A wide-dynamic-range vacuum leak detection device

Abstract

The present invention relates to a wide-dynamic-range vacuum leak detection device, belonging to the technical field of vacuum leak detection. The leak detection device of the present invention adopts a linkage mode of QMS and anode ignition technology, and with the cooperation of a high-precision control loop, it can achieve vacuum leak detection in the dynamic range from 10 2 Pa to 10 ‑9 Pa, filling the technical gap of wide-dynamic-range vacuum leak detection in the current market; moreover, the tracer gas of this leak detection device is not limited to helium, and it has a wide range of application prospects.

Description

Technical Field

[0001] The present invention relates to a wide-dynamic-range vacuum leak detection device, belonging to the technical field of vacuum leak detection. Background Art

[0002] Existing vacuum leak detection technologies widely use helium mass spectrometry leak detection or residual gas analysis technology for leak detection. Both of the above two technologies utilize the principle that the detector responds to the change of the tracer gas to reflect the change of the vacuum leak rate. However, the dynamic range of the vacuum leak detection environment they apply is small, and the tracer gas is single, and they cannot cover the leak detection environments of medium vacuum, high vacuum, and ultra-high vacuum at the same time. Among them, referring to the reference standard GB / T3163-93, the vacuum regions are roughly divided as follows: low vacuum 10 5 Pa~10 2 Pa, medium vacuum 10 2 Pa~10 -1 P, high vacuum 10 -1 Pa~10 -5 Pa, ultra-high vacuum <10 -5 Pa. Summary of the Invention

[0003] Aiming at the deficiencies of the existing technology, the present invention provides a wide-dynamic-range vacuum leak detection device. The device adopts the linkage mode of QMS and anode ignition technology, and utilizes the "high-sensitivity ion selection characteristic of QMS" and the "anode ignition current-vacuum change curve". With the cooperation of a high-precision control loop, vacuum leak detection with a dynamic range of 10 2 Pa to 10 -9 Pa is realized, filling the technical blank of wide-dynamic-range vacuum leak detection in the current market, and having a wide application prospect.

[0004] The object of the present invention is achieved through the following technical solutions.

[0005] A wide-dynamic-range vacuum leak detection device, the leak detection device includes a vacuum gauge, a tracer gas source, an ion source sampling unit, a QMS unit, a vacuum chamber, and a high-precision control loop;

[0006] The ion source sampling unit includes an ionization chamber, an anode, a filament, a magnet, and ion beam lens electrodes; the ionization chamber is processed with a sampling port and an ion outlet, the anode passes through the ionization chamber and is fixedly installed at the upper end of the ionization chamber, the filament is located inside the ionization chamber, the magnet is placed outside the ionization chamber, and the four ion beam lens electrodes are installed in sequence up and down at the ion outlet at the lower end of the ionization chamber;

[0007] The high-precision control loop includes a power supply unit and a data processing unit;

[0008] The sampling ports of the vacuum gauge, the tracer gas source, and the ionization chamber are respectively connected to the vacuum component to be inspected. The ion outlet of the ionization chamber is connected to the information acquisition end of the QMS unit. The anode is respectively connected to the power supply unit and the data processing unit. The information output end of the QMS unit is connected to the data processing unit. The ion source sampling unit and the QMS unit are placed in the vacuum chamber.

[0009] The working principle of the leak detection device is as follows: According to the vacuum degree of the vacuum component to be inspected fed back by the vacuum gauge, switch to the anode ignition mode for leak detection or the QMS mode for leak detection;

[0010] Leak detection in QMS mode: When it is determined that the vacuum component to be inspected is in medium vacuum or high vacuum according to the detection result of the vacuum gauge, the power supply unit outputs a low voltage to the anode. The tracer gas molecules entering the ionization chamber are ionized by the energy electrons emitted by the filament to generate ions. The ions move towards the ion beam lens electrode under the collimation of the magnetic field of the magnet and the repulsion of the electric field of the anode, and enter the QMS unit through the ion outlet of the ionization chamber for analysis. The data processing unit collects the current output by the QMS unit. Since the tracer gas concentration is proportional to the intensity of the QMS mass spectrum peak, the leak rate of the vacuum component to be inspected can be calculated according to the magnitude of the current;

