Method and device for estimating the gas discharge rate of discharge tube

Abstract

The present application provides a method and device for estimating the deflation rate of a discharge tube, the method comprising: ionizing the gas in the discharge tube, and measuring the vacuum degree in the discharge tube at intervals for multiple times until the vacuum degree in the discharge tube tends to a steady state; obtaining a vacuum degree decay curve based on the vacuum degree obtained by multiple measurements; estimating the deflation rate of the discharge tube according to the vacuum degree decay curve and the vacuum volume inside the discharge tube. The above scheme can detect the deflation rate inside the discharge tube and improve the accuracy of quality control detection of the discharge tube.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of discharge tubes, and in particular to a method and device for estimating a gas release rate of a discharge tube. Background Art

[0002] For some discharge tubes such as X-ray tubes and magnetrons, they usually have a vacuum-sealed tube shell and several electrodes. The discharge tube is evacuated to a vacuum, and the residual gas pressure needs to meet certain requirements to maintain the vacuum requirements. For example, the X-ray tube has harsh operating conditions of high vacuum, high temperature, and high voltage. The degassing rate of the materials that make up the X-ray tube should be limited to a lower level to maintain the high vacuum in the X-ray tube. However, due to the limitations of the raw material manufacturing process and methods, there are certain substances such as oxygen, water molecules, and oil molecules on the surface and inside of the material. Therefore, in order to ensure the vacuum degree in the discharge tube, the discharge tube needs to be baked and aged after assembly to remove as many impurities as possible that can evaporate from the material. In engineering practice, it is found that the degassing rate of raw materials from different manufacturers is very different, and the degassing rate of raw materials produced by different batches of the same manufacturer is also different. Even after the aging test, the degassing rate inside the discharge tube will change.

[0003] At present, the outgassing rate of the material itself is mainly tested before the discharge tube is prepared. However, for the discharge tube that has been manufactured and formed into a closed system, the inside of the discharge tube is already in a high vacuum environment, and the outgassing rate inside the discharge tube cannot be tested. Summary of the invention

[0004] The technical problem solved by the embodiment of the present invention is that it is impossible to detect the degassing rate in the manufactured discharge tube.

[0005] To solve the above technical problems, an embodiment of the present invention provides a method for estimating the degassing rate of a discharge tube, comprising: ionizing the gas in the discharge tube, and measuring the vacuum degree in the discharge tube at intervals for multiple times until the vacuum degree in the discharge tube tends to a steady state; obtaining a vacuum degree decay curve based on the vacuum degrees obtained by the multiple measurements; and estimating the degassing rate of the discharge tube according to the vacuum degree decay curve and the vacuum volume inside the discharge tube.

[0006] Optionally, measuring the vacuum degree in the discharge tube multiple times at intervals includes any one of the following: measuring the vacuum degree in the discharge tube multiple times at fixed measurement cycle intervals; dynamically adjusting the duration of the next measurement cycle based on the rate of change of the vacuum degree measured in two adjacent measurement cycles.

[0007] Optionally, the duration of the next measurement cycle is dynamically adjusted based on the rate of change of the vacuum degree obtained by measuring two adjacent measurement cycles, including: when the rate of change of the vacuum degree is less than or equal to the set change rate, using a first measurement cycle to measure the vacuum degree in the discharge tube; when the rate of change of the vacuum degree is greater than the set change rate, using a second measurement cycle to measure the vacuum degree in the discharge tube, and the duration of the second measurement cycle is greater than the duration of the first measurement cycle.

[0008] Optionally, the vacuum degrees obtained by the multiple measurements include at least the initial vacuum degree in the discharge tube before ionization and the steady-state vacuum degree after the vacuum degree in the discharge tube tends to a steady state, and the vacuum degree decay curve obtained based on the vacuum degrees obtained by the multiple measurements includes: obtaining the vacuum degree decay curve based on the vacuum degree obtained in each measurement, the initial vacuum degree, the steady-state vacuum degree, the vacuum volume inside the discharge tube, and the pumping speed, wherein the process of ionizing the gas in the discharge tube is equivalent to the process of evacuating the discharge tube at the pumping speed using a vacuum pumping device.

[0009] Optionally, the vacuum degree decay curve satisfies the following formula: ; Wherein, P(t) is the vacuum degree measured at time point t; P0 is the initial vacuum degree; P steady is the steady-state vacuum degree; S is the pumping speed; V is the vacuum volume inside the discharge tube; and t is time.

[0010] Optionally, estimating the deflation rate of the discharge tube according to the vacuum degree decay curve and the vacuum volume inside the discharge tube includes: calculating the deflation rate of the discharge tube based on the pumping speed obtained from the vacuum degree decay curve, the vacuum volume inside the discharge tube and the steady-state vacuum degree.

[0011] Optionally, the degassing rate of the discharge tube is calculated using the following formula: ; Among them, Q leak is the gas release rate of the discharge tube; P steady is the steady-state vacuum degree; S is the pumping speed; V is the vacuum volume inside the discharge tube.

