake thin-walled component.

[0026] In another aspect, the present invention further provides a vacuum control method, using the vacuum chamber body assembly as described above, comprising the following steps:

[0027] A1. Open the fourth valve, the first valve, the second valve, and the third valve, and roughly evacuate the vacuum chamber;

[0028] A2. When the vacuum degree reaches the first preset vacuum degree, the molecular pump is started to further evacuate the air;

[0029] A3. When the vacuum degree reaches the second preset vacuum degree, the fourth valve, the first valve, the second valve, and the third valve are closed, and the first cryogenic pump, the second cryogenic pump, and the third cryogenic pump are started;

[0030] A4. When each cryopump is working at full pumping speed, open the first valve, the second valve, and the third valve to start further vacuuming;

[0031] A5. When the vacuum degree reaches the third preset vacuum degree, the annular resistance heater is started to heat up the suction thin-walled part;

[0032] A6. When the air-inhaling thin-walled component is heated up to the air-inhaling activation temperature, the air-inhaling thin-walled component is activated to start inhaling air. At this time, any one of the cryopumps is selected to work, and the other two cryopumps are regenerated or shut down to achieve the third preset vacuum degree of the vacuum chamber.

[0033] By regulating the above process, it is possible to maintain a high vacuum degree in the vacuum chamber for a relatively long time. Moreover, when the preset vacuum degree is reached, due to the presence of the air-intake thin-walled member, only one cryopump can be turned on, and the other cryopumps do not need to be turned on, which can significantly reduce the demand for the number of cryopumps and the pumping speed requirements.

[0034] The present invention has the following beneficial effects: the present invention provides a structure of an air-intake thin-walled component, which is used to solve the technical problem in the prior art that the compact cyclotron itself is small in size and the available space is small, and it is difficult to maintain a high vacuum state in the vacuum chamber for a long time by installing multiple low-temperature cold plates or adding multiple vacuum pumps; the present invention adds an air-intake thin-walled component in the vacuum chamber to assist the existing vacuum pump to jointly maintain a high vacuum state in the vacuum chamber for a long time, thereby reducing the requirements for the vacuum pump's own pumping speed, so that the pumping speed of the existing commonly used vacuum pump can meet the requirements. At the same time, the presence of the through-hole does not affect the movement of the gas itself, and the multiple openings increase the surface area of ​​the air-intake thin-walled component, thereby improving the air-intake efficiency of the air-intake thin-walled component; in addition, the air-intake thin-walled component is installed around the inner wall of the vacuum chamber body, which can protect the inner wall of the vacuum chamber, help intercept part of the lost beam, and thus reduce the possibility of radioactivity generated by the activation of the inner wall of the vacuum chamber due to the beam loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to make the purpose, technical solution and advantages of the invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings, in which:

[0036] Figure 1 Schematic diagram of the structure of the air-intake thin-walled component according to an embodiment of the present invention.

[0037] Figure 2 It is an exploded view of the vacuum chamber component structure according to an embodiment of the present invention.

[0038] Figure 3 Schematic diagram of the cross-sectional structure of a vacuum chamber assembly according to an embodiment of the present invention.

[0039] Figure 4 This is a large-scale diagram of the first annular slot and the second annular slot structure of an embodiment of the present invention.

[0040] Figure 5 Schematic diagram of the mold structure of an embodiment of the present invention.

[0041] Explanation of the reference numerals: 100, air-intake thin-walled part; 101, opening; 102, resistor heater; 103, through-hole; 200, vacuum chamber assembly; 201, vacuum chamber body; 202, first magnet; 203, second magnet; 204, bushing; 205, beam outlet; 206, first protrusion; 207, second protrusion; 208, acceleration space; 209, first annular gap; 210, second annular gap; 211, first annular slot; 212, second annular slot; 301, molecular pump; 302, first cryogenic pump; 303, second cryogenic pump; 304, third cryogenic pump; 305, fourth valve; 306, first valve; 307, second valve; 308, third valve; 400, mold; 401, bump; 402, groove; 403, track; 404, scraper. DETAILED DESCRIPTION

[0042] To make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0043] It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In the description of the present invention, it should be noted that the orientation or position relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the invention product is usually placed when used, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. In addition, the terms "horizontal", "vertical", etc. do not mean that the components are absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted. In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] The present invention can be applied to the field of cyclotrons, and in particular to maintaining a high vacuum state for a long time in a vacuum chamber in the field of compact cyclotrons. It solves the technical problem in the prior art that the compact cyclotron itself has a small size and thus a small available space, making it difficult to maintain a high vacuum state in the vacuum chamber for a long time by installing multiple low-temperature cold plates or adding multiple vacuum pumps.

