Hydrogen leak detector
The hydrogen leak detector's innovative design with re-inflow suppression structures and hydrogen trap members addresses the challenge of prolonged recovery times by minimizing re-inflow, ensuring rapid background stabilization and improved measurement accuracy.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- SHIMADZU EMIT
- Filing Date
- 2022-01-27
- Publication Date
- 2026-06-25
- Estimated Expiration
- Not applicable · inactive patent
Smart Images
Figure 0007880030000001 
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Abstract
Description
Technical Field
[0001] The present invention relates to a hydrogen leak detector used for inspecting the airtightness of a vacuum vessel and the like.
Background Art
[0002] A mass spectrometer type hydrogen leak detector guides hydrogen gas flowing in from the leak location of a test object to an analysis tube and measures the leak amount.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] In a hydrogen leak detector, compared with a helium leak detector, it is difficult to stabilize the background, and for example, after measuring a large leak, it takes a considerable amount of time for the background to recover to a level where the next measurement can be performed. Therefore, it may be difficult to obtain sufficient measurement accuracy in a short time.
[0005] The main object of the present invention is to facilitate the stabilization of the background in a hydrogen leak detector, significantly shorten the time required for the background to recover, and enable sufficient measurement accuracy to be obtained in a short time.
Means for Solving the Problems
[0006] In other words, the leak detector according to the present invention detects hydrogen gas leaking from a test specimen by introducing it into an analysis tube, and is characterized in that the analysis tube comprises an ion source section that ionizes the hydrogen gas introduced inside to generate hydrogen ions, an ion collector section that detects the amount of current of the hydrogen ions ejected from the ion source section, and a re-inflow suppression structure that suppresses the re-inflow of hydrogen gas that has become uncharged from ions in the ion collector section into the ion source section. [Effects of the Invention]
[0007] With this type of design, the re-inflow suppression structure inhibits the re-ionization of regenerated uncharged hydrogen, which has become uncharged from hydrogen ions due to measurement, by refluxing it back into the ion source. This reduces the probability of re-ionization, making it possible to practically shorten the background recovery time after measurement. [Brief explanation of the drawing]
[0008] [Figure 1] This schematic cross-sectional view shows the internal structure of the 270-degree deflection angle type analytical tube in the comparative example, and also explains the reinflow path of regenerated uncharged hydrogen into the ion source section. [Figure 2] This is a schematic cross-sectional view showing the internal structure of a 90-degree deflection angle type analytical tube in a comparative example, and illustrating the reinflow path of regenerated uncharged hydrogen into the ion source section. This is a data explanatory diagram showing an example of a processing recipe in the same embodiment. [Figure 3] This schematic cross-sectional view shows the internal structure of a 180-degree deflection angle type analytical tube in a comparative example, and also explains the reinflow path of regenerated uncharged hydrogen into the ion source section. [Figure 4] This is a schematic diagram showing the overall structure of a leak detector in one embodiment of the present invention. [Figure 5] This is a schematic cross-sectional view showing the internal structure of the analysis tube in the same embodiment. [Figure 6] This is a schematic cross-sectional view showing the internal structure of an analytical tube in another embodiment of the present invention. [Modes for carrying out the invention]
[0009] Before describing embodiments of the present invention, we will describe comparative analytical tubes and elaborate on their problems. Figures 1 to 3 show comparative analytical tubes. The analysis tube 100 illustrated in Figure 1 is a magnetic field deflection mass spectrometer comprising an ion source section 1 equipped with an ion chamber (anode) 11, a filament 12, and an ion source slit 13; an ion collector section 2 equipped with a sector-type deflection electrode 21, an ion collection device 22 such as an MCP or Faraday cup, and an ion collector slit 23; a case 3 that houses the ion source section 1 and the ion collector section 2 and forms a magnetic field space 32 with an intermediate slit 31 provided between them; and a magnet 4 that generates a magnetic field perpendicular to the plane of the paper.
[0010] The analysis tube 100 is constantly evacuated to a high vacuum by a high vacuum pump connected to the exhaust port 51, and hydrogen gas introduced into the analysis tube 100 is ionized in the ion chamber (anode) 11 by thermionic electrons emitted from the filament.
[0011] The generated ions are ejected from the ion source slit 13 into the magnetic field space 32. The ions trace an arc according to Fleming's rule, but the radius of the arc varies depending on the ion's mass, and hydrogen ions trace a unique orbit with a mass number of 2.