[0012] Optionally, when ionizing the gas in the discharge tube, the pumping speed is dynamically adjusted according to the measured rate of change of the vacuum degree.

[0013] Optionally, estimating the deflation rate of the discharge tube according to the vacuum degree decay curve and the vacuum volume inside the discharge tube includes: after completing one deflation rate estimation, placing the discharge tube so that the vacuum degree of the discharge tube returns to an equilibrium state, performing multiple deflation rate estimations on the discharge tube in the same environment to obtain multiple deflation rates, and obtaining the deflation rate of the discharge tube based on the multiple deflation rates.

[0014] Optionally, obtaining the deflation rate of the discharge tube based on multiple deflation rates includes: judging whether the multiple deflation rates satisfy Gaussian distribution; if they satisfy Gaussian distribution, taking the deflation rate within a set confidence interval as the deflation rate of the discharge tube.

[0015] Optionally, the method for estimating the deflation rate of the discharge tube further includes: if the Gaussian distribution is not satisfied, eliminating abnormal deflation rates from multiple deflation rates to obtain a processed deflation rate, and judging whether the Gaussian distribution is satisfied based on the processed deflation rate.

[0016] Optionally, before ionizing the gas in the discharge tube, the method further includes: performing a preliminary gas leakage detection on the discharge tube, and determining that the gas leakage rate of the discharge tube is less than or equal to a set threshold.

[0017] Optionally, the preliminary leakage detection of the discharge tube and determining that the leakage rate of the discharge tube is less than or equal to a set threshold value include any of the following detection methods: placing the discharge tube in a closed pressure vessel and monitoring the pressure change rate of the pressure vessel. If the pressure change rate is less than or equal to a set pressure change rate threshold within a set time period, determining that the leakage rate of the discharge tube is less than or equal to the set threshold; placing the discharge tube in a closed pressure vessel and, after evacuating the pressure vessel, monitoring the change rate of the vacuum degree in the pressure vessel. If the change rate of the vacuum degree in the pressure vessel is less than or equal to a set vacuum change rate threshold, determining that the leakage rate of the discharge tube is less than or equal to the set threshold, wherein the vacuum degree of the pressure vessel after evacuation is less than the vacuum degree of the discharge tube; monitoring the changes in temperature and resistance of the test filament in the discharge tube. If, within a set time period, the temperature decay rate is greater than or equal to the set decay rate and / or the resistance change is greater than or equal to the set change threshold, determining that the leakage rate of the discharge tube is greater than the set threshold.

[0018] Optionally, the method for estimating the gas release rate of the discharge tube further includes: when ionizing the gas in the discharge tube, applying a magnetic field to the discharge tube outside the discharge tube so that the electron beam used to ionize the gas performs a spiral motion.

[0019] The present invention also provides a device for estimating the degassing rate of a discharge tube, comprising: an ionization unit connected to the discharge tube, and used to ionize the gas in the discharge tube; a measuring unit, used to measure the vacuum degree in the discharge tube at intervals for multiple times until the vacuum degree in the discharge tube tends to a steady state; a vacuum degree decay curve determination unit, used to obtain a vacuum degree decay curve based on the vacuum degrees obtained by multiple measurements; and a degassing rate calculation unit, used to estimate the degassing rate of the discharge tube according to the vacuum degree decay curve and the vacuum volume inside the discharge tube.

[0020] Compared with the prior art, the technical solution of the embodiment of the present invention has the following beneficial effects:

[0021] By ionizing the gas in the discharge tube and measuring the vacuum degree in the discharge tube at intervals for multiple times until the vacuum degree in the discharge tube tends to a steady state, a vacuum degree decay curve is obtained based on the vacuum degree obtained by multiple measurements, and the degassing rate of the discharge tube is estimated according to the vacuum degree decay curve and the vacuum volume inside the discharge tube. Since the degassing rate affects the change of the vacuum degree, the degassing rate of the discharge tube can be estimated by ionizing the gas in the discharge tube according to the vacuum degree measured multiple times and the vacuum degree decay curve. By using the above method, even if the discharge tube has been produced, the degassing rate inside the discharge tube can still be detected, thereby improving the accuracy of quality control detection of the discharge tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a flow chart of a method for estimating a gas discharge rate of a discharge tube in an embodiment of the present invention;

[0023] Figure 2 is a flow chart of another method for estimating the gas discharge rate of a discharge tube in an embodiment of the present invention;

[0024] Figure 3 This is a simulation diagram of the vacuum degree change in the initial state of the X-ray tube;

[0025] Figure 4 This is a simulation diagram of the vacuum degree change in the X-ray tube after ionization;

[0026] Figure 5 It is a schematic diagram of the vacuum decay curve;

