JP2777327B2 - Gas inlet valve for mass spectrometry - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas inlet valve for mass spectrometry, particularly a mass spectrometer for analyzing a gas sample, and a mass spectrometer connected to a sample gas generating chamber to be analyzed by the mass spectrometer. The present invention relates to a gas inlet valve for mass spectrometry for introducing a sample gas into an ionization chamber of a spectrometer at a desired pressure.

[0002]

2. Description of the Related Art FIG. 5 shows a schematic configuration of a gas sample mass spectrometer. In particular, FIG.
2 is connected by a gas introduction valve 14 and the internal structure of the mass spectrometer 12 is shown in a broken state. The sample gas generation chamber 10 is provided with an outlet flange 10a, and the mass spectrometer 12 is provided with an inlet flange 12a. The inlet flange 14a at the gas inlet end of the gas inlet valve 14 and the outlet flange 14b at the gas outlet end of the gas inlet valve 14 are connected to the two flanges 10a and 12a in an airtight manner, respectively. It is led to the mass spectrometer 12 through the introduction valve 14.

A well-known ion source 16 is provided in the mass spectrometer 12. In an ionization chamber 18 in the ion source 16, a sample gas is ionized by being subjected to electron impact by an ionized electron beam. The path of the sample gas in the mass spectrometer 12 is performed through an introduction pipe 20 and a connection pipe 22 extending from the inlet flange 12a, and ions generated in the ionization chamber 18 are connected to the ionization chamber 18 and the main body. The ion beam accelerated by the acceleration voltage applied to the slit 24 and passed through the main slit 24 is sent to the ion separation unit 26. As is well known, the ions separated by the ion separation unit 26 are detected by the ion detection unit 28, and mass analysis of the sample gas is performed.

What is important in such mass spectrometry is to guide the sample gas in the sample gas generation chamber 10 to the mass spectrometer 12 at a desired pressure.
It is necessary not only to control the introduction and shielding of the sample gas, but also to perform the pressure adjustment.

For this reason, the conventional gas introduction valve has a first
A passage 101 and a second passage 102 are provided.
By performing the switching of 02, pressure adjustment is performed. The first passage 101 is used when the pressure of the sample gas is low, and is opened and closed by the main valve 30. on the other hand,
The second passage 102 is used when the pressure of the sample gas is high. An orifice 32 for reducing pressure is provided in the passage. Opening and closing of the second passage 102 is controlled by an orifice valve 34. Therefore, when the pressure of the sample gas is lower than a predetermined value, for example, 0.1 Pascal, the sample gas is guided to the mass spectrometer 12 through the first passage 101, so that the main valve 30 is opened, and Orifice valve 3
4 is closed. When the pressure of the sample gas is higher than 0.1 Pa, the flow rate of the sample gas is reduced.
The main valve 30 is closed, while the orifice valve 34 is open. Therefore, in this high pressure state, the sample gas is reduced in pressure to a desired pressure through the orifice 32 and the mass spectrometer 1
2 can be led. Needless to say, the diameter of the passage of the orifice 32 is previously selected to an appropriate value in order to perform a desired pressure reduction according to the sample gas. In order to completely shut off the sample gas generating chamber 10 from the mass spectrometer 12, both the main valve 30 and the orifice valve 34 are closed, and the sample gas generating chamber 1
Introducing the atmosphere to zero makes it possible to easily repair the inside of the gas generating chamber. For example, when analyzing and measuring the atmospheric gas in a chemical reaction chamber in a semiconductor process chamber or the like, it is necessary to maintain a vacuum in the mass spectrometer when exchanging substances inside the reaction chamber, etc. Blocking with a gas introduction valve is extremely effective.

As described above, the conventional gas introducing valve for mass spectrometry requires at least two passages with different throttle amounts, and it is desirable that the gas introducing valve can be made to be in a shielded state.

