A quantitative analysis system and method for cathode poisoning gas

Abstract

A kind of cathode poisoning gas quantitative analysis system and method, the system includes vacuum main pipe and poisoning gas source branch pipe, initial vacuum pump, molecular pump, poisoning gas source, built-in double-switch permanent magnet valve, built-in double-switch leak hole parallel permanent magnet valve, cathode poisoning test tube (including cathode flange, water-cooled anode flange) etc., the system is closed loop vacuum system, can be vacuumized and measures vacuum degree, with the characteristics of small volume, light weight.The system is suitable for vacuum electron field, can provide quantitative analysis to cathode poisoning gas and activate poisoned cathode.

Description

Technical Field

[0001] This invention relates to a quantitative analysis system and method for cathode poisoning gas, particularly capable of quantitatively analyzing the amount of gas that poisons the cathode and activating a cathode that has been poisoned by the gas. Background Technology

[0002] Vacuum electronic devices are widely used in military and civilian fields such as radar, communications, nuclear fusion, and medicine. The cathode is the core component of a vacuum electronic device, emitting an electron beam. The energy of this electron beam can be converted into microwave energy. Therefore, the cathode is a crucial component in vacuum electronic devices, and its performance determines the device's reliability, lifespan, and other technical specifications. Cathode lifespan is positively correlated with the vacuum level inside the device. However, under the same vacuum conditions, cathode lifespan is related to the gas composition inside the tube. Water vapor, oxygen, and carbon dioxide are common gases that can easily poison the cathode.

[0003] If the concentration of gases such as water vapor, oxygen, or carbon dioxide near the cathode exceeds a certain level, it will lead to a decrease in electron emission density, a condition known as cathode poisoning. Different cathodes have different resistance to poisoning. Cathode poisoning is caused by a layer of gas adsorbed on the cathode's emitting surface. The adsorbed gas forms charged dipoles on the cathode surface, which increases the work function and thus causes a decrease in emission.

[0004] Many factors influence cathode poisoning, including the material properties of the cathode, the structure of the cathode assembly, the quality of the vacuum level, and the concentration of poisoning gases. The lack of effective quantitative indicators for the poisoning gases in cathode assemblies poses significant challenges to cathode manufacturing and its use in vacuum electronic devices.

[0005] Regarding the aforementioned technologies, the inventors developed a test system for measuring cathode poisoning activation through experiments. This system can quantitatively analyze gases (oxygen, carbon dioxide, water vapor, etc.) that cause cathode poisoning and identify the threshold values ​​for different gases that induce cathode poisoning. Summary of the Invention

[0006] This invention provides a quantitative analysis system and method for cathode poisoning gases, and verifies the poisoning characteristics of different cathodes (barium-tungsten cathode, lanthanum hexaboride cathode, and tungsten carbide cathode) to gases such as oxygen, carbon dioxide, and water vapor through experimental testing. The verification shows that cathode poisoning is caused by damage from positive ion impacts, increased gas pressure leading to a decrease in vacuum, and the formation of a gas layer adsorbed on the emission surface. This provides designers with a quantitative analytical basis for selecting cathodes suitable for use in poisoning environments.

[0007] The technical solution adopted by this invention to solve its technical problem is:

[0008] A quantitative analysis system for cathode poisoning gas includes a vacuum main pipeline, a high-vacuum molecular pump, an eighth built-in double-switch permanent magnet valve, a seventh built-in double-switch leak-hole permanent magnet valve, a vacuum gauge, a third type of cathode poisoning test tube, a second type of cathode poisoning test tube, a first type of cathode poisoning test tube, an oxygen source, a carbon dioxide source, a water vapor source, and an initiating vacuum pump for obtaining a vacuum. The initiating vacuum pump for obtaining a vacuum is sequentially connected to the high-vacuum molecular pump, the eighth built-in double-switch permanent magnet valve, the seventh built-in double-switch leak-hole permanent magnet valve, and the vacuum main pipeline. The vacuum main pipeline is connected to the vacuum gauge, the first type of cathode poisoning test tube, the second type of cathode poisoning test tube, and the third type of cathode poisoning test tube, respectively. The oxygen source for the first type of cathode poisoning is sequentially connected to the first built-in double-switch leak-hole permanent magnet valve, the second built-in double-switch permanent magnet valve, and the vacuum main pipeline.

[0009] The carbon dioxide gas source is sequentially connected to the third built-in double-switch perforated permanent magnet valve, the fourth built-in double-switch permanent magnet valve, and the vacuum main pipeline.

[0010] The steam source is sequentially connected to the fifth built-in double-switch perforated permanent magnet valve, the sixth built-in double-switch permanent magnet valve, and the vacuum main pipeline.

