Intermediate energy ionization chamber system

Abstract

The invention provides an intermediate-energy ionization chamber system, which comprises a low-vacuum ionization chamber and an air exhaust and inflation system communicated with the low-vacuum ionization chamber, the low-vacuum ionization chamber comprises a main cavity and two end face flanges arranged at the upstream and downstream of the main cavity, the end face flanges are provided with Be windows, and the thickness of each end face flange is 25-200 [mu] m; the air exhaust and inflation system comprises a first pressure adjusting pipeline, a second air exhaust pipeline and a third air exhaust pipeline, wherein the air exhaust rates of the first pressure adjusting pipeline, the second air exhaust pipeline and the third air exhaust pipeline are sequentially increased, and the first pressure adjusting pipeline has the air exhaust function and the air inflation function. The intermediate-energy ionization chamber system is provided with a plurality of air exhaust pipelines, so that the extrusion of pressure change in the cavity to the sealing window at the moment of vacuumizing can be reduced, and the cavity can be vacuumized at a relatively high speed.

Description

Technical Field

[0001] The invention belongs to the field of X-ray flux testing, and in particular relates to a medium-energy ionization chamber system. Background Art

[0002] Synchrotron X-ray absorption spectroscopy (XAS) technology can analyze the coordination environment, chemical state and electronic structure around the absorbing atoms, and plays a key role in the dynamic reconstruction and reaction mechanism research of catalyst surfaces; the transformation law and pollution migration mechanism of heavy metals in the environment; the ion intercalation pathway and capacity attenuation mechanism in electrode materials, and the nutrient absorption mechanism of plants.

[0003] Accurately measuring the incident X-ray flux, I0, is crucial for obtaining high-quality spectroscopic data. Different detection equipment is used for I0 monitoring in different energy ranges. For example, for soft X-rays with energies below 2keV, XAS oscillations are strong, and monitoring the flux using metal mesh or foil is fully sufficient for XAS testing.

[0004] For medium-energy and hard X-rays above 2 keV, the extended edge fine structure (EXAFS) component of XAS exhibits gentle oscillations. Previous monitoring solutions no longer meet these requirements. The excellent linear relationship between energy and flux in gas ionization chambers can meet these requirements. However, strong absorption of medium-energy X-rays (between 2 and 5 keV) by the gas ionization chamber window sealant and the chamber filler gas results in an orders-of-magnitude reduction in the X-ray flux incident on the sample, rendering it unusable. Current commercial ionization chambers exhibit significant absorption of low-energy X-rays, resulting in a sharp decrease in the X-ray flux reaching the sample, effectively substandard sample flux. It is important to note that according to theoretical formulas, the optimal absorption of the incident X-ray flux by the ionization chamber used in absorption spectrum testing is 20%.

[0005] Therefore, there is an urgent need to design a new medium-energy ionization chamber system to ensure accurate measurements of medium-energy XAFS experiments. Summary of the Invention

[0006] The object of the present invention is to provide a medium energy ionization chamber system, which can reduce the pressure change in the chamber at the moment of vacuuming on the sealing window and can vacuum the chamber at a faster speed.

[0007] To achieve the above-mentioned object, the present invention provides a medium-energy ionization chamber system, comprising a low-vacuum ionization chamber and an exhaust and inflation system connected to the low-vacuum ionization chamber, wherein the low-vacuum ionization chamber comprises a main cavity, two end flanges arranged upstream and downstream of the main cavity, the end flanges being equipped with Be windows having a thickness of 25-200 μm; the exhaust and inflation system comprises a first pressure regulating pipeline, a second exhaust pipeline, and a third exhaust pipeline, the exhaust rates of which increase successively, and the first pressure regulating pipeline has both exhaust and inflation functions.

[0008] Preferably, the first pressure regulating pipeline includes an air intake leakage valve, a first three-way pipeline, and a pre-extraction needle valve which are sequentially connected in series through a pressure regulating pipeline from a low vacuum ionization chamber.

[0009] Preferably, one end of the first three-way pipe other than the end connected to the pressure regulating pipe is connected to an air intake pipe, and the air intake pipe is connected to the air distribution system through a valve.

[0010] Preferably, the second exhaust pipeline includes a slow exhaust angle valve and a second exhaust pipeline, and the slow exhaust angle valve adopts a 1 / 4 inch needle valve; the third exhaust pipeline includes a fast exhaust angle valve and a third exhaust pipeline, the fast exhaust angle valve adopts an ordinary angle valve, and the third exhaust pipeline adopts a bellows.