[0027] Figure 6 It is a structural schematic diagram of a discharge tube degassing rate estimation device in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] As mentioned above, after the discharge tube is assembled, it needs to be baked and aged to remove as many impurities as possible from the material. Even so, it is found in engineering practice that the degassing rates of raw materials from different manufacturers vary greatly, and the degassing rates of raw materials produced by different batches of the same manufacturer also vary. Even after the aging test, the degassing rate inside the discharge tube will change, which poses a great challenge to the quality control of the discharge tube. At present, the degassing rate of the material itself is mainly tested before the preparation of the discharge tube. However, for the discharge tube that has been manufactured and formed into a closed system, the inside of the discharge tube is already in a high vacuum environment, and the degassing rate inside the discharge tube cannot be tested. In addition, there are some solutions to detect the vacuum degree inside the discharge tube. However, the vacuum degree of some discharge tubes meets the quality control requirements, but in reality, the discharge tube is prone to failure during use due to the high degassing rate, the quality control detection accuracy is low, and the quality control effect is poor.

[0029] To solve the above problem, in an embodiment of the present invention, the gas in the discharge tube is ionized, and the vacuum degree in the discharge tube is measured at intervals for multiple times until the vacuum degree in the discharge tube tends to a steady state, a vacuum degree decay curve is obtained based on the vacuum degree obtained by multiple measurements, and the degassing rate of the discharge tube is estimated according to the vacuum degree decay curve and the vacuum volume inside the discharge tube. Since the degassing rate affects the change of the vacuum degree, the degassing rate of the discharge tube can be estimated by ionizing the gas in the discharge tube, according to the vacuum degree measured multiple times, and the vacuum degree decay curve. By adopting the above method, even if the discharge tube has been produced, the degassing rate inside the discharge tube can still be detected, thereby improving the accuracy of quality control detection of the discharge tube.

[0030] In order to make the above-mentioned purposes, features and beneficial effects of the embodiments of the present invention more obvious and understandable, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0031] The present application provides a method for estimating the degassing rate of a discharge tube, which is used to estimate the overall degassing rate of the material inside the discharge tube. The degassing rate can be estimated just after the discharge tube is produced, or after the discharge tube has been stored for a long time, or after the discharge tube has been in service or stored for a long time. The degassing rate refers to the rate at which a material degasses at high temperatures. The discharge tube may include an X-ray tube, a magnetron, etc.

[0032] Reference Figure 1 , a flow chart of a method for estimating the deflation rate of a discharge tube in an embodiment of the present invention is given, and the method for estimating the deflation rate of a discharge tube specifically comprises the following steps:

[0033] Step 11, ionizing the gas in the discharge tube, and measuring the vacuum degree in the discharge tube at intervals for multiple times until the vacuum degree in the discharge tube tends to a steady state.

[0034] Step 12, obtaining a vacuum degree decay curve based on the vacuum degrees obtained through multiple measurements.

[0035] Step 13: Estimate the degassing rate of the discharge tube according to the vacuum degree decay curve and the vacuum volume inside the discharge tube.

[0036] It can be seen from the above scheme that by ionizing the gas in the discharge tube and measuring the vacuum degree in the discharge tube at intervals for multiple times until the vacuum degree in the discharge tube tends to a steady state, a vacuum degree decay curve is obtained based on the vacuum degree obtained by multiple measurements, and the degassing rate of the discharge tube is estimated according to the vacuum degree decay curve and the vacuum volume inside the discharge tube. Since the degassing rate affects the change of the vacuum degree, the degassing rate of the discharge tube can be estimated by ionizing the gas in the discharge tube according to the vacuum degree measured multiple times and the vacuum degree decay curve. By using the above method, even if the discharge tube has been produced, the degassing rate inside the discharge tube can still be detected, thereby improving the accuracy of quality control detection of the discharge tube.

[0037] In a non-limiting implementation of step 11, the gas in the discharge tube can be ionized in the following manner. Specifically, a vacuum gauge is selected, the cathode port of the vacuum gauge is connected to the filament of the discharge tube (e.g., X-ray tube), the grid of the vacuum gauge is connected to the shell of the discharge tube (e.g., X-ray tube), and the collector of the vacuum gauge is connected to the anode end of the discharge tube (e.g., X-ray tube). The vacuum gauge heats the filament through the cathode lead to generate thermally emitted free electrons to form an electron beam, which flies to the tube shell with a high potential. During the flight of the electron beam, the residual gas in the discharge tube (e.g., X-ray tube) is ionized, and the generated positive ions fly to the collector, thereby generating current. By measuring the ionized current, the vacuum degree of the discharge tube (e.g., X-ray tube) is obtained.

[0038] In some embodiments, measuring the vacuum degree in the discharge tube multiple times at intervals may be measuring the vacuum degree in the discharge tube multiple times at intervals according to a fixed measurement period.

[0039] In other embodiments, the duration of the next measurement cycle is dynamically adjusted based on the rate of change of the vacuum degree measured in two adjacent measurement cycles. That is, the duration of the measurement cycle is dynamically adjusted according to the rate of change of the vacuum degree. Each measurement of the vacuum degree in the discharge tube is regarded as a sampling, which can optimize the sampling process and help improve the accuracy of the estimation of the degassing rate.

