Analysis device

Abstract

The present invention provides an analyzing device with which an inflow volume of a gas into a vacuum pump when a power supply to the vacuum pump is stopped can be reduced by means of a simple construction. This analyzing device (100) comprises a charged particle generation source (2) for generating charged particles, vacuum chambers (16,19, 28) having an evacuated interior, a fine hole (7) for introducing the charged particles from the charged particle generation source (2) into the vacuum chamber (16), and vacuum pumps (18, 22) connected to the vacuum chambers (16, 19, 28), wherein the analyzing device (100) is provided with a sealing plug (41) capable of sealing the fine hole (7), and the sealing plug (41) seals the fine hole (7) when conduction of electricity to the vacuum pump (18, 22) stops.

Description

Technical Field

[0001] The present invention relates to an analytical apparatus such as a mass spectrometer.

Background Art

[0002] A mass spectrometer includes an ion source for ionizing a sample, a separation unit for separating ions according to mass, a measurement unit for measuring the separated ions, and the like. Components contained in the sample are ionized into ions that can be separated electromagnetically and then introduced into the separation unit. The separation unit is composed of a vacuum chamber to ensure the flight path of ions and separates ions according to the mass-to-charge ratio. In the measurement unit, the intensity of ions separated for each mass is detected using an electron multiplier tube or the like.

[0003] The vacuum chamber is partitioned into a plurality of rooms and differentially evacuated for each room. The separation unit is accommodated in the vacuum chamber on the front stage side, and a roughing dry pump or the like is connected thereto. The separation unit and the measurement unit are accommodated in the vacuum chamber on the rear stage side, and a turbo molecular pump for fine evacuation is connected thereto. An ion introduction electrode is provided between the container accommodating the ion source and the vacuum chamber.

[0004] A counter plate for generating an electric field is provided on the side of the ion introduction electrode where the container accommodating the ion source is located. Further, a pore is formed to communicate between the container accommodating the ion source and the vacuum chamber so as to penetrate the ion introduction electrode. Ions generated from the sample by the ion source are introduced into the vacuum chamber through the pore due to the potential difference between the ion source and the counter plate and the pressure difference between the container accommodating the ion source and the vacuum chamber.

[0005] In recent years, further improvement in the sensitivity of mass spectrometers has been demanded. The sensitivity of ion detection improves when the amount of ions introduced into the measurement unit housed in the vacuum chamber is increased. However, conventionally, the pores formed in the ion introduction electrode have a high flow path resistance. If the pore diameter of the pores is enlarged, the flow path resistance is suppressed, and thus the amount of ions introduced is expected to increase. However, if the pore diameter of the pores is enlarged, the amount of gas flowing in also increases, resulting in a decrease in the degree of vacuum in the vacuum chamber.

[0006] In order to improve the sensitivity of ion detection, it is also necessary to maintain a high degree of vacuum in the vacuum chamber. A high degree of vacuum can be achieved by a vacuum pump with a high exhaust speed. However, a vacuum pump with a high exhaust speed is large in size and costly in terms of equipment. These days, in response to such problems, the pore diameter is enlarged and the number of vacuum pumps is increased as a countermeasure.

[0007] In a mass spectrometer, when a power outage occurs in the power supply system, there is a problem that power supply to the vacuum pump stops. When the power supply to the vacuum pump stops, differential exhaust becomes impossible, the roughing pump stops, and excessive pressure is applied to the backing pump. Since the stoppage of power supply to the vacuum pump leads to damage to the vacuum pump, measures are taken to protect the vacuum system.

[0008] Patent Document 1 discloses a vacuum pump shut-off valve equipped with a pilot valve. When the backing pump starts, the pilot valve closes and shuts off the vacuum pump shut-off valve from the discharge / exhaust side of the backing pump (see paragraph 0030). On the other hand, when the backing pump loses power, the pilot valve opens and exposes the vacuum pump shut-off valve to the discharge / exhaust side of the backing pump (see paragraph 0031).

[0009] Patent Document 2 discloses an atmospheric pressure ionization mass spectrometer provided with a leak valve in the intermediate pressure section. When the vacuum pump for evacuating the intermediate pressure section and the vacuum pump for evacuating the analysis section stop, the leak valve opens and an inert gas is introduced into the intermediate pressure section. The leak valve is provided in place of a vacuum holding valve provided in the second pore electrode section or a butterfly valve provided at the upper part of a turbo molecular pump.

[0010] Patent Document 3 discloses a vacuum device provided with a valve that is opened and closed by an interlock so that the vacuum pump is not damaged. In this vacuum device, when the dry pump stops during the rotation of the turbo molecular pump, the turbo molecular pump is protected by a hard interlock that instantaneously closes the valves on the exhaust side and the intake side.

[0011] Patent Document 4 discloses an exhaust device provided with a turbo molecular pump and an electric valve. In this exhaust device, the electric valve provided between the roughing pump and the exhaust port of the turbo molecular pump and the electric valve provided between the turbo molecular pump and the chamber are closed when a power failure occurs.