[0011] Preferably, one end of the first pressure regulating pipeline, the second exhaust pipeline and the third exhaust pipeline is connected to the low vacuum ionization chamber, and the other end is connected to the vacuum pump through a four-way pipeline.

[0012] Preferably, the Be window has a thickness of 25 μm.

[0013] Preferably, the main cavity of the vacuum ionization chamber is connected to a vacuum gauge via a fifth side flange.

[0014] Preferably, the distance from the end surface of the fifth side flange to the outer wall surface of the main cavity is at least 4 cm.

[0015] Preferably, the medium energy ionization chamber system further comprises an ionization chamber adjustment mechanism, and the low vacuum ionization chamber is fixed above the ionization chamber adjustment mechanism; the ionization chamber adjustment mechanism comprises a group of orthogonally placed translation motors.

[0016] Preferably, the ionization chamber adjustment mechanism further includes a bottom mounting plate below the translation motor, and the low vacuum ionization chamber is fixed above the ionization chamber adjustment mechanism through a support system.

[0017] In another aspect, the present invention provides a method for using a medium energy ionization chamber system, comprising:

[0018] S0: Provide a medium energy ionization chamber system according to the above description;

[0019] S1: Open the first pressure regulating pipeline, the second exhaust pipeline and the third exhaust pipeline in sequence to pump the low vacuum ionization chamber to high vacuum;

[0020] S2: Using the first pressure regulating pipeline, replenishing gas to the low vacuum ionization chamber that has been evacuated to high vacuum;

[0021] S3: Based on the energy range requirements of the test, execute step S2 again to continue replenishing the gas; or, vacuum clean the first pressure regulating pipeline and then use the first pressure regulating pipeline to replenish the gas.

[0022] The medium energy ionization chamber system of the present invention is equipped with multiple exhaust pipes, which can reduce the pressure change in the chamber at the moment of vacuuming on the sealing window and can vacuum the chamber at a faster speed.

[0023] Furthermore, the present invention achieves appropriate control of the gas flow rate into the ionization chamber by closely monitoring the pressure, ensuring that the pressure of the gas within the chamber is precisely within the required range. This maintains the excellent linear relationship between energy and flux found in conventional gas ionization chambers, while also adjusting the ionization chamber's absorption ratio of incident X-ray energy by regulating the gas pressure, meeting the testing requirements of medium-energy XAFS.

[0024] Furthermore, in order to ensure that the X-rays can completely pass through the upstream and downstream windows of the low vacuum ionization chamber, the ionization chamber adjustment mechanism of the ionization chamber has a certain fine-tuning function to ensure that the center line connecting the upstream and downstream windows of the low vacuum ionization chamber can be adjusted to a position that basically coincides with the center of the X-rays. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a three-dimensional structural diagram of a low vacuum ionization chamber.

[0026] Figure 2 This is the overall structural diagram of the air extraction and inflation system.

[0027] Figure 3 This is a three-dimensional structural diagram of the first pipeline.

[0028] Figure 4 This is a three-dimensional structural diagram of the second and third pipelines.

[0029] Figure 5 This is a partial enlarged view of the connection between the second and third exhaust pipelines and the low vacuum ionization chamber.

[0030] Figure 6 This is a schematic diagram of the installation of the low vacuum ionization chamber, support system and ionization chamber adjustment mechanism.

[0031] Figure 7 yes Figure 6 Exploded diagram. DETAILED DESCRIPTION

[0032] The preferred embodiments of the present invention are given below in conjunction with the accompanying drawings and described in detail.

[0033] like Figure 1-Figure 7 As shown, the medium-energy ionization chamber system of the present invention includes a low-vacuum ionization chamber 10, an exhaust and inflation system 20, a support system 30, and an ionization chamber adjustment mechanism 40. The low-vacuum ionization chamber 10 is fixed above the ionization chamber adjustment mechanism 40 via the support system 30. The support system 30 is used to connect and secure the low-vacuum ionization chamber 10 and the ionization chamber adjustment mechanism 40. The ionization chamber adjustment mechanism 40 is used to adjust the position of the low-vacuum ionization chamber. The exhaust and inflation system 20 is in communication with the low-vacuum ionization chamber 10.

