Low-pressure ionization chamber and accelerator

Abstract

The low-pressure ionization chamber comprises a closed chamber, a low-pressure environment lower than the standard atmospheric pressure is formed in the closed chamber, and an electrode plate assembly is arranged in the closed chamber to collect electron-ion pairs in the closed chamber in the low-pressure environment; by arranging the negative-pressure closed chamber, the air density is reduced under the condition of low air pressure, so that the number of gas molecules in unit volume is reduced, the total number of charges generated by radiation ionization of a gas medium is reduced, and then the charge density and the ion recombination probability are reduced, so that the saturation characteristic of the ionization chamber is influenced.

Description

Technical Field

[0001] The present invention relates to the technical field of radiotherapy dose monitoring, and particularly relates to a low-pressure ionization chamber and an accelerator. Background Art

[0002] An ionization chamber is a detector that measures ionizing radiation using the ionization effect of ionizing radiation. The ionization chamber consists of electrodes at different potentials and the medium therebetween. Ionizing radiation generates ion pairs in the medium, and under the action of an electric field, positive and negative ions drift towards the negative electrode and the positive electrode respectively, forming an ionization current. Since the ionization current is proportional to the intensity of the radiation, measuring this current can obtain the intensity of the ionizing radiation.

[0003] Ultra-high dose rate and ultra-short pulse are the core radiation characteristics of FLASH radiotherapy, but they are obstacles to existing conventional dose detection methods (especially detectors). Under FLASH conditions, a large amount of dose is instantaneously deposited, generating a super-high density of positive and negative charge carriers. These carriers are extremely likely to meet and undergo ion recombination during the migration and collection process, resulting in a significantly unpredictable decrease in the charge collection efficiency. At the same time, a large amount of charge will cause serious electric field distortion and then aggravate the polarization effect. This physical-level ion migration and recombination process is extremely complex and extremely sensitive to the internal structure and electric field of the ionization chamber, making it difficult to accurately predict and calculate, that is, we cannot eliminate this influence through theoretical correction. Therefore, an atmospheric-pressure penetration-type air ionization chamber is not suitable for dose monitoring of ultra-high dose rate radiotherapy equipment.

[0004] The inventors found that the ion recombination effect can be effectively avoided in an environment below standard atmospheric pressure. Therefore, based on the above considerations, dose measurement of ultra-high dose rate rays is carried out under near-vacuum conditions.

[0005] In the prior art, the electrode plates are completely attached to the upper and lower surfaces of the main cavity, and the gap between the electrode plates and the main cavity is very small, which is not conducive to gas circulation. And a low-pressure ionization chamber needs to use a vacuum pump to evacuate the inside of the ionization chamber to achieve an internal environment below standard atmospheric pressure. The design of the electrode plates completely attached to the main cavity will hinder gas circulation, and if the existing design is adopted, due to the existence of the pressure difference, the electrode plates will deform or move during the evacuation process. Summary of the Invention

[0006] The low-pressure environment poses higher requirements for the design, manufacture, assembly of the ionization chamber sealing structure and the formation of the low-pressure state. At the same time, in order to ensure the treatment space, the installation space left for the ionization chamber by the treatment head is very small, which further increases the design difficulty of the ionization chamber.

[0007] In view of the deficiencies of the prior art, a low-pressure ionization chamber and an accelerator are proposed, which solve the problem that the atmospheric pressure penetration type air ionization chamber in the above-mentioned background art is not suitable for the dose monitoring of ultra-high dose rate radiotherapy equipment.

[0008] To achieve the above object, the present invention proposes the following technologies for implementation:

[0009] The low-pressure ionization chamber includes a sealed chamber, a low-pressure environment lower than the standard atmospheric pressure is formed in the sealed chamber, an electrode plate assembly is arranged in the sealed chamber to collect electron-ion pairs in the sealed chamber under the low-pressure environment, the sealed chamber is located between a cover plate and a main cavity body, grooves are respectively opened on the upper and lower sides of the main cavity body to form a transmission window, a first gas flow port is arranged at the edge of the groove, and the first gas flow port communicates the groove and the sealed chamber.