Prior Art Documents

Patent Documents

[0012]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0013] When a power outage occurs in the power supply system of the analysis device, the power supply to the vacuum pump stops, and the drive by power is no longer performed. However, the rotating blades of the vacuum pump continue to rotate for a while due to inertia. During the period until the rotating blades stop, gas continues to flow into the intake side of the vacuum pump. The intake side of the vacuum pump is pressurized, and excessive pressure is applied to the rotating blades of the vacuum pump, resulting in a problem that the vacuum pump is damaged. The service life of the vacuum pump is shortened, or the rotating blades of the vacuum pump are damaged or broken.

[0014] In particular, a turbo molecular pump used as a vacuum pump gradually decelerates from a full rotation of about tens of thousands of revolutions per minute (rpm) and stops after continuing to rotate for about ten-odd minutes when the drive of the rotating blades is stopped. The operating pressure range of the turbo molecular pump is limited, and it is generally used in combination with a roughing vacuum pump. When a power outage occurs, the exhaust on the exhaust side of the turbo molecular pump by the roughing vacuum pump also stops, so the load on the rotating blades of the vacuum pump increases.

[0015] In recent years, in the field of mass spectrometers and the like, there has been a trend to increase the aperture diameter of the pores communicating between the container housing the ion source and the vacuum chamber in order to improve the sensitivity of ion detection. When the aperture diameter of the pores is increased, the amount of ions introduced into the vacuum chamber increases, but the inflow rate and inflow amount of the gas flowing into the intake side of the vacuum pump also increase when a power outage occurs. Since excessive pressure is applied to the rotating blades of the vacuum pump, it is assumed that the possibility of damage to the vacuum pump is increased.

[0016] Generally, damage to the vacuum pump due to a power outage does not occur with a very high probability. However, once damaged, replacement is required, resulting in a large equipment cost. Generally, as a countermeasure against power outages, the use of an uninterruptible power supply device can also be considered. However, if an uninterruptible power supply device is added, the entire analysis device becomes larger and the equipment cost also increases. Therefore, in protecting the vacuum pump of the analysis device when a power outage occurs, a countermeasure using a low-cost and simple structure is desired.

[0017] In the technology of Patent Document 1, since a pressure difference occurs with the pilot valve as the boundary, there is a possibility of suppressing a rapid decrease in the degree of vacuum in the vacuum chamber. However, the pilot valve is provided between the backing pump and the vacuum pump. With such a structure, the flow path resistance increases due to the pilot valve, so the exhaust speed by the vacuum pump decreases, and the degree of vacuum in the vacuum chamber becomes low. When a high degree of vacuum is required, a vacuum pump with a high exhaust speed is needed, the entire apparatus becomes large, and the equipment cost also increases.

[0018] In the technology of Patent Document 2, it is possible to prevent a decrease in gain of a multiplier or the like which is an ion detector. However, providing a vacuum holding valve in the second pore electrode portion not only causes problems such as clogging of the pores of the second pore electrode due to contamination and cost problems, but also causes a problem of generation of electric field disturbance. In addition, due to peeling of contamination caused by the operation of the vacuum holding valve, the problem of pore clogging is likely to occur. Maintenance work for removing contamination is required, and the mass spectrometry work is hindered. When electric field disturbance occurs, it affects the trajectory of charged particles, and there is a risk that the ion transmission rate in the separation section becomes low. On the other hand, providing a butterfly valve on the upper part of the turbo molecular pump causes a problem of equipment cost. In the case of a normal exhaust sequence, even with a roughing vacuum pump, the load on the main turbo molecular pump can be reduced. Therefore, in the countermeasure of providing a butterfly valve for the case of a power failure, there is a problem in cost performance.

[0019] In the technology of Patent Document 3, valves that are opened and closed by an interlock are provided on the intake side and the exhaust side of the turbo molecular pump. However, generally, the piping on the intake side and the exhaust side of the turbo molecular pump is provided with a relatively large inner diameter. Considering the exhaust speed of the turbo molecular pump, when a valve is provided at such a location, the flow path resistance increases to a non-negligible extent. In the synthetic conductance considering the valve, the effective exhaust speed becomes low. In addition, problems such as an increase in power consumption due to the operation of the valve itself and the problem that the entire apparatus becomes large occur.

[0020] In the technique of Patent Document 4, an electric valve is provided between the roughing pump and the exhaust port of the turbo molecular pump, or between the turbo molecular pump and the chamber. However, as in the case of Patent Document 3, when an electric valve is provided on the intake side or the exhaust side of the turbo molecular pump, the effective exhaust speed decreases. In addition, problems such as an increase in power consumption due to the operation of the electric valve itself and an increase in the size of the entire apparatus occur.

[0021] Therefore, an object of the present invention is to provide an analyzer capable of reducing the amount of gas flowing into a vacuum pump by a simple structure when power supply to the vacuum pump is stopped.

