Ionization chamber structure

Abstract

The embodiment of the invention provides an ionization chamber structure. The ionization chamber structure comprises an incidence assembly, a collection assembly, a pressure reduction ring, a high-voltage electrode, a collection electrode and an adjustment assembly. The incidence assembly comprises an incidence window. The incident assembly and the collecting assembly are arranged at intervals in the height direction. The multiple pressure reduction rings are arranged in the height direction and detachably arranged at the interval between the incidence assembly and the collection assembly so as to define an ionization cavity with the incidence assembly and the collection assembly. The high-voltage electrode is arranged in the ionization cavity and located on one side of the incidence assembly. The collecting electrode is arranged in the ionization cavity and located on one side of the collecting assembly. The two opposite ends of the adjusting assembly are connected with the incidence assembly and the collecting assembly correspondingly so as to adjust the spacing distance between the incidence assembly and the collecting assembly. The ionization chamber structure provided by the embodiment of the invention is relatively high in universality.

Description

Technical Field

[0001] The present application relates to the technical field of ionization chambers, and in particular to an ionization chamber structure. Background Art

[0002] With the continuous deepening of low-energy X-ray applications, its absolute intensity measurement is required in many fields. For example, in the fields of medicine and industry, low-energy X-rays are widely used in radiotherapy, radiodiagnosis, radiation protection, environmental radiation monitoring and public safety.

[0003] The ionizing radiation measurement of low-energy X-rays is the basis of all these applications. Effective measurement of the dose of low-energy X-rays can ensure the health and safety of workers.

[0004] However, the ionization chamber structure in the related art has poor environmental adaptability and weak versatility. Summary of the invention

[0005] In view of this, the main purpose of the embodiments of the present application is to provide an ionization chamber structure with strong versatility.

[0006] To achieve the above purpose, the technical solution of the embodiment of the present application is implemented as follows:

[0007] The embodiment of the present application provides an ionization chamber structure, including:

[0008] An incident component, the incident component comprising an incident window;

[0009] A collecting component, wherein the incident component and the collecting component are spaced apart in a height direction;

[0010] A plurality of decompression rings arranged along the height direction, wherein the decompression rings are detachably arranged at the interval between the incident component and the collecting component to enclose the incident component and the collecting component to form an ionization chamber;

[0011] A high voltage electrode, which is disposed in the ionization chamber and located on one side of the incident component;

[0012] A collecting electrode, the collecting electrode is arranged in the ionization chamber and located on one side of the collecting component;

[0013] An adjusting component, wherein two opposite ends of the adjusting component are respectively connected to the incident component and the collecting component to adjust the spacing distance between the incident component and the collecting component.

[0014] In one embodiment, the incident component has a plurality of first connecting holes, each of which is arranged at intervals along the circumference of the incident component, and the collecting component has a plurality of second connecting holes, each of which is arranged at intervals along the circumference of the collecting component and corresponds one-to-one to the first connecting holes. The adjusting component includes a plurality of connecting rods and a plurality of adjusting nuts, and the connecting rods can be movably inserted into the first connecting holes and the second connecting holes. The adjusting nuts are respectively provided at the connection points between the connecting rods and the first connecting holes and the second connecting holes, so that the spacing distance between the incident component and the collecting component can be adjusted by the adjusting nuts.

[0015] In one embodiment, the collecting assembly includes a protective electrode, which is arranged around the circumference of the collecting electrode and is spaced apart from the collecting electrode.

[0016] In one embodiment, the high voltage electrode, the protective electrode and the pressure reducing ring are connected in series and electrically connected to a power supply assembly, the protective electrode and the collecting electrode are at the same potential, and a potential difference is formed between the high voltage electrode and the collecting electrode.

[0017] In one embodiment, the high voltage electrode is a first conductive layer disposed on a side of the incident window close to the ionization chamber, and the collecting electrode is a second conductive layer disposed on a side of the collecting component close to the ionization chamber.

[0018] In one embodiment, the thickness of the first conductive layer is greater than or equal to 3 mm and less than or equal to 5 mm.

[0019] In one embodiment, a third conductive layer is provided on the inner surface of the pressure reducing ring, and the incident component, the pressure reducing ring and the collecting component respectively have electrical connection holes so that the first conductive layer, the second conductive layer and the third conductive layer are electrically connected to the power supply component.

[0020] In one embodiment, the ionization chamber structure includes a resistor, and the resistor is provided at least one of between the high voltage electrode and the pressure reducing ring, between adjacent pressure reducing rings, and between the pressure reducing ring and the protective electrode, and the resistance value of the resistor is greater than or equal to 15M and less than or equal to 25M.