[0010] Further, the first gas flow port includes a first notch at the edge of the groove that communicates the sealed chamber with the groove.

[0011] Further, a protrusion is arranged at the edge of the groove, and the protrusion supports the electrode plate assembly to form the first gas flow port.

[0012] Further, the first gas flow port includes a second notch opened on the electrode plate.

[0013] Further, the electrode plate assembly includes a collecting electrode and a high-voltage electrode, a collecting chamber is located between the collecting electrode and the high-voltage electrode, an insulating member for spacing the collecting electrode and the high-voltage electrode is arranged on the periphery of the collecting chamber, a plurality of the insulating members are arranged along the circumferential direction, and a second gas flow port is formed between adjacent two of the insulating members to facilitate gas flow.

[0014] Further, the insulating member is made of ceramic material.

[0015] Further, the pressure range in the sealed chamber is 0.01 atm - 0.5 atm.

[0016] On the other hand, an accelerator is also proposed, which includes the low-pressure ionization chamber described in any one of the above.

[0017] Compared with the prior art, the comprehensive effects brought by the present invention include:

[0018] By setting a sealed chamber with negative pressure, under low-pressure conditions, the air density decreases, resulting in a reduction in the number of gas molecules per unit volume and a reduction in the total number of ionized electron-ion pairs, thereby weakening the recombination effect of ion pairs, and thus improving the accuracy and reliability of measurement. Description of the Drawings

[0019] Figure 1Schematic diagram of the overall explosion structure of the embodiment of the present invention;

[0020] Figure 2 Schematic diagram of the overall external structure of the embodiment of the present invention;

[0021] Figure 3 Schematic diagram of the sectional structure of the transition pipe of the embodiment of the present invention;

[0022] Figure 4 is Figure 3 Schematic diagram of the partial structure at position B in

[0023] Figure 5 Schematic diagram of the top view structure of the embodiment of the present invention;

[0024] Figure 6 Schematic diagram of the first sinking groove structure of the embodiment of the present invention;

[0025] Figure 7 Schematic diagram of the first gas circulation port structure of the embodiment of the present invention;

[0026] Figure 8 Schematic diagram of the convex structure of the embodiment of the present invention.

[0027] Legend: 1. Upper cover plate; 2. Main cavity; 3. First seal; 4. Gas channel; 5. Transition pipe; 6. Second seal; 7. Plug; 8. Shielding part; 9. Transmissive window; 10. Collector electrode; 11. High-voltage electrode; 12. Insulating part; 13. Lower cover plate; 14. Plug mounting part; 15. Bracket; 16. First sinking groove; 17. Second sinking groove; 18. Wiring groove; 19. Groove; 20. First gas circulation port; 21. Second gas circulation port; 22. Convexity. Detailed implementation manners

[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the present invention.

[0029] In this article, terms such as "upper", "lower", "left", "right", "top", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It 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 to the present invention. As Figures 1 to 8As shown, a low-pressure ionization chamber includes a sealed chamber, a low-pressure environment lower than the standard atmospheric pressure is formed inside the sealed chamber, and an electrode plate assembly is arranged inside the sealed chamber to collect electron-ion pairs generated after the medium inside the sealed chamber under the low-pressure environment is ionized by X-rays.

[0030] The principle of the ionization chamber for measuring radiation dose is based on the ionization effect produced by radiation in a medium (usually air). By setting a sealed chamber with negative pressure, under low-pressure conditions, the air density decreases, resulting in a decrease in the number of gas molecules per unit volume, thereby weakening the recombination effect of ion pairs, and thus affecting the response of the ionization chamber.

[0031] In other embodiments, the ionization chamber can also be used for dose rate monitoring of radiotherapy equipment such as electrons, protons, and heavy ions.

