KR20230001493A - Leak detector and ion source for leak detector - Google Patents

Abstract

(Problem) Improve insulation durability between electrodes without changing the size or weight of an ion source.
(Solution Means) The gas from the subject (X) is guided to the vacuum-processed analysis tube (4), and the gas is ionized and detected using the ion source (6) provided in the analysis tube (4) to detect the subject (X). A leak detector (100) for leak testing X), wherein an ion source (6) includes a filament (61) that emits thermal electrons for ionizing gas, an electrode (65) electrically connected to the filament (61), and an electrode 65 is formed in the base member 66 that divides the interior space 6S where the filament 61 is disposed and the outside, and the through-hole 66h for electrodes formed in the base member 66, The first insulating member 67 that insulates the electrode 65 and the base member 66 and the surface formed around the electrode 65 and facing the internal space 6S of the base member 66 is an internal space A second insulating member 68 extending toward (6S) was provided.

Description

Leak detector and ion source for leak detector {LEAK DETECTOR AND ION SOURCE FOR LEAK DETECTOR}

The present invention relates to a leak detector and an ion source for the leak detector.

As a conventional leak detector, as shown in Patent Literature 1, there is a so-called helium leak detector that detects helium gas flowing into a subject by guiding it to an analysis tube.

This leak detector has a structure in which helium is induced by subjecting the analysis tube to vacuum with a vacuum pump, and helium is ionized by an ion source formed in the analysis tube.

To explain the ion source in more detail, this ion source heats the filament by passing an electric current between a pair of electrodes on which the filament is mounted, and emits hot electrons. is configured to

In this configuration, the electrode is supported by a base member that divides the inside and outside of the ion source. More specifically, the electrode is formed to pass through glass as an insulator inserted into the through hole of the base member, and the glass insulates the electrode and the base member, while maintaining the insulation between the electrodes.

However, when a component derived from the oil used in the vacuum pump described above or the oil adhering to the test subject is attracted to the vacuum-treated analyzer tube and flies near the ion source, it is carbonized by the heat of the filament, and the carbide It adheres to the above-mentioned glass. As a result, the adhesion between the electrode and the base member becomes impossible to maintain the insulation due to the adhered carbide, the electrodes are bridging to cause dielectric breakdown, and problems such as thermal electrons not being emitted occur.

In order to prevent such a dielectric breakdown, it is considered to take a large distance between the electrode and the base member, but in this case, the size of the parts around the electrode and the accompanying weight increase are caused, and handling of the ion source becomes difficult. Another problem arises that makes you uncomfortable.

Japanese Unexamined Patent Publication No. 2020-197127

Then, this invention was made in view of the above-mentioned problem, and makes it a subject to improve the insulation durability between electrodes.

A first aspect of the present invention is a leak detector that conducts a leak test on the subject by guiding gas from a subject to a vacuum-processed analysis tube and ionizing and detecting the gas using an ion source formed in the analysis tube. The ion source includes a filament that emits thermal electrons for ionizing the gas, an electrode electrically connected to the filament, and a base member that divides the interior space where the filament is disposed and the outside while the electrode penetrates, , a first insulating member formed in a through hole for an electrode formed in the base member and interposed between the electrode and the base member, and a surface formed around the electrode and facing the inner space of the base member. It relates to a leak detector having a second insulating member extending toward an inner space.

A second aspect of the present invention is an ion source for a leak detector that is used in a leak detector for inspecting a subject for leak detection, and is formed in a vacuum-processed analysis tube and ionizes a gas from the subject guided into the analysis tube, A filament that emits hot electrons for ionizing the gas, an electrode electrically connected to the filament, a base member formed on the base member that divides the interior space where the filament is disposed and the outside while the electrode penetrates, A first insulating member formed in the through hole for an electrode and interposed between the electrode and the base member, and a first insulating member formed around the electrode and extending toward the inner space from a surface of the base member facing the inner space. 2 It relates to an ion source for a leak detector provided with an insulating member.