[0045] Specifically, in order to elaborate on the technical solution of the present invention, the present invention discloses the following embodiments.

[0046] Example 1, please refer to Figure 1 This embodiment aims to improve the technical problem in the prior art that it is difficult to maintain a high vacuum state in the vacuum chamber for a long time by installing multiple low-temperature cold plates or adding multiple vacuum pumps due to the small size and small available space of the compact cyclotron itself. This embodiment provides a suction thin-walled member 100 for detachable installation in the vacuum chamber of the cyclotron. The suction thin-walled member can be activated and adsorb the gas in the vacuum chamber body 201; the suction thin-walled member 100 is used to surround the position close to the inner wall of the vacuum chamber body; and the suction thin-walled member is provided with a through hole for beam extraction. The suction thin-walled member 100 provided in this embodiment is small in size, and utilizes the narrow space between the magnet in the vacuum chamber and the inner wall of the vacuum chamber, thereby improving the space utilization rate, while not occupying the space of other functional components in the vacuum chamber, and not occupying the additional space outside the vacuum chamber, and assisting the vacuum pump installed on the vacuum chamber. No additional vacuum pump is needed, and the vacuum chamber can be jointly maintained for a long time. High vacuum state, thereby reducing the requirements for the vacuum pump's own pumping speed, can be met by using a conventional vacuum pump. Specifically, jointly maintaining a high vacuum state in the vacuum chamber means jointly maintaining a working vacuum degree in the vacuum chamber at 10 -5 ~10 -6 Pa range.

[0047] At the same time, if there is gas in the vacuum chamber, the perforations will help the gas flow in the vacuum chamber so that it can be extracted or adsorbed as quickly as possible, without causing the gas molecules to be blocked in the narrow gap between the air-absorbing thin-walled part 100 and the inner wall of the vacuum chamber and difficult to be extracted or adsorbed, resulting in a decrease in the vacuum degree.

[0048] In addition, the air-intake thin-walled member 100 is installed around the inner wall of the vacuum chamber body 201, which can protect the inner wall of the vacuum chamber. Because when the vacuum chamber is working, the beam will be lost, and the lost beam will hit the inner wall of the vacuum chamber, thereby activating the inner wall of the vacuum chamber and generating radioactivity. At this time, the air-intake thin-walled member 100 can help intercept part of the lost beam, thereby reducing the possibility of activating the inner wall of the vacuum chamber and generating radioactivity due to the beam loss.

[0049] In Embodiment 1, preferably, the air-intake thin-walled member 100 is used to surround a position close to the inner wall of the vacuum chamber body 201; the air-intake thin-walled member 100 has a plurality of openings 101, and the surface area of ​​the inner wall of each opening 101 is at least twice the cross-sectional area of ​​the corresponding opening 101. The plurality of openings 101 increase the surface area of ​​the air-intake thin-walled member 100, thereby improving the air-intake efficiency of the air-intake thin-walled member 100.

[0050] In Example 1, as some of the implementations of the getter thin-walled member having the getter performance, the getter thin-walled member is made of an alloy having the getter performance, or the surface of the getter thin-walled member has a getter film. As the alloy having the getter performance, titanium-based alloys can be used, including but not limited to titanium-aluminum-based alloys (such as Ti-Al-V) or titanium-zirconium-based alloys (such as Ti-Zr-V). As the getter thin-walled member having the getter film on its surface, the getter film is a titanium-based film or a titanium-based coating, and correspondingly, the frame structure of the getter thin-walled member is made of aluminum or zirconium. During preparation, an aluminum or zirconium material frame is first prepared, and then a titanium-based film or a titanium-based coating is prepared on the surface.

[0051] In Embodiment 1, the shape of the opening 101 is a square hole, a round hole, a polygonal hole or an irregular hole.

[0052] In Example 1, the thickness of the air-intake thin-walled member 100 is 10 mm.