[0034] By reducing the pressure of the ionization chamber's filling gas (e.g., air at several kilopascals or Ar at tens of torr), the present invention ensures that the linearity of test energy and flux is maintained while ensuring that the flux monitoring device's X-ray absorption meets the optimal theoretical value (approximately 20%) required for XAFS testing. To ensure that the filling gas pressure within the ionization chamber remains stable within the experimentally required pressure range for an extended period, the medium-energy ionization chamber's cavity should be designed using ultra-high vacuum standards, i.e., a low-vacuum ionization chamber 10.

[0035] The low vacuum ionization chamber 10 is installed on the synchrotron radiation beamline and is used to measure medium energy X-rays. The low vacuum ionization chamber 10 adopts ultra-high vacuum design requirements to ensure that the gas filled into the main cavity of the ionization chamber can maintain a low vacuum state of tens of Torr for a long time. The overall structure is shown in the figure below. Figure 1 As shown, the low vacuum ionization chamber 10 includes a main cavity 1, two end flanges 2 arranged upstream and downstream of the main cavity, and five side flanges connected to the main cavity 1 (including a first side flange 3, a second side flange 4, a third side flange 5, a fourth side flange 6, and a fifth side flange 7).

[0036] The end flange 2 is preferably a CF35 standard flange, and the side flange is preferably a CF16 standard flange. All end flanges 2 and side flanges are sealed with oxygen-free copper sealing rings to ensure that the low vacuum ionization chamber 10 can maintain a low vacuum state of tens of Torr for a long time.

[0037] The main chamber 1 is preferably a standard pipe. It is equipped with multiple electrode plates and a plate holder for securing them. The plates are made of pure copper plated with nickel, with an effective length of 15 cm, a spacing of 17.5 cm between the plates, and a width of 17.5 cm. The plate holder is made of a high-vacuum-compatible ceramic material. It should be noted that the internal structure of the low-vacuum ionization chamber is identical to conventional ionization chambers on the market and is not covered by this patent.

[0038] The first side flange 3 features a BNC port for receiving low-current signals, while the second side flange 4 features an SHV port for supplying high voltage to the plate. The plate connects to external electronics and a high-voltage power supply via vacuum feedthroughs (i.e., the BNC and SHV ports) fixed to the first and second side flanges 3 and 4, respectively, thereby receiving and providing electrical signals from the outside world.

[0039] The main chamber 1 is connected to a vacuum gauge via the fifth side flange 7, so that the main chamber 1 monitors the vacuum level within the low vacuum ionization chamber 10 via the vacuum gauge on the fifth side flange 7. The distance between the end face of the fifth side flange 7 and the outer wall of the main chamber 1 is at least 4 cm. This connection method can reduce the influence of the vacuum gauge on the plate signal within the main chamber 1 and prevent crosstalk between the low vacuum ionization chamber and the vacuum gauge.

[0040] The end flange 2 is fitted with a Be window (i.e., a Be window) that serves to separate the upstream and downstream sides of the synchrotron radiation beamline and allow X-rays to pass through. The Be window is preferably 25 μm thick. Because the low-vacuum ionization chamber 10 is designed for medium-energy X-rays, the present invention utilizes a Be window as the ionization chamber window sealing material. Based on current commercial standards and costs, a thin 25 μm Be window is selected. This ensures the window can withstand a pressure differential of one atmosphere while significantly reducing absorption of low-energy X-rays. Currently, the maximum diameter of a commercially available 25 μm Be window is 13 mm. Therefore, this design utilizes a Be window of this specification.

[0041] To accurately calculate the X-ray flux detected by a medium-energy ionization chamber, the purity and pressure of the gases used within the chamber must be precisely controlled. This typically requires evacuating the chamber chamber before injecting the gas at the required pressure. Furthermore, if the chamber pressure exceeds the required range due to leak rates and other factors, the evacuation and refilling operations must be repeated. Therefore, compared to conventional ionization chambers, medium-energy ionization chambers must be designed to ultra-high vacuum standards and equipped with both evacuation and refilling systems.