[0021] In one embodiment, the incident component includes a shielding plate and a fixing plate, a partial area of ​​the shielding plate is opened to form a mounting hole, and the incident window is fixed in the mounting hole through the fixing plate.

[0022] In one embodiment, the incident window is a polyimide film; and / or,

[0023] The shielding plate is a lead plate; and / or,

[0024] The fixing plate is a copper plate.

[0025] The embodiment of the present application provides an ionization chamber structure, including an incident component, a collecting component, a decompression ring, a high voltage electrode, a collecting electrode and an adjusting component. The incident component includes an incident window. The incident component and the collecting component are arranged at intervals along the height direction. A plurality of decompression rings are arranged along the height direction and can be detachably arranged at the interval between the incident component and the collecting component to enclose the incident component and the collecting component to form an ionization chamber. The high voltage electrode is arranged in the ionization chamber and is located on one side of the incident component. The collecting electrode is arranged in the ionization chamber and is located on one side of the collecting component. The opposite ends of the adjusting component are respectively connected to the incident component and the collecting component to adjust the interval distance between the incident component and the collecting component. Therefore, on the one hand, the interval distance between the incident component and the collecting component is adjusted by the adjusting component, so that the ionization chamber can be adjusted according to radiation of different energies and types, thereby improving the versatility of the ionization chamber structure. On the other hand, the decompression ring is arranged at the interval between the incident component and the collecting component, which can prevent the adjustment component from being damaged due to excessive pressure between the incident component and the collecting component when the adjusting component is fixing the incident component and the collecting component. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic structural diagram of the ionization chamber structure of the first embodiment of the present application;

[0027] Figure 2 for Figure 1 A cross-sectional view of the structure of the medium ionization chamber;

[0028] Figure 3 This is a schematic structural diagram of an incident component according to a second embodiment of the present application;

[0029] Figure 4 for Figure 2 A cross-sectional view of the middle pressure relief ring, wherein the shaded portion in the figure is the third conductive layer;

[0030] Figure 5 A schematic structural diagram of an ionization chamber structure according to a third embodiment of the present application;

[0031] Figure 6 A circuit diagram of an ionization chamber structure according to a fourth embodiment of the present application;

[0032] Figure 7 This is a layout diagram of an ionization chamber saturation curve measurement experiment according to the fifth embodiment of the present application.

[0033] Description of Reference Numerals

[0034] 10. Incident component; 11. Incident window; 10a. First connecting hole; 12. High voltage pole; 13. Shielding plate; 14. Fixing plate; 20. Collecting component; 21. Collecting pole; 20a. Second connecting hole; 20b. Electrical connecting hole; 30. Pressure reducing ring; 41. Connecting rod; 50. Resistor.

[0035] 10. Incident component 10; 11. Incident window 11; 10a. First connecting hole 10a; 12. High voltage pole 12; 13. Shielding plate 13; 14. Fixing plate 14; 20. Collecting component 20; 21. Collecting pole 21; 20a. Second connecting hole 20a; 20b. Electrical connecting hole 20b; 30. Pressure reducing ring 30; 41. Connecting rod 41; 50. Resistor 50. DETAILED DESCRIPTION

[0036] Air kerma is an important parameter for low-energy X-ray quantity transfer. Based on the "ionization method", the low X-ray air kerma dose determination technology is studied.

[0037] When the ionization chamber structure is placed in the pulsed X-ray radiation field, assuming that the charged particle balance is satisfied, the air kerma K of the pulsed X-ray in the sensitive volume of the ionization chamber structure is pulse and the generated charge J g Bragg-Gray equation

[0038] Where K is the X-ray air kerma, W is the average energy consumed to produce a pair of ions in the gas; J g is the total charge of ions of one sign released per unit mass of gas in the cavity, Q g J can be measured by the electronic system g =Q g / m g .

[0039] Among them, m g is the mass of the gas in the cavity m g =V / ρ, V is the volume of the cavity, ρ is the density of the gas in the cavity; It is the ratio of the mass collision stopping power of the medium to the mass collision stopping power of the gas that produces charged ionized particles. The medium should be the outer wall of the cavity ionization chamber structure. This value can be obtained by referring to the ICRU report. W is the average energy consumed to produce a pair of ions in the gas, which can be obtained from the ICRU report. e is the unit ion charge; is the ratio of the mass energy absorption coefficient of the cavity gas and the outer wall of the ionization chamber structure, which can be obtained from the ICRU report; Πk i is the correction factor.