[0040] In some non-limiting embodiments, the duration of the next measurement cycle can be dynamically adjusted in the following manner. Specifically, when the rate of change of the vacuum degree is less than or equal to the set rate of change, the first measurement cycle is used to measure the vacuum degree in the discharge tube; when the rate of change of the vacuum degree is greater than the set rate of change, the second measurement cycle is used to measure the vacuum degree in the discharge tube, and the duration of the second measurement cycle is greater than the duration of the first measurement cycle. Among them, the rate of change of the vacuum degree refers to the rate of decrease of the vacuum degree. In this way, in the initial stage, there is more residual gas in the discharge tube, and more gas is ionized each time, and the rate of decrease of the vacuum degree is fast. A relatively short measurement cycle can be used to perform more intensive sampling, such as sampling once every 2-5 minutes. After the vacuum degree tends to stabilize, the duration of the measurement cycle can be extended at this time, and a relatively long measurement cycle can be used for sampling. For example, the sampling interval can be extended to 10-20 minutes, so that the data processing volume can be reduced while taking into account accuracy. It should be noted that the measurement periods of 2-5 minutes and 10-20 minutes are merely illustrative examples for ease of understanding and can be configured in practice according to actual needs, and do not limit the scope of protection of the present application.

[0041] It is understandable that, in practice, the set change rate can be further subdivided into multiple gradient change rates, and each gradient change rate can have a corresponding measurement cycle. In this way, the sampling process can be further optimized. The specific value of the vacuum degree change rate, the gradient setting, etc. can be configured according to needs.

[0042] In a specific implementation, the vacuum degrees obtained by the multiple measurements at least include an initial vacuum degree in the discharge tube before ionization and a steady-state vacuum degree after the vacuum degree in the discharge tube tends to a steady state.

[0043] In a specific implementation of step 12, the vacuum degree decay curve can be obtained based on the vacuum degree, initial vacuum degree, steady-state vacuum degree, vacuum volume inside the discharge tube and pumping speed obtained in each measurement. The process of ionizing the gas in the discharge tube is equivalent to the process of evacuating the discharge tube using a vacuum pumping device at the pumping speed. The pumping speed can also be called the pumping rate.

[0044] Through research, it is found that during the evacuation process of the discharge tube, the change of the gas pressure (also called pressure intensity) in the discharge tube obeys the differential equation (1). The pressure in the discharge tube represents the vacuum degree in the discharge tube, that is, the change of the vacuum degree in the discharge tube obeys the differential equation (1).

[0045] ; (1)

[0046] Among them, P is the pressure, S is the pumping speed, V is the vacuum volume inside the discharge tube, Q leak is the gas release rate of the discharge tube, and t is the time.

[0047] When the pressure in the discharge tube reaches dynamic equilibrium, the pumping speed and the leakage rate reach equilibrium. , P steady is the steady-state pressure, which is also the steady-state vacuum degree.

[0048] The solution of the above differential equation (1) is the vacuum decay curve.

[0049] In some embodiments, the vacuum decay curve satisfies the following formula (2):

[0050] ; (2)

[0051] Wherein, P(t) is the vacuum degree measured at time point t; P0 is the initial vacuum degree; P steady is the steady-state vacuum degree; S is the pumping speed; V is the vacuum volume inside the discharge tube, and t is time.

[0052] The vacuum degree, corresponding time t, initial vacuum degree P0, and steady-state vacuum degree P obtained through multiple measurements steady And the vacuum volume V inside the discharge tube can be solved to obtain the pumping speed S in formula (2). That is, the unknown parameter S in the vacuum degree decay curve can be obtained by fitting.

[0053] In a specific implementation of step 13, the degassing rate of the discharge tube is calculated based on the pumping speed obtained from the vacuum degree decay curve, the vacuum volume inside the discharge tube, and the steady-state vacuum degree.

[0054] The gas release rate of the discharge tube is calculated using the following formula (3):

[0055] ; (3)

[0056] Among them, Q leak is the gas release rate of the discharge tube; P steady is the steady-state vacuum degree; S is the pumping speed; V is the vacuum volume inside the discharge tube.

[0057] In some non-limiting embodiments, when the gas in the discharge tube is ionized, the pumping speed is dynamically adjusted according to the measured rate of change of the vacuum degree. If the rate of change of the vacuum degree is less than or equal to the set change threshold, the pumping speed is reduced. If the rate of change of the vacuum degree is less than or equal to the set change threshold, it means that there is less residual gas in the discharge tube, and the vacuum degree tends to a steady state at this time, and the pumping speed can be reduced. If the rate of change of the vacuum degree is greater than the set change threshold, it means that there is more residual gas in the discharge tube, and increasing the pumping speed can speed up the ionization efficiency, so that more residual gas is ionized, and the duration of the vacuum degree tending to a steady state is shortened. For example, the pumping speed can be adjusted by changing the voltage-on time applied by the vacuum gauge to the discharge tube during ionization. A shorter voltage-on time means that less residual gas is converted into cations, that is, the pumping speed is lower. Conversely, a longer voltage-on time means that more residual gas is converted into cations, that is, the pumping speed is higher.