[0011] Leak detection in anode ignition mode: When it is determined that the vacuum component to be inspected is in ultra-high vacuum according to the detection result of the vacuum gauge, the power supply unit outputs a high voltage to the anode. After the tracer gas enters the ionization chamber, the high voltage applied to the anode can induce a small amount of particles to excite a small amount of electrons. The electrons move in a spiral motion under the Lorentz force of the magnetic field of the magnet, and trigger more tracer gas to be ionized, releasing more electrons, which are finally captured by the anode to generate a current. The data processing unit collects the current generated by the anode. Since the current is proportional to the tracer gas concentration, the leak rate of the vacuum component to be measured can be calculated according to the magnitude of the current.

[0012] Furthermore, a titanium oxide coating is prepared on the inner surface of the ionization chamber to avoid the corrosive damage of the corrosive tracer gas to the leak detection device; The materials of the filament and the ion beam lens electrode are selected as α+β titanium alloy with high strength, corrosion resistance, and heat resistance, which can extend the service life of the leak detection device and improve its stability and reliability.

[0013] Regarding the specific mass-to-charge ratio of the tracer gas, the current generated by the tracer gas in high vacuum and medium vacuum environments is used as a quantitative index for the vacuum leak rate. The tracer gas is not limited to common helium gas, and hydrogen, Freon, and carbon tetrachloride can also be selected.

[0014] Furthermore, the high voltage is 2.7 kV to 3.3 kV, and the low voltage is 140 V to 160 V.

[0015] Further, the power supply unit consists of a low-voltage power supply, a high-voltage power supply, and a single-pole double-throw switch. The anode is connected to the low-voltage power supply or the high-voltage power supply through the single-pole double-throw switch. The voltage output by the low-voltage power supply is 140V - 160V, and the voltage output by the high-voltage power supply is 2.7kV - 3.3kV.

[0016] Further, the high-precision control loop further includes a human-machine interface, which is connected to the data processing unit, and the current information collected by the data processing unit is displayed on the human-machine interface.

[0017] Beneficial effects:

[0018] (1) The leak detection device according to the present invention realizes leak detection in a wide dynamic range vacuum by only relying on circuit switching without adding hardware according to the interval where the vacuum degree is located;

[0019] (2) The tracer gases required for the two leak detection modes are not limited to helium, and common gases such as hydrogen, Freon, and carbon tetrachloride on the market can all be used as tracer gases;

[0020] (3) The anode ignition mode has low power consumption and high sensitivity, and undoubtedly has more prospects in the ultra-high vacuum leak detection market;

[0021] (4) The use of titanium oxide coating and titanium alloy materials in the ion source injection unit can resist corrosive environments and improve the overall service life. Description of the drawings

[0022] Figure 1 It is a schematic structural diagram of the leak detection device described in the embodiment.

[0023] Figure 2 It is a schematic structural diagram of the ion source injection unit.

[0024] Among them, 1 - magnet, 2 - ionization chamber, 3 - anode, 4 - injection port, 5 - ion beam lens electrode, 6 - insulating screw, 7 - filament, 8 - ion outlet. Specific implementation manners

[0025] The present invention will be further described below in conjunction with the drawings and specific implementation manners.

[0026] Embodiment 1

[0027] The wide dynamic range vacuum leak detection device includes a vacuum gauge, a tracer gas source, an ion source injection unit, a QMS unit, a vacuum chamber, and a high-precision control loop;

[0028] The vacuum component to be detected is selected as a standard leak hole (metal flattened leak hole 5×10 -5 Pa·L / s);

[0029] The tracer gas in the tracer gas source is selected as carbon tetrachloride;

[0030] The ion source injection unit includes an ionization chamber 2, an anode 3, a filament 7, a magnet 1, and ion beam lens electrodes 5; the ionization chamber 2 is machined with an injection port 4 and an ion outlet 8, and there is a layer of titanium oxide cladding layer on the inner wall of the ionization chamber 2. The anode 3 passes through the ionization chamber 2 and is fixedly installed at the upper end of the ionization chamber 2. The filament 7 is located inside the ionization chamber 2. The magnet 1 is placed outside the ionization chamber 2. The four ion beam lens electrodes 5 are installed in the ion outlet 8 at the lower end of the ionization chamber 2 in the up and down order;