[0040] An embodiment of the present application provides an ionization chamber structure, see Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 6 The ionization chamber structure includes an incident component 10, a collecting component 20, a plurality of pressure reducing rings 30 arranged along the height direction, a high voltage electrode 12, a collecting electrode 21 and an adjusting component.

[0041] The incident component 10 includes an incident window 11 .

[0042] The incident component 10 and the collecting component 20 are arranged at intervals along the height direction.

[0043] The pressure relief ring 30 can be detachably disposed at the interval between the incident component 10 and the collecting component 20 to enclose the incident component 10 and the collecting component 20 to form an ionization chamber.

[0044] The high voltage electrode 12 is disposed in the ionization chamber and is located at one side of the incident component 10 .

[0045] The collecting electrode 21 is disposed in the ionization chamber and is located on one side of the collecting assembly 20 .

[0046] The opposite ends of the adjustment component are respectively connected to the incident component 10 and the collecting component 20 to adjust the spacing distance between the incident component 10 and the collecting component 20.

[0047] Specifically, the incident component 10 refers to a component in the ionization chamber structure for allowing radiation to enter.

[0048] The type of rays is not limited. For ease of description, the rays in the embodiments of the present application are X-rays.

[0049] The incident window 11 refers to a component that allows X-rays to smoothly enter the interior of the ionization chamber structure while reducing the attenuation and scattering of the X-rays during the process of entering the interior of the ionization chamber structure.

[0050] The material type of the incident window 11 is not limited. For example, the incident window 11 is a polyimide film.

[0051] The collecting component 20 refers to a component in the ionization chamber structure that collects charges generated by ionization.

[0052] The high voltage electrode 12 and the collecting electrode 21 are formed in any manner.

[0053] For example, the high voltage electrode 12 is a first conductive layer disposed on a side of the incident window 11 close to the ionization chamber, and the collecting electrode 21 is a second conductive layer disposed on a side of the collecting component 20 close to the ionization chamber.

[0054] Specifically, the first conductive layer has good conductivity and low resistance.

[0055] The first conductive layer may be formed in any manner, for example, by spraying a conductive material on a side of the incident window 11 close to the ionization chamber to form the first conductive layer.

[0056] The thickness of the first conductive layer is not limited, as long as the resistance of the first conductive layer is less than or equal to 5KΩ.

[0057] Exemplarily, the thickness of the first conductive layer is greater than or equal to 3 mm and less than or equal to 5 mm. For example, the thickness of the first conductive layer is 3 mm, 4 mm or 5 mm. Thus, the measurement efficiency of the ionization chamber structure can be improved.

[0058] The second conductive layer has good conductivity and low resistance, thereby significantly improving the ion collection efficiency.

[0059] The second conductive layer may be formed in any manner, for example, by spraying a conductive material on one side of the collecting assembly 20 close to the ionization chamber to form the second conductive layer.

[0060] The type of the conductive material is not limited. For example, the conductive material is a graphite coating agent conductive paint.

[0061] The pressure reducing ring 30 is arranged along the height direction and can be separately placed at the interval between the incident component 10 and the collecting component 20 to form an ionization chamber after being enclosed with the incident component 10 and the collecting component 20. At the same time, it can also adjust the pressure distribution in the chamber and between the incident component 10 and the collecting component 20, which helps to stabilize the ionization process and ensure that the ionization chamber structure can work stably under different environmental conditions.

[0062] The number of the pressure relief rings 30 is not limited and is adjusted according to the spacing between the incident component 10 and the collecting component 20. For example, the number of the pressure relief rings 30 is 2 or more.

[0063] The high voltage electrode 12 is arranged in the ionization chamber at one side of the incident component 10 and opposite to the collecting electrode 21. The high voltage electrode 12 is connected to a high voltage power supply and forms an electric field with the collecting electrode 21, so that the ions generated by the radiation ionization entering the ionization chamber can move in a directional manner under the action of the electric field.

[0064] The collector 21 is disposed in the ionization chamber at one side of the collection assembly 20. The collector 21 collects electrons or ions generated by ionization, and by measuring the amount of charge collected on the collector 21, the radiation dose entering the ionization chamber structure can be measured.

[0065] The material type of the incident component 10, the collecting component 20 and the pressure relief ring 30 is not limited. For example, the material type of the incident component 10, the collecting component 20 and the pressure relief ring 30 is PMMA.

[0066] The adjustment component can adjust the spacing distance between the incident component 10 and the collecting component 20, so that the ionization chamber structure can adapt to different measurement requirements and conditions by changing the size of the internal ionization cavity.