[0011] Furthermore, the first type of cathode poisoning test tube, the second type of cathode poisoning test tube, and the third type of cathode poisoning test tube have the same structure. The first type of cathode poisoning test tube includes a cathode component and an anode component; the cathode component includes a stainless steel flange core, an insulating ceramic tube, a thermocouple, a cathode heating wire, a cathode, and a filament lead; the filament lead passes through the core and connects to the cathode heating wire; the thermocouple passes through the core and is arranged outside the cathode; an insulating ceramic tube is installed at the contact point between the filament lead and the core; the stainless steel flange core is equipped with a cathode component flange;

[0012] The anode component includes a casing, a water-cooled anode flange, a water-cooled anode, and a vacuum exhaust pipe; the casing is located inside the water-cooled anode flange, and the water-cooled anode is located at the other end of the casing; the vacuum exhaust pipe is located on the lower side wall of the casing; a cooling water outlet and a cooling water inlet are located on the outer side of the water-cooled anode;

[0013] The cathode component flange and the water-cooled anode flange are fixed by a combination of screws and nuts, thereby forming a sealed cavity inside the tube shell; the temperature measuring thermocouple, the cathode heating wire and the cathode are located in the sealed cavity.

[0014] Furthermore, the cathode poisoning gas quantitative analysis system measures the difference in the emitted electron current voltage-current characteristic before and after cathode poisoning. This emitted electron current voltage-current characteristic is measured by an emitted electron current voltage-current characteristic measurement system, which includes an adjustable power supply, a first adjusting resistor, a second voltmeter, a first ammeter, an adjustable filament power supply, a second adjusting resistor, a first voltmeter, and a second ammeter. The first terminal of the adjustable power supply is sequentially connected to the first adjusting resistor, the first ammeter, the water-cooled anode, the cathode, and the second terminal of the adjustable power supply. The second voltmeter is connected in parallel with the adjusting resistor. The first terminal of the cathode heating wire is sequentially connected to the second adjusting resistor, the second ammeter, the adjustable filament power supply, and the second terminal of the cathode heating wire. One end of the first voltmeter is connected to the first terminal of the cathode heating wire, and the other end of the first voltmeter is connected to the second terminal of the cathode heating wire.

[0015] Furthermore, the vacuum main pipeline is connected in parallel with a first type of cathode poisoning test tube, a second type of cathode poisoning test tube, and a third type of cathode poisoning test tube.

[0016] Furthermore, the first type of cathode poisoning test tube, the second type of cathode poisoning test tube, and the third type of cathode poisoning test tube, when measuring the volt-ampere characteristics of different cathode electron emission currents under the same poisoning gas environment, have the ability to resist poisoning.

[0017] Furthermore, a metal sealing ring is provided at the connection between the stainless steel flange core and the tube shell; preferably, the thickness of the metal sealing ring is variable to control the distance between the cathode and the water-cooled anode.

[0018] The first built-in dual-switch leak-hole permanent magnet valve includes a first upper permanent magnet, a first lower permanent magnet, a first valve body, a second valve body, a first pure iron ball cover, a cathode-poisoned first input connecting pipe, a U-shaped pipe, and a cathode-poisoned output connecting pipe;

[0019] The first upper permanent magnet is located above the first valve body, and the first lower permanent magnet is located below the first valve body; the first end of the first input connecting pipe is the inlet, and the top of the second end is provided with a first ball holder, on which a first pure iron ball cover is placed; the second end of the first input connecting pipe passes through the first lower permanent magnet and the first valve body in sequence and extends into the interior of the first valve body;

[0020] The second upper permanent magnet is located above the second valve body, and the second lower permanent magnet is located below the second valve body;

[0021] The top of the first and second ends of the U-shaped tube are respectively provided with ball supports, and pure iron ball caps are placed on the ball supports respectively; the first end of the U-shaped tube passes through the first lower permanent magnet and the first valve body in sequence and extends into the interior of the first valve body; the second end of the U-shaped tube passes through the second lower permanent magnet and the second valve body in sequence and extends into the interior of the second valve body.

[0022] The first end of the output connecting pipe is the outlet, and the top of the second end is equipped with a ball support, on which a pure iron ball cover is placed; the second end of the output connecting pipe passes through the second lower permanent magnet and the second valve body in sequence and extends into the interior of the second valve body;

[0023] Preferably, inside the first valve body, the first input connecting pipe and the U-shaped pipe are connected through a leakage hole.

[0024] Furthermore, the first built-in dual-switch perforated permanent magnet valve controls the flow rate of oxygen during cathode poisoning, the third built-in dual-switch perforated permanent magnet valve controls the flow rate of carbon dioxide during cathode poisoning, and the fifth built-in dual-switch perforated permanent magnet valve controls the flow rate of water vapor during cathode poisoning.