[0042] Although commercial Be windows can withstand a pressure differential of one atmosphere, they can still rupture due to the sudden pressure change during the ionization chamber vacuum pumping / breaking. A ruptured window during operation can disrupt the vacuum of the entire synchrotron radiation facility and even cause serious consequences (such as a full-circle beam kick). Therefore, the pumping system of a medium-energy ionization chamber must not only provide vacuum pumping but also mitigate the sudden pressure change within the chamber during pumping. This is referred to as a slow pumping system. Similarly, a slow pumping system is required to ensure that the Be window does not break during the instantaneous filling of the medium-energy ionization chamber under vacuum, and to precisely control the flow rate of the filling system to ensure that the filling pressure within the chamber remains within the desired range. Therefore, a protection system is essential to prevent damage to the low-vacuum ionization chamber caused by rapid filling and pumping, and to prevent a vacuum break caused by a sudden pressure differential exceeding one atmosphere.

[0043] Secondly, the gas pressure in the ionization chamber is closely related to the absorption of the monitored X-ray flux by the ionization chamber, so the pressure value of the gas in the ionization chamber must be closely monitored, and the air flow rate into the ionization chamber must be properly controlled to ensure that the pressure value of the gas in the ionization chamber is exactly within the required range.

[0044] In addition, to ensure that the gas entering the medium energy ionization chamber is not contaminated by the air in the inflation pipe, which would cause a change in purity, the pipe must be vacuumed and pre-sweeped before inflation. Therefore, the inflation pipe must have a pre-sweep function.

[0045] The pumping and filling system 20 is used to pump air down to a high vacuum and then fill it with a specific gas, thereby creating a low vacuum environment within the low-vacuum ionization chamber 10. Because the intermediate-energy ionization chamber system of the present invention resides within a high-vacuum optical path, and the optical path connected to the system is always in a high-vacuum environment, the first requirement for the intermediate-energy ionization chamber system of the present invention is safety, and experimental efficiency must also be considered. Therefore, this case innovatively utilizes multiple pumping systems with different pumping speeds.

[0046] like Figure 2 As shown, in this embodiment, the exhaust and inflation system 20 includes a first pressure regulating line 21, a second exhaust line 22, and a third exhaust line 23, each with different pumping speeds. The first pressure regulating line 21 performs both exhaust and inflation functions. The exhaust rates of the first pressure regulating line 21, the second exhaust line 22, and the third exhaust line 23 increase in sequence. Slow exhaust speeds ensure vacuum safety, while fast exhaust speeds improve exhaust efficiency. These three lines work together to balance safety and efficiency.

[0047] One end of the first pressure regulating pipeline 21 , the second exhaust pipeline 22 and the third exhaust pipeline 23 are connected to the low vacuum ionization chamber 10 , and the other ends are connected to the vacuum pump 24 through the four-way pipeline 25 .

[0048] In this embodiment, the first pressure regulating pipeline 21 is connected to the fourth side flange 6 of the low vacuum ionization chamber, and the second exhaust pipeline 22 and the third exhaust pipeline 23 are connected to the third side flange 5 of the low vacuum ionization chamber 10 through the second three-way pipe 26.

[0049] like Figure 3 As shown, the first pressure regulating pipeline 21 has both the functions of exhausting and charging. The first pressure regulating pipeline 21 includes an air inlet leakage valve 212, a first three-way pipeline 213, and a pre-extraction needle valve 214 connected in series from the low vacuum ionization chamber 10 through a pressure regulating pipeline 211.

[0050] The air inlet leakage valve 212 is a solenoid valve whose opening and closing can be remotely controlled by software. The air inlet leakage valve 212 is set to open when pumping and filling the low vacuum ionization chamber 10, and closed at all other times. The low vacuum ionization chamber 10 requires different filling gases depending on the operating state. Therefore, the air must be pumped out first to remove any residual gas inside the chamber, and then filled with the required gas. Therefore, the air inlet valve needs to be opened and closed at different times depending on the operating state.

[0051] The pre-pump needle valve 214 is a 1 / 16-inch needle valve used for fine-tuning the pumping rate.

[0052] One end of the first three-way pipe 213 other than the one connected to the pressure regulating pipe 211 is connected to an air intake pipe 215 . The air intake pipe 215 is used to connect to a gas distribution system through a valve, so that gas with a specific ratio can be filled in.

[0053] As described above, the second exhaust pipeline 22 and the third exhaust pipeline 23 are both connected to the third side flange 5 of the low vacuum ionization chamber 10 through the second three-way pipeline 26, and the other ends are connected to the vacuum pump 24 through the four-way pipeline 25.