[0053] Example 2, based on Example 1, please refer to Figure 1 , continue to improve the structure of the air intake thin-walled component 100, the outer periphery of the air intake thin-walled component 100 is provided with a resistance heater, the resistance heater is electrically connected to an external power supply, the resistance heater can be powered on to generate heat and heat the air intake thin-walled component 100 to the air intake activation temperature, and the air intake activation temperature is used to activate the air intake thin-walled component 100 to make it inhale air. The resistance heater can generate heat when powered on, and transfer the temperature to the air intake thin-walled component 100 so that the air intake thin-walled component 100 is heated synchronously, and the heating temperature is gradually increased to the air intake activation temperature, so that the air intake thin-walled component 100 starts to work. If it is necessary to stop the air intake work of the air intake thin-walled component 100, it is only necessary to turn off the power of the resistance heater. In addition, since the air intake thin-walled component 100 itself is a porous structure, it is easy to be heated by the resistance heater, so that the air intake thin-walled component 100 can be activated relatively quickly. In addition, the temperature of the resistance heater also has a baking effect on the vacuum chamber during the heating stage before it rises to the temperature that activates the air-intake thin-walled component, which can reduce the probability of the gas in the vacuum chamber adhering to the inner wall of the vacuum chamber, so that the gas in the vacuum chamber can be extracted as much as possible or adsorbed by the air-intake thin-walled component.

[0054] In Example 2, specifically, the gas absorption activation temperature ranges from 150 to 600°C, preferably from 500 to 600°C.

[0055] Example 3, based on Example 2, please refer to Figure 1 , continue to improve the structure of the air-intake thin-walled member 100, the air-intake thin-walled member 100 is a tubular structure with a circular cross-section; the resistance heater is an annular resistance heater, the annular resistance heater surrounds the radial periphery of the tubular structure, and is located in the middle of the radial periphery of the tubular structure. Correspondingly, this solution is suitable for a vacuum chamber whose side wall is also a circular tubular structure, can better adapt to the shape of the vacuum chamber side wall, can help intercept part of the lost beam as much as possible, and reduce the possibility of radioactivity generated by activation of the inner wall of the vacuum chamber due to beam loss. Fixing the annular resistance heater to the middle of the radial periphery of the tubular structure can make the resistance heater heat the air-intake thin-walled member 100 more evenly, and can make the getter film activated at the same time as much as possible to enter the air-intake state.

[0056] Example 4, based on Example 1 or 3, please refer to Figure 1 The getter thin-walled member 100 includes a tubular frame, and each of the openings 101 is evenly opened on the tubular frame. The inner and outer surfaces of the tubular frame and the inner wall surface of each opening 101 are covered with a getter film, and the getter film can adsorb the gas in the vacuum chamber body 201. The getter film structure can increase the getter area on the surface of the getter thin-walled member 100 as much as possible. The surface of the getter thin-walled member 100 first contacts the gas molecules. The surface film structure can enable the getter thin-walled member 100 to quickly adsorb gas molecules when working. At the same time, the inner and outer surfaces and the inner wall surface of the opening 101 are covered with a getter film, which can increase the adsorption amount of gas and enhance the air absorption effect, so that the high vacuum state in the vacuum chamber can be maintained more easily. In Example 4, specifically, the activation temperature of the getter film ranges from 500 to 600°C.

[0057] Embodiment 5, based on Embodiment 1 and Embodiment 4, this embodiment provides a method for preparing an air-intake thin-walled component, which is used to prepare the air-intake thin-walled component as described above, comprising the following steps:

[0058] S1. Prepare two flat plate frames, and evenly open a plurality of openings on the flat plate frames;

[0059] S2, forging the two flat plate frames obtained in step S1 into semi-cylindrical structures respectively, and welding the two ends of the two semi-cylindrical structures respectively to form a tubular frame with a circular cross section;

[0060] S3, annealing the tubular frame obtained in step S2, and cleaning and drying it;

[0061] S4. Put the cleaned and dried tubular frame into a vacuum environment. When the vacuum environment reaches a preset vacuum degree, introduce an inert gas into the vacuum environment. Use a getter material as a raw material to evenly coat a getter film on the surface of the tubular frame. After coating, continue to heat at a constant temperature for a preset time to obtain the getter thin-walled component.