[0025] Furthermore, the method of using the analysis system includes: when all valves on the analysis system are opened, evacuating the main vacuum pipeline, the cathode poisoning test tube, and the poisoning gas source branch, recording the vacuum level, connecting the adjustable filament power supply and the adjustable power supply, the cathode begins to decompose and activate, and the volt-ampere characteristics of the cathode thermionic emission are measured; injecting cathode poisoning gas, recording the vacuum level, and measuring the volt-ampere characteristics of the thermionic emission after cathode poisoning; opening the seventh and eighth built-in double-switch permanent magnet valves to evacuate the vacuum, recording the instantaneous vacuum measurement value, for the activation of the cathode after poisoning, and measuring the volt-ampere characteristics of the activated thermionic emission after cathode poisoning.

[0026] A method for quantitative analysis of cathode poisoning gas, using the system described above, the method comprising the following steps:

[0027] I. Measure the volt-ampere characteristics of thermionic emission of the first type of cathode poisoning test tube, the second type of cathode poisoning test tube, and the third type of cathode poisoning test tube under normal vacuum conditions;

[0028] 2. Introducing oxygen: Close the first built-in dual-switch leak-hole permanent magnet valve, close the third built-in dual-switch leak-hole permanent magnet valve, close the fourth built-in dual-switch permanent magnet valve, close the fifth built-in dual-switch leak-hole permanent magnet valve, and close the sixth built-in dual-switch permanent magnet valve.

[0029] 1) Open the second built-in dual-switch permanent magnet valve.

[0030] 2) Observe the decrease in vacuum level of the vacuum gauge and the change in the volt-ampere characteristic of thermionic emission.

[0031] 3) The amount of poisonous gas, the amount of oxygen entering the first cathode poisoning test tube through the leak, and the value displayed by the vacuum gauge are all determined.

[0032] 4) Close the second built-in dual-switch permanent magnet valve and record the oxygen vacuum measurement value.

[0033] 5) Measure the volt-ampere characteristics of thermionic emission from the first, second, and third cathode poisoning test tubes after oxygen poisoning.

[0034] 6) Activation: Under the condition that the cathode is restored to normal vacuum: record the vacuum level, and after the cathode measurement power supply is turned on, the cathode begins its second decomposition, activation, and measurement of the volt-ampere characteristics of the cathode thermionic emission;

[0035] 2. Using the same method, introduce carbon dioxide gas, introduce water vapor, and measure the volt-ampere characteristics of the cathode thermionic emission.

[0036] By adopting the above technical solution:

[0037] The cathodic poisoning gas supply branch is equipped with a first leak hole with a built-in double-switch permanent magnet valve assembly, a third leak hole with a double-switch permanent magnet valve assembly, and a fifth leak hole with a double-switch permanent magnet valve assembly. The inlets of these three assemblies are respectively connected to the cathodic poisoning oxygen source, carbon dioxide source, water vapor source, and cathodic poisoning gas source. The gas flows into the main pipe through the respective leak holes and is connected in parallel to the first type of cathodic poisoning test tube, the second type of cathodic poisoning test tube, and the third type of cathodic poisoning test tube.

[0038] By adopting the above technical solution:

[0039] Actual measurements of the first, second, and third cathodes, under the same toxic gas environment, showed that the cathodes' electron emission current characteristics were resistant to poisoning.

[0040] By adopting the above technical solution:

[0041] The cathode poisoning test tube has a flange on the cathode core and a flange on the anode. The sealing port of the cathode and anode separation joint is equipped with a metal sealing ring, screws and nuts, and can be disassembled and replaced with various new cathodes, which is very convenient.

[0042] By adopting the above technical solution:

[0043] The thickness of the metal sealing ring is variable, controlling the distance between the cathode and the anode.

[0044] By adopting the above technical solution:

[0045] The first to eighth built-in dual-switch perforated permanent magnet valves are 100% unaffected by air in the closed-loop system, where the permanent magnet attracts the soft iron sealing ball from the outside of the valve body when the valve is open, and from the outside of the valve body to the inside of the valve body when the valve is closed.

[0046] The beneficial effects of this invention are as follows:

[0047] By adopting the above technical solution:

[0048] The built-in double-switch permanent magnet valve in the leak hole is fully open, starting the vacuum pump and high-vacuum molecular pump to evacuate all pipelines affected by cathode poisoning.

[0049] In this invention, a leak hole is provided so that the leak hole meets a preset detection standard.

[0050] By adopting the above technical solution:

[0051] The cathode poisoning system includes a starting vacuum pump, a molecular pump for obtaining high vacuum, and the outlet of this pump is sequentially connected to an eighth built-in double-switch permanent magnet valve and a seventh built-in double-switch permanent magnet valve. When all valves on the system are opened, the main pipe, cathode poisoning test tube, and poisoning gas source branch are evacuated, and the vacuum level is recorded. After the cathode measurement power supply is turned on, the cathode begins to decompose and activate, and the volt-ampere characteristics of the thermionic emission are measured. Cathode poisoning gas is injected, the vacuum level is recorded, and the volt-ampere characteristics of the thermionic emission after cathode poisoning are measured. The vacuum level is recorded.