[0054] The second and third exhaust lines 22 and 23 are both exhaust lines, each suitable for different exhaust rates. Slow exhaust rates ensure vacuum safety, while fast exhaust rates improve exhaust efficiency. The second exhaust line 22 includes a slow exhaust angle valve 221 and a second exhaust pipe 222. The slow exhaust angle valve 221 uses a 1 / 4-inch needle valve, and the second exhaust pipe 222 uses a conventional vacuum pipe. The third exhaust line 23 includes a fast exhaust angle valve 231 and a third exhaust pipe 232. The fast exhaust angle valve 231 uses a conventional angle valve, and the third exhaust pipe 232 uses a bellows to provide a high exhaust speed and facilitate assembly.

[0055] Figure 5 A partial enlarged view of the connection between the second exhaust pipeline 22 and the third exhaust pipeline 23 and the low vacuum ionization chamber is shown, in which the specific positions of the second three-way pipe 26, the fast exhaust angle valve 231, and the slow exhaust angle valve 221 are shown.

[0056] Since the light-transmitting window size of commercially available Be windows ≤25 microns thick is relatively small (maximum diameter 13 mm), the light spot size of the medium-energy experimental station near the low-vacuum ionization chamber 10 is likely to be similar (the bent iron light source can even reach 6 mm by 10 mm). Furthermore, to reduce the absorption of radiation by excessive window material, the upstream window of the low-vacuum ionization chamber 10 also serves as a sealed window at the end of the entire high-vacuum X-ray optical path (i.e., the low-vacuum ionization chamber 10 is directly connected to the optical path). Therefore, to ensure that the slightly smaller light spot can pass through the sealed window, the fixing and position adjustment of the ionization chamber are particularly important. To ensure that X-rays can completely pass through the upstream and downstream windows of the low-vacuum ionization chamber 10, the ionization chamber adjustment mechanism has a certain fine-tuning function to ensure that the center line connecting the upstream and downstream windows of the low-vacuum ionization chamber 10 can be adjusted to a position that basically coincides with the center of the X-ray.

[0057] Figure 6 FIG. 1 is a diagram showing the installation of the low vacuum ionization chamber 10, the support system 30, and the ionization chamber adjustment mechanism 40. Figure 6 As shown, the low vacuum ionization chamber 10 is fixed above the ionization chamber adjustment mechanism 40 through a support system 30 .

[0058] like Figure 6 and Figure 7 As shown, the support system 30 includes a support member 31 for supporting the low vacuum ionization chamber 10 and a clamp 32 that cooperates with the support member 31 to secure the low vacuum ionization chamber 10. The support member 31 is used to support the low vacuum ionization chamber with an accuracy of ±1 mm. The clamp is used to secure the low vacuum ionization chamber 10 to the groove of the support member 31.

[0059] The ionization chamber adjustment mechanism 40 includes a set of orthogonally positioned translation motors that provide movement in two orthogonal directions within a plane perpendicular to the X-ray optical path. The translation motors include a vertical motor 41 that provides vertical movement, and a horizontal motor 42 that provides horizontal movement perpendicular to the X-ray optical path. The ionization chamber adjustment mechanism 40 also includes a bottom mounting plate 43 below the translation motors for mounting them in a desired position.

[0060] The support member 31 and the bottom mounting plate 43 are provided to adjust the adaptability of the mechanism. When the low vacuum system is used in different experimental environments, only the structure of the bottom mounting plate 43 and the height of the support member 31 need to be adjusted.

[0061] Based on the medium energy ionization chamber system described above, the method for using the medium energy ionization chamber system specifically includes:

[0062] Step S0: providing the medium energy ionization chamber system described above;

[0063] Step S1: Open the first pressure regulating pipeline 21, the second exhaust pipeline 22 and the third exhaust pipeline 23 in sequence to evacuate the low vacuum ionization chamber 10 to a high vacuum;

[0064] Step S1 specifically includes:

[0065] Step S11: closing the slow extraction angle valve of the second exhaust pipeline 22 and the fast extraction angle valve of the third exhaust pipeline 23, and opening the pre-extraction needle valve and the air intake leakage valve of the first pressure regulating pipeline 21;

[0066] Step S12: Turn on the vacuum pump to slowly evacuate the first pressure regulating pipeline 21;

[0067] Step S13: Observe the reading of the vacuum gauge of the low vacuum ionization chamber 10. When the vacuum degree in the main cavity 1 of the low vacuum ionization chamber 10 reaches 10 Torr, open the slow pumping angle valve of the second exhaust line 22 to allow the second exhaust line 22 to be evacuated at a medium speed.