[0062] Embodiment 6, based on Embodiment 4 and Embodiment 5, the getter film is a titanium-based film. Titanium-based film is used. Due to the molecular characteristics of titanium, the titanium-based film has a large air intake capacity, and the titanium-based film is covered on the surface of the frame, which can provide a uniform surface coverage, which helps to improve the air intake efficiency. In addition, the titanium-based film has a low infrared emissivity, which is beneficial to reduce thermal radiation losses, and is beneficial to the uniform distribution of temperature in the vacuum chamber, and improves the operating stability of the cyclotron. In specific implementation, physical vapor deposition and other methods can be used to uniformly deposit the titanium film on various substrates. The activation temperature of the titanium-based film ranges from 500 to 600°C.

[0063] The technical solution of Example 6 adopts the preparation method as described in Example 5 to prepare the air-intake thin-walled parts, which can reduce the difficulty of preparation and improve the actual application rate. In actual application, the thickness of the air-intake thin-walled parts is about 10 mm. Therefore, a flat plate frame is prepared first, and then the semi-cylindrical structure is forged. Finally, the two semi-cylindrical structures are welded to obtain an air-intake thin-walled part with a relatively precise preset shape. In addition, the air-intake thin-walled parts have multiple openings, which can make the titanium film evenly plated on the outer surface and inner surface of the tubular frame, as well as the inner wall surface of each opening, to ensure that the obtained air-intake thin-walled parts can achieve good air-intake function on the basis of structural integrity. Specifically, the flat plate frame in step S1 is made of aluminum. Specifically, in step S1, please refer to Figure 5 The preparation method using aluminum as the flat frame material is as follows: first, prepare a mold 400, wherein the mold 400 has a plurality of protrusions 401, wherein the cross-sectional shape of each protrusion 401 matches the shape of the opening 101, and each protrusion 401 has a groove 402; then, a sufficient amount of molten aluminum is poured into the groove 402 to ensure that all positions of the groove 402 are filled with molten aluminum; a track 403 is provided at one end of the mold 400, and a scraper 404 is slidably connected to the track 403. When all the grooves 402 are filled with molten aluminum, the scraper 404 is slid from one end of the mold 400 along the track 403 to the other end to scrape off excess molten aluminum. The moving end of the scraper 404 corresponds to the position of the groove 402, and an outflow groove is reserved for allowing excess molten aluminum to flow out; after the molten aluminum is completely solidified, demolding is performed to obtain the flat frame.

[0064] Specifically, in step S3, the annealed tubular frame is ultrasonically cleaned, and the parts are wiped multiple times with ethanol and a dust-free cloth to ensure the cleanliness of the tubular frame, and then the tubular frame is dried.

[0065] Specifically, in step S4, the multi-arc ion plating method is used for coating, and the preset vacuum degree is greater than 4×10 -3 Pa, the getter material is a titanium target with a purity of 99.99%, the inert material is argon with a purity of 99.995%, and the ionization rate of each arc spot is 60-90%.

[0066] Specifically, in step S4, a multi-arc ion plating method is implemented using a multi-arc ion plating machine, and the specific operation process is: first prepare the multi-arc ion plating machine, and place the cleaned and dried tubular frame in the plating machine, and start vacuuming to prepare for plating; set corresponding parameters according to the normal plating process, including power, current, voltage, temperature and other parameters; turn on the titanium target power supply, set the plating time according to the actual needs of the coating thickness, and wait for the titanium film to be deposited; heat the coated tubular frame and maintain a constant temperature for 2 hours, so that the titanium film is completely bonded to the tubular frame; after the deposition is completed, turn off the plating machine, take out the completed air-intake thin-walled part of the coated part, and then install the annular resistance heater and other subsequent assembly processes normally.