[0052] Cathode poisoning is a common phenomenon in vacuum electronic devices. A poisoned cathode suffers a severe decline in emission capability, lifespan, and reliability, sometimes to the point of irreversibility. Currently, there are no effective methods or means for quantitative analysis of the gas causing cathode poisoning. This invention designs a vacuum pipeline that uses a built-in dual-switch leak-hole permanent magnet valve to gradually introduce a quantitative amount of cathode poisoning gas into the pipeline. A vacuum gauge is used to obtain the gas pressure within the pipeline. A quantitative analysis power supply system for poisoning gas is then used to accurately measure the amount of gas causing cathode poisoning. Attached Figure Description

[0053] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0054] Figure 1 Schematic diagram of a cathode poisoning gas quantitative analysis system;

[0055] Figure 2 Schematic diagram of the cathode poisoning test tubes (10, 20, 30);

[0056] Figure 3 Schematic diagram of a power supply system for quantitative analysis of cathode poisoning gases;

[0057] Figure 4 (a) Schematic diagram of the built-in dual-switch perforated permanent magnet valve and (b) Schematic diagram of the built-in dual-switch permanent magnet valve.

[0058] In the diagram: 00-Vacuum main pipeline, 010-Vacuum gauge, 10-First type of cathode poisoning test tube, 20-Second type of cathode poisoning test tube, 30-Third type of cathode poisoning test tube, 1-First built-in double-switch leak-hole permanent magnet valve, 2-Second built-in double-switch permanent magnet valve, 3-Third built-in double-switch leak-hole permanent magnet valve, 4-Fourth built-in double-switch permanent magnet valve, 5-Fifth built-in double-switch leak-hole permanent magnet valve, 6-Sixth built-in double-switch permanent magnet valve, 7-Seventh built-in double-switch permanent magnet valve, 8-Eighth built-in double-switch permanent magnet valve, 101-Starting vacuum pump, 102-High vacuum molecular pump, 201-Water vapor source, 202-Carbon dioxide source, 203-Oxygen source;

[0059] 3.1-Combination screw and nut, 301-Core post, 302-Insulating ceramic tube, 303-Tube shell, 304-Vacuum exhaust pipe, 305-Thermocouple, 306-Metal sealing ring, 307-Water-cooled anode flange, 308-Cathode heating wire, 309-Cathode, 310-Water-cooled anode, 311-Cooling water outlet, 312-Cooling water inlet, 313-Filament lead wire;

[0060] Y1 - Adjustable power supply, R1 - First adjusting resistor, V2 - Second voltmeter, mA - First ammeter, Y2 - Adjustable filament power supply, R2 - Second adjusting resistor, V1 - First voltmeter, A - Second ammeter;

[0061] 401-1-First upper permanent magnet, 401-2-Second upper permanent magnet, 402-1-First pure iron ball cover, 402-2-Second pure iron ball cover, 403-1-First ball holder, 403-2-Second ball holder, 404-1-First input connecting pipe, 404-2-Second input connecting pipe, 405-1-First lower permanent magnet, 405-2-Second lower permanent magnet, 406-1-First valve body, 406-2-Second valve body, 407-Output connecting pipe, 408-Leakage hole, 409-U-shaped tube. Detailed Implementation

[0062] The following is in conjunction with the appendix Figure 1 --4. The present invention will be described in further detail.

[0063] This invention discloses a quantitative analysis system and method for cathode poisoning gases, which can quantitatively analyze barium tungsten cathodes, lanthanum hexaboride cathodes, tungsten carbide cathodes, and other easily poisoned cathodes. (Refer to...) Figure 1-4A quantitative analysis system for cathode poisoning gas includes a vacuum main pipeline 00 for containing cathode gas poisoning and activating the vacuum system, a high-vacuum molecular pump 102, an eighth built-in double-switch permanent magnet valve 8, a seventh built-in double-switch permanent magnet valve 7, a vacuum gauge 010, a third type of cathode poisoning test tube 30, a second type of cathode poisoning test tube 20, a first type of cathode poisoning test tube 10, an oxygen source 203, a carbon dioxide gas source 202, a water vapor source 201, and an initiating vacuum pump 101 for vacuum acquisition. The initiating vacuum pump 101 is sequentially connected to the high-vacuum molecular pump 102, the eighth built-in double-switch permanent magnet valve 8, the seventh built-in double-switch permanent magnet valve 7, and the vacuum main pipeline 00. The vacuum main pipeline 00 is connected to the vacuum gauge 010, the first type of cathode poisoning test tube 10, the second type of cathode poisoning test tube 20, and the third type of cathode poisoning test tube 30, respectively.