[0012] The intermediate slit 31 is positioned on the hydrogen ion orbital S1, and only hydrogen ions pass through the intermediate slit 31 to reach the ion collector slit 23. The hydrogen ions are deflected by the electrostatic field at the sector-type deflection electrode 21 and return to uncharged hydrogen with the supply of free electrons at the ion collection device 22. At this time, free electrons are supplied in proportion to the number of hydrogen ions. A hydrogen leak detector is a device that measures the amount of free electrons supplied as an electric current and converts and outputs it as the amount of hydrogen leakage.
[0013] As a measurement procedure, the measurement is started by waiting until the inside of the analysis tube 100 becomes below a predetermined background and blowing hydrogen gas onto the leak test location of the test body.
[0014] However, in a hydrogen leak detector, compared with a helium leak detector, it is difficult to stabilize the background. For example, after measuring a large leak, it takes a considerable amount of time for the background to recover to a level at which the next measurement can be performed, so it may be difficult to obtain sufficient measurement accuracy in a short time.
[0015] Regarding this phenomenon, the inventor of the present application believes that one of the reasons is that hydrogen takes more time to be discharged compared to helium. Therefore, after flowing into the analysis tube and being ionized, the detected hydrogen, that is, the measured hydrogen that has returned to a charge-free state from an ion after receiving the supply of free electrons by the ion collection device (hereinafter also referred to as regenerated charge-free hydrogen), returns to the ion source part again and is ionized much more frequently than in the case of helium.
[0016] In addition, in the case of a large leak, a large amount of air is sucked, so water molecules contained in the air are decomposed into hydrogen ions during ionization, and as a result, more regenerated charge-free hydrogen than expected is generated and flows into the ion source again, which is also considered to be one of the reasons. Therefore, the inventor of the present application has advanced the study and examined by which route the regenerated charge-free hydrogen re-enters the ion source part. For the ease of understanding of the content, it will be explained somewhat qualitatively below.
[0017] There are several types of this kind of analysis tube with different deflection angles. The analysis tube of FIG. 1 described above is of the type with a deflection angle of 270 degrees. In addition, there are also analysis tubes such as the type with a deflection angle of 90 degrees as shown in FIG. 2 and the type with a deflection angle of 180 degrees as shown in FIG. 3. In each figure, the components corresponding to each other are denoted by the same reference numerals.
[0018] Reaching the ion collection device 22, the regenerated charge-free hydrogen that has received the supply of free electrons and become charge-free from ions diffuses linearly in all directions without being affected by the magnetic field and electric field. Therefore, the re-inflow path through which the regenerated charge-free hydrogen returns to the ion source unit 1 again can be approximated by one or more straight lines, including cases where it collides with the inner surface of the case (such as the bottom surface) and diffuses and bounces back in various directions. Since a part of the hydrogen molecules traveling along this re-inflow path undergoes a chemical reaction and is trapped inside the inner wall every time they collide with the inner wall of the case, it is assumed that in this re-inflow path, the more times the hydrogen molecules bounce back, the smaller the amount (number) of hydrogen molecules returning to the ion source unit.
[0019] Under this premise, the re-inflow path S2 of the regenerated charge-free hydrogen in each of FIGS. 1 to 3 is indicated by an arrow, and the amount of the regenerated charge-free hydrogen re-inflowing into the ion source unit 1 is qualitatively indicated by the thickness of the arrow.
[0020] As described above, FIG. 2 shows an analysis tube 100 with a deflection angle of 90 degrees, indicating that a very large amount of the regenerated charge-free hydrogen directly re-inflows into the ion source unit 1. This is because there is no shielding between the ion collector slit 23 and the ion source slit 13, and the re-inflow path S1 is formed by a single straight line connecting them.
[0021] FIG. 3 shows an analysis tube 100 with a deflection angle of 180 degrees. From this structure, it can be seen that there is a possibility that hydrogen molecules that have collided with the inner wall of the case at least once re-inflow into the ion source unit 1.
[0022] FIG. 1 shows an analysis tube with a deflection angle of 270 degrees. From this structure, it can be seen that there is a possibility that hydrogen molecules that have collided with the inner wall of the case at least twice re-inflow into the ion source unit 1.
[0023] From the above, although it can be seen that the structure of FIG. 1 can most reduce the amount of hydrogen molecules re-inflowing into the ion source unit 1, in any case, it can be grasped that the amount of hydrogen molecules re-inflowing into the ion source unit 1 cannot be sufficiently reduced.