[0067] Embodiment 7: This embodiment provides a vacuum chamber assembly 200. Figure 2 and Figure 3 , used in a cyclotron, comprising a vacuum chamber body 201, wherein the air-intake thin-walled member 100 described in Example 1 is installed in the vacuum chamber body 201; the vacuum chamber body 201 is enclosed by a first magnet 202, a second magnet 203 and a bushing 204 structure, wherein the first magnet 202 and the second magnet 203 are respectively sealed and installed at both ends of the bushing 204 structure; the air-intake thin-walled member 100 is installed around a position close to the inner wall of the bushing 204; the bushing 204 has a beam outlet 205, and a through-hole 103 is opened at a corresponding position on the air-intake thin-walled member 100, and the beam can pass through the through-hole 103 and be led out from the beam outlet 205. In this embodiment, a small-volume air-absorbing thin-walled member 100 is installed in the vacuum chamber, and the narrow space between the magnet in the vacuum chamber and the inner wall of the vacuum chamber is utilized, thereby improving the space utilization rate. At the same time, it does not occupy the space of other functional components in the vacuum chamber, nor does it occupy additional space outside the vacuum chamber. There is no need to add an additional vacuum pump, and the technical effect of maintaining a high vacuum state in the vacuum chamber for a long time can be achieved.

[0068] Example 8, based on Example 7, please refer to Figure 2 , Figure 3 and Figure 4The opposite sides of the first magnet 202 and the second magnet 203 respectively have a plurality of relatively protruding first protrusions 206 and a plurality of second protrusions 207, and an acceleration space 208 is provided between the opposite sides of each of the first protrusions 206 and each of the second protrusions 207; a first annular gap 209 is provided between the outer peripheral side of each of the first protrusions 206 and the inner wall of the bushing 204, and a second annular gap 210 is provided between the outer peripheral side of each of the second protrusions 207 and the inner wall of the bushing 204; a first annular slot 211 is fixed on the first magnet 202 in the first annular gap 209, and a second annular slot 212 is fixed on the second magnet 203 in the second annular gap 210, the notches of the first annular slot 211 and the second annular slot 212 are opposite, and the first annular slot 211 and the second annular slot 212 are respectively used to plug in the two ends of the air-intake thin-walled component 100, so that the acceleration space 208 is located within the surrounding range of the air-intake thin-walled component 100. The air-intake thin-walled member 100 is arranged between the first annular gap 209 and the second annular gap 210, so that the air-intake thin-walled member 100 can be as close to the inner wall of the bushing 204 as possible. Moreover, the acceleration space 208 is located within the surrounding range of the air-intake thin-walled member 100, which can ensure that the lost beam can be intercepted by the air-intake thin-walled member 100 as much as possible, and can reduce the possibility of radioactivity generated by the activation of the inner wall of the vacuum chamber due to beam loss. In addition, the use of plug-in form makes the installation, disassembly and replacement of the air-intake thin-walled member 100 very convenient. If the air-intake performance of the air-intake thin-walled member 100 is found to be reduced or disappeared, it can be directly taken out and replaced with the same part to work normally.

[0069] In Example 8, the first annular slot and the second annular slot are made of insulating and heat-insulating materials, preferably ceramics.

[0070] In Example 8, please refer to Figure 3 and Figure 4 The cross-sections of the first annular slot 211 and the second annular slot 212 are V-shaped or concave arc-shaped.

[0071] Example 9, based on Example 8, please refer to Figure 2, a molecular pump 301 and a first cryogenic pump 302 are installed on the first magnet 202, and correspondingly, the pump outlets of the molecular pump 301 and the first cryogenic pump 302 are respectively connected to the interior of the vacuum chamber body 201; the pump outlet of the molecular pump 301 is provided with a fourth valve 305, and the pump outlet of the first cryogenic pump 302 is provided with a first valve 306; a second cryogenic pump 303 and a third cryogenic pump 304 are installed on the second magnet 203, and correspondingly, the pump outlets of the second cryogenic pump 303 and the third cryogenic pump 304 are respectively connected to the interior of the vacuum chamber body 201; the pump outlet of the second cryogenic pump 303 is provided with a second valve 307; the pump outlet of the third cryogenic pump 304 is provided with a third valve 308. The molecular pump 301 changes the movement direction of the gas molecules through a high-speed rotating rotor, so that it moves along a specific path, thereby achieving vacuumization. The molecular pump in this embodiment can be a turbomolecular pump, a diffusion pump, or the like. The pumping speed of the molecular pump 301 is usually higher than that of the cryogenic pump, which is suitable for rapid vacuumization and can reach 10 -9 mbar or even lower vacuum, can be operated without oil, avoiding oil vapor contamination. Cryogenic pumps achieve vacuum by adsorbing gas molecules on a low-temperature surface (usually cooled by liquid nitrogen or liquid helium). They are suitable for occasions requiring extremely high vacuum, and can reach 10 -12 mbar or even lower vacuum degree, the low temperature surface of the cryopump can absorb a variety of gas molecules, including water vapor, and the cryopump can usually achieve a higher vacuum degree than the molecular pump 301. When in use, first use the molecular pump 301 to quickly evacuate the vacuum, and when the vacuum degree reaches the vacuum degree of the getter, activate the getter thin-walled component 100 to maintain the high vacuum degree of the main vacuum chamber. At this time, the getter thin-walled component 100 and each cryopump are used to cooperate to maintain the vacuum state. When the air absorption performance of the getter thin-walled component 100 reaches the limit, it is only necessary to close the gate valve installed at the front end of the vacuum chamber. When the vacuum degree is reduced to the vacuum atmospheric pressure, open the vacuum chamber and replace the new getter thin-walled component 100.