Means for Solving the Problems

[0022] In order to solve the above problems, an analyzer according to the present invention includes a charged particle generation source that generates charged particles, a vacuum chamber whose interior is evacuated, a pore that introduces the charged particles from the charged particle generation source into the vacuum chamber, and a vacuum pump connected to the vacuum chamber. In the analyzer, a sealing plug capable of sealing the pore is provided. The sealing plug operates by a pressure difference between the pore and the vacuum chamber when the vacuum pump is energized, opens the pore, and seals the pore when the power supply to the vacuum pump is stopped.

Effects of the Invention

[0023] According to the present invention, it is possible to provide an analyzer capable of reducing the amount of gas flowing into a vacuum pump by a simple structure when power supply to the vacuum pump is stopped.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2A

Figure 2B

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7A

Figure 7B

Embodiments for Carrying Out the Invention

[0025] Hereinafter, an analyzer according to an embodiment of the present invention will be described with reference to the drawings. In the following drawings, the same reference numerals are given to common configurations, and redundant explanations are omitted.

[0026] FIG. 1 is a diagram showing the configuration of an analyzer according to an embodiment of the present invention. As shown in FIG. 1, the analyzer 100 according to the present embodiment includes an ion source (charged particle generation source) 2 that generates ions (charged particles), vacuum chambers 16, 19, 28 whose interiors are evacuated, vacuum pumps 18, 22, and the like. The analyzer 100 includes a sealing plug 41 that can seal a first pore 7 (introduction hole) for introducing ions generated by the ion source 2 from the ion source 2 into the vacuum chamber 16.

[0027] In FIG. 1, as the analyzer 100, a mass spectrometer equipped with an ion source 2 using an electrospray ionization method (Electro Spray Ionization: ESI) is shown. In the analyzer 100, the components contained in the sample solution 1 are mass-analyzed. As the sealing plug 41, a pressure type that operates by the pressure difference and its own weight is provided.

[0028] The ion source 2 ionizes the sample contained in the sample solution 1 to generate ions. The ions 4 generated by the ion source 2 are released into the interior of the ion source container 9. The ion source 2 is fixed to the ion source container 9. The ion source container 9 is formed of a metal such as an aluminum alloy or stainless steel. The ion source container 9 has an atmospheric pressure atmosphere in ESI.

[0029] The vacuum chambers 16, 19, and 28 are partitioned into a plurality of rooms. In FIG. 1, the vacuum chambers 16, 19, and 28 are composed of a first differential evacuation chamber 16, a second differential evacuation chamber 19, and an analysis chamber 28.

[0030] The ion source container 9 and the first differential evacuation chamber 16 are separated by an ion introduction electrode 6. A first pore 7 is formed in the ion introduction electrode 6 so as to penetrate the center. The ion source container 9 and the first differential evacuation chamber 16 communicate with each other through the first pore 7.

[0031] The first differential evacuation chamber 16 and the second differential evacuation chamber 19 are separated by a first pore electrode 15. A second pore is formed in the first pore electrode 15 so as to penetrate the center. The first differential evacuation chamber 16 and the second differential evacuation chamber 19 communicate with each other through the second pore.

[0032] The second differential evacuation chamber 19 and the analysis chamber 28 are separated by a second pore electrode 20. A third pore is formed in the second pore electrode 20 so as to penetrate the center. The second differential evacuation chamber 19 and the analysis chamber 28 communicate with each other through the third pore.

[0033] Vacuum pumps 18 and 22 are connected to the vacuum chambers 16, 19, and 28. The intake side of the turbo molecular pump 22 is connected to the second differential evacuation chamber 19 and the analysis chamber 28. The intake side of the dry pump 18 is connected to the first differential evacuation chamber 16 and the exhaust side of the turbo molecular pump 22. The turbo molecular pump 22 is a pump that makes the rotating blades collide with gas molecules, bounces the gas molecules, and exhausts the gas. Under a high pressure with a large number of gas molecules, a large load is applied to the rotating blades, so the exhaust side is exhausted by the dry pump 18.

[0034] The ion guide 11 is housed in the first differential evacuation chamber 16. The ion thermalizer 17 is housed in the second differential evacuation chamber 19. The mass filter 24 is housed in the analysis chamber 28. The ion guide 11, the ion thermalizer 17, and the mass filter 24 constitute an ion analysis unit that separates ions.

[0035] The conversion dynode 30, the scintillator 31, and the photomultiplier tube 32 are housed in the analysis chamber 28. The conversion dynode 30, the scintillator 31, and the photomultiplier tube 32 constitute an ion detection unit that detects ions.

[0036] As the ion source 2, an ESI ion source that ionizes a sample by the electrospray ionization method (ESI) is provided. The ion source 2 includes a capillary 3, a sample introduction tube (not shown), a power supply, and the like. The sample introduction tube forms a passage for the sample solution 1 from the outside of the ion source container 9 to the inside of the ion source 2. The capillary 3 forms a passage for the sample solution 1 from the inside of the ion source 2 to the inside of the ion source container 9.