[0032] In the low-pressure ionization chamber of this embodiment, the sealed chamber includes a sealed chamber located between the cover plate and the main cavity 2. A first seal 3 is embedded on the main cavity 2, and the cover plate presses the first seal 3 to achieve the sealing of the sealed chamber.

[0033] Specifically, the cover plate includes an upper cover plate 1. The sealed chamber is actually a cavity formed by enclosing between the upper cover plate 1 and the main cavity 2. The sealed chamber is in a low-pressure state, which will cause a decrease in the total number of ions and ion density under the low-pressure environment, thereby reducing the ion recombination probability. Preferably, the pressure range is 0.01 atm - 0.5 atm.

[0034] It should be noted that the upper cover plate 1 and the main cavity 2 are sealed through the first seal 3. The first seal 3 can adopt indium wire. The first seal 3 is arranged along the edge of the sealed chamber, and a sealing groove is opened on the main cavity 2 to facilitate the embedding of the first seal 3.

[0035] Preferably, the upper cover plate 1 and the main cavity 2 are connected by connecting bolts. There are multiple connecting bolts arranged along the outer edge of the sealing groove. Through the above settings, when assembling the upper cover plate 1 and the main cavity 2, the first seal 3 will be subjected to certain extrusion, so that the first seal 3 fits more closely with the sealing grooves on the upper cover plate 1 and the main cavity 2, thereby ensuring the airtightness of the sealed chamber. The first seal 3 is arranged along the contour of the first sinking groove 16 inside the main cavity. The first seal 3 is arranged around the contour of the first sinking groove 16. In this embodiment, the first seal 3 is arranged along the circumferential side of the contour of the first sinking groove 16 to form a closed figure, which can effectively ensure the airtightness between the main cavity 2 and the upper cover plate 1.

[0036] In the low-pressure ionization chamber of this embodiment, a first sinking groove 16 is opened on the main cavity 2 to form a sealed chamber for accommodating the electrode plate assembly. One end of the first sinking groove 16 is communicated with a gas channel 4 to facilitate the discharge of gas to form a negative pressure environment.

[0037] Specifically, the gas channel 4 can be used to connect a negative pressure pump such as an ion pump to evacuate the gas in the sealed chamber, so that the sealed chamber is in a low-pressure state.

[0038] Specifically, the gas channel 4 penetrates through the side wall of the main cavity 2 and is connected to the main cavity 2 by brazing. The gas channel 4 is made of oxygen-free copper tube. The oxygen-free copper tube has a low oxygen content, which can ensure the weld quality and airtightness during brazing.

[0039] In the low-pressure ionization chamber of this embodiment, transmissive windows 9 are respectively arranged on the upper cover plate 1 and the main cavity 2 in a relatively arranged manner, and the electrode plate assembly is located between the two transmissive windows 9, so that X-rays can pass through the transmissive windows 9 and enter the collection cavity inside the electrode plate assembly.

[0040] Specifically, to maintain good airtightness, the upper cover plate 1 and the transmissive window 9 are integrally formed. The transmissive window 9 is formed by processes such as milling and grinding. The transmissive window 9 on the main cavity 2 also adopts processes such as milling and grinding and is integrally formed with the transmissive window 9. When assembling the upper cover plate 1 and the main cavity 2, bolts are driven at the thicker part outside the transmissive window 9, and the assembly holes of the bolts are at a certain distance from the transmissive window 9, so as to effectively avoid the deformation of the transmissive window 9 when assembling.

[0041] Preferably, the edge of the transmissive window 9 is smoothly connected to the main cavity 2. From the cross-sectional view, a smooth arc transition is formed between the left part / right part of the main cavity 2 and the transmissive window 9. Through the above setting, stress concentration is avoided, and thus the anti-deformation ability of the transmissive window 9 is improved.

[0042] Preferably, at one end of the sealed chamber where the gas channel 4 is provided, a second sink 17 is further provided on the bottom surface of the first sink 16. The height difference formed between the first sink 16 and the second sink 17 can expand the volume of the ionization chamber.