FIG. 6 shows an example of another conventional gas introduction valve, and the same or corresponding members as in FIG. In the conventional example shown in FIG. 6, a passage connecting the two flanges 14a and 14b in a straight line is formed as a second passage 102 including the orifice 32, while a detour is configured as a first passage 101. Each of the passages 101 and 102 is provided with a main valve 30 and an orifice valve 34 as in the conventional example of FIG.

[0008]

However, in the above-described conventional gas introduction valve, since the two paths having different throttle amounts are provided as separate paths, the sample gas passes through the gas introduction valve 14 when the gas flows through the gas introduction valve 14. It is not possible to pass through a straight path, but must pass through a detour, and as a result, the sample gas may be deteriorated. That is, if the generated sample gas collides with the vessel wall before being guided to the ionization chamber 18 of the mass spectrometer 12, a phenomenon occurs in which a chemical reaction occurs on the vessel wall or is adsorbed on the vessel wall. In particular, strongly adsorbable gas such as moisture, highly reactive active gas such as halogen, or condensable gas components with low vapor pressure will react sensitively if they collide with the vessel wall before measurement. As a result, a change occurs in the sample gas component. Therefore, the conventional gas introduction valve has a problem that an error occurs in the measurement result.

Therefore, in the prior art, it is desirable that the sample gas be moved from the generation chamber 10 to the mass spectrometer 12 through a linearly visible conduit. A situation has arisen in which such a straight outlook cannot be satisfied.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide an improvement capable of securing a linear view of gas introduction even when the throttle of a sample gas is changed. To provide a gas introduction valve for mass analysis.

[0011]

In order to achieve the above object, the present invention provides a gas inlet valve for mass spectrometry having a gas inlet connected to a sample gas generating chamber and a gas outlet connected to a mass spectrometer. In the valve body, a straight gas passage that can be seen straight from the gas introduction end to the gas outlet end is provided, a switching valve seat is provided in the middle of the gas passage, and the switching valve seat is provided. Is characterized in that a switching valve for switching a gas conduit to an open state or a throttle state is mounted.

The present invention also provides a mass spectrometry gas introduction valve having a gas introduction end connected to a sample gas generation chamber and a gas exit end connected to a mass spectrometer.
A straight gas passage that can be seen linearly from the gas introduction end to the gas outlet end is provided, and a switching valve seat is provided in the middle of the gas passage, and the switching valve seat has a gas passage opened. A switching valve for switching to a state or a throttle state is mounted, an on-off valve seat is further provided in the middle of the gas conduit, and an on-off valve for switching the gas conduit to open or closed is mounted on the on-off valve seat. It is characterized by being.

[0013]

As described above, according to the present invention, the generated sample gas is guided to the mass spectrometer by a single linearly visible gas passage provided in the valve body of the gas introduction valve, and the amount of restriction is reduced. Alternatively, the pressure is adjusted by the switching valve provided in the straight gas passage, so that passing through the gas introduction valve may adversely affect the mass spectrometry result without passing through a conventional bypass. There is an effect that there is no.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 is a sectional view showing a first preferred embodiment of a gas inlet valve for mass spectrometry according to the present invention.

In FIG. 1, the gas introduction valve 14 includes a valve main body 36, and the above-mentioned two flanges 14a and 14b are fixed to both ends of the main body 36 in an airtight state. The valve body 36 has two flanges 14a, 14a.
A straight gas passage 38 is provided between the gas inlet end 36a and the gas outlet end 36b. In the embodiment, the gas conduit 38 includes a first conduit 38a having a large diameter and a switching valve to be described later, and a second conduit 38b having a small diameter and a switching valve to be described later. You.

A switching valve seat 40 tapered in a direction perpendicular to the axis of the gas conduit 38 is provided in the middle of the first conduit 38a, and a switching valve 42 is mounted in the switching valve seat 40. Have been. In the embodiment, the switching valve 42 is provided with an orifice 44, and when the switching valve 42 enters the switching valve seat 40 as shown in FIG. 1, the orifice 44 controls the throttle of the gas conduit 38. Control can be performed, and the aperture state can be provided.