[0064] Reference Figure 1 The oxygen source 203 branch of the first type of cathode poisoning is sequentially connected to the first built-in double-switch leak-hole permanent magnet valve 1, the second built-in double-switch permanent magnet valve 2, and the vacuum main pipeline 00.

[0065] Reference Figure 1 The carbon dioxide gas source 202 is sequentially connected to the third built-in double-switch perforated permanent magnet valve, the fourth built-in double-switch permanent magnet valve 4, and the vacuum main pipeline 00.

[0066] Reference Figure 1 The steam source 201 is sequentially connected to the fifth built-in double-switch perforated permanent magnet valve, the sixth built-in double-switch permanent magnet valve 6, and the vacuum main pipeline 00.

[0067] The vacuum main pipeline 00 is connected in parallel to the first type of cathode poisoning test tube 10, the second type of cathode poisoning test tube 20, and the third type of cathode poisoning test tube 30.

[0068] Reference Figure 2 The first type of cathode poisoning test tube 10, the second type of cathode poisoning test tube 20, and the third type of cathode poisoning test tube 30 have the same structure. The first type of cathode poisoning test tube 10 includes a cathode component and an anode component.

[0069] The cathode component includes a stainless steel flange core 301, an insulating ceramic tube 302, a thermocouple 305, a cathode heating wire 308, a cathode 309, and a filament lead 313. The filament lead 313 passes through the core 301 and connects to the cathode heating wire 308. The thermocouple 305 passes through the core 301 and is positioned outside the cathode 309. An insulating ceramic tube 302 is located at the contact point between the filament lead 313 and the core 301. The stainless steel flange core 301 has a cathode component flange. The thermocouple 305, cathode 309, and cathode heating wire 308 are mounted on the core 301. An insulating ceramic tube 302 is positioned between the filament lead 313 and the flange core 301. A metal sealing ring 306 and a combination screw and nut 3.1 are provided at the connection between the water-cooled anode flange 307 and the cathode component flange core column 301. A tube shell 303 is provided on the inner diameter of the anode flange. A water-cooled anode 310 is provided at the other end of the tube shell. A cooling water inlet 312 and a cooling water outlet 311 are provided on the outside of the water-cooled anode. A vacuum exhaust pipe 304 is provided on the side of the tube shell 303.

[0070] The anode component includes a shell 303, a water-cooled anode flange 307, a water-cooled anode 310, and a vacuum exhaust pipe 304; the water-cooled anode 310 is disposed at the bottom of the inner side of the shell 303, and the water-cooled anode flange 307 is fixedly disposed on the outer side of the upper side wall of the shell 303; the vacuum exhaust pipe 304 is disposed on the lower side wall of the shell 303; the water-cooled anode 310 is provided with a cooling water outlet 311 and a cooling water inlet 312 on the outside.

[0071] The cathode component flange and the water-cooled anode flange 307 are fixed by a combination screw and nut 3.1, thereby forming a sealed cavity inside the shell 303; the temperature measuring thermocouple 305, the cathode heating wire 308 and the cathode 309 are located in the sealed cavity.

[0072] Reference Figure 3The cathode poisoning measurement activation system measures the difference in the volt-ampere characteristics of emitted electrons before and after cathode poisoning of cathode 309 and water-cooled anode 310. The power supply for measuring the volt-ampere characteristics of emitted electrons includes an adjustable power supply Y1, a first adjusting resistor R1, a second voltmeter V2, a first ammeter mA, an adjustable filament power supply Y2, a second adjusting resistor R2, a first voltmeter V1, a second ammeter A, and a cathode heating wire 308. The first terminal of the adjustable power supply Y1 is sequentially connected to the first adjusting resistor R1, the first ammeter mA, the water-cooled anode 310, the cathode 309, and the second terminal of the adjustable power supply Y1; the second voltmeter V2 is connected in parallel with the adjusting resistor R1; the first terminal of the cathode heating wire 308 is sequentially connected to the second adjusting resistor R2, the second ammeter A, the adjustable filament power supply Y2, and the second terminal of the cathode heating wire 308; one end of the first voltmeter V1 is connected to the first terminal of the cathode heating wire 308, and the other end of the first voltmeter V1 is connected to the second terminal of the cathode heating wire 308.

[0073] The first built-in dual-switch perforated permanent magnet valve 1, the third built-in dual-switch perforated permanent magnet valve 3, and the fifth built-in dual-switch perforated permanent magnet valve 5 have the same structure.