[0043] The gas channel 4 is arranged in the middle and lower part of the second sink 17. Through the above setting, a height difference is formed between the communication port connecting the gas channel 4 in the second sink 17 and the electrode plate assembly on the first sink 16. When the negative pressure pump evacuates the air, the gas will not directly disturb the electrode plate, and the deformation or movement of the electrode plate can be avoided. Similarly, when the gas flows, it will not disturb the relatively thin transmissive window 9, thereby preventing the deformation of the transmissive window 9 and playing a protective role. During use, if there is a problem with the airtightness of the ionization chamber and environmental gas enters the ionization chamber, because there is a relatively large cavity structure, when the amount of entering gas is not very large, the pressure change of the ionization chamber is much smaller than that without this cavity structure, which can ensure that the test results will not have large fluctuations. That is, compared with the ionization chamber with a small volume, the ionization chamber in this technology has a larger volume, so the pressure fluctuation is smaller.

[0044] For a sealed chamber with the same air pressure, compared with a gas chamber with a small volume, the total number of gas molecules in a gas chamber with a large volume is larger. In fact, during the use of the ionization chamber, gas molecules will be consumed. The gas chamber with a large volume can provide more gas molecules for X-ray dose monitoring, and can maintain the stability of the gas composition in the chamber for a long time, thereby ensuring the accuracy of dose monitoring of the ionization chamber for a long time.

[0045] Preferably, the thickness at the transmission window 9 is 0.05 mm - 0.1 mm. A thinner thickness can reduce the dose loss of X-rays.

[0046] In the low-pressure ionization chamber of this embodiment, the other end of the first sink 16 is connected to a transition tube 5 disposed opposite to the gas channel 4. The end of the transition tube 5 away from the sealed chamber is hermetically connected to a plug 7 through a second seal 6 to facilitate power supply to the electrode plate assembly in the sealed chamber.

[0047] Specifically, the transition tube 5 is provided for installing the plug 7, and at the same time facilitates the routing of the wire between the plug 7 and the electrode plate assembly. The plug uses an aviation plug to ensure high airtightness.

[0048] Specifically, a plug mounting member 14 is further provided between the transition tube 5 and the plug 7. The outer end of the plug mounting member 14 is matched with the plug 7, and the other end is inserted into the transition tube 5. A circumferential groove is opened on the end surface of the transition tube 5 for installing the second seal 6. The second seal 6 is also made of indium wire. Using indium wire instead of a rubber gasket can resist radiation and prevent aging, and improve the service life.

[0049] Preferably, the part of the transition tube 5 inserted into the main cavity 2 is welded to the main cavity 2 to ensure sealing. The contact position between the end of the transition tube 5 located inside the main cavity 2 and the main cavity 2 is welded. The position where the part of the transition tube 5 located outside the main cavity 2 contacts the main cavity 2 is welded to strengthen the connection strength between the transition tube 5 and the main cavity 2. The position where the outer surface of the transition tube 5 located outside the main cavity 2 contacts the main cavity 2 is welded. The plug mounting member 14 fits against the end of the transition tube 5 to squeeze the second seal 6 to enhance the sealing effect.

[0050] Preferably, a wire routing groove 18 is opened at one end of the sealed chamber where the transition tube 5 is provided on the basis of the first sink 16 to facilitate the routing of the wire of the plug 7. On the basis of the above structure, the area from the plug mounting member 14 to the wire routing groove 18, as well as the space where the electrode plate assembly is located and the second sink 17 forms the sealed chamber.

[0051] In the low-pressure ionization chamber of this embodiment, a shielding member 8 for preventing X-ray leakage is provided at one end of the main cavity 2 away from the gas channel 4. The transition tube 5 penetrates through the shielding member 8 and the side wall of the main cavity 2 to communicate with the sealed chamber.