[0024] Furthermore, if a large amount of hydrogen molecules re-enter the ion source section 1 in this manner, ionization occurs repeatedly, which is detected as an electric current. As mentioned above, this is thought to be a factor that requires a considerable amount of time for background stabilization and recovery.
[0025] Next, I will describe an embodiment of the present invention. As schematically shown in Figure 4, the leak detector X in this embodiment is connected via a test port P to a test object W, such as a vacuum vessel, which is the target of the leak inspection. This leak detector X comprises three exhaust pumps: a low-vacuum pump (e.g., an oil rotary pump) P3, a first high-vacuum pump (e.g., a turbomolecular pump) P1, and a second high-vacuum pump (e.g., a mechanical dry pump) P2; three valves V1, V2, and V3 for opening and closing the exhaust path; and an analysis tube 100. Note that P1 and P2 may also be composed of a single combined pump.
[0026] The analysis tube 100 is connected by piping to a low vacuum pump P3 via a first high vacuum pump P1, a second high vacuum pump P2, and a valve V2. The vacuum chamber 100 is connected to a low vacuum pump P3 via a test port P and a valve V1. Leak testing of the test specimen is performed using the following procedure.
[0027] (1) Close valves V1 and V3, and open valve V2 to evacuate the inside of the analysis tube 100 using the first high vacuum pump P1, the second high vacuum pump P2, and the low vacuum pump P3 in series until a predetermined background value is reached.
[0028] (2) After the temperature inside the analysis tube 100 has dropped to a predetermined background value, valve V2 is closed and valve V1 is opened, and the inside of the test specimen W is evacuated (rough evacuation) with the low vacuum pump P3.
[0029] (3) By closing valve V1 and opening valves V2 and V3, hydrogen (H2) gas is blown onto the leak test site of the test specimen W, thereby initiating leak gas detection by the analysis tube 100. At this time, each exhaust pump P1 to P3 continues to operate.
[0030] (4) If there is a leak at the leak test site of test specimen W, hydrogen gas enters test specimen W, and an amount of hydrogen gas proportional to its partial pressure enters the analysis tube 100 via valve V3 and turbomolecular pump P1. The amount of leak in test specimen W is measured by the detection of this hydrogen gas by the analysis tube.
[0031] As shown in the schematic side cross-sectional view in Figure 5, the analysis tube 100 comprises a case 3, an ion source section 1, an ion collector section 2, and a magnetic field space 32 formed between them, all of which are located within the case 3. The same reference numerals are used for the components corresponding to the analysis tube described in Figure 1.
[0032] Case 3 is a metal object (in this case, made of aluminum) that has a rectangular prism shape, for example, with a front, back, left and right sides, top, and bottom. Note that the directions such as up, down, left, and right mentioned below are relative for explanatory purposes and do not represent absolute directions. The shape of Case 3 is not limited to a rectangular prism.
[0033] In this case 3, a first room 61 is formed at the upper rear side, a second room 62 at the upper front side, and a third room 63 is formed below the first room 61 and the second room 62. A first partition wall 14 is provided at the boundary between the first room 61 and the third room 63, and a second partition wall 24 is provided at the boundary between the second room 62 and the third room 63.
[0034] The ion source unit 1 comprises an ion chamber (anode) 11 and a filament 12 located within the first chamber 61, and an ion source slit 13 penetrating the first partition wall 14. The hydrogen molecules in the first chamber 61 are ionized by electrons emitted from the filament, and these hydrogen ions are ejected from the ion source slit 13 toward the second chamber 62 below.
[0035] The magnetic field space 32 is formed in the third chamber 63. Specifically, a magnet 4 is placed outside the third chamber 63, and this magnet 4 forms a magnetic field in the third chamber 63. Hydrogen ions ejected from the ion source section 1 into the magnetic field space 32 are bent by the magnetic field in a predetermined trajectory S1. An intermediate partition wall 33 is provided in the center of the third chamber 63, and an intermediate slit 31 is provided through the portion of this intermediate partition wall 33 where it intersects with the trajectory S1. Since other ions have different trajectories than hydrogen ions, only hydrogen ions pass through this intermediate slit 31.