[0031] Among them, the preparation of the titanium oxide cladding layer is as follows: The powdered titanium oxide material is pre-coated on the inner wall of the ionization chamber 2, and then heated with a high-power density laser to melt it and then quickly solidify, forming a uniform and dense cladding layer on the inner wall of the ionization chamber 2, which can avoid the corrosive damage of the tracer gas;

[0032] The high-precision control loop includes a power supply unit, a data processing unit, and a human-machine interface; among them, the power supply unit is composed of a high-voltage power supply, a low-voltage power supply, and a single-pole double-throw switch. The voltage of the low-voltage power supply is 150V, and the voltage of the high-voltage power supply is 3kV;

[0033] The vacuum gauge, the tracer gas source, and the injection port 4 of the ionization chamber 2 are respectively connected to the vacuum component to be tested. The ion outlet 8 of the ionization chamber 2 is connected to the information acquisition end of the QMS unit. The anode 3 is connected to the low-voltage power supply or the high-voltage power supply through a single-pole double-throw switch. The data processing unit is respectively connected to the anode 3, the information output end of the QMS unit, and the human-machine interface. The ion source injection unit and the QMS unit are placed in the vacuum chamber.

[0034] The working principle of the leak detection device is as follows:

[0035] Leak detection in QMS mode: The vacuum gauge detects that the vacuum of the vacuum component to be tested is 3×10 -2 Pa. The single-pole double-throw switch connects the low-voltage power supply to the anode 3 and lights up the filament 7; after the tracer gas leaking from the vacuum component to be tested enters the ionization chamber 2, the tracer gas molecules are ionized by the 70eV energy electrons emitted by the filament 7 to generate ions. The ions move in the direction of the ion beam lens electrodes 5 under the collimation of the magnetic field of the magnet 1 and the repulsion of the 150V electric field of the anode 3, and enter the QMS unit through the ion outlet 8 of the ionization chamber 2 for analysis. The data processing unit collects the current output by the QMS unit and displays it on the human-machine interface. Since the tracer gas concentration is proportional to the intensity of the QMS mass spectrometry peak, according to the measured current value (1μA) and the leak rate of the standard leak hole (5×10 -5 Pa·L / s), the leak detection sensitivity of 5×10 -5Pa·L / (s·μA); If the standard leak hole is replaced with the actual vacuum component to be inspected, and the above steps are repeated, assuming the collected current value is 0.01 μA, then the leak rate of the vacuum component to be inspected can be calculated as 5×10 -7 Pa·L / s;

[0036] Leak detection by anode ignition mode: The vacuum gauge detects that the vacuum of the vacuum component to be inspected is 5×10 -6 Pa. The single-pole double-throw switch connects the high-voltage power supply to the anode 3, and at this time, the filament 7 is not lit; after the tracer gas leaking from the vacuum component to be inspected enters the ionization chamber 2, the 3 kV voltage applied to the anode 3 can slightly induce particles to excite a small number of electrons. These electrons move in a spiral due to the Lorentz force of the magnetic field of the magnet 1, and more tracer gas is ionized, releasing more electrons, which are finally captured by the anode 3 to generate a current. The data processing unit collects the current generated by the anode 3 and displays it on the human-machine interface. Since the current is proportional to the concentration of the tracer gas, according to the measured current value (1 μA) and the leak rate of the standard leak hole (5×10 -5 Pa·L / s), the leak detection sensitivity is obtained as 5×10 -5 Pa·L / (s·μA); If the standard leak hole is replaced with the actual vacuum component to be inspected, and the above steps are repeated, assuming the collected current value is 0.01 μA, then the leak rate of the vacuum component to be inspected can be calculated as 5×10 -7 Pa·L / s.