According to the present invention, since the base member is provided with a second insulating member extending toward the inner space from the surface facing the inner space, the outer circumferential surface of the second insulating member can increase the insulation distance between the electrode and the base member. As a result, it becomes possible to significantly improve the insulation durability between the electrodes.

1 is a schematic diagram showing the overall configuration of a leak detector in one embodiment of the present invention.
Fig. 2 is a schematic diagram showing the internal configuration of an analysis tube of the same embodiment.
3 is a schematic diagram showing the configuration of the ion source of the same embodiment.
4 is a schematic diagram showing the internal configuration of the ion source of the same embodiment.
Fig. 5 is a cross-sectional view showing the configuration of a second insulator of the same embodiment.
Fig. 6 is a schematic diagram for explaining the action and effect of the second insulator of the same embodiment.
Fig. 7 is a cross-sectional view showing the configuration of a second insulating member in another embodiment.
Fig. 8 is a cross-sectional view showing the configuration of a second insulating member in another embodiment.
Fig. 9 is a cross-sectional view showing the configuration of a second insulating member in another embodiment.
10 is a cross-sectional view showing the configuration of a cover member in another embodiment.

A leak detector according to an embodiment of the present invention will be described with reference to the drawings.

[Full configuration]

The leak detector 100 of the present embodiment is used for leak testing a subject X such as a vacuum container, for example, and as shown in FIG. 1 , a subject ( It is piping connected to X).

Specifically, the leak detector 100 includes three vacuum pumps of an oil rotary pump 1, a drag pump 2, and a turbo molecular pump 3, and three valves (V1) that open and close an exhaust path and a helium introduction path. to V3) and an analysis tube 4 at least. Further, the open/closed state of each of the valves V1 to V3 is controlled by a control device (not shown) based on an instruction from an operator of the leak detector 100 . In addition, the number of vacuum pumps and valves is not limited to the aspect shown in Fig. 1 and may be appropriately changed according to the configuration of the apparatus.

The analysis tube 4 is piped to the oil rotary pump 1 via a turbo molecular pump 3, a drag pump 2, and a valve V1. The subject X to be subjected to the leak test is piping connected to the oil rotary pump 1 via a test port P and a valve V2. In addition, the subject X is piped to the exhaust port 3a of the turbo molecular pump 3 via a test port P and a valve V3, and this valve V3 is a helium leak detector Opened in reverse diffusion exhaust mode (or other modes such as intermediate exhaust mode and direct flow may be used).

The leak test of the subject (X) is performed in the following procedure. Also, because of simplicity, only the case of the de-diffusion exhaust mode is described here.

(1) Closing the valves V2 and V3, and opening the valve V1, the turbo molecular pump 3, the drag pump 2, and the oil rotary pump 1 in series move through the analyzer tube 4. According to the configuration, the vacuum is evacuated until it becomes less than a predetermined vacuum level (helium background value).

(2) The subject (X) of the leak test is attached to the test port (P).

(3) After the inside of the analyzer tube 4 has decreased below a predetermined background value, the valve V2 is opened and the inside of the subject X is evacuated by the oil rotary pump 1 (roughing vacuum exhaust).

(4) The valve V2 is closed and the valve V3 is opened to start leak detection by the analysis tube 4. That is, helium (He) gas is tried to flow into the subject X from the outside of the subject X through the leak test point.

(5) If there is a leak at the leak test point of the subject (X), He gas penetrates into the subject (X). This He gas reaches the analysis tube 4 via the open valve V3 and the turbo molecular pump 3. When the analyzer tube 4 detects the helium gas, the leak amount of the subject X is measured.

Next, the analysis tube 4 will be described using FIG. 2 .

The analyzer tube 4 includes an ion source 6 disposed in an airtight container 5, a permanent magnet 7 forming a magnetic field from which helium ions ionized by the ion source 6 are emitted, and a magnet bent by the magnetic field. An intermediate slit 8 that allows helium ions to pass but does not allow other ions (eg, ions derived from components contained in the air) to pass through, and an ion collector for detecting helium ions that have passed through the intermediate slit 8 ( 9) is provided.