[0058] In some embodiments, in order to improve the accuracy of the obtained degassing rate of the discharge tube, after completing one degassing rate estimation, the discharge tube is placed so that the vacuum degree of the discharge tube is restored to an equilibrium state, and the degassing rate of the discharge tube is estimated multiple times in the same environment to obtain multiple degassing rates, and the degassing rate of the discharge tube is obtained based on the multiple degassing rates.

[0059] Further, it is determined whether the multiple deflation rates satisfy Gaussian distribution; if they satisfy Gaussian distribution, the deflation rate within the set confidence interval is taken as the deflation rate of the discharge tube. In the absence of interference from other factors, the measured deflation rate should satisfy Gaussian distribution. If it satisfies Gaussian distribution, it indicates that there are no other interference factors when estimating the deflation rate, and the credibility of the obtained multiple deflation rates is good. Further, selecting the deflation rate from the set confidence interval can improve the accuracy of the obtained deflation rate of the discharge tube.

[0060] In some non-limiting embodiments, the confidence interval may be set at 95%-99%.

[0061] In some non-limiting embodiments, when there are multiple deflation rates within a set confidence interval, the deflation rate with the highest confidence level can be taken as the deflation rate of the discharge tube, or a weighted average can be taken for the multiple deflation rates within the set confidence interval, and the weighted average value can be taken as the deflation rate of the discharge tube.

[0062] In some embodiments, if the Gaussian distribution is not satisfied, the multiple deflation rates are subjected to abnormal deflation rates elimination to obtain the processed deflation rate, and whether the Gaussian distribution is satisfied is determined based on the processed deflation rate. If the Gaussian distribution is not satisfied, it indicates that there are interference factors in the deflation rate estimation, and the credibility of the obtained deflation rate is low. By eliminating the abnormal deflation rate, the credibility of the deflation rate used to determine the discharge tube can be improved to improve the accuracy of the obtained deflation rate of the discharge tube. The higher the accuracy of the obtained deflation rate of the discharge tube, the higher the fit between the estimated deflation rate and the actual deflation rate of the discharge tube.

[0063] In some embodiments, before ionizing the gas in the discharge tube, a preliminary gas leakage detection is performed on the discharge tube, and it is determined that the gas leakage rate of the discharge tube is less than or equal to a set threshold. By performing a preliminary gas leakage detection on the discharge tube, discharge tubes with obvious gas leakage points can be excluded to avoid burning the filament of the discharge tube during ionization.

[0064] Specifically, refer to Figure 2 Before executing step 11, steps 21 and 22 may also be executed.

[0065] Step 21, performing a preliminary leakage detection on the discharge tube.

[0066] Step 22, determining whether the leakage rate of the discharge tube is less than or equal to a set threshold.

[0067] If the judgment result is yes, that is, the leakage rate of the discharge tube is less than or equal to the set threshold, step 11 is executed; if the judgment result is no, that is, the leakage rate of the discharge tube is greater than the set threshold, step 23 is executed.

[0068] Step 23, perform other processing.

[0069] Among them, other processing may be to detect the degassing rate in other ways, or not to detect the discharge tube with a leakage rate greater than a set threshold, which is not limited in the present invention.

[0070] In a specific implementation, a variety of methods may be used to perform preliminary gas leakage detection on the discharge tube, and determine whether the gas leakage rate of the discharge tube is less than or equal to a set threshold.

[0071] In some embodiments, the discharge tube is placed in a sealed pressure vessel, and the pressure change rate of the pressure vessel is monitored. If the pressure change rate within a set time period is less than or equal to a set pressure change rate threshold, it is determined that the leakage rate of the discharge tube is less than or equal to the set threshold.

[0072] In other embodiments, the discharge tube is placed in a sealed pressure vessel, and after the pressure vessel is evacuated, the rate of change of the vacuum degree in the pressure vessel is monitored. If the rate of change of the vacuum degree in the pressure vessel is less than or equal to a set vacuum degree change rate threshold, it is determined that the leakage rate of the discharge tube is less than or equal to the set threshold, wherein the vacuum degree of the pressure vessel after evacuation is less than the vacuum degree of the discharge tube.

[0073] Usually the vacuum degree of the pressure vessel is 10 -1 -10 3 Pa, which is a low vacuum environment, while the vacuum degree of the discharge tube is usually 10 -4 -10 -7 Pa, which belongs to an ultra-high vacuum environment. When there is an obvious leak in the discharge tube, after the discharge tube is placed in a closed pressure vessel, the vacuum degree in the pressure vessel will increase, and then it can be determined whether the discharge tube has an obvious leak according to the rate of change of the vacuum degree in the pressure vessel. If the rate of change of the vacuum degree in the pressure vessel is less than or equal to the set vacuum degree change rate threshold, it is determined that the leakage rate of the discharge tube is less than or equal to the set threshold, that is, there is no obvious leak in the discharge tube. Correspondingly, if the rate of change of the vacuum degree in the pressure vessel is greater than the set vacuum degree change rate threshold, it is determined that the leakage rate of the discharge tube is greater than the set threshold, that is, there is an obvious leak in the discharge tube.