[0072] Example 10, based on Example 9, please refer to Figure 2 and Figure 3 , a vacuum control method is provided, using the vacuum chamber body 201 assembly as described above, comprising the following steps:

[0073] A1. Open the fourth valve 305, the first valve 306, the second valve 307, and the third valve 308, and roughly evacuate the vacuum chamber. Since the air-intake thin-walled member 100 has a plurality of openings 101, there will be no local over-pressure area in the vacuum chamber during the rough evacuation, and the presence of the air-intake thin-walled member 100 will not affect the rough evacuation process.

[0074] A2. When the vacuum degree reaches the first preset vacuum degree, the molecular pump 301 is started to further evacuate the air;

[0075] A3. When the vacuum degree reaches the second preset vacuum degree, the fourth valve 305, the first valve 306, the second valve 307, and the third valve 308 are closed, and the first cryopump 302, the second cryopump 303, and the third cryopump 304 are started;

[0076] A4. When all cryopumps are working at full pumping speed, the first valve 306, the second valve 307, and the third valve 308 are opened to start further vacuuming;

[0077] A5. When the vacuum degree reaches the third preset vacuum degree, the annular resistance heater is started to heat the air-intake thin-walled part 100;

[0078] A6. When the getter thin-walled component 100 is heated to the getter activation temperature, the getter film is activated. At this time, any one cryopump is selected to work, and the other two cryopumps are regenerated or shut down to maintain the preset vacuum degree of the vacuum chamber.

[0079] By regulating the above process, it is possible to maintain a high vacuum degree in the vacuum chamber for a relatively long time. Moreover, when the preset vacuum degree is reached, due to the presence of the air-intake thin-walled member, only one cryopump can be turned on, and the other cryopumps do not need to be turned on, which can significantly reduce the demand for the number of cryopumps and the pumping speed requirements.

[0080] Specifically, in step A6, when any cryopump needs to be regenerated, the corresponding valve is closed for regeneration, and any other cryopump that does not need to be regenerated is opened.

[0081] Specifically, as one embodiment of each preset vacuum degree value, the first preset vacuum degree is 10Pa, and correspondingly, the second preset vacuum degree is 10 -3 Pa, the third preset vacuum degree is 10 -5 Pa.

[0082] In summary, the air-intake thin-walled component and preparation method, vacuum chamber assembly and vacuum control method disclosed in the present invention have the following technical effects:

[0083] 1. The present invention aims to improve the technical problem in the prior art that it is difficult to maintain a high vacuum state in the vacuum chamber for a long time by installing multiple low-temperature cold plates or adding multiple vacuum pumps due to the small size of the compact cyclotron itself and the small available space. The air suction thin-walled part provided by the present invention is small in size and utilizes the narrow space between the magnet in the vacuum chamber and the inner wall of the vacuum chamber, thereby improving the space utilization rate while not occupying the space of other functional components in the vacuum chamber or the space outside the vacuum chamber. It assists the vacuum pump installed on the vacuum chamber without adding an additional vacuum pump, and can achieve the long-term high vacuum state in the vacuum chamber, thereby reducing the requirements for the vacuum pump's own pumping speed, and the requirements can be met by using a conventional vacuum pump. The air suction thin-walled part can be detachably installed for easy replacement.