[0067] The embodiment of the present application provides an ionization chamber structure, including an incident component 10, a collecting component 20, a decompression ring 30, a high voltage pole 12, a collecting pole 21 and an adjustment component. The incident component 10 includes an incident window 11. The incident component 10 and the collecting component 20 are arranged at intervals in the height direction. A plurality of decompression rings 30 are arranged in the height direction and can be detachably arranged at the interval between the incident component 10 and the collecting component 20 to enclose the incident component 10 and the collecting component 20 to form an ionization chamber. The high voltage pole 12 is arranged in the ionization chamber and is located on one side of the incident component 10. The collecting pole 21 is arranged in the ionization chamber and is located on one side of the collecting component 20. The opposite ends of the adjustment component are respectively connected to the incident component 10 and the collecting component 20 to adjust the interval distance between the incident component 10 and the collecting component 20. Therefore, on the one hand, the interval distance between the incident component 10 and the collecting component 20 is adjusted by the adjustment component, so that the ionization chamber structure can be adjusted according to radiation of different energies and types, thereby improving the versatility of the ionization chamber structure. On the other hand, a pressure relief ring 30 is provided at the interval between the incident component 10 and the collecting component 20 to prevent the ionization chamber structure from being damaged due to excessive pressure between the incident component 10 and the collecting component 20 when the adjusting component is fixing the incident component 10 and the collecting component 20 .

[0068] In one embodiment, please refer to Figure 1 and Figure 3 The incident component has a plurality of first connection holes 10a, each of which is arranged at intervals along the circumference of the incident component 10; the collecting component 20 has a plurality of second connection holes 20a, each of which is arranged at intervals along the circumference of the collecting component 20 and corresponds to the first connection holes 10a one by one; the adjusting component includes a plurality of connecting rods 41 and a plurality of adjusting nuts, the connecting rods 41 can be movably inserted into the first connecting holes 10a and the second connecting holes 20a, and the connecting rods 41 are connected to the first connecting holes 10a and the second connecting holes 20a respectively. The connecting nuts are respectively provided at the connection points between the connecting rods 41 and the first connecting holes 10a and the second connecting holes 20a, so as to adjust the spacing distance between the incident component 10 and the collecting component 20 through the adjusting nuts. Therefore, on the one hand, through the adjusting component, the ionization chamber structure can quickly adjust the distance between the incident component 10 and the collecting component 20 according to different experimental requirements, thereby improving the adaptability and versatility of the device. On the other hand, by connecting the connecting rod 41 with the first connecting hole 10a and the second connecting hole 20a and fixing them with the adjusting nut, a stable mechanical structure is formed, which can keep the relative position of the incident component 10 and the collecting component 20 stable during the use of the ionization chamber structure, thereby ensuring the normal operation of the ionization chamber structure.

[0069] Specifically, the first connection holes 10a refer to hole structures located on the incident component 10, arranged at intervals along the circumference of the incident component 10, and cooperating with the adjustment component.

[0070] The number of the first connection holes 10a is not limited.

[0071] The second connection holes 20a are hole structures located on the collecting component 20. These holes are arranged at intervals along the circumference of the collecting component 20 and correspond one-to-one with the first connection holes 10a. They are used to cooperate with the adjusting component to realize the connection between the incident component 10 and the collecting component 20.

[0072] The number of the second connection holes 20a is not limited, as long as the number thereof corresponds to the first connection holes 10a.

[0073] The connecting rod 41 can movably pass through the first connecting hole 10a and the second connecting hole 20a. The spacing distance between the incident component 10 and the collecting component 20 can be adjusted by adjusting the relative positions of the first connecting hole 10a and the second connecting hole 20a on the connecting rod 41.

[0074] The material type of the connecting rod 41 is not limited, as long as it has a certain strength and rigidity and can withstand the force generated when adjusting the distance between the incident component 10 and the collecting component 20.

[0075] The number of the connecting rods 41 is not limited, as long as the number thereof corresponds to the first connecting holes 10 a.

[0076] The adjusting nut is installed at the connection between the connecting rod 41 and the first connecting hole 10a and the second connecting hole 20a. By rotating the adjusting nut, the position of the first connecting hole 10a and the second connecting hole 20a on the connecting rod 41 can be changed, thereby adjusting the spacing distance between the incident component 10 and the collecting component 20.

[0077] In one embodiment, the collecting assembly 20 includes a protective electrode, which is arranged around the circumference of the collecting electrode 21 and is spaced apart from the collecting electrode 21. Thus, by providing the protective electrode, the influence of the electric field inhomogeneity and the leakage current can be reduced, thereby improving the measurement accuracy of the ionization chamber structure for ionizing radiation.