[0037] The capillary 3 injects droplets of the sample solution 1 into the interior of the ion source container 9. The inner diameter of the tip of the capillary 3 is provided, for example, in the range of several tens to several hundreds of μm. The capillary 3 is electrically connected to a power source (not shown). A positive voltage or a negative voltage of several kV is applied to the capillary 3 from the power source. The sample solution 1 is introduced into the sample introduction tube by a syringe pump or the like (not shown), and then enters the capillary 3. Then, while a high voltage is applied to the capillary 3, it is injected into the interior of the ion source container 9.

[0038] The ion source 2 can be provided with a nebulizer tube (not shown). The nebulizer tube can be arranged concentrically with the capillary 3 so as to surround the periphery of the capillary 3. The nebulizer tube injects an inert gas such as nitrogen gas or argon gas. When the sample solution 1 is injected from the capillary 3, injecting an inert gas from the nebulizer tube can atomize the droplets finely.

[0039] The ion source 2 can be provided with an auxiliary heating gas tube (not shown). The auxiliary heating gas tube can be arranged concentrically with the nebulizer tube so as to surround the periphery of the nebulizer tube. The auxiliary heating gas tube injects an inert gas such as heated nitrogen gas. When the sample solution 1 is injected from the capillary 3, injecting an inert gas heated to several hundreds of °C by a heater (not shown) from the auxiliary heating gas tube can assist ionization and atomization of the droplets.

[0040] The sample solution 1 is injected as droplets from the tip of the capillary 3 toward the interior of the ion source container 9. Evaporation and collision of the solvent of the droplets of the sample solution 1 are promoted by the injection of the inert gas. As atomization of the droplets progresses due to evaporation and collision of the solvent, the electric field on the surface of the droplets increases. When the repulsive force between charges exceeds the surface tension of the droplets, the droplets undergo fission. The injected droplets are repeatedly fragmented and atomized, and finally ions 4 at the single-molecule level are generated.

[0041] In FIG. 1, as the ion source 2, an ESI ion source based on the electrospray ionization method (ESI) is provided. According to ESI, positive and negative ions contained in a trace amount of liquid can be detected. It is possible to perform mass spectrometry on polymers without causing fragmentation. However, as the ion source 2, a device using other ionization methods may also be provided.

[0042] Examples of other ionization methods include atmospheric pressure chemical ionization method (APCI), chemical ionization method (CI), electron impact ionization method (EI), etc. As the ion source 2, an ECR (Electron Cyclotron Resonance) plasma ion source using microwaves, an ICP (Inductively Coupled Plasma) ion source, a Penning ion source, a laser ion source, etc. may be provided.

[0043] An ion introduction electrode 6 is provided between the ion source container 9 and the first differential evacuation chamber 16. The ion introduction electrode 6 is provided with a conical shape on the upstream side and a cylindrical shape on the downstream side. A first pore 7 is formed near the central axis of the ion introduction electrode 6. The first pore 7 communicates the ion source container 9 and the first differential evacuation chamber 16.

[0044] The upstream side of the ion introduction electrode 6 is covered by a counter plate 5. The counter plate 5 is provided with a conical shape. An opening with a diameter of several mm is formed in the counter plate 5 so as to penetrate the center. The opening of the counter plate 5, together with the first pore 7, forms a passage for the ions 4.

[0045] The counter plate 5 is electrically connected to a power source (not shown). A positive voltage or a negative voltage is applied to the counter plate 5 from the power source. The atomized gas generated by the ion source 2 contains ions 4 obtained by ionizing the sample, neutral particles other than ions, and droplets of the sample solution 1 that have not vaporized. These components are introduced from the ion source container 9 into the first pore 7 by an electric field formed between the capillary 3 and the counter plate 5 and a pressure difference between the ion source container 9 and the first differential evacuation chamber 16.

[0046] The counter plate 5 forms a gas flow path with the ion introduction electrode 6. A counter gas 8 flows through the gas flow path from the inlet side of the first pore 7 toward the inside of the ion source container 9. Examples of the counter gas 8 include inert gases such as nitrogen gas. By injecting the counter gas 8 in the reverse direction, entry of neutral particles other than ions and droplets of the sample solution 1 into the first pore 7 is prevented.

[0047] The counter plate 5 and the ion introduction electrode 6 are heated to a high temperature by a heater (not shown). For example, they are heated to about 200°C. When the counter plate 5 and the ion introduction electrode 6 are at a high temperature, droplets of the sample solution 1 approaching them can be vaporized. Since the amount of adhesion of the sample solution 1 to the counter plate 5 and the ion introduction electrode 6 is reduced, measurement errors due to carry-over of dirt can be reduced.

[0048] Ions 4 and the like generated by the ion source 2 are introduced into the first differential evacuation chamber 16 through the first pore 7 and a shaft offset portion 10 provided downstream of the first pore 7 by an electric field and a pressure difference. The first pore 7 is provided, for example, as a through-hole having a circular cross-section. The pore diameter of the first pore 7 can be set to about 0.5 mm or more and 1.5 mm or less. The length of the first pore 7 can be set to several tens of mm.