[0052] Specifically, a shielding member 8 is provided to avoid X-ray interference with other components in the radiotherapy device. In the entire radiotherapy device, above the ionization chamber is a collimator, and the outer diameter of the transmission window 9 is not less than the output aperture of the collimator: The ionization chamber itself can be regarded as being located in a tungsten disk in the shape of a ring, and the shape and size of the transmission window 9 of the ionization chamber are adapted to the output aperture of the collimator. Preferably, the output aperture can be equal to or less than the diameter of the transmission window 9. After the ionization chamber is installed, the shielding member 8 is located at one end of the main cavity 2, and the position of the shielding member 8 is equivalent to an opening on the side surface of the tungsten disk where the ionization chamber is inserted, which can prevent X-rays from leaking out from the side surface of the tungsten disk.

[0053] Preferably, the shielding member 8 can be made of tungsten alloy material, and brackets 15 are respectively provided at both ends of the shielding member 8 to facilitate the fixed installation of the ionization chamber.

[0054] In the low-pressure ionization chamber of this embodiment, the electrode plate assembly includes a collecting electrode 10 and a high-voltage electrode 11 fixedly connected to the main cavity 2. The collecting electrode 10 is located on the side of the high-voltage electrode 11 away from the main cavity 2, and the collecting cavity is located between the collecting electrode 10 and the high-voltage electrode 11.

[0055] Specifically, the electrode plate assembly uses an electrode plate with a composite structure. The base of the electrode plate is made of ceramic material. One reason for choosing ceramic is to ensure that the electrode plate has a certain stiffness and is not easily deformed, and the other is to be radiation-resistant and prevent aging.

[0056] The upper surface of the main cavity 2 is connected to the electrode plate by bolts. The diameter of the electrode plate is larger than the diameter of the transmission window 9 on the main cavity 2, so that there is enough distance between the bolt mounting holes and the transmission window 9 to avoid deforming the transmission window 9 when installing the bolts.

[0057] The high-voltage electrode 11 in the electrode plate is connected to the plug 7 by a wire. After being energized and irradiated by X-rays, ionization occurs. The collecting electrode 10 collects the electron-ion pairs in the gas in the collecting cavity after being ionized by X-rays to facilitate the detection and measurement of the X-ray dose rate.

[0058] In the prior art, the electrode plates are completely attached to the upper and lower surfaces of the main cavity, and the gap between the electrode plates and the main cavity is very small, which is not conducive to gas circulation. In the present invention, a negative pressure pump is needed to evacuate the inside of the ionization chamber to achieve an internal environment below the standard atmospheric pressure. The design of completely attaching the electrode plates to the main cavity will hinder gas circulation, and if the existing design is adopted, due to the existence of the pressure difference, the electrode plates will deform or move during the evacuation process. Therefore, the design of the main cavity in the existing ionization chamber is also not applicable to the low-pressure ionization chamber in the present invention.

[0059] In the low-pressure ionization chamber of this embodiment, grooves 19 are respectively formed on the upper and lower sides of the main cavity 2 to form a transmission window 9. A first gas flow port 20 is arranged at the edge of the groove 19, and the first gas flow port 20 communicates the groove 19 and the sealed chamber.

[0060] Specifically, the transmission window 9 on the main cavity 2 is formed by milling to form the groove 19. The bottom surfaces of the upper and lower grooves 19 are the transmission window 9. Since the thickness of the transmission window 9 is relatively thin and the distance between the electrode plate and the main cavity 2 is relatively close, it is easy to cause the gas in the groove 19 not to flow, so that a pressure difference is easily formed between the groove 19 and the sealed chamber during negative pressure pumping. Furthermore, due to the pressure, the transmission window 9 is deformed. Therefore, the first gas flow port 20 is provided to enhance the connection between the space in the groove 19 and the sealed chamber, ensure the smooth progress of negative pressure pumping, and avoid the deformation of the transmission window 9.