[0078] Specifically, the protection electrode is disposed around the circumference of the collector 21 and is spaced apart from the collector 21. That is, the protection electrode is an annular electrode extending around the circumference of the collector 21, and the spaced area between the protection electrode and the collector 21 is an annular spaced area.

[0079] The width of the protective electrode is not limited and can be determined based on actual conditions.

[0080] There is no strict restriction on the spacing distance between the protection electrode and the collecting electrode 21, which can be determined according to actual conditions.

[0081] In one embodiment, please refer to Figure 5 , the high voltage electrode 12, the protective electrode and the pressure reducing ring 30 are connected in series and are electrically connected to the power supply assembly, the protective electrode and the collecting electrode 21 are equipotential, and a potential difference is formed between the high voltage electrode 12 and the collecting electrode 21. Therefore, on the one hand, the protective electrode and the collecting electrode 21 are equipotential, which avoids the problem of inaccurate charge collection caused by uneven electric field or external interference. The ions generated by ionization can smoothly reach the collecting electrode 21 without interference, ensuring the accuracy of the ionization chamber structure in measuring radiation dose. On the other hand, the potential difference between the high voltage electrode 12 and the collecting electrode 21 generates a stable electric field, which provides power for the ionization process.

[0082] Specifically, the equipotentiality of the protective electrode and the collecting electrode 21 means that the protective electrode and the collecting electrode 21 have the same potential in the electric field, thereby ensuring that the collecting electrode 21 can accurately collect the charges generated by ionization without being affected by the uneven electric field.

[0083] A potential difference is formed between the high voltage electrode 12 and the collecting electrode 21. The electric field generated by the potential difference is the driving force for the ions generated by ionization to move within the ionization chamber structure. The potential of the high voltage electrode 12 is greater than the potential of the collecting electrode 21. Thus, the ions can move from the high potential high voltage electrode 12 to the low potential collecting electrode 21.

[0084] In one embodiment, please refer to Figure 1 , Figure 2 and Figure 5 , the inner surface of the pressure reducing ring 30 is provided with a third conductive layer, and the incident component 10, the pressure reducing ring 30 and the collecting component 20 respectively have electrical connection holes 20b, so that the first conductive layer, the second conductive layer and the third conductive layer are electrically connected to the power supply component. By providing the third conductive layer on the inner surface of the pressure reducing ring 30, and providing the electrical connection holes 20b on the incident component 10, the pressure reducing ring 30 and the collecting component 20, a stable and reliable electrical connection between the first conductive layer, the second conductive layer and the third conductive layer is achieved. Thus, it is ensured that the high voltage electrode 12, the collecting electrode 21 and the pressure reducing ring 30 can obtain a stable power supply, maintain the stability of the electric field in the ionization chamber structure, and ensure the smooth progress of the ionization and charge collection process.

[0085] Specifically, the third conductive layer has good conductivity and low resistance.

[0086] The third conductive layer may be formed in any manner. For example, the third conductive layer may be formed by spraying a conductive material on the inner surface of the pressure reducing ring 30 .

[0087] The thickness of the third conductive layer is not limited and can be set according to actual conditions.

[0088] The thickness of the conductive layer will affect the response of the main standard, and the stability of its adhesion determines the long-term stability index and general quality characteristic index of the main standard. It can be seen that the spraying method of the conductive material has a decisive effect on the performance of the conductive layer.

[0089] In a specific embodiment, the method for spraying the conductive material includes:

[0090] Step S1: ultrasonically clean the incident component 10, the collecting component 20 and the decompression ring 30, and wipe them with a dust-free cloth.

[0091] Step S2: Spray the graphite coating agent conductive paint on the sprayed surface multiple times through the nozzle to form a sprayed surface, and the distance between the nozzle and the sprayed surface is greater than or equal to 15 cm and less than or equal to 20 mm. During the spraying process, the hand moves at a slow speed.

[0092] Step S3: Drying the sprayed surface.

[0093] Step S4: Repeat steps S2 and S3 to spray the surface 5 times.

[0094] Step S5: After the spraying is completed, the incident component 10, the collecting component 20 and the decompression ring 30 are placed in a drying machine for drying.

[0095] Step S6: Measure the resistance of the sprayed surface after drying. If the resistance of the sprayed surface is greater than 5 kΩ, repeat step S5 until the resistance is less than or equal to 5 kΩ.

[0096] The electrical connection holes 20b are respectively arranged on the incident component 10, the pressure reducing ring 30 and the collecting component 20. They are channels for realizing electrical connection between the components and between the components and the power supply component. By inserting conductive components (such as wires, etc.) into the electrical connection holes 20b, a stable electrical connection can be established.