[0074] Reference Figure 4 (a) The first built-in dual-switch leak-hole permanent magnet valve 1 includes: a first upper permanent magnet 401-1, a first valve body 406-1, a first pure iron ball cover 402-1, a first ball support 403-1, a first input connecting pipe 404-1, a first lower permanent magnet 405-1, a leak-hole 408, a U-shaped pipe 409, and an output connecting pipe 407. The first upper permanent magnet 401-1 is located above the first valve body 406-1, and the first lower permanent magnet 405-1 is located below the first valve body 406-1; the first end of the first input connecting pipe 404-1 is the inlet, and the top of the second end is provided with a second ball holder 403-2, on which a second pure iron ball cover 402-2 is placed; the second end of the second input connecting pipe 404-2 passes through the second lower permanent magnet 405-2 and extends into the interior of the second valve body 406-2; the second upper permanent magnet 401-2 is located above the second valve body 406-2, and the second lower permanent magnet 405-2 is located below the second valve body 406-2. The first and second ends of the U-shaped tube 409 are each topped with a ball holder, and a pure iron ball cap is placed on the ball holder. The first end of the U-shaped tube 409 passes through the first lower permanent magnet 405-1 and extends into the first valve body 406-1. The second end of the U-shaped tube 409 passes through the second lower permanent magnet and extends into the second valve body. The first end of the output connecting pipe 407 is an outlet, and the top of the second end is topped with a ball holder, on which a pure iron ball cap is placed. The second end of the output connecting pipe 407 passes through the second lower permanent magnet and extends into the second valve body. Inside the first valve body 406-1, the first input connecting pipe 404-1 and the U-shaped tube are connected through a drain hole 408.

[0075] like Figure 4As shown in (b), the second built-in double-switch permanent magnet valve 2, the fourth built-in double-switch permanent magnet valve 4, the sixth built-in double-switch permanent magnet valve 6, the seventh built-in double-switch permanent magnet valve 7, and the eighth built-in double-switch permanent magnet valve 8 have the same structure. The only difference between the second built-in double-switch permanent magnet valve 2 and the first built-in double-switch leak-hole permanent magnet valve 1 is that in the second built-in double-switch permanent magnet valve 2, there is no connecting pipe and no leak hole between the first input connecting pipe 404-1 and the U-shaped pipe.

[0076] Lift the first upper permanent magnet 401-1 upwards, lift the first pure iron ball cover 402-1 upwards, open the first ball support 403-1, evacuate the gas source pipeline, lift the first lower permanent magnet 405-1, move the first pure iron ball cover 402-1 upwards and cover the first ball support 403-1 downwards, and the poisoned gas passes sequentially through the first input connecting pipe 404-1, the leak hole 408, the U-shaped pipe 409, the output connecting pipe 407, the vacuum main pipe 00, the first type of cathode gas poisoning test tube 10, the second type of cathode gas poisoning test tube 20, and the third type of cathode gas poisoning test tube 30.

[0077] The first built-in dual-switch perforated permanent magnet valve 1 controls the flow rate of oxygen during cathode poisoning, the third built-in dual-switch perforated permanent magnet valve 3 controls the flow rate of carbon dioxide during cathode poisoning, and the fifth built-in dual-switch perforated permanent magnet valve 5 controls the flow rate of water vapor during cathode poisoning.

[0078] The method for cathode poisoning activation measurement includes the following steps:

[0079] I. Measurement of the thermionic emission characteristics of the first type of cathode poisoning test tube 10, the second type of cathode poisoning test tube 20, and the third type of cathode poisoning test tube 30 under normal vacuum conditions.

[0080] Second, introduce oxygen: Close the first built-in double-switch leak-hole permanent magnet valve 1, close the third built-in double-switch leak-hole permanent magnet valve 3, close the fourth built-in double-switch permanent magnet valve 4, close the fifth built-in double-switch leak-hole permanent magnet valve 5, close the sixth built-in double-switch permanent magnet valve 6, and open the second built-in double-switch permanent magnet valve 2. Oxygen flows into the vacuum main pipeline 00, vacuum gauge 010, first type of cathode poisoning test tube 10, second type of cathode poisoning test tube 20, and third type of cathode poisoning test tube 30 through the leak 408 and the second built-in double-switch permanent magnet valve 2.

[0081] 3. Observe the decrease in vacuum level measured by the vacuum gauge and the change in the volt-ampere characteristic of thermionic emission.

[0082] 4. Close the second built-in double-switch permanent magnet valve 2, evacuate to the vacuum level before oxygen is introduced, give the three cathodes a second decomposition and activation after poisoning, and measure the volt-ampere curve.

[0083] The amount of poisonous gas enters the poisoning test tube through the leak, and the amount of poisonous oxygen is determined by the value displayed on the vacuum gauge 010. The second built-in double-switch permanent magnet valve 2 is closed, and the vacuum measurement value of oxygen is recorded.