[0068] Step S14: Read the vacuum gauge of the low vacuum ionization chamber 10. When the vacuum degree in the main cavity 1 of the low vacuum ionization chamber 10 reaches 10-2 torr, open the fast extraction angle valve of the third exhaust line 23 to quickly evacuate the third exhaust line 23 to a high vacuum.

[0069] That is to say, the vacuum range of the first pipeline is from atmospheric pressure to 10 torr; the vacuum range of the second pipeline is from 10 torr to 10-2 torr; and the vacuum range of the third pipeline is from 10-2 torr to very high vacuum.

[0070] Step S15: Read the vacuum gauge of the low vacuum ionization chamber 10. When the vacuum degree in the main cavity 1 of the low vacuum ionization chamber 10 reaches 10-7 torr or above, close the fast-draw angle valve and the slow-draw angle valve.

[0071] Since the pumping speed varies with the vacuum degree, this pumping method can greatly reduce the impact of the pump group on the ionization chamber sealing window at the moment of vacuuming to protect the experimental optical path, and can also ensure an overall faster pumping rate.

[0072] Step S2: using the first pressure regulating pipeline 21 to replenish gas to the low vacuum ionization chamber 10 evacuated to a high vacuum;

[0073] Step S2 specifically includes:

[0074] Step S21: confirming that the vacuum level in the chamber is above 10-7 torr;

[0075] In this case, if the pumping process has just been completed, keep the pre-pumping needle valve and the air inlet leak valve open and confirm that the vacuum degree in the chamber is above 10-7 Torr.

[0076] Step S22: closing the pre-evacuation needle valve and the air intake valve of the first pressure regulating pipeline 21, and opening the valve of the gas distribution system to allow the mixed gas to enter the first pressure regulating pipeline 21;

[0077] The gas distribution system can provide one of the following gases (pure gas) or a mixture of helium, nitrogen, argon, and xenon. The gas to be filled depends on the experimental requirements.

[0078] Step S23: Slowly open the air inlet valve through the computer to allow the mixed gas to slowly enter the low vacuum ionization chamber. When the vacuum gauge shows that the gas pressure has reached the required level (e.g., within a few tens of Torr), close the air inlet valve.

[0079] Step S3: according to the energy range requirement of the test, execute step S2 again to continue to replenish gas; alternatively, vacuum clean the first pressure regulating pipeline 21 and then use the first pressure regulating pipeline 21 to replenish gas.

[0080] That is to say, if the same type of gas is already in the low vacuum ionization chamber, the gas can be continuously replenished; or in order to fill other types of mixed gases, the inflation pipe can be vacuum cleaned and then the gas can be replenished.

[0081] The first pressure regulating pipeline 21 is vacuum-cleaned and then gas is replenished, specifically including:

[0082] Step S31: closing the pre-pump needle valve and the air intake leakage valve of the first pressure regulating pipeline 21;

[0083] Step S32: Turn on the vacuum pump and the pre-evacuation needle valve and keep them on for 10 minutes to vacuum clean the first pressure regulating pipeline 21;

[0084] Step S33 : closing the pre-extraction needle valve of the first pressure regulating pipeline 21 , and opening the valve of the gas distribution system to allow the mixed gas to enter the first pressure regulating pipeline 21 .

[0085] Step S34: Repeat step S33 until the pressure in the low vacuum ionization chamber reaches a desired range.

[0086] The medium energy ionization chamber system of the present invention is equipped with multiple exhaust pipes, which can not only reduce the pressure change in the chamber at the moment of vacuuming on the sealing window (protective window), but also can vacuum the chamber at a faster speed.

[0087] Furthermore, the present invention achieves appropriate control of the gas flow rate into the ionization chamber by closely monitoring the pressure, ensuring that the pressure of the gas within the chamber is precisely within the required range. This maintains the excellent linear relationship between energy and flux found in conventional gas ionization chambers, while also adjusting the ionization chamber's absorption ratio of incident X-ray energy by regulating the gas pressure, meeting the testing requirements of medium-energy XAFS.