[0097] In a specific embodiment, the ionization chamber structure includes a connecting component, which is inserted into the electrical connection hole 20b, and the inner wall of the electrical connection hole 20b is threaded. Therefore, when the connecting component is connected to the electrical connection hole 20b, a more secure connection can be achieved through threaded matching to prevent the connection from loosening due to factors such as vibration during use.

[0098] In a specific embodiment, a sealing structure is provided around the electrical connection hole 20b, thereby preventing moisture, dust, etc. in the external environment from entering the connection portion and affecting the reliability of the electrical connection.

[0099] Specifically, the sealing structure can be designed as an annular groove, in which the sealing ring is embedded, and the sealing ring is sealed and matched with the connecting component.

[0100] In a specific embodiment, the ionization chamber structure includes a signal processor, the collecting component 20 has a signal connection hole, and the collecting electrode 21 is electrically connected to the signal processor through the signal connection hole.

[0101] In one embodiment, please refer to Figure 5 The ionization chamber structure includes a resistor 50, and at least one of the high voltage pole 12 and the pressure relief ring 30, between adjacent pressure relief rings 30, and between the pressure relief ring 30 and the protection pole is provided with a resistor 50, and the resistance value of the resistor 50 is greater than or equal to 15M, and less than or equal to 25M. For example, the resistance value of the resistor 50 is 15M, 20M or 25M. Thus, by setting the resistor 50, it is ensured that the electric field strength of each part in the ionization chamber structure is in a suitable range, and it is avoided that the electric field is too strong or too weak to cause adverse effects on the ionization process and the charge collection process.

[0102] Specifically, the resistor 50 is provided at least one of between the high voltage pole 12 and the pressure reducing ring 30 , between adjacent pressure reducing rings 30 , and between the pressure reducing ring 30 and the protection pole, which means that the position and number of the resistor 50 are not limited.

[0103] For example, the resistor 50 is provided only in one of between the high voltage electrode 12 and the pressure reducing ring 30 , between adjacent pressure reducing rings 30 , and between the pressure reducing ring 30 and the protection electrode.

[0104] For example, the resistor 50 is respectively provided in any two of between the high voltage electrode 12 and the pressure reducing ring 30 , between adjacent pressure reducing rings 30 , and between the pressure reducing ring 30 and the protection electrode.

[0105] For example, resistors 50 are disposed between the high voltage electrode 12 and the pressure reducing ring 30 , between adjacent pressure reducing rings 30 , and between the pressure reducing ring 30 and the protection electrode.

[0106] In one embodiment, please refer to Figure 2 The incident component 10 includes a shielding plate 13 and a fixing plate 14. A hole is opened in a part of the shielding plate 13 to form a mounting hole, and the incident window 11 is fixed in the mounting hole through the fixing plate 14. Therefore, on the one hand, the shielding plate 13 effectively reduces electromagnetic interference and radio frequency interference, ensuring that the measurement result of the ionization chamber structure is more accurate and reliable. On the other hand, the fixing plate 14 is used to fix the incident window 11 in the mounting hole of the shielding plate 13, ensuring the position stability of the incident window 11 during the operation of the ionization chamber structure.

[0107] Specifically, the shielding plate 13 is a part of the incident component 10, and its main function is to block external interference from entering the ionization chamber structure.

[0108] The fixing plate 14 is used to fix the incident window 11 in the mounting hole of the shielding plate 13. It plays the role of fixing and supporting the incident window 11, ensuring the position of the incident window 11 is stable during the operation of the ionization chamber structure, and maintaining the stability of the channel for the rays to enter.

[0109] The mounting hole is a hole of the shielding plate 13 for mounting the incident window 11. Its shape, size and position match the size and shape of the incident window 11 to achieve a stable mounting of the incident window 11.

[0110] The material type of the shielding plate 13 is not limited. For example, the shielding plate 13 is a lead plate.

[0111] The material type of the fixing plate 14 is not limited. For example, the fixing plate is a copper plate.

[0112] In a specific embodiment, a saturation characteristic experiment of an ionization chamber structure is conducted.

[0113] Specifically, the saturation curve of the ionization chamber structure refers to the saturation curve of the ionization chamber structure obtained by increasing the polarization voltage attached to the ionization chamber structure from zero under radiation of a certain intensity, measuring the ionization current output by the ionization chamber structure until the ionization current output by the ionization chamber structure is saturated.

[0114] To test whether the ionization chamber structure is assembled properly, select the appropriate polarization voltage. 137 Cs-γ irradiation device, the geometric center of the ionization chamber structure is 2.5m away from the 137Cs beam outlet, where the true value of the dose rate is about 16.8μGy / h. The experimental layout is as follows Figure 7 As shown, a Unidos E electrometer is used as a high voltage power supply and ionization current measurement device.