[0049] The shaft displacement portion 10 is provided with a pore that communicates the first pore 7 and the first differential exhaust chamber 16. The central axis of the pore of the shaft displacement portion 10 is eccentric with respect to the central axis of the first pore 7. Due to the eccentricity, a collision wall is formed at a position intersecting the central axis of the first pore 7. The pore of the shaft displacement portion 10 is offset and open with respect to the collision wall. According to the shaft displacement portion 10, heavy components such as droplets of the sample solution 1 can be separated from light components such as ions. The heavy components collide with the collision wall and cannot pass through the shaft displacement portion 10, while the light components can pass through the shaft displacement portion 10 and flow into the first differential exhaust chamber 16.

[0050] The first differential exhaust chamber 16 is evacuated by a dry pump 18. The first differential exhaust chamber 16 is maintained at a degree of vacuum of about several hundred Pa during the operation of the dry pump 18. An ion guide 11 is accommodated in the first differential exhaust chamber 16.

[0051] The ion guide 11 is composed of a multipole electrode or the like and transmits ions 4 while converging them. The multipole electrode is formed by a round bar of metal, ceramic, or the like. A high-frequency voltage with opposite polarities is applied between adjacent electrode rods. The ions 4 pass through the space surrounded by the electrode rods, are converged by the electric field, and unnecessary components are removed.

[0052] The ion guide 11 can be configured, for example, with an octupole on the upstream side and a quadrupole on the downstream side. The central axis of the upstream electrode group and the central axis of the downstream electrode group can be offset in a direction perpendicular to the traveling direction of the ions. By providing an offset of about several millimeters, neutral particles other than ions can be efficiently removed while allowing predetermined ions 4 to pass through.

[0053] The ions 4 and the like converged in the first differential exhaust chamber 16 are introduced into the second differential exhaust chamber 19 through the second pore by an electric field or a pressure difference. The second pore is provided, for example, as a through hole that penetrates a first pore electrode 15 provided in a flat plate shape. The pore diameter of the second pore can be set to several millimeters. The thickness of the first pore electrode 15 can be set to several millimeters.

[0054] The second differential exhaust chamber 19 is evacuated by a turbo molecular pump 22. The exhaust side of the turbo molecular pump 22 is exhausted by a dry pump 18. The second differential exhaust chamber 19 is maintained at a vacuum level of about several Pa during the operation of the turbo molecular pump 22. An ion thermalizer 17 is accommodated in the second differential exhaust chamber 19.

[0055] The ion thermalizer 17 is composed of a multipole electrode or the like, and attenuates the kinetic energy of the ions 4 while converging the ions 4. The multipole electrode is formed by a round bar of metal, ceramic or the like. A high-frequency voltage with opposite polarities is applied between adjacent electrode rods. Also, a neutral gas such as helium or nitrogen is introduced. The ions 4 pass through the space surrounded by the electrode rods and are converged by an electric field while colliding with neutral gas molecules. Since the kinetic energy of the ions 4 is reduced by the collision with neutral gas molecules, noise due to spectral interference is reduced and the sensitivity of low mass number components is improved.

[0056] The ions 4 and the like converged in the second differential exhaust chamber 19 are introduced into the analysis chamber 28 through the third pore by an electric field or a pressure difference. The third pore is provided, for example, as a through hole penetrating a second pore electrode 20 provided in a flat plate shape. The pore diameter of the third pore can be set to several mm. The thickness of the second pore electrode 20 can be set to several mm.

[0057] The analysis chamber 28 is evacuated by a turbo molecular pump 22. The exhaust side of the turbo molecular pump 22 is exhausted by a dry pump 18. The analysis chamber 28 is maintained at a vacuum level of about 10 -3 Pa during the operation of the turbo molecular pump 22. A mass filter 24, a conversion dynode 30, a scintillator 31, and a photomultiplier tube 32 are accommodated in the analysis chamber 28.

[0058] The mass filter 24 is composed of a first mass filter 25, a collision chamber 26, and a second mass filter 27. The first mass filter 25 and the second mass filter 27 are composed of multipole electrodes, and the high-frequency voltage and the DC voltage are controlled. The collision chamber 26 is composed of a cell in which the multipole electrodes are housed, and a neutral gas such as helium or nitrogen is introduced.

[0059] The first mass filter 25 allows only precursor ions having a specific mass-to-charge ratio (m / Z) to pass through by controlling the voltage. The collision chamber 26 causes the precursor ions to collide with neutral gas molecules. The precursor ions dissociate at sites where the chemical bonds are weak by collision-induced dissociation, and predetermined product ions are dissociated. The second mass filter 27 allows only product ions having a specific mass-to-charge ratio (m / Z) to pass through by controlling the voltage.