[0084] 2. If there is gas in the vacuum chamber, multiple openings help the gas flow in the vacuum chamber, so that it can be extracted or adsorbed as quickly as possible, and the gas molecules will not be blocked by the narrow gap between the air-intake thin-walled member and the inner wall of the vacuum chamber, making it difficult to extract or adsorb, resulting in a decrease in the vacuum degree. In addition, multiple openings increase the surface area of ​​the air-intake thin-walled member, thereby improving the air-intake efficiency of the air-intake thin-walled member.

[0085] 3. The air-intake thin-walled member is installed around the inner wall of the vacuum chamber body, which can protect the inner wall of the vacuum chamber. Because when the vacuum chamber is working, the beam will be lost, and the lost beam will hit the inner wall of the vacuum chamber, thereby activating the inner wall of the vacuum chamber and generating radioactivity. At this time, the air-intake thin-walled member can help intercept part of the lost beam, thereby reducing the possibility of generating radioactivity due to the activation of the inner wall of the vacuum chamber by the beam loss.

[0086] 4. The air intake thin-walled component disclosed in the present invention is also equipped with a resistance heater which can generate heat when powered on, and transfer the temperature to the air intake thin-walled component to make the air intake thin-walled component generate heat synchronously, and gradually increase the heating temperature to the air intake activation temperature, thereby making the air intake thin-walled component start working; in addition, the temperature of the resistance heater also has a baking effect on the vacuum chamber during the heating stage before it rises to the temperature that activates the air intake thin-walled component, which can reduce the probability of the gas in the vacuum chamber adhering to the inner wall of the vacuum chamber, so that the gas in the vacuum chamber can be extracted as much as possible or adsorbed by the air intake thin-walled component.

[0087] 5. The present invention also provides a getter thin-walled part with a getter film coated on the surface, which reduces the difficulty of preparation and improves the contact efficiency between gas molecules and getter materials, thereby improving the getter efficiency.

[0088] 6. The present invention also provides a vacuum chamber assembly equipped with an air-intake thin-walled member, which utilizes the narrow space between the magnet in the vacuum chamber and the inner wall of the vacuum chamber, thereby improving the space utilization rate without occupying the space of other functional components in the vacuum chamber or the additional space outside the vacuum chamber. There is no need to add an additional vacuum pump, and the technical effect of maintaining a high vacuum state in the vacuum chamber for a long time can be achieved.

[0089] 7. The present invention provides a vacuum control method based on the provided vacuum chamber assembly. Through control, it is possible to maintain a high vacuum degree in the vacuum chamber for a relatively long time without adding an additional vacuum pump. Moreover, when the preset vacuum degree is reached, due to the presence of the air-intake thin-walled member, only one cryopump can be turned on, and the other cryopumps do not need to be turned on, which can significantly reduce the number and pumping speed requirements for cryopumps and can significantly reduce the operating frequency and energy consumption of existing vacuum pumps.

[0090] It is understood that the present invention is described by some embodiments, and those skilled in the art are aware that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. Under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. The embodiments described in the present invention are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings herein may be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all other embodiments obtained by ordinary technicians in the art without creative work based on the embodiments in the present invention belong to the scope of protection of the present invention.

Claims

1. A thin-walled air-intake member for detachably mounting in a vacuum chamber of a cyclotron, characterized in that: The air-absorbing thin-walled member can be activated and absorb the gas in the vacuum chamber body; the air-absorbing thin-walled member is used to surround a position close to the inner wall of the vacuum chamber body; and a hole is opened on the air-absorbing thin-walled member for beam extraction.

2. The air-intake thin-walled part according to claim 1, characterized in that: The air-intake thin-walled part includes a tubular frame, which has a plurality of openings, and the surface area of ​​the inner wall of each opening is at least twice the cross-sectional area of ​​the corresponding opening; each opening is evenly opened on the tubular frame, and the inner and outer surfaces of the tubular frame and the inner wall surface of each opening are covered with an air-intake agent film, and the air-intake agent film can absorb the gas in the vacuum chamber body.

3. The air-intake thin-walled part according to claim 2, characterized in that: The getter film is a titanium-based film.

4. The air-intake thin-walled part according to claim 1, characterized in that: A resistance heater is arranged on the periphery of the air intake thin-walled member, and the resistance heater is electrically connected to an external power supply. The resistance heater can be powered on to generate heat and heat the air intake thin-walled member to an air intake activation temperature, and the air intake activation temperature is used to activate the air intake thin-walled member to enable it to inhale air.