[0061] Preferably, as Figure 7 and Figure 8 shown, the first gas flow port 20 is a groove formed on the main cavity 2 at the edge of the groove 19, and the internal space of the groove 19 is communicated with the external sealed chamber through the groove opening. In addition, the gas communication port can also be formed by supporting the electrode plate through the protrusion 22 on the main cavity 2 to form a gap between the electrode plate and the main cavity 2, ensuring that there is a gap when the electrode plate is assembled on the main cavity 2, and allowing the gas to flow.

[0062] Preferably, the first gas flow port includes a second notch formed on the electrode plate.

[0063] In the prior art, the electrode plate includes a collecting electrode plate, a high-voltage electrode plate, and an insulating member arranged between the collecting electrode plate and the high-voltage electrode plate. The traditional insulating member is a closed ring, and this insulating member can play a good supporting role for the electrode plate. However, in the present invention, a negative pressure pump is required to pump air inside the ionization chamber to achieve an internal environment lower than the standard atmospheric pressure. The existence of the closed ring will hinder the gas flow. Therefore, the closed ring structure is not applicable to the low-pressure ionization chamber. And if the existing design is adopted, due to the existence of the pressure difference and the unsmooth air flow channel, the electrode plate will move or deform during the air pumping process, which will further affect the distance between the high-voltage electrode and the collecting electrode, affect the total amount of the medium between the high-voltage electrode plate and the collecting electrode plate, and thus affect the generation efficiency of electron-ion pairs, and finally affect the X-ray dose monitoring result.

[0064] In the low-pressure ionization chamber of this embodiment, an insulating member 12 for spacing the collecting electrode 10 and the high-voltage electrode 11 is arranged on the periphery of the collecting chamber. A plurality of insulating members 12 are arranged along the circumferential direction, and a second gas flow port 21 is formed between adjacent two insulating members 12 to facilitate gas flow.

[0065] Specifically, the electrode plate includes three layers. The upper layer is the collector electrode 10, the middle layer is the insulator 12, and the lower layer is the high-voltage electrode 11. In this embodiment, four insulators 12 are arranged between the upper layer and the lower layer, and the four insulators 12 are arranged at intervals along the circumference, which can make the upper layer and the lower layer evenly stressed. At the same time, gas can quickly flow in from the second gas flow port 21 formed by the intervals between the insulators 12, avoiding the deformation or movement of the electrode plate during the vacuum pumping process of the ionization chamber. The deformation of the electrode plate will affect the electric field strength, affect the distance between the high-voltage electrode 11 and the collector electrode 10, and affect the total amount of the medium between the high-voltage electrode plate and the collector electrode plate, thereby affecting the generation efficiency of electron-ion pairs and ultimately affecting the collection effect of electron-ion pairs.

[0066] Preferably, the insulator 12 uses a ceramic sheet, which can play a good insulating role. Compared with using insulating materials such as rubber, which will age under X-ray irradiation, the ceramic sheet has a better radiation resistance and anti-aging effect, thus improving the service life.

[0067] In the low-pressure ionization chamber of this embodiment, the cover plate further includes a lower cover plate 13, and there is also a sealed chamber located between the lower cover plate 13 and the main cavity 2. The lower cover plate 13 and the upper cover plate 1 are oppositely arranged with respect to the main cavity 2, and a transmission window 9 is provided on the lower cover plate 13. First sinking grooves 16 are respectively opened on the upper and lower sides of the main cavity 2 to form an upper sealed chamber and a lower sealed chamber to accommodate the electrode plate assembly.

[0068] Preferably, the entire ionization chamber adopts a centrosymmetric design. The upper and lower sealed chambers are centrosymmetric. The first sinking groove 16 on the upper surface of the main cavity 2 is convex-shaped, and the first sinking groove 16 on the lower surface is convex-shaped with the opposite orientation. The second sinking groove 17 for connecting the gas channel 4 and the wiring groove 18 for wiring are respectively located at both ends of the convex shape.