[0060] According to the multi-stage mass filter 24, only specific product ions dissociated from the precursor ions are separated. Since the influence of ions other than the detection target with approximate masses can be excluded, highly sensitive quantitative analysis of the product ions to be detected becomes possible. The product ions separated by the mass filter 24 enter the conversion dynode 30.

[0061] The conversion dynode 30 is composed of a secondary electron multiplier electrode. The secondary electron multiplier electrode is placed in a vacuum atmosphere, and a high voltage of a polarity different from that of the ions to be detected is applied. The secondary electron multiplier electrode generates secondary electrons when ions collide. According to the conversion dynode 30, secondary electrons can be generated efficiently from the product ions.

[0062] The scintillator 31 converts electrons into light. The electrons generated by the conversion dynode 30 are converted into light by the back photoelectron spectroscopy by the scintillator 31. According to the scintillator 31, the detection signal of the product ions is converted from secondary electrons into light. When the light conversion is performed, the influence of ions other than the detection target existing inside the analysis chamber 28 can be reduced.

[0063] The photomultiplier tube 32 converts light into electrons and amplifies the electrons. The light converted by the scintillator 31 is converted into electrons by the photoelectric effect in the photomultiplier tube 32 and then amplified in a cascade manner by a plurality of electron multiplication electrodes. The amplified analog signal of the electrons is converted into a digital signal by the analog / digital converter 33.

[0064] The detection result of the ions detected in the ion detection unit is displayed on the monitor 34 as a mass spectrum or the like. The mass spectrum includes information such as the mass-to-charge ratio (m / Z) of the ions separated from the sample solution 1 and the detection intensity of the ions. By comparing the detection result of the ions with previously acquired known data, qualitative analysis and quantitative analysis of the components contained in the sample solution 1 can be performed.

[0065] As shown in FIG. 1, in the analyzer 100 according to the present embodiment, the ion introduction electrode 6 is provided with a stopper hole 40 so as to be connected to the middle part of the first pore 7. One end of the stopper hole 40 opens to the middle part of the first pore 7. The other end of the stopper hole 40 opens to the upper part of the ion introduction electrode 6. A sealing plug 41 that can seal the first pore 7 is inserted into the stopper hole 40.

[0066] The other end of the stopper hole 40 is connected to a bypass pipe 43 via a vacuum joint 42 at the upper part of the ion introduction electrode 6. The other end of the bypass pipe 43 is connected to the analysis chamber 28 via a vacuum joint 42. As the bypass pipe 43, a resin pipe or a metal pipe having pressure resistance and flexibility compatible with vacuum can be used. A vacuum valve 44 is provided in the middle part of the bypass pipe 43.

[0067] The sealing plug 41 is a pressure type that opens and closes due to the pressure difference formed through the bypass pipe 43 and its own weight. The pressure difference is formed between the first pore 7 and the analysis chamber 28 through the bypass pipe 43. The first pore 7 has an intermediate pressure between the ion source container 9, which is under an atmospheric pressure atmosphere regardless of the energization of the vacuum pumps 18 and 22, and the first differential exhaust chamber 16. The analysis chamber 28 is maintained at the highest degree of vacuum among the vacuum chambers 16, 19, and 28.

[0068] When a power failure occurs and the energization of the vacuum pumps 18 and 22 stops, the sealing plug 41 drops from the inside of the plug hole 40 to the first pore 7 due to its own weight and closes the first pore 7. On the other hand, when the vacuum pumps 18 and 22 are energized, the sealing plug 41 floats from the first pore 7 into the inside of the plug hole 40 due to the pressure difference formed through the bypass pipe 43 and opens the first pore 7.

[0069] When a power failure occurs and the energization of the vacuum pumps 18 and 22 stops, the driving by the power of the vacuum pumps 18 and 22 stops. However, even when the energization of the vacuum pumps 18 and 22 stops, the rotating blades of the vacuum pumps 18 and 22 continue to rotate temporarily due to inertia. The ion source container 9 is under an atmospheric pressure atmosphere, while the first differential exhaust chamber 16 is under a vacuum atmosphere. Therefore, there is a possibility that gas may flow from the ion source container 9 into the first differential exhaust chamber 16 before the rotating blades of the vacuum pumps 18 and 22 stop.

[0070] When gas flows from the ion source container 9 into the first differential exhaust chamber 16, the pressure in the first differential exhaust chamber 16, the second differential exhaust chamber 19, and the analysis chamber 28 gradually increases in this order. When the pressure in the first differential exhaust chamber 16, the second differential exhaust chamber 19, or the analysis chamber 28 increases, the intake side of the vacuum pumps 18 and 22 becomes high pressure. Since an excessive pressure is applied to the rotating blades of the vacuum pumps 18 and 22, the vacuum pumps 18 and 22 may be damaged.

[0071] In particular, the turbo molecular pump 22 has a limited operating pressure range and is used in combination with the roughing dry pump 18. The exhaust side of the turbo molecular pump 22 is exhausted by the dry pump 18. However, in the event of a power outage, the exhaust by the dry pump 18 also stops, so the load on the rotating blades of the turbo molecular pump 22 tends to increase.