5. The air-intake thin-walled part according to claim 4, characterized in that: The air intake thin-walled member is a tubular structure with a circular cross section, and the resistance heater is an annular resistance heater, which surrounds the middle part of the radial outer periphery of the air intake thin-walled member.

6. A method for preparing an air-intake thin-walled component, used for preparing the air-intake thin-walled component as claimed in claim 2, characterized in that: The following steps are involved: S1. Prepare two flat plate frames, and evenly open a plurality of openings on the flat plate frames; S2, forging the two flat plate frames obtained in step S1 into semi-cylindrical structures respectively, and welding the two ends of the two semi-cylindrical structures respectively to form a tubular frame with a circular cross section; S3, annealing the tubular frame obtained in step S2, and cleaning and drying it; S4. Put the cleaned and dried tubular frame into a vacuum environment. When the vacuum environment reaches a preset vacuum degree, introduce an inert gas into the vacuum environment. Use a getter material as a raw material to evenly coat a getter film on the surface of the tubular frame. After coating, continue to heat at a constant temperature for a preset time to obtain the getter thin-walled component.

7. A vacuum chamber assembly for use in a cyclotron, characterized in that: It comprises a vacuum chamber body, in which the air-intake thin-walled member according to claim 1 is installed; The vacuum chamber body is surrounded by a first magnet, a second magnet and a bushing structure, wherein the first magnet and the second magnet are respectively sealed and installed at two ends of the bushing structure; the air suction thin-walled member is installed around a position close to the inner wall of the bushing; the bushing is provided with a beam outlet, and a through-hole is opened at a corresponding position on the air suction thin-walled member, and the beam can pass through the through-hole and be led out from the beam outlet.

8. The vacuum chamber assembly according to claim 7, characterized in that The first magnet and the second magnet have a plurality of first protrusions and a plurality of second protrusions protruding relatively on one side thereof, respectively, and an acceleration space is provided between the opposite sides of each of the first protrusions and each of the second protrusions; A first annular gap is formed between the outer peripheral side of each of the first protrusions and the inner wall of the bushing, and a second annular gap is formed between the outer peripheral side of each of the second protrusions and the inner wall of the bushing; A first annular slot is fixed on the first magnet in the first annular slot, and a second annular slot is fixed on the second magnet in the second annular slot. The notches of the first annular slot and the second annular slot are opposite to each other. The first annular slot and the second annular slot are respectively used to plug in the two ends of the air-intake thin-walled component, so that the acceleration space is located within the surrounding range of the air-intake thin-walled component.

9. The vacuum chamber assembly according to claim 8, characterized in that A molecular pump and a first cryogenic pump are installed on the first magnet, and correspondingly, the pump outlets of the molecular pump and the first cryogenic pump are respectively connected to the interior of the vacuum chamber body; a fourth valve is provided at the pump outlet of the molecular pump, and a first valve is provided at the pump outlet of the first cryogenic pump; A second cryopump and a third cryopump are installed on the second magnet, and correspondingly, the pump outlets of the second cryopump and the third cryopump are respectively connected to the interior of the vacuum chamber body; a second valve is provided at the pump outlet of the second cryopump; and a third valve is provided at the pump outlet of the third cryopump.

10. A vacuum control method, using the vacuum chamber body assembly as claimed in claim 9, characterized in that: The following steps are involved: A1. Open the fourth valve, the first valve, the second valve, and the third valve, and roughly evacuate the vacuum chamber; A2. When the vacuum degree reaches 10Pa, start the molecular pump to further evacuate the air; A3. When the vacuum degree reaches 10 -3 At Pa, the fourth valve, the first valve, the second valve, and the third valve are closed, and the first cryogenic pump, the second cryogenic pump, and the third cryogenic pump are started; A4. When each cryopump is working at full pumping speed, open the first valve, the second valve, and the third valve to start further vacuuming; A5. When the vacuum degree reaches the preset vacuum degree, start the annular resistance heater to heat up the suction thin-walled parts; A6. When the temperature of the getter thin-walled component rises to the getter activation temperature, the getter film is activated. At this time, any one cryopump is selected to work, and the other two cryopumps are regenerated or shut down to maintain the preset vacuum degree of the vacuum chamber.

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