[0069] The two plugs 7 are located on the same side of the main cavity 2 and are arranged horizontally side by side. The two gas channels 4 are located on the side of the main cavity 2 away from the plugs 7 and are arranged horizontally side by side. The wiring groove 18 and the second sinking groove 17 in the upper sealed chamber are arranged in a staggered manner with the wiring groove 18 and the second sinking groove 17 in the lower sealed chamber, so as to make full use of the main cavity 2 and at the same time reduce the overall thickness of the main cavity 2. Setting the upper and lower sealed chambers can effectively improve the space utilization rate of the entire ionization chamber, increase the volume of the sealed chamber, and make the volume of the treatment head smaller, thereby leaving more treatment space for the patients in the radiotherapy room. In other embodiments, the shape of the first sinking groove 16 includes but is not limited to circular, oval, square, and irregular shapes.

[0070] It should be noted that the positions of the screw holes for connecting the upper electrode plate and the main cavity 2 are offset from those for connecting the lower electrode plate and the main cavity 2. The purpose of this setting is to ensure that the thickness of the main cavity 2 is relatively thin. If the upper and lower screw holes are on the same vertical line, the two originally sealed chambers above and below will be connected. To avoid this situation, the upper and lower screw holes are offset.

[0071] Preferably, the upper and lower cover plates are made of aluminum alloy and are respectively connected to the main cavity 2 by countersunk head screws. The aluminum alloy material has good X-ray transmittance, thus reducing dose loss. The main cavity 2 uses stainless steel, which is easy to weld with the transition pipe 5 and the gas channel 4. Correspondingly, the transition pipe 5 also uses stainless steel material.

[0072] On the other hand, the present application also proposes an accelerator, which includes the low-pressure ionization chamber described in any one of the above embodiments. It can be expected that the accelerator in this embodiment has the beneficial effects of the low-pressure ionization chamber described in any one of the above embodiments, which will not be elaborated here.

[0073] In the present invention, unless otherwise clearly defined and limited, terms such as "installation", "setting", "connection", "fixation", "rotation" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. It can be the communication inside two elements or the interaction relationship between two elements. Unless otherwise clearly defined, for those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0074] Although the embodiments of the present invention have been shown and described in detail, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and deformations can be made to these embodiments without departing from the principles and spirits of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A low pressure ionization chamber, characterized in that: The invention comprises a sealed chamber, wherein a low-pressure environment lower than the standard atmospheric pressure is formed in the sealed chamber, wherein an electrode plate assembly is arranged in the sealed chamber to collect electron-ion pairs in the sealed chamber under the low-pressure environment, wherein the sealed chamber is located between a cover plate and a main cavity, wherein grooves are respectively arranged on the upper and lower sides of the main cavity to form a transmission window, wherein a first gas flow port is arranged at an edge of the groove, wherein the first gas flow port connects the groove and the sealed chamber.

2. The low-pressure ionization chamber according to claim 1, characterized in that: The first gas flow port includes a first notch at the edge of the groove connecting the sealed chamber and the groove.

3. The low-pressure ionization chamber according to claim 1, characterized in that: A protrusion is provided at the edge of the groove, and the protrusion supports the electrode plate assembly to form the first gas flow opening.

4. The low-pressure ionization chamber according to claim 1, characterized in that: The first gas flow port includes a second notch opened on the electrode plate.

5. The low-pressure ionization chamber according to claim 1, characterized in that: The electrode plate assembly includes a collecting electrode and a high-voltage electrode, the collecting chamber is located between the collecting electrode and the high-voltage electrode, and an insulating member for separating the collecting electrode and the high-voltage electrode is disposed at the periphery of the collecting chamber. Several insulating members are disposed circumferentially, and a second gas flow port is formed between two adjacent insulating members to facilitate gas flow.

6. The low-pressure ionization chamber according to claim 5, characterized in that: The insulating member is made of ceramic material.

7. The low-pressure ionization chamber according to any one of claims 1 to 6, characterized in that: The pressure in the sealed chamber ranges from 0.01 atm to 0.5 atm.

8. An accelerator, characterized in that: A low-pressure ionization chamber comprising any one of claims 1-7.

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