[0036] The ion collector unit 2 comprises a sector-type deflection electrode 21 and an ion collection device 22 such as an MCP or Faraday cup, located within the second chamber 62, and an ion collector slit 23 that penetrates the second partition wall 24. The ion collector slit 23 is positioned on the orbital S1 of hydrogen ions. Hydrogen ions ejected from the ion source slit 13 are deflected by 180 degrees in the magnetic field space 32 of the second chamber 62, pass through the ion collector slit 23, and are then deflected by another 90 degrees by the sector-type deflection electrode 21 before being irradiated onto the ion collection device 22. There, the hydrogen ions are given free electrons and return to uncharged hydrogen molecules. The amount of hydrogen leakage is measured by detecting the current flowing through the ion collection device 22 at that time.
[0037] However, in this embodiment, three types of re-inflow suppression structures 71, 72, and 73 are provided to suppress the re-inflow of hydrogen that has become uncharged from ions in the ion collector section 2 (hereinafter also referred to as regenerated uncharged hydrogen) into the ion source section 1. The first re-inflow prevention mechanism 71 is composed of hydrogen trap members 71a installed at required locations inside the case 3.
[0038] The material used for this hydrogen trap component 71a has superior hydrogen adsorption properties compared to the material used for case 3. Since case 3 is made of aluminum, stainless steel, which has superior hydrogen adsorption properties than aluminum, is used here. Hydrogen adsorption properties are determined by the difference between hydrogen adsorption and / or absorption and dissociation.
[0039] As shown in Figure 5, the hydrogen trap members 71a are installed on the bottom surface of the second chamber 62 (magnetic field space 32), the intermediate partition wall 33, and the surface of the first partition wall 14.
[0040] The hydrogen trap member 71a, provided on the bottom surface of the second chamber 62, is plate-shaped and, more specifically, is interchangeably attached to a location including the intersection of the straight line connecting the ion source slit 13 and the intermediate slit 31 (part of the reinflow path S2) and the bottom surface of the second chamber 62. The intermediate partition wall 33 and the first partition wall 14 are made of stainless steel plates that serve as hydrogen trap members 71a, and these are also removable.
[0041] This configuration reduces the proportion of regenerated uncharged hydrogen that bounces off the inner surface of case 3, the ion source slit 13, or the intermediate slit 31, and as a result, reduces the amount of regenerated uncharged hydrogen that flows back into the ion source section 1.
[0042] Furthermore, since the hydrogen trap component 71a is detachable from the case 3, even if the hydrogen adsorption capacity deteriorates due to saturation or other reasons, it is easy to restore the original performance simply by replacing the hydrogen trap component 71a.
[0043] Furthermore, the hydrogen trap material is not limited to stainless steel. Any material with superior hydrogen adsorption properties compared to aluminum is acceptable, and single metals such as titanium, copper, and iron, as well as various alloys, can also be used.
[0044] Case 3 itself may be constructed using hydrogen trap components, and the placement of the hydrogen trap components is not limited to the locations mentioned above; for example, they may be placed in the ion collector slit 23.
[0045] The second re-inflow prevention mechanism 72 is equipped with a shielding wall 72a located outside the hydrogen ion orbital S1 and on the re-inflow orbital S2. The shielding wall 72a here is flange-shaped and protrudes upward from the outer peripheral edge of the ion source slit 13 in the first partition wall 14 toward the third chamber 62.
[0046] This configuration reduces the amount of regenerated uncharged hydrogen flowing into the ion source section 1. This shielding wall 72a can be provided in places other than the first partition wall 14. For example, as shown in Figure 6, it may be provided on the periphery of the intermediate slit 31 in the intermediate partition wall 33, or it may be provided independently of the partition wall on the inflow track S2. Furthermore, this shielding wall may be made of the hydrogen trap member, or a hydrogen trap member may be attached to its surface.
[0047] The third re-inflow prevention mechanism 73 is equipped with a second exhaust port 73a that opens into the third chamber 63 (magnetic field space 32). This second exhaust port 73a is connected by piping to the high vacuum pump P1. This configuration allows the regenerated uncharged hydrogen generated in the ion collector section 2 to be discharged before it reaches the ion source section 1, thereby reducing the amount of regenerated uncharged hydrogen flowing into the ion source section 1. Furthermore, it is possible to actively exhaust heavier molecules (such as water molecules) to suppress the generation of hydrogen ions.