[0072] When the rate at which the intake sides of the vacuum pumps 18 and 22 are pressurized or the pressure difference between the intake side and the exhaust side of the vacuum pumps 18 and 22 exceeds a certain threshold value, the rotating blades will suffer significant damage. The service life of the vacuum pumps 18 and 22 will be shortened, or the rotating blades of the vacuum pumps 18 and 22 will be damaged or broken. This will lead to the problem that the vacuum pumps 18 and 22 need to be replaced, incurring a great deal of cost. The problems of damage and cost are more prominent in the turbo molecular pump 22 compared to the dry pump 18.

[0073] On the other hand, when the sealing plug 41 is provided, when the power supply to the vacuum pumps 18 and 22 is stopped, the first pore 7 can be sealed without power, so the inflow of gas from the ion source container 9 toward the first differential exhaust chamber 16 can be significantly reduced. When the power supply to the vacuum pumps 18 and 22 is stopped, the inflow rate of gas into the vacuum pumps 18 and 22 can be reduced by a simple structure. Even when the power supply to the vacuum pumps 18 and 22 is stopped, the load on the rotating blades can be reduced, so the damage to the vacuum pumps 18 and 22 can be reduced and the service life can be extended.

[0074] Figures 2A and 2B are diagrams showing the operation of the pressure-type sealing plug in the analyzer. Figure 2A shows the state during energization of the vacuum pumps 18 and 22 when power is being supplied to the analyzer 100. Figure 2B shows the state during a power outage of the vacuum pumps 18 and 22 when the power supply to the analyzer 100 has stopped. As shown in Figures 2A and 2B, the pressure-type sealing plug 41 can be configured to operate by switching the pressure difference formed through the bypass pipe 43 with the vacuum valve 44.

[0075] The plug hole 40 is preferably provided in a structure bent in an L shape. In FIGS. 2A and 2B, the plug hole 40 has a section 40a extending upward from the middle part of the first pore 7, a section 40b extending horizontally at a medium height, and a section 40c extending upward from the medium height. The section 40a and the section 40b communicate with each other at a bent part in an L shape. The section 40b and the section 40c communicate with each other at a bent part in an inverted L shape.

[0076] The pore diameter of the section 40a extending upward from the middle part of the first pore 7 is provided to be equal to the outer diameter of the sealing plug 41. The pore diameter of the section 40b extending horizontally at a medium height is provided to be smaller than the pore diameter of the section 40a extending upward from the middle part of the first pore 7 and the outer diameter of the sealing plug 41. The pore diameter of the section 40c extending upward from the medium height is provided to such an extent that the flow of gas is not hindered.

[0077] The sealing plug 41 is placed in the section 40a extending upward from the middle part of the first pore 7. According to such a structure, in the section 40a extending upward from the middle part of the first pore 7, the sealing plug 41 can be moved up and down by the pressure difference and its own weight. In the structure and arrangement of the existing ion introduction electrode 6, the plug hole 40 can be opened with respect to the middle part of the first pore 7 while ensuring the connection of the bypass pipe 43 to the plug hole 40.

[0078] The vacuum valve 44 has a function of switching the flow path of the bypass pipe 43 by stopping the energization when a power failure occurs. The vacuum valve 44 includes a valve body 45, a coil housing 46, a solenoid coil 47, a movable magnetic member 48, and a spring 49.

[0079] The valve body 45 is provided with movability and includes a plurality of ports and a flow path communicating the ports with each other. The coil housing 46 houses the solenoid coil 47. The solenoid coil 47 is connected to a power source (not shown) and generates an electromagnetic force when energized.

[0080] The movable magnetic member 48 has magnetism and is provided with mobility by electromagnetic force. The tip of the movable magnetic member 48 supports the valve body 45. The proximal end of the movable magnetic member 48 is inserted into the inside of the solenoid coil 47 so as to be able to advance and retreat. The spring 49 elastically connects between the valve body 45 and the coil housing 46. The spring 49 biases the valve body 45 toward the coil housing 46 so that the valve body 45 is in the communication position for communicating with the bypass pipe 43.

[0081] The vacuum valve 44 is provided so as to be able to mutually switch the connection between the plug hole 40 and the analysis chamber 28 and the connection between the plug hole 40 and the space in the atmospheric pressure environment for the flow path of the bypass pipe 43. The valve body 46 is provided with two inlet ports and two outlet ports.

[0082] One of the inlet ports can be switched between opening and closing with respect to the section on the analysis chamber 28 side of the bypass pipe 43. The other inlet port can be switched between opening and closing with respect to the space in the atmospheric pressure environment. One of the outlet ports communicates with one of the inlet ports inside the valve body 45 and can be switched between opening and closing with respect to the section on the plug hole 40 side of the bypass pipe 43. The other outlet port communicates with the other inlet port inside the valve body 45 and can be switched between opening and closing with respect to the section on the plug hole 40 side of the bypass pipe 43.