[0074] Furthermore, before conducting a preliminary leak test on the discharge tube, a sealing test can be conducted on the sealed pressure vessel. Under a constant test environment temperature, if the change in the vacuum degree in the pressure vessel is less than the set value within the set time, it indicates that the sealing performance of the pressure vessel meets the sealing requirements. For example, after 0.5 hours, the change in the vacuum degree in the pressure vessel is less than 5%-10%. If the sealing performance of the sealed pressure vessel meets the sealing requirements, the discharge tube can be placed in the sealed pressure vessel for leak detection. Place the discharge tube in a sealed pressure vessel, connect a three-way pipe to the outside of the pressure vessel, the first channel port of the three-way pipe is connected to the pressure vessel, the second channel port of the three-way pipe is connected to a vacuum valve, the vacuum valve is then connected to a vacuum pump or a vacuum unit (including but not limited to a combination of a dry vacuum pump and a Roots pump, etc.), and the third channel port of the three-way pipe is connected to a vacuum gauge and a vacuum gauge. Open the vacuum valve, start the vacuum pump, and read the vacuum degree inside the pressure vessel from the vacuum gauge. After the pressure vessel is in a low vacuum environment (for example, at 10 -1 Pa-10 3 Pa), close the vacuum valve and the vacuum pump. Record the reading of the vacuum gauge at this time. Let it stand for 5-10 minutes. If the reading of the vacuum gauge continues to decrease, for example, the vacuum degree decrease rate exceeds 50%, it means that the gas in the pressure vessel continues to enter the inside of the discharge tube from the gap, indicating that there is a leak in the discharge tube. On the contrary, if the vacuum degree decrease rate does not exceed 50%, it means that there is no obvious leak in the discharge tube.

[0075] In some other embodiments, the changes in the temperature and resistance of the test filament in the discharge tube are monitored. If the temperature decay rate is greater than or equal to the set decay rate and / or the resistance change is greater than or equal to the set change threshold within the set time, it is determined that the leakage rate of the discharge tube is greater than the set threshold. That is, there is a leak in the discharge tube. Specifically, a test filament can be set in the discharge tube or a filament can be selected as a test filament to change the temperature and resistance of the test filament. By measuring the temperature decay rate and resistance change, it is determined whether the discharge tube has a leak. When the temperature decay rate and resistance change significantly, for example, the temperature drop rate of the filament after the filament temperature is lit (for example, 2100°C) exceeds 350-400°C / s, it means that in addition to transferring the heat of the test filament to the environment through thermal radiation, a part of the heat is transferred to the residual gas in the discharge tube through heat conduction, proving that the vacuum in the discharge tube is poor and there is a potential leak.

[0076] In some embodiments, when ionizing the gas in the discharge tube, a magnetic field is applied to the discharge tube outside the discharge tube so that the electron beam used to ionize the gas performs a spiral motion. In this way, the interaction between the electron beam and the residual gas in the discharge tube can be more sufficient, thereby improving the ionization efficiency of the gas and improving the efficiency of the degassing rate estimation.

[0077] For ease of understanding, the method for estimating the gas discharge rate of the discharge tube is described below by taking an X-ray tube as an example through a non-limiting specific example.

[0078] First, simulate the process of using the ionization method to obtain the vacuum degree of the X-ray tube. Figure 3 The simulation diagram of the vacuum degree change in the initial state of the X-ray tube is given, such as Figure 4 The simulation diagram of the vacuum degree change in the X-ray tube after ionization is given. It should be noted that Figure 3 and Figure 4 It is a screenshot of the simulation result obtained in the simulation software. In order to intuitively represent the change of vacuum degree, different colors are used to distinguish the change of vacuum degree. The specific color does not limit the protection scope of this application. Figure 3 In the initial state, the vacuum degree in the X-ray tube is 10 -4 Pa, the process of measuring the vacuum degree of the X-ray tube using the ionization method can be equivalent to connecting an external ion pump with a pumping speed of 20L / s. After 1000s, the vacuum inside the X-ray tube is Figure 4 As shown in the figure, the vacuum degree inside the X-ray tube changes with time, and the vacuum degree inside the X-ray tube reaches 2.65×10 -6 Pa.

[0079] Multiple vacuum degrees are measured at intervals. The vacuum volume V in the X-ray tube is approximately equal to 0.083m 3The vacuum decay curve obtained by fitting is y=9.307×10 -5 e -0.000569t +2.6596×10 -6 , the vacuum decay curve is as follows Figure 5 shown.