[0048] The location of the second exhaust port 73a can be anywhere on the ion collector section 2 side of the ion source section 1. In the example described above, the second exhaust port 73a is provided on the same side (back side) of the case 3 as the first exhaust port 51 is provided to simplify the piping layout. However, for example, the second exhaust port may be provided on the ion collector section 2 side of the intermediate slit 31 of the third chamber 63, or it may be opened on the bottom or side of the case 3. Furthermore, the second exhaust port may be opened in the second chamber 62 in which the ion collector section 2 is formed. The characteristics of the leak detector X described above can be summarized as follows:
[0049] (1) The analysis tube 100 is characterized by comprising an ion source section 1 that ionizes hydrogen gas introduced inside it to generate hydrogen ions, an ion collector section 2 that detects the amount of current of hydrogen ions ejected from the ion source section 1, and re-inflow suppression structures 71, 72, and 73 that suppress the re-inflow of hydrogen that has become uncharged from ions in the ion collector section 2 back into the ion source section 1. With this method, the regeneration of uncharged hydrogen, which has been converted from hydrogen ions to an uncharged state by measurement, can be recirculated to the ion source section 1, thereby suppressing re-ionization. This makes it possible to achieve a sufficiently fast background recovery time compared to the conventional helium method. Furthermore, since hydrogen is more abundant and inexpensive than helium, the risk of resource depletion and price increases can be avoided.
[0050] (2) The re-inflow suppression structure 71 is characterized by comprising a hydrogen trap member 71a provided on the inner surface of the analysis tube 100. With this design, the proportion of regenerated uncharged hydrogen that bounces off the inner surface of the analysis tube 100 can be reduced, and the amount of regenerated uncharged hydrogen that re-flows into the ion source section 1 due to the bounce can be reduced.
[0051] (3) The case 3 constituting the analysis tube 100 is made of aluminum, and the hydrogen trap member 71a is made of stainless steel. With this type of design, for example, while manufacturing case 3 from easily processable aluminum as before, the re-inflow suppression structure 71 can be constructed inexpensively without placing a significant burden on manufacturing by attaching stainless steel plates to the required areas on the inner surface.
[0052] (4) The hydrogen trap member 71a is provided on at least one of the following: the inner surface of the magnetic field space 32 between the ion source section 1 and the ion collector section 2; the surface of the first partition wall 14 that forms the ion source slit 13 from which hydrogen ions are ejected from the ion source section 1; or the surface of the intermediate partition wall 33 that forms the intermediate slit 31 provided on the orbital S1 of hydrogen ions in the magnetic field space 32. With this design, it is possible to more effectively reduce the amount of regenerated uncharged hydrogen that flows back into the ion source unit 1.
[0053] (5) The reinflow suppression structure 72 is characterized in that it is provided with a shielding wall 72a located on the reinflow path S2, which is represented as a straight line including bounces on the inner surface of the analysis tube, connecting the ion collector section 2 and the ion source section 1, and outside the hydrogen ion orbital S1. With this configuration, the shielding wall 72a can prevent the regenerated uncharged hydrogen from flowing into the ion source section 1.
[0054] (6) The ion source unit 1 is equipped with an ion source slit 13 for ejecting hydrogen ions, characterized in that the shielding wall 72a is provided so as to rise from the periphery of the ion source slit 13. With this design, a shielding wall 72a can be easily provided by modifying the existing ion source slit 13.
[0055] (7) The shielding wall 72a or the surface portion of the shielding wall 72a is made of a hydrogen trap member 71a. With such a setup, the synergistic effect of the shielding wall 72a and the hydrogen trap member 71a can dramatically reduce the amount of regenerated uncharged hydrogen flowing into the ion source section 1.
[0056] (8) In the ion source section 1, a first exhaust port 51 is provided, and the re-inflow suppression structure 73 is characterized in that it includes a second exhaust port 73a provided on the ion collector section 2 side of the ion source section 1. With this design, the regenerated uncharged hydrogen before it returns to the ion source unit 1 can be efficiently discharged from the second exhaust port 73a, thereby reducing the amount of regenerated uncharged hydrogen flowing into the ion source unit 1. Furthermore, it becomes possible to actively exhaust heavier molecules such as other molecules (e.g., water molecules) to suppress the generation of hydrogen ions.
[0057] (9) The first exhaust port 51 and the second exhaust port 73a are provided on the same surface of the case 3 that constitutes the analysis tube 100. With this design, the piping structure connected to the exhaust ports 51 and 73a can be simplified.