And since the leak detector 100 concerning this invention is characterized by this ion source 6, it explains in detail below.

As shown in Fig. 3, the ion source 6 heats the filament 61 to emit hot electrons, and ionizes helium by the hot electrons.

As an example of the specific structure of the ion source 6, as shown in FIG. 3, what was provided with the filament 61, the anode 62, the shield 63, and the acceleration slit 64 is mentioned. In this configuration, the hot electrons emitted from the surface of the filament 61 fly toward the anode 62 to which a positive potential is applied, but since the anode 62 here is made of a thin metal wire, most of the hot electrons are at the anode ( 62) to the shield 63. Then, since negative potential is applied to the shield 63, the thermal electrons do not reach the shield 63 and immediately continue to fly. In this way, when the reciprocating thermal electrons collide with the gas existing between the filament 61 and the shield 63, the gas is ionized into ions and electrons. Ions thus ionized fly from the anode 62, which is the positive electrode, toward the accelerating slit 64, which is the negative electrode, and passes through the opening 641 formed in the accelerating slit 64 to be emitted into the magnetic field. In addition, the configuration of the ion source 6 is not limited to this, and various types may be used.

As shown in FIG. 4 , the ion source 6 of the present embodiment includes a filament 61 and a pair of columnar electrodes 65 electrically connected to each of the filaments 61, and these electrodes ( 65), the filament 61 is heated to emit thermal electrons. In this embodiment, a pair of filaments 61 are formed, and a conductive member 611 is interposed between the filaments 61 and the electrode 65. In addition, the electrode 65 is also electrically connected to the anode 62 described above, and a constant potential can be applied to the anode 62 through the electrode 65.

In such a configuration, since dielectric breakdown occurs when the plurality of electrodes 65 described above are electrically connected, these electrodes 65 need to be insulated from each other.

Therefore, as shown in FIGS. 4 and 5 , the ion source 6 is a first device that insulates the metal base member 66 supporting the electrode 65 from the electrode 65 and the base member 66. An insulating member 67 is provided.

As shown in FIG. 5 , the base member 66 supports the electrode 65 and is of a flat plate shape that divides the interior space 6S where the filaments 61 are placed and the outside. The base member 66 here is, for example, a disc made of iron, and a through-hole 66h for electrodes formed therethrough in the thickness direction thereof is formed. However, the material and shape of the base member 66 are not limited to those shown, and may be appropriately changed.

The through-hole 66h for electrodes has a circular shape, for example, through which the electrode 65 penetrates. In this embodiment, a plurality of through-holes for electrodes 66h are formed around the center of the base member 66 at regular intervals, for example. However, the shape, arrangement, and number of through-holes for electrodes 66h are not limited to the illustrated aspect, and may be appropriately changed.

The 1st insulating member 67 is an insulator, such as glass, formed in the above-mentioned through-hole 66h for electrodes. In this embodiment, the through-hole 66h for electrodes is previously filled with the glass which is the 1st insulating member 67, and the electrode 65 is cooled by inserting the electrode 65 in the state which melted this glass, and the electrode 65 It is supported by the base member 66 in a state where the first insulating member 67 is passed through. Thus, the first insulating member 67 is interposed between the electrode 65 and the base member 66 to insulate them.

And, as shown in FIGS. 4 and 5 , the ion source 6 of the present embodiment has a second insulation that insulates between the electrode 65 and the base member 66 in cooperation with the first insulation member 67. A member 68 is further provided.

This second insulating member 68 is an insulating material such as alumina formed around the electrode 65, and is different from the first insulating member 67 in the present embodiment. However, the second insulating member 68 may be integral with the first insulating member 67 .

More specifically, as shown in FIGS. 4 and 5 , the second insulating member 68 is cylindrical, for example, and has an insertion hole 68h into which the electrode 65 is inserted. The second insulating member 68 is inserted into the electrode 65 through the insertion hole 68h, so that the second insulating member 68 is disposed so as to surround the outer circumferential surface of the electrode 65.