On the other hand, in order to open the gas conduit 38, the switching valve 42 can be retracted from the switching valve seat 40, and an opening / closing mechanism 46 for this purpose is provided on the outer wall of the valve body 36. The opening / closing mechanism 46 includes a casing 48, and a support shaft 50 for moving the switching valve 42 in the axial direction is built in the casing 48. The casing 48 and the support shaft 50 are used to keep the support shaft 50 airtight within the casing 48. A bellows 52 is provided between the bellows 50 and the bellows 52. The axial movement of the support shaft 50 is performed by a nut 54 and a push screw 56 fixed to the casing 48.
6 engages with a locking seat 60 provided at the lower end of the support shaft 50, and rotates the support shaft 50, that is, the switching valve 42, when the push screw 56 rotates. It can move only in the axial direction without having to do so. A switching handle 62 is provided at the lower end of the push screw 56, and a user can rotate the switching handle 62 to adjust the position of the switching valve 42 when adjusting the aperture of the passage.

In the first embodiment, an on-off valve seat 64 is provided in the second conduit 38b of the gas conduit 38, and an on-off valve 66 is mounted on the on-off valve seat 64, and the on-off valve 66 moves in the axial direction. This controls the opening and closing of the second conduit 38b.

At the upper end of the valve body 36, the on-off valve 6
An opening / closing mechanism 68 for moving the shaft 6 in the axial direction is provided,
Since the opening / closing mechanism 68 has the same configuration as that of the opening / closing mechanism 46, detailed description of each part is omitted.

As described above, according to the first embodiment of the present invention, the pressure of the sample gas is switched or throttled only by the single straight gas passage 38 provided in the valve body 36. Volume switching can be performed. That is, the feature of this embodiment is that the gas conduit 38 is provided with a switching valve 42 for switching between the open state and the restricted state of the gas conduit 38, and the amount of restriction of the sample gas only by the axial movement of the switching valve 42. Adjustments can be made. Similarly, according to the first embodiment, an on-off valve 66 for controlling the opening and closing of the gas conduit 38 is further provided in the single gas conduit 38 so that the gas introduction is shielded or opened by a single and introduced gas. There is an advantage that the process can be performed using only the gas conduit 38 that can be seen straight from the end to the outlet end.

The operation of the first embodiment will be described with reference to FIGS.

FIG. 2 shows a state in which the switching valve 42 is in close contact with the switching valve seat 40 as in FIG. 1. In this state, the orifice 44 is located on the central axis of the gas conduit 38, and thereby the introduced gas is introduced. Is controlled dominantly by the orifice 44, and this pressure can be reduced when the pressure of the sample gas is high.

As is apparent from FIG. 2, when the gas conduit 38 is in the throttled state, the switching valve 42 is in close contact with the switching valve seat 40. However, the gas compression in the closing portion may hinder the close contact between the switching valve 42 and the switching valve seat 40. In the embodiment, the switching valve 42 has a gas leak hole connecting the closing portion and the gas conduit 38. By providing 42a, such inconvenience due to such gas compression is prevented.

In the state shown in FIG. 2, the opening / closing valve 66 is retracted from the opening / closing valve seat 64 by the opening / closing mechanism, and is open in this state.

FIG. 3 shows a state in which the gas conduit 38 is opened by the switching valve 42. As described above, the opening / closing mechanism 46 moves the switching valve 42 downward in FIG. As described above, the switching valve 42 is completely retracted from the switching valve seat 40 and the gas conduit 38, and in this state, the throttle amount or the pressure of the sample gas is reduced by the gas conduit 38, particularly the second conduit 38b.
And the sample gas can be efficiently guided to the mass spectrometer 12 when the gas pressure is low.