[0115] Table 1 records the ionization current values ​​collected by the ionization chamber structure probe at different voltages. 137 The dose rate output by the Cs-γ irradiation device remains unchanged.

[0116] Table 1 Saturation characteristics experiment

[0117]

[0118]

[0119] From Table 1, it can be seen that the ionization chamber structure enters the saturation region after the high voltage exceeds 250 V, and its plateau region is relatively wide. According to the air ionization saturation characteristics, the polarization voltage is selected to be 400 V, which is in the middle of the plateau region.

[0120] In a specific embodiment, the leakage current test is performed through an ionization chamber structure.

[0121] Specifically, the leakage current performance of the ionization chamber structure is related to the performance of the insulating material between the collecting electrode and the protective electrode, and is also related to the cleanliness of the processing equipment. It is an important indicator to measure the performance of the ionization chamber structure. Especially under low dose rate conditions, the leakage current performance will affect the accurate measurement of the ionization current.

[0122] pass 137 The leakage current of the ionization chamber structure is tested using the Cs standard reference radiation field. First, the ionization chamber structure is placed in a sufficiently low background environment to avoid large ionization signals from the background environment; the ionization chamber structure is connected to the electrometer, and the electrical quantity measurement mode is selected after the power is turned on; the maximum working voltage of 400V is applied to the ionization chamber structure, and the zeroing operation is performed after sufficient preheating; the current value is read and the test results are recorded; the average value of the measurement results is calculated as the leakage current test result. The Unidos E electrometer is used as a high-voltage power supply and ionization current measurement device. After applying a 400V polarization voltage to the ionization chamber structure, the leakage of the ionization chamber structure is measured. Table 2 shows that the average value of the leakage measurement results for 10 times is 71.6fA.

[0123] Table 2 Ionization chamber structure leakage current test

[0124]

[0125]

[0126] In a specific embodiment, an ionization chamber structure repeatability study is performed using an ionization chamber structure.

[0127] Specifically, select an air kerma rate of about 1 / 2 of the most sensitive range of the instrument under test and measure it 10 times continuously under the same conditions. Record the dose rate value measured by the device under test and calculate the relative standard deviation. The specific steps include:

[0128] Step S1: Connect the ionization chamber structure to the UNIDOSE electrometer and input the response parameter N (Gy / C); in the X-ray standard radiation field, place the ionization chamber structure within the uniform irradiation field of the X-ray reference radiation field through the mobile trolley and the laser positioning system. The reference point of the ionization chamber structure coincides with the calibration point on the central axis of the irradiation beam. Fix the test device in its calibration direction at the known air kerma rate agreed true value K. T at the measuring point.

[0129] Step S2: The UNIDOSE electrometer applies the maximum operating voltage of 400V to the ionization chamber structure and performs a zeroing operation after preheating.

[0130] Step S3: Measure the background reading K of the measuring point without turning on the irradiation device IB , record the readings for no less than 10 times.

[0131] Step S4: Select the agreed true value K of the air kerma rate through the ray device control system in the main control room T The corresponding radiation quality.

[0132] Step S5: Open the shielding door of the γ irradiation device, wait for 5 minutes for stabilization, and then start a set of measurements and record the dose rate, with no less than 10 sets of data.

[0133] Step S6: Turn off the X-ray irradiation device and select the next agreed true value K of the air kerma rate T Corresponding to the radiation source, the mobile calibration vehicle is accurately positioned at the measurement point.

[0134] Step S7: Repeat steps S1 to S6 to measure and record, as shown in Table 3.

[0135] Table 3 Repeatability experiment

[0136]

[0137] In a specific embodiment, the ionization chamber structure linear response measurement is performed by the ionization chamber structure.

[0138] Specifically, in 137 The linear response measurement of the ionization chamber structure is carried out in the Cs-γ standard reference radiation field. The ionization chamber structure is directly opposite to the beam outlet, and the geometric center of the ionization chamber structure is 1m away from the beam outlet of the optical machine. The principle is to place the standard instrument at the calibration point of the radiation field, obtain the dose standard value through measurement, and then accurately place the calibrated instrument at the same position and make the reference point of the calibrated instrument coincide with the calibration point, obtain the instrument reading through measurement, and compare the measurement results of the two to obtain the calibration factor, as shown in formula (1).

[0139]

[0140] Where R is the calibration factor of the ionization chamber structure, dimensionless; is the reference value of the radiation field, in Gy / h; It is the measurement value of the ionization chamber structure after temperature and pressure correction, and the unit is Gy / h.