The first insulating member 67 and the second insulating member 68 are disposed to face each other, and the opposing surfaces 671 and 681 of the first insulating member 67 and the second insulating member 68 are in contact with each other. are doing That is, the second insulating member 68 here extends from the surface of the first insulating member 67 facing the internal space 6S toward the internal space 6S.

In this embodiment, the opposing surface 681 of the second insulating member 68 is smaller than the opposing surface 671 of the first insulating member 67, and the opposing surface 671 of the first insulating member 67 The entire opposing surface 681 of the second insulating member 68 is inside. However, the opposing surface 681 of the second insulating member 68 may be the same size (same shape) as the opposing surface 671 of the first insulating member 67, and the opposing surface of the first insulating member 67 It may be greater than (671).

And, as shown in FIG. 5, this 2nd insulating member 68 is the surface 661 which faces the interior space 6S of the above-mentioned base member 66 (henceforth, it is also called base surface 661) ) to the inner space 6S side, in other words, the outer peripheral surface 682 of the second insulating member 68 extends to the inner space 6S side than the base surface 661 .

The outer circumferential surface 682 of the second insulating member 68 extends in a direction orthogonal to the base surface 661 or in a direction inclined from the orthogonal direction, and in a specific shape, wavy along the extending direction. A wavy shape (ripple shape), a concave-convex shape formed along the same direction, or a straight tube shape extending straight along the same direction, and the like are exemplified.

In this embodiment, the second insulating member 68 is a normal one whose axial direction is orthogonal to the base surface 661, for example, an insulator or the like is used.

The longer the outer peripheral surface 682 of the second insulating member 68 along the axial direction is, the longer the insulation distance between the base member 66 and the electrode 65 is. Therefore, from the viewpoint of increasing the insulating distance between the base member 66 and the electrode 65, the dimension along the axial direction (height dimension) of the second insulating member 68 is preferably longer, specifically, the second insulating member 68 It is preferably at least 1/2 times the diameter of the member 68 or more. Alternatively, the dimension (height dimension) of the second insulating member 68 along the axial direction is preferably 10% or more of the height of the electrode 65, more preferably 30% or more, still more preferably 50% or more. more than 1% Alternatively, the dimension (height dimension) of the second insulating member 68 along the axial direction is preferably 2 mm or more, more preferably 4 mm or more. In particular, it was found from the experiment that the carbide described below is difficult to adhere to a region having a height of 2 mm or more.

[Operation and effect of the present embodiment]

According to the leak detector 100 structured in this way, since it is provided with the 2nd insulating member 68 which extends to the inner space 6S side rather than the base surface 661 in the base member 66, this 2nd insulating member The insulating distance between the electrode 65 and the base member 66 can be earned by the outer peripheral surface 682 of the 68.

Specifically, the surface contributing to insulation is the surface of the first insulating member 67 that is parallel to the base member 66 and faces the interior space 6S, and the second insulating member 68 , the insulation distance can be increased by being constituted by the outer peripheral surface 682 orthogonal to the base member 66 and the surface parallel to the base member 66 .

As a result, it becomes possible to significantly improve the insulation durability between the electrodes 65 without substantially changing the size or weight of the ion source 6.

More specifically, since components derived from the oil used in the vacuum pumps 1 to 3 and the oil adhering to the subject X are carbonized by the heat of the filament 61, the carbonized material is As a result of flying from the direction, the carbide tends to adhere to the first insulating member 67. However, since the carbide comes from the direction of the filament 61, as shown in FIG. 6, it is difficult for the carbide to adhere to the outer circumferential surface 682 of the second insulating member 68 in the direction. By this outer peripheral surface 682, insulation between the electrode 65 and the base member 66 can be maintained, and as mentioned above, the insulation durability between the electrodes 65 can be improved.

[Other embodiments]

Other embodiments are described.