[0088] Furthermore, in order to ensure that the X-rays can completely pass through the upstream and downstream windows of the low vacuum ionization chamber 10, the ionization chamber adjustment mechanism of the ionization chamber has a certain fine-tuning function to ensure that the center line of the upstream and downstream windows of the low vacuum ionization chamber 10 can be adjusted to a position that basically coincides with the center of the X-rays.

[0089] According to the energy range of the medium-energy experimental station, with the reasonable selection of the subsequent electronic system, a reasonable gas filling amount can be set for the ionization chamber (determining the type of filling gas in the cavity and the pressure value in the cavity after filling), so that the medium-energy ionization chamber can monitor the flux of the entire energy range of the experimental station under the same state, reducing the window rupture caused by frequent replacement of the ionization chamber filling gas due to frequent replacement of test elements.

[0090] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Various modifications and variations are possible. In other words, any simple, equivalent changes and modifications made in accordance with the claims and description of the present invention are within the scope of protection of the patent claims. Anything not fully described in this invention constitutes conventional technology.

Claims

1. A medium energy ionization chamber system, characterized in that: The invention comprises a low vacuum ionization chamber and an exhaust and inflation system connected to the low vacuum ionization chamber, wherein the low vacuum ionization chamber comprises a main cavity and two end flanges arranged upstream and downstream of the main cavity, wherein the end flanges are provided with Be windows having a thickness of 25-200 μm; the exhaust and inflation system comprises a first pressure regulating pipeline, a second exhaust pipeline and a third exhaust pipeline, wherein the exhaust rates of the first pressure regulating pipeline increase successively, and the first pressure regulating pipeline has both exhaust and inflation functions.

2. The medium energy ionization chamber system according to claim 1, characterized in that: The first pressure regulating pipeline includes an air intake leakage valve, a first three-way pipeline, and a pre-extraction needle valve which are sequentially connected in series through a pressure regulating pipeline from a low vacuum ionization chamber.

3. The medium energy ionization chamber system according to claim 2, characterized in that: One end of the first three-way pipe other than the pressure regulating pipe is connected to an air intake pipe, and the air intake pipe is connected to the air distribution system through a valve.

4. The medium energy ionization chamber system according to claim 1, characterized in that: The second exhaust pipeline includes a slow exhaust angle valve and a second exhaust pipeline, and the slow exhaust angle valve adopts a 1 / 4 inch needle valve; the third exhaust pipeline includes a fast exhaust angle valve and a third exhaust pipeline, and the fast exhaust angle valve adopts an ordinary angle valve, and the third exhaust pipeline adopts a bellows; one end of the first pressure regulating pipeline, the second exhaust pipeline and the third exhaust pipeline are connected to the low vacuum ionization chamber, and the other end is connected to the vacuum pump through a four-way pipeline.

5. The medium energy ionization chamber system according to claim 1, characterized in that: The thickness of the Be window is 25 μm.

6. The medium energy ionization chamber system according to claim 1, characterized in that: The main cavity of the low vacuum ionization chamber is connected to a vacuum gauge through a fifth side flange.

7. The medium energy ionization chamber system according to claim 6, characterized in that: The distance between the end surface of the fifth side flange and the outer wall surface of the main cavity is at least 4 cm.

8. The medium energy ionization chamber system according to claim 1, characterized in that: It also includes an ionization chamber adjustment mechanism, wherein the low vacuum ionization chamber is fixed above the ionization chamber adjustment mechanism; the ionization chamber adjustment mechanism includes a group of orthogonally placed translation motors.

9. The medium energy ionization chamber system according to claim 8, characterized in that: The ionization chamber adjustment mechanism further includes a bottom mounting plate below the translation motor, and the low vacuum ionization chamber is fixed above the ionization chamber adjustment mechanism through a support system.

10. A method for using a medium energy ionization chamber system, characterized in that: include: Step S0: providing a medium energy ionization chamber system according to any one of claims 1 to 9; Step S1: Open the first pressure regulating pipeline, the second exhaust pipeline and the third exhaust pipeline in sequence to pump the low vacuum ionization chamber to high vacuum; Step S2: using the first pressure regulating pipeline to replenish gas to the low vacuum ionization chamber that has been evacuated to a high vacuum; Step S3: Based on the energy range requirements of the test, execute step S2 again to continue to replenish gas; alternatively, vacuum clean the first pressure regulating pipeline and then use the first pressure regulating pipeline to replenish gas.

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