[0141] The linear response measurement results of the ionization chamber structure are shown in Table 4.

[0142] Table 4 Linear response measurement results of ionization chamber structure

[0143]

[0144]

[0145] In a specific embodiment, N series of X-ray reference radiation mass-energy response experiments are carried out using an ionization chamber structure.

[0146] Specifically, using an N-series X-ray reference radiation mass, the calibration factors of the ionization chamber structure are measured in the reference radiation field, and the response at each energy is calculated. 137 The response of the Csγ reference radiation is normalized, and the normalized response value is:

[0147] In the formula, R' E is the energy response value of the ionization chamber structure, dimensionless; R E is the ionization chamber structure calibration factor at each energy, dimensionless; R CS for 137 Ionization chamber structure calibration factor for Cs-γ reference radiation, dimensionless. Ionization chamber structure energy response measurement, the results are shown in Table 5.

[0148] Table 5 Experimental results of the mass-energy response of the N series X-ray reference radiation

[0149]

[0150] In the description of the present application, the description with reference to the terms "in one embodiment", "in some embodiments", "in a specific embodiment", or "exemplary" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In the present application, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine different embodiments or examples described in the present application and the features of different embodiments or examples without contradiction.

[0151] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application are included in the protection scope of the present application.

Claims

1. An ionization chamber structure, characterized in that: include: An incident component, the incident component comprising an incident window; A collecting component, wherein the incident component and the collecting component are spaced apart in a height direction; A plurality of decompression rings arranged along the height direction, wherein the decompression rings are detachably arranged at the interval between the incident component and the collecting component to enclose the incident component and the collecting component to form an ionization chamber; A high voltage electrode, which is disposed in the ionization chamber and located on one side of the incident component; A collecting electrode, the collecting electrode is arranged in the ionization chamber and located on one side of the collecting component; An adjusting component, wherein two opposite ends of the adjusting component are respectively connected to the incident component and the collecting component to adjust the spacing distance between the incident component and the collecting component.

2. The ionization chamber structure according to claim 1, characterized in that: The incident component has a plurality of first connecting holes, each of which is arranged at intervals along the circumference of the incident component. The collecting component has a plurality of second connecting holes, each of which is arranged at intervals along the circumference of the collecting component and corresponds one-to-one to the first connecting holes. The adjusting component includes a plurality of connecting rods and a plurality of adjusting nuts, the connecting rods can be movably inserted into the first connecting holes and the second connecting holes, and the adjusting nuts are respectively provided at the connection between the connecting rods and the first connecting holes and the second connecting holes, so that the spacing distance between the incident component and the collecting component can be adjusted by the adjusting nuts.

3. The ionization chamber structure according to claim 1, characterized in that: The collecting assembly includes a protection electrode, which is arranged around the circumference of the collecting electrode and is spaced apart from the collecting electrode.

4. The ionization chamber structure according to claim 3, characterized in that: The high-voltage electrode, the protective electrode and the pressure reducing ring are connected in series and are electrically connected to a power supply assembly. The protective electrode and the collecting electrode have the same electric potential, and a potential difference is formed between the high-voltage electrode and the collecting electrode.

5. The ionization chamber structure according to any one of claims 1 to 3, characterized in that: The high voltage electrode is a first conductive layer arranged on a side of the incident window close to the ionization chamber, and the collecting electrode is a second conductive layer arranged on a side of the collecting component close to the ionization chamber.

6. The ionization chamber structure according to claim 5, characterized in that: The thickness of the first conductive layer is greater than or equal to 3 mm and less than or equal to 5 mm.

7. The ionization chamber structure according to claim 5, characterized in that: A third conductive layer is provided on the inner surface of the decompression ring, and the incident component, the decompression ring and the collecting component respectively have electrical connection holes to electrically connect the first conductive layer, the second conductive layer and the third conductive layer to the power supply component.

8. The ionization chamber structure according to claim 3, characterized in that: The ionization chamber structure includes a resistor, and the resistor is arranged at least one of between the high-voltage electrode and the pressure-reducing ring, between adjacent pressure-reducing rings, and between the pressure-reducing ring and the protective electrode. The resistance value of the resistor is greater than or equal to 15M and less than or equal to 25M.

9. The ionization chamber structure according to any one of claims 1 to 4, characterized in that: The incident component comprises a shielding plate and a fixing plate. A hole is opened in a partial area of ​​the shielding plate to form a mounting hole. The incident window is fixed in the mounting hole through the fixing plate.

10. The ionization chamber structure according to claim 9, characterized in that: The incident window is a polyimide film; and / or, The shielding plate is a lead plate; and / or, The fixing plate is a copper plate.

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