For example, although the aspect in which the 1st insulating member 67 and the 2nd insulating member 68 contact each other was demonstrated in the said embodiment, as shown in FIG. 7, the 1st insulating member 67 and the 2nd insulating member 67 The insulating member 68 may be non-contact. In this case, with the 1st insulating member 67, it is not necessary to fill the whole 66h of through-holes for electrodes. Moreover, as the 2nd insulating member 68, while extending from the base surface 661 to the internal space 6S side, the aspect arrange|positioned so that the through-hole 66h for electrodes may be blocked is mentioned.

In addition, the second insulating member 68 is not limited to a cylindrical one, and may be, for example, a normal one having a triangular, rectangular, or polygonal cross section, and the inner space ( 6S), as long as it extends to the side, it does not have to be normal, and various shapes may be used.

In the above embodiment, an aspect in which the first insulating member 67 and the second insulating member 68 are separate bodies has been described, but as shown in FIG. 8 , the first insulating member 67 and the second insulating member 68 may be integrated, and the second insulating member 68 in this case is a portion located closer to the inner space 6S than the base surface 661 .

In addition, from the viewpoint of preventing adhesion of carbide to the second insulating member, as shown in FIG. 9 , the opposing surface 681 facing the first insulating member 67 in the second insulating member 68 ) may be non-contact with the first insulating member 67. If this is the case, carbide hardly adheres to a part of the opposing surface 681, and insulation between the electrode 65 and the base member 66 can be maintained.

Further, from the viewpoint of preventing adhesion of carbide to the first insulating member 67, as shown in FIG. 10, the first insulating member is formed closer to the inner space 6S than the first insulating member 67. You may be provided with the cover member 69 which covers 67. In this case, the cover member 69 does not necessarily have insulating properties, and various materials may be used.

In addition, variations and combinations of various embodiments may be performed as long as they do not contradict the spirit of the present invention.

[mode]

It is understood by those skilled in the art that the plurality of exemplary embodiments described above or variations thereof are specific examples of the following aspects.

(Claim 1) A leak detector according to one aspect guides a gas from a subject to a vacuum into an analysis tube and ionizes the gas using an ion source formed in the analysis tube to detect the leakage of the subject. As a leak detector to inspect,

The ion source,

a filament that emits thermal electrons that ionize the gas;

an electrode electrically connected to the filament;

A base member through which the electrode penetrates and divides an interior space in which the filament is disposed and an exterior;

A first insulating member formed in a through hole for an electrode formed in the base member and interposed between the electrode and the base member;

A second insulating member formed around the electrode and extending toward the inner space from a surface of the base member facing the inner space.

According to the leak detector configured as described above, since the base member is provided with a second insulating member extending into the inner space from the surface facing the inner space where the filament is disposed, the electrode and the base member are directed from this surface toward the inner space. The insulation distance between them can be earned, and as a result, it becomes possible to significantly improve the insulation durability of the electrode. The first insulating member has an insulating effect on a plane parallel to the base member, and the second insulating member has an insulating effect on a plane parallel to the plane orthogonal to the base member. On the surface of the second insulating member orthogonal to the base member, since carbides are difficult to adhere to, the insulating effect can be maintained very well.

(Item 2) In a leak detector according to another aspect, in the leak detector of item 1, the second insulating member is separate from the first insulating member.

With such a configuration, the existing ones can be used as the first insulating member or the base member on which the first insulating member is formed, so that the insulation durability of the electrode can be greatly improved without significantly changing the device configuration so far.

(Item 3) In a leak detector according to another aspect, in the leak detector according to item 1 or 2, the second insulating member has an insertion hole into which the electrode is inserted.

With such a structure, since the insulating distance between the electrode and the base member can be increased by inserting the second insulating member into the electrode, productivity can be ensured.

(Item 4) In a leak detector according to another aspect, in the leak detector according to any one of items 1 to 3, the second insulating member is cylindrical, and the dimension along the axial direction is 2 mm or more to be.

Experiments have shown that carbides are less likely to adhere to a region where the height of the second insulating member is 2 mm or more. Therefore, with such a configuration, a more remarkable effect on insulation can be exhibited.