[0080] Among them, compared with formula (2), P steady =2.6596×10 -6 , P0-P steady =9.307×10 -5 , =0.000569. Based on formula (3), the degassing rate Q of the X-ray tube is calculated as leak :

[0081] Q leak= 2.6596×10 -6 ×0.000569×0.083=1.256×10 -10 Pa·m 3 / s.

[0082] X-ray tube outgassing rate Q leak Close to 10 -10 Pa·m 3 / s, basically in line with quality control requirements.

[0083] It should be noted that, although the above embodiment is described by taking an X-ray tube as an example, it should be noted that the solution of this embodiment is applicable not only to X-ray tubes, but also to other types of discharge tubes such as magnetrons.

[0084] The present invention also provides a device for estimating the deflation rate of a discharge tube, which can be used to implement the above-mentioned deflation rate estimation method. Figure 6 The degassing rate estimation device 60 includes: an ionization unit 61, connected to the discharge tube, for ionizing the gas in the discharge tube; a measuring unit 62, for measuring the vacuum degree in the discharge tube at intervals for multiple times until the vacuum degree in the discharge tube tends to a steady state; a vacuum degree decay curve determination unit 63, for obtaining a vacuum degree decay curve based on the vacuum degrees obtained by multiple measurements; and a degassing rate calculation unit 64, for estimating the degassing rate of the discharge tube according to the vacuum degree decay curve and the vacuum volume inside the discharge tube.

[0085] Regarding the specific working principle and working process of the deflation rate estimation device 60, please refer to the description of the deflation rate estimation method provided in the above embodiment, which will not be repeated here.

[0086] The term "multiple" in the examples of this application refers to two or more than two. The term "multiple" refers to two or more than two.

[0087] The first, second, etc. descriptions appearing in the embodiments of the present application are only used for illustration and distinction of the description objects. There is no order, nor do they indicate any special limitation on the number of devices in the embodiments of the present application, and cannot constitute any limitation on the embodiments of the present application.

[0088] It should be pointed out that the serial numbers of the steps in this embodiment do not limit the execution order of the steps.

[0089] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A method for estimating the gas release rate of a discharge tube, characterized in that: include: Ionizing the gas in the discharge tube, and measuring the vacuum degree in the discharge tube at intervals for multiple times until the vacuum degree in the discharge tube tends to a steady state; A vacuum degree decay curve is obtained by fitting the vacuum degrees obtained by multiple measurements; estimating a degassing rate of the discharge tube according to the vacuum degree decay curve and the vacuum volume inside the discharge tube; The vacuum degree obtained by the multiple measurements at least includes the initial vacuum degree in the discharge tube before ionization and the steady-state vacuum degree after the vacuum degree in the discharge tube tends to a steady state. The vacuum degree decay curve obtained by fitting the vacuum degree obtained by the multiple measurements includes: fitting the unknown parameter pumping speed in the vacuum degree decay curve through the vacuum degree obtained by the multiple measurements, the corresponding time, the initial vacuum degree, the steady-state vacuum degree, and the vacuum volume inside the discharge tube, wherein the process of ionizing the gas in the discharge tube is equivalent to the process of evacuating the discharge tube by using a vacuum pumping device at the pumping speed; The estimating the degassing rate of the discharge tube according to the vacuum degree decay curve and the vacuum volume inside the discharge tube comprises: calculating the degassing rate of the discharge tube based on the pumping speed obtained from the vacuum degree decay curve, the vacuum volume inside the discharge tube and the steady-state vacuum degree; The degassing rate of the discharge tube is calculated using the following formula: ； Among them, Q leak is the gas release rate of the discharge tube; P steady is the steady-state vacuum degree; S is the pumping speed; V is the vacuum volume inside the discharge tube.

2. The method for estimating the gas discharge rate of a discharge tube according to claim 1, characterized in that: The step of measuring the vacuum degree in the discharge tube multiple times at intervals includes any one of the following: measuring the vacuum degree in the discharge tube multiple times at fixed measurement period intervals; The duration of the next measurement cycle is dynamically adjusted based on the rate of change of the vacuum degree measured in two adjacent measurement cycles.

3. The method for estimating the gas discharge rate of a discharge tube according to claim 2, characterized in that: The dynamically adjusting the duration of the next measurement cycle based on the rate of change of the vacuum degree measured in two adjacent measurement cycles includes: When the rate of change of the vacuum degree is less than or equal to the set rate of change, the first measurement cycle is used to measure the vacuum degree in the discharge tube; when the rate of change of the vacuum degree is greater than the set rate of change, the second measurement cycle is used to measure the vacuum degree in the discharge tube, and the duration of the second measurement cycle is greater than the duration of the first measurement cycle.

4. The method for estimating the gas discharge rate of a discharge tube according to claim 1, characterized in that: The vacuum decay curve satisfies the following formula: ； Wherein, P(t) is the vacuum degree measured at time point t; P0 is the initial vacuum degree; P steady is the steady-state vacuum degree; S is the pumping speed; V is the vacuum volume inside the discharge tube; and t is time.