[0084] The volt-ampere characteristics of thermionic emission from the first type of cathode poisoning test tube 10, the second type of cathode poisoning test tube 20, and the third type of cathode poisoning test tube 30 after oxygen poisoning were measured.

[0085] Activation: Under the condition that the cathode is restored to normal vacuum: record the vacuum level, and after the cathode measurement power supply is turned on, the cathode begins its second decomposition, activation, and measurement of the cathode thermionic emission voltage-current characteristics.

[0086] 2. Using the same method, introduce carbon dioxide gas and water vapor, and measure the volt-ampere characteristics of the cathode thermionic emission.

[0087] The above are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A system for quantitative analysis of cathode poisoning gases, characterized by, The vacuum main pipeline (00), the high vacuum molecular pump (102), the eighth built-in double-switch permanent magnet valve (8), the seventh built-in double-switch permanent magnet valve (7), the vacuum gauge (010), the third cathode poisoning test tube (30), the second cathode poisoning test tube (20), the first cathode poisoning test tube (10), the oxygen source (203), the carbon dioxide source (202), the water vapor source (201) and the initial vacuum pump (101) for obtaining vacuum are connected in sequence. The initial vacuum pump (101) is connected with the high vacuum molecular pump (102), the eighth built-in double-switch permanent magnet valve (8), the seventh built-in double-switch permanent magnet valve (7) and the vacuum main pipeline (00) in sequence, and the vacuum main pipeline (00) is communicated with the vacuum gauge (010), the third cathode poisoning test tube (30), the second cathode poisoning test tube (20) and the first cathode poisoning test tube (10) respectively. The oxygen source (203) is connected with the first built-in double-switch leak hole permanent magnet valve (1), the second built-in double-switch permanent magnet valve (2) and the vacuum main pipeline (00) in sequence. The carbon dioxide source (202) is connected with the third built-in double-switch leak hole permanent magnet valve (3), the fourth built-in double-switch permanent magnet valve (4) and the vacuum main pipeline (00) in sequence. The water vapor source (201) is connected with the fifth built-in double-switch leak hole permanent magnet valve (5), the sixth built-in double-switch permanent magnet valve (6) and the vacuum main pipeline (00) in sequence. The first cathode poisoning test tube (10), the second cathode poisoning test tube (20) and the third cathode poisoning test tube (30) have the same structure. The cathode part comprises a stainless steel flange core column (301), a ceramic tube (302), a temperature measuring thermocouple (305), a cathode heating wire (308), a cathode (309) and a filament lead-out wire (313). The filament lead-out wire (313) is connected with the cathode heating wire (308) through the core column (301), the temperature measuring thermocouple (305) passes through the core column (301) and is arranged outside the cathode (309), and the ceramic tube (302) is arranged at the contact position of the filament lead-out wire (313) and the core column (301) and the contact position of the temperature measuring thermocouple (305) and the core column (301) for insulation. The stainless steel flange core column (301) is provided with a cathode part flange. The anode part comprises a tube shell (303), a water-cooled anode flange (307), a water-cooled anode (310) and a vacuum exhaust pipe (304). The tube shell (303) is arranged in the inner diameter of the water-cooled anode flange (307), and the water-cooled anode (310) is arranged at the other end of the tube shell (303). The vacuum exhaust pipe (304) is arranged on the lower side wall of the tube shell (303). The water-cooled anode (310) is provided with a cooling water outlet (311) and a cooling water inlet (312) outside. The cathode component flange and the water-cooled anode flange (307) are fixed by a combination of screw nuts (3.1), thereby forming a closed cavity inside the tube shell (303); the temperature measuring thermocouple (305), cathode heating wire (308) and cathode (309) are located in the closed cavity.

2. The system of claim 1, wherein, The cathode poisoning gas quantitative analysis system measures the difference in emission electron current volt-ampere characteristics before and after poisoning of the cathode (309), and the emission electron current volt-ampere characteristics are measured by an emission electron current volt-ampere characteristic measuring system, which comprises an adjustable power supply (Y1), a first adjusting resistor (R1), a second voltmeter (V2), a first ammeter (mA), an adjustable filament power supply (Y2), a second adjusting resistor (R2), a first voltmeter (V1) and a second ammeter (A); the first end of the adjustable power supply (Y1) is connected in sequence with the first adjusting resistor (R1), the first ammeter (mA), the water-cooled anode (310), the cathode (309) and the second end of the adjustable power supply (Y1); the second voltmeter (V2) is connected in parallel with the adjusting resistor (R1); the first end of the cathode heating wire (308) is connected in sequence with the second adjusting resistor (R2), the second ammeter (A), the adjustable filament power supply (Y2) and the second end of the cathode heating wire (308); one end of the first voltmeter (V1) is connected with the first end of the cathode heating wire (308), and the other end of the first voltmeter (V1) is connected with the second end of the cathode heating wire (308).