[0058] It should be noted that the present invention is not limited to the embodiments described above. For example, the same effects can be obtained by applying the present invention to analytical tubes of the type with a deflection angle of 90 degrees or 180 degrees as described above. The re-inflow suppression structure does not need to use all three described above; one or two of them may be used. Furthermore, the present invention can be modified in various ways without departing from its spirit. [Explanation of symbols]
[0059] X... Leak Detector 100...Analysis tube 1. Ion Source Unit 13. Ion Source Slit 14. First partition wall 2. Ion Collector Section 3 cases 31...Intermediate slit 32...magnetic field space 33...Intermediate partition wall 71, 72, 73... Re-inflow suppression structure 71a...Hydrogen trap component 71a 72a...Shielding wall 73a... Second exhaust port S1... Hydrogen ion orbital S2...Re-inflow route
Claims
1. This method involves introducing hydrogen gas leaking from the test specimen into an analysis tube for detection. The analysis tube comprises an ion source section that ionizes hydrogen introduced inside to generate hydrogen ions, an ion collector section that detects the amount of current of hydrogen ions ejected from the ion source section, and a re-inflow suppression structure that suppresses the re-inflow of hydrogen that has become uncharged from ions in the ion collector section back into the ion source section. The aforementioned re-inflow suppression structure includes a hydrogen trap member provided on the inner surface of the analysis tube, A leak detector characterized in that the case constituting the analysis tube is made of aluminum and the hydrogen trap member is made of stainless steel.
2. A method for detecting hydrogen gas leaking from a test specimen by introducing it into an analysis tube, The analysis tube comprises an ion source section that ionizes hydrogen introduced inside to generate hydrogen ions, an ion collector section that detects the amount of current of hydrogen ions ejected from the ion source section, and a re-inflow suppression structure that suppresses the re-inflow of hydrogen that has become uncharged from ions in the ion collector section back into the ion source section. The re-inflow suppression structure is provided with a shielding wall located on the re-inflow path, which is shown as a straight line including bounces on the inner surface of the analysis tube, connecting the ion collector section and the ion source section, and outside the orbit of the hydrogen ions. A leak detector in which the ion source section is equipped with an ion source slit for ejecting hydrogen ions, wherein the shielding wall is provided to rise from the periphery of the ion source slit.
3. A method for detecting hydrogen gas leaking from a test specimen by introducing it into an analysis tube, The analysis tube comprises an ion source section that ionizes hydrogen introduced inside to generate hydrogen ions, an ion collector section that detects the amount of current of hydrogen ions ejected from the ion source section, and a re-inflow suppression structure that suppresses the re-inflow of hydrogen that has become uncharged from ions in the ion collector section back into the ion source section. A leak detector in which a first exhaust port is provided in the ion source section, wherein the re-inflow suppression structure includes a second exhaust port provided on the ion collector section side of the ion source section.
4. The leak detector according to claim 1 or 3, wherein the re-inflow suppression structure comprises a shielding wall provided on the re-inflow path, which is shown as a straight line including bounces on the inner surface of the analysis tube, connecting the ion collector and the ion source, and outside the orbit of the hydrogen ions.
5. The re-inflow suppression structure comprises a hydrogen trap member provided on the inner surface of the analysis tube, The leak detector according to claim 2 or 4, wherein the shielding wall or the surface portion of the shielding wall is composed of the hydrogen trapping member.
6. The leak detector according to claim 3, wherein the first exhaust port and the second exhaust port are provided on the same surface of the case constituting the analysis tube.
7. The re-inflow suppression structure comprises a hydrogen trap member provided on the inner surface of the analysis tube, The leak detector according to any one of claims 1 to 6, wherein the hydrogen trapping member is provided on at least one of the following: the inner surface of the magnetic field space between the ion source portion and the ion collector portion; the surface of the first partition wall in which an ion source slit is formed from which hydrogen ions are ejected from the ion source portion; or the surface of the intermediate partition wall in which an intermediate slit is formed on the trajectory of hydrogen ions in the magnetic field space.
8. This method involves introducing hydrogen gas leaking from the test specimen into an analysis tube for detection. The analysis tube comprises an ion source section that ionizes hydrogen introduced inside to generate hydrogen ions, an ion collector section that detects the amount of current of hydrogen ions ejected from the ion source section, and a case that houses the ion source section and the ion collector section and forms a magnetic field space between them with an intermediate slit. A leak detector characterized in that the deflection angle of the analysis tube is 270 degrees.
9. The leak detector according to claim 8, further comprising a re-inflow suppression structure that suppresses the re-inflow of hydrogen, which has become uncharged from ions in the ion collector section, into the ion source section.