5. The method for estimating the gas discharge rate of a discharge tube according to claim 1, characterized in that: When ionizing the gas in the discharge tube, the pumping speed is dynamically adjusted according to the measured rate of change of the vacuum degree.

6. The method for estimating the gas discharge rate of a discharge tube according to any one of claims 1 to 5, characterized in that: The step of estimating the degassing rate of the discharge tube according to the vacuum degree decay curve and the vacuum volume inside the discharge tube comprises: After completing one deflation rate estimation, the discharge tube is placed to restore the vacuum degree of the discharge tube to an equilibrium state, and the deflation rate of the discharge tube is estimated multiple times in the same environment to obtain multiple deflation rates, and the deflation rate of the discharge tube is obtained based on the multiple deflation rates.

7. The method for estimating the gas discharge rate of a discharge tube according to claim 6, characterized in that: The step of obtaining the deflation rate of the discharge tube based on a plurality of deflation rates comprises: Determine whether multiple deflation rates satisfy Gaussian distribution; If the Gaussian distribution is satisfied, the deflation rate within the set confidence interval is taken as the deflation rate of the discharge tube.

8. The method for estimating the gas discharge rate of a discharge tube according to claim 7, characterized in that: Also includes: If the Gaussian distribution is not satisfied, the abnormal deflation rates are eliminated from the multiple deflation rates to obtain the deflation rate after processing, and whether the Gaussian distribution is satisfied is determined based on the deflation rate after processing.

9. The method for estimating the gas discharge rate of a discharge tube according to claim 1, characterized in that: Before ionizing the gas in the discharge tube, it also includes: Perform a preliminary gas leakage detection on the discharge tube, and determine whether the gas leakage rate of the discharge tube is less than or equal to a set threshold.

10. The method for estimating the gas discharge rate of a discharge tube according to claim 9, characterized in that: The preliminary leakage detection of the discharge tube and determining that the leakage rate of the discharge tube is less than or equal to a set threshold value includes any of the following detection methods: The discharge tube is placed in a sealed pressure container, and the pressure change rate of the pressure container is monitored. If the pressure change rate within a set time period is less than or equal to a set pressure change rate threshold, it is determined that the leakage rate of the discharge tube is less than or equal to the set threshold; The discharge tube is placed in a sealed pressure vessel, and after the pressure vessel is evacuated, the change rate of the vacuum degree in the pressure vessel is monitored, and if the change rate of the vacuum degree in the pressure vessel is less than or equal to a set vacuum degree change rate threshold, it is determined that the leakage rate of the discharge tube is less than or equal to the set threshold, wherein the vacuum degree of the pressure vessel after evacuation is less than the vacuum degree of the discharge tube; Monitor the changes in temperature and resistance of the test filament in the discharge tube. If, within a set time period, the temperature decay rate is greater than or equal to the set decay rate and / or the resistance change is greater than or equal to the set change threshold, it is determined that the leakage rate of the discharge tube is greater than the set threshold.

11. The method for estimating the gas discharge rate of a discharge tube according to claim 1, characterized in that: Also includes: When the gas in the discharge tube is ionized, a magnetic field is applied to the discharge tube from the outside of the discharge tube so that the electron beam used to ionize the gas performs a spiral motion.

12. A device for estimating the gas discharge rate of a discharge tube, characterized in that: include: an ionization unit, connected to the discharge tube, and used to ionize the gas in the discharge tube; A measuring unit, used for measuring the vacuum degree in the discharge tube at intervals for multiple times until the vacuum degree in the discharge tube tends to a steady state; A vacuum degree decay curve determination unit, used for obtaining a vacuum degree decay curve based on vacuum degree fitting obtained by multiple measurements; a deflation rate calculation unit, configured to estimate the deflation rate of the discharge tube according to the vacuum degree decay curve and the vacuum volume inside the discharge tube; The vacuum degree obtained by the multiple measurements at least includes the initial vacuum degree in the discharge tube before ionization and the steady-state vacuum degree after the vacuum degree in the discharge tube tends to a steady state. The vacuum degree decay curve determination unit is used to fit the unknown parameter pumping speed in the vacuum degree decay curve through the vacuum degree obtained by the multiple measurements, the corresponding time, the initial vacuum degree, the steady-state vacuum degree, and the vacuum volume inside the discharge tube, wherein the process of ionizing the gas in the discharge tube is equivalent to the process of evacuating the discharge tube by using a vacuum pumping device at the pumping speed; The degassing rate calculation unit is used to calculate the degassing rate of the discharge tube based on the pumping speed obtained from the vacuum degree decay curve, the vacuum volume inside the discharge tube, and the steady-state vacuum degree; The degassing rate calculation unit is used to calculate the degassing rate of the discharge tube using the following formula: ； Among them, Q leak is the gas release rate of the discharge tube; P steady is the steady-state vacuum degree; S is the pumping speed; V is the vacuum volume inside the discharge tube.

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