3. The system of claim 1, wherein: The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00).

4. The system of claim 1, wherein: The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00).

5. The system of claim 1, wherein: The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00).

6. The system of claim 4, wherein: The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline (00). The first, second and third cathode poisoning test tubes (10, 20 and 30) are connected in parallel on the vacuum main pipeline The first upper permanent magnet (401-1) is located above the first valve body (406-1), and the first lower permanent magnet (405-1) is located below the first valve body (406-1); the first end of the first input communication pipe (404-1) is an inlet, and the top of the second end is provided with a first ball holder (403-1), and a first pure iron ball cover (402-1) is placed on the first ball holder (403-1); the second end of the first input communication pipe (404-1) penetrates the first lower permanent magnet (405-1) and the first valve body in sequence and extends into the first valve body; The second upper permanent magnet is located above the second valve body, and the second lower permanent magnet is located below the second valve body; The first end and the second end of the U-shaped pipe are both provided with a ball holder at the top, and a pure iron ball cover is placed on the ball holder; the first end of the U-shaped pipe penetrates the first lower permanent magnet (405-1) and the first valve body in sequence and extends into the first valve body; the second end of the U-shaped pipe penetrates the second lower permanent magnet and the second valve body in sequence and extends into the second valve body; The first end of the output communication pipe (407) is an outlet, and the top of the second end is provided with a ball holder, and a pure iron ball cover is placed on the ball holder; the second end of the output communication pipe (407) penetrates the second lower permanent magnet and the second valve body in sequence and extends into the second valve body; In the first valve body (406-1), the first input communication pipe (404-1) and the U-shaped pipe are communicated through a leakage hole.

7. The system of claim 5, wherein: The first built-in double-switch leakage hole permanent magnet valve (1) controls the flow of oxygen in the cathode poisoning, the third built-in double-switch leakage hole permanent magnet valve (3) controls the flow of carbon dioxide in the cathode poisoning, and the fifth built-in double-switch leakage hole permanent magnet valve (5) controls the flow of water vapor in the cathode poisoning.

8. The system of claim 1, wherein: The analysis system uses method includes, when opening all valves on the analysis system, vacuuming the vacuum main pipeline (00), the cathode poisoning test tube, and the poisoning gas source branch, recording the vacuum degree, connecting the adjustable filament power supply and the adjustable power supply, and then the cathode starts to decompose, activate, and measure the volt-ampere characteristic of the hot electron emission of the cathode; injecting cathode poisoning gas, recording the vacuum degree, and measuring the volt-ampere characteristic of the hot electron emission after the cathode poisoning; the seventh built-in double-switch permanent magnet valve (7) and the eighth built-in switch permanent magnet valve (8) are opened to vacuumize, and the instantaneous vacuum degree value is recorded, which is used to activate the cathode after poisoning and measure the volt-ampere characteristic of the hot electron emission of the activated cathode after poisoning.

9. A method for quantitative analysis of cathode poisoning gas, characterized by: The system according to any one of claims 1-8, the method comprising the following steps: I. Measure the volt-ampere characteristic of the hot electron emission of the first cathode poisoning test tube (10), the second cathode poisoning test tube (20), and the third cathode poisoning test tube (30) in a normal vacuum environment; II. Introduce oxygen: close the first built-in double-switch leakage hole permanent magnet valve (1), close the third built-in double-switch leakage hole permanent magnet valve (3), close the fourth built-in double-switch permanent magnet valve (4), close the fifth built-in double-switch leakage hole permanent magnet valve (5), and close the sixth built-in double-switch permanent magnet valve (6); 1) Open the second built-in double-switch permanent magnet valve (2), 2) Observe the vacuum degree drop of the vacuum gauge and the change value of the volt-ampere characteristic of the hot electron emission, 3) The amount of the poisoning gas, the leak into the first kind of cathode poisoning test tube, the value of the vacuum gauge (010) to determine the amount of oxygen poisoning, 4) Close the second built-in double switch permanent magnet valve (2) and record the oxygen vacuum value, 5) Measure the first kind of cathode poisoning test tube (10), the second kind of cathode poisoning test tube (20) and the third kind of cathode poisoning test tube (30) after oxygen poisoning. The volt-ampere characteristic of the hot electron emission, 6) Activation: the cathode returns to the normal vacuum state condition: record the vacuum degree, turn on the cathode power supply after the cathode begins to decompose for the second time, activate, measure the volt-ampere characteristic of the hot electron emission of the cathode; Three, use the same method to introduce carbon dioxide gas, introduce water vapor and measure the volt-ampere characteristic of the hot electron emission of the cathode.

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