(Item 5) An ion source for a leak detector according to one aspect is used for a leak detector that inspects a test subject for leak, and is formed in a vacuum-processed analysis tube and is guided into the analysis tube. As an ion source for a leak detector that ionizes gas,

a filament that emits thermal electrons that ionize the gas;

an electrode electrically connected to the filament;

A base member through which the electrode penetrates and divides an interior space in which the filament is disposed and an exterior;

A first insulating member formed in the through hole for an electrode formed in the base member and interposed between the electrode and the base member;

An ion source for a leak detector, comprising: a second insulating member formed around the electrode and extending toward the inner space from a surface of the base member facing the inner space.

According to the ion source for a leak detector configured as described above, the effect is the same as that of the leak detector described above, that is, the effect that the insulation distance between the electrode and the base member can be increased by the second insulating member, and the insulation durability between the electrodes is greatly improved. can exert

(Claim 6) A leak detector according to one aspect guides gas from a subject to a vacuum-processed analysis tube and ionizes the gas using an ion source formed in the analysis tube to detect the leakage of the subject. As a leak detector to inspect,

The ion source,

a filament that emits thermal electrons that ionize the gas;

an electrode electrically connected to the filament;

A base member through which the electrode penetrates and divides an interior space in which the filament is disposed and an exterior;

a first insulating member formed in a through hole for an electrode formed in the base member and insulating the electrode and the base member;

and a cover member formed closer to the inner space than the first insulating member and covering the first insulating member.

According to the leak detector structured as described above, since adhesion of carbide to the first insulating member can be suppressed by the cover member, it becomes possible to improve the insulation durability between the electrodes.

100: leak detector
X: subject
4 : Analyst tube
6: ion source
61: filament
62: anode
63 : Shield
64: acceleration slit
65: electrode
66: base member
66h: through hole for electrode
661: base surface
67: first insulating member
671: opposite surface
6S: Inner space
68: second insulating member
68h: insertion hole
681: opposite surface
682: outer surface
69: cover member

Claims (6)

A leak detector that conducts a leak test on the subject by guiding the gas from the subject to a vacuum-processed analysis tube and ionizing the gas using an ion source formed in the analysis tube to detect it,
The ion source,
a filament that emits thermal electrons that ionize the gas;
an electrode electrically connected to the filament;
A base member through which the electrode penetrates and divides an interior space in which the filament is disposed and an exterior;
A first insulating member formed in the through hole for an electrode formed in the base member and interposed between the electrode and the base member;
and a second insulating member formed around the electrode and extending toward the inner space from a surface of the base member facing the inner space. According to claim 1,
The leak detector, wherein the second insulating member is separate from the first insulating member. According to claim 1 or 2,
The leak detector, wherein the second insulating member is formed with an insertion hole into which the electrode is inserted. According to claim 1 or 2,
The leak detector, wherein the second insulating member is cylindrical and has a dimension along an axial direction of 2 mm or more. An ion source for a leak detector that is used in a leak detector for leak testing a subject, is formed in a vacuum-treated analysis tube, and ionizes gas from the subject guided into the analysis tube,
a filament that emits thermal electrons that ionize the gas;
an electrode electrically connected to the filament;
A base member through which the electrode penetrates and divides an interior space in which the filament is disposed and an exterior;
A first insulating member formed in the through hole for an electrode formed in the base member and interposed between the electrode and the base member;
An ion source for a leak detector, comprising: a second insulating member formed around the electrode and extending toward the inner space from a surface of the base member facing the inner space. A leak detector that conducts a leak test on the subject by guiding the gas from the subject to a vacuum-processed analysis tube and ionizing the gas using an ion source formed in the analysis tube to detect it,
The ion source,
a filament that emits thermal electrons that ionize the gas;
an electrode electrically connected to the filament;
A base member through which the electrode penetrates and divides an interior space in which the filament is disposed and an exterior;
a first insulating member formed in a through hole for an electrode formed in the base member and insulating the electrode and the base member;
A leak detector comprising: a cover member formed closer to the inner space than the first insulating member and covering the first insulating member.

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