[0037] In summary, the above is only a preferred embodiment of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A wide-dynamic-range vacuum leak detection device, characterized in that: The leak detection device includes a vacuum gauge, a tracer gas source, an ion source injection unit, a QMS unit, a vacuum chamber, and a high-precision control circuit; The ion source injection unit includes an ionization chamber (2), an anode (3), a filament (7), a magnet (1), and an ion beam lens electrode (5); an injection port (4) and an ion outlet (8) are machined on the ionization chamber (2), the anode (3) passes through the ionization chamber (2) and is fixedly installed at the upper end of the ionization chamber (2), the filament (7) is located inside the ionization chamber (2), the magnet (1) is placed outside the ionization chamber (2), and four ion beam lens electrodes (5) are installed in sequence up and down at the ion outlet (8) at the lower end of the ionization chamber (2); The high-precision control circuit includes a power supply unit and a data processing unit; The vacuum gauge, the tracer gas source, and the injection port (4) of the ionization chamber (2) are respectively connected to the vacuum component to be detected. The ion outlet (8) of the ionization chamber (2) is connected to the information acquisition end of the QMS unit. The anode (3) is respectively connected to the power supply unit and the data processing unit. The information output end of the QMS unit is connected to the data processing unit. The ion source injection unit and the QMS unit are placed in the vacuum chamber; The leak detection device switches between leak detection in the anode ignition mode or leak detection in the QMS mode according to the vacuum degree of the vacuum component to be detected fed back by the vacuum gauge; Leak detection in the QMS mode: When it is determined according to the detection result of the vacuum gauge that the vacuum component to be detected is in medium vacuum or high vacuum, the power supply unit outputs a low voltage to the anode. The tracer gas molecules entering the ionization chamber are ionized by the energy electrons emitted by the filament to generate ions. The ions move in the direction of the ion beam lens electrode under the collimation of the magnetic field of the magnet and the repulsion of the electric field of the anode, and enter the QMS unit through the ion outlet of the ionization chamber for analysis. The data processing unit collects the current output by the QMS unit. Since the tracer gas concentration is proportional to the intensity of the QMS mass spectrum peak, the leak rate of the vacuum component to be detected can be calculated according to the magnitude of the current; Leak detection in the anode ignition mode: When it is determined according to the detection result of the vacuum gauge that the vacuum component to be detected is in ultra-high vacuum, the power supply unit outputs a high voltage to the anode. After the tracer gas enters the ionization chamber, the high voltage applied to the anode can induce a small amount of particles to excite a small amount of electrons. The electrons make a spiral motion under the Lorentz force of the magnetic field of the magnet and trigger more tracer gas to be ionized, releasing more electrons, which are finally captured by the anode to generate a current. The data processing unit collects the current generated by the anode. Since the current is proportional to the tracer gas concentration, the leak rate of the measured vacuum component can be calculated according to the magnitude of the current; For the specific mass-to-charge ratio of the tracer gas, the current generated by the tracer gas in a high-vacuum and medium-vacuum environment is used as a quantitative index for the vacuum leak rate; A titanium oxide coating is prepared on the inner surface of the ionization chamber (2); The materials of the filament (7) and the ion beam lens electrode (5) are selected as α+β titanium alloy.

2. The wide-dynamic-range vacuum leak detection device according to claim 1, wherein: The tracer gas in the tracer gas source is selected from helium, hydrogen, Freon, or carbon tetrachloride.

3. The wide-dynamic-range vacuum leak detection device according to claim 1, wherein: The high voltage output by the power supply unit to the anode (3) is 2.7 kV to 3.3 kV, and the low voltage output by the power supply unit to the anode (3) is 140 V to 160 V.

4. The wide-dynamic-range vacuum leak detection device according to claim 1, wherein: The power supply unit consists of a low-voltage power supply, a high-voltage power supply and a single-pole double-throw switch. The voltage output by the low-voltage power supply is 140V - 160V, and the voltage output by the high-voltage power supply is 2.7kV - 3.3kV; the anode (3) is connected to the low-voltage power supply or the high-voltage power supply through the single-pole double-throw switch.

5. The wide-dynamic-range vacuum leak detection device according to claim 1, wherein: The high-precision control loop further includes a human-machine interface, and the human-machine interface is connected to the data processing unit.

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