In the state shown in FIG. 3, the sample gas passage is not different from the throttle state shown in FIG. 2 and shares a straight gas passage 38 which can be seen straight from the gas introduction end 36a to the gas outlet end 36b. In addition, it is possible to reliably prevent inconvenience such as deterioration of the sample gas caused by the conventional curved detour.

Embodiment 2 FIG. 4 shows a second preferred embodiment according to the present invention. In this second embodiment, only the switching valve is mounted on the gas conduit 38, and the second embodiment is different from the first embodiment. The on-off valve has been removed.

As described above, according to the second embodiment, the gas conduit 38 cannot be cut off, but the throttle amount or the pressure can be adjusted in accordance with the pressure of the sample gas. gate valve or straight valve corresponding to the opening and closing valve in the mass spectrometer or example 1 is also useful with the mass spectrometer that is already set.

[0030]

As described above, according to the gas introduction valve according to the present invention, when the sample gas is introduced into the mass spectrometer, the sample gas does not collide with the container wall or the like, and the gas of the valve is directly introduced. The sample gas is guided in a state where the sample gas can be seen straight from the introduction end to the discharge end, and can be guided to the ionization chamber without alteration of the sample gas, which is extremely useful for accurate mass spectrometry. According to the present invention, it is possible to extremely easily select whether to introduce the sample gas without decompression or to introduce it through the orifice for decompression by opening and closing the switching valve. It is possible to perform accurate and precise measurement even for an adsorbing gas such as a gas, a highly reactive active gas such as a halogen, or a condensable gas component having a low vapor pressure.

Further, according to the present invention, the amount of restriction of the orifice in the second conduit is changed by simple replacement of the switching valve, and the gas introduction valve is connected between the sample gas generation chamber and the mass spectrometer. There is an advantage that it can be easily performed simply by replacing the switching valve even in the mounted state.

[Brief description of the drawings]

FIG. 1 is a first diagram of a gas inlet valve for mass spectrometry according to the present invention.
It is a partial sectional view showing an example.

FIG. 2 is a partial cross-sectional view illustrating a gas introducing operation in a throttle state according to the first embodiment of the present invention.

FIG. 3 is a partial sectional view showing an open state in the first embodiment of the present invention.

FIG. 4 is a partial sectional view showing a second preferred embodiment of the gas inlet valve for mass spectrometry according to the present invention.

FIG. 5 is a partially broken view showing a state in which a conventional gas introduction valve is mounted between a sample gas generation chamber and a mass spectrometer.

FIG. 6 is a sectional view showing another conventional gas introduction valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Sample gas generation chamber 12 Mass spectrometer 14 Gas introduction valve 36 Valve main body 36a Gas introduction end 36b Gas outlet end 38 Gas conduit 40 Switching valve seat 42 Switching valve 44 Orifice 46 Opening / closing mechanism 64 Opening / closing valve seat 66 Opening / closing valve

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01J 49/04 G01N 27/62

Claims (2)

(57) [Claims] 1. A gas inlet valve for mass spectrometry having a gas inlet connected to a sample gas generation chamber and a gas outlet connected to a mass spectrometer, wherein the valve body has a straight line from the gas inlet to the gas outlet. A straight gas passage that can be seen through the gas passage is provided.A switching valve seat is provided in the middle of the gas passage, and a switching valve that switches the gas passage to an open state or a throttle state is provided in the switching valve seat. Gas inlet valve for mass spectrometry characterized by being mounted. 2. A gas inlet valve for mass spectrometry having a gas inlet connected to a sample gas generation chamber and a gas outlet connected to a mass spectrometer, wherein the valve body has a straight line from the gas inlet to the gas outlet. A straight gas passage that can be seen through the gas passage is provided.A switching valve seat is provided in the middle of the gas passage, and a switching valve that switches the gas passage to an open state or a throttle state is provided in the switching valve seat. An on-off valve seat is further provided in the middle of the gas conduit, and an on-off valve for opening or closing the gas conduit is attached to the on-off valve seat for mass spectrometry. Gas introduction valve.