[0083] As shown in FIG. 2A, when power is supplied to the analyzer 100, the solenoid coil 47 is energized. The solenoid coil 47 generates an electromagnetic force by energization and attracts and pulls up the movable magnetic member 48 with the electromagnetic force. The valve body 45 supported by the movable magnetic member 48 is maintained in the communication position for communicating with the bypass pipe 43 against the biasing force of the spring 49.

[0084] At the communication position, the stopper hole 40 and the analysis chamber 28 communicate with each other through the bypass pipe 43. When a power failure occurs, the first orifice 7 reaches an intermediate pressure between the ion source container 9 and the first differential evacuation chamber 16. On the other hand, the analysis chamber 28 is maintained at a higher degree of vacuum than the first differential evacuation chamber 16. Therefore, at the stopper hole 40, the pressure below the sealing plug 41 becomes a low vacuum close to atmospheric pressure, and the pressure above the sealing plug 41 becomes a high vacuum.

[0085] When switched to the communication position, a large pressure difference is applied across the sealing plug 41. Therefore, the sealing plug 41 floats against its own weight due to the pressure difference, is held inside the stopper hole 40, and opens the first orifice 7. The sealing plug 41 collides with the inner wall at the bent portion of the stopper hole 40 and is stopped.

[0086] On the other hand, as shown in FIG. 2B, when the power supply to the analyzer 100 stops, the energization of the solenoid coil 47 stops. The solenoid coil 47 does not generate electromagnetic force and does not pull up the movable magnetic member 48. The valve body 45 supported by the movable magnetic member 48 is maintained at the open position that opens the bypass pipe 43 to the atmospheric pressure environment according to the biasing by the spring 49.

[0087] At the open position, the stopper hole 40 and the analysis chamber 28 do not communicate with each other through the bypass pipe 43, and the stopper hole 40 is opened to the space of the atmospheric pressure environment. When a power failure occurs, the first orifice 7 reaches an intermediate pressure between the ion source container 9 and the first differential evacuation chamber 16. On the other hand, air 50 flows into the stopper hole 40 from the space of the atmospheric pressure environment. Therefore, at the stopper hole 40, the pressure below the sealing plug 41 becomes a low vacuum close to atmospheric pressure, and the pressure above the sealing plug 41 becomes a pressure close to atmospheric pressure.

[0088] When switched to the open position, a large pressure difference is no longer applied across the sealing plug 41. Therefore, the sealing plug 41 falls by its own weight and closes the first orifice 7. After that, when the power supply to the analyzer 100 is restarted, the solenoid coil 47 is energized, so the first orifice 7 is opened again. The vacuum pumps 18, 22 can be restarted to resume the analysis by the analyzer 100.

[0089] According to such a pressure type sealing plug 41, when the power supply to the analyzer 100 is stopped and the power supply to the vacuum pumps 18 and 22 is stopped, the power supply to the solenoid coil 47 is also stopped. Therefore, the first pore 7 can be closed without power. Since the first pore 7 is closed, the inflow of gas into the intake sides of the vacuum pumps 18 and 22 can be prevented. Even if the first pore 7 is not completely closed, when the sealing plug 41 penetrates into the first pore 7, it is possible to make the gas inflow rate smaller than the allowable inflow rate when the turbo molecular pump 22 is decelerated. Therefore, the load on the rotating blades of the vacuum pumps 18 and 22 can be reduced, and the vacuum pumps 18 and 22 can be protected.

[0090] In FIGS. 1, 2A, and 2B, the sealing plug 41 is configured to operate by the pressure difference between the ion source container 9 and the analysis chamber 28. The analysis chamber 28 is the space maintained at the maximum degree of vacuum among the vacuum chambers 16, 19, and 28. Therefore, when the bypass pipe 43 is connected between the plug hole 40 and the analysis chamber 28, the sealing plug 41 can be easily lifted by the pressure difference.

[0091] However, as long as the pressure difference necessary for the operation is ensured, the sealing plug 41 may be configured to operate by the pressure difference between the ion source container 9 and the second differential evacuation chamber 19, or may be configured to operate by the pressure difference between the ion source container 9 and the first differential evacuation chamber 16. Instead of between the plug hole 40 and the analysis chamber 28, the bypass pipe 43 may be connected between the plug hole 40 and the second differential evacuation chamber 19, or between the plug hole 40 and the first differential evacuation chamber 16.

[0092] FIG. 3 is a diagram for explaining a method of forming a plug hole in the analyzer. As shown in FIG. 3, the plug hole 40 can be formed by drilling the ion introduction electrode 6. By combining linear through holes, sections 40a, 40b, and 40c that communicate with each other at the bent portions can be formed.

[0093] In the ion introduction electrode 6, through holes corresponding to a section 40a extending upward from the middle part of the first pore 7, through holes corresponding to a section 40b extending horizontally at a medium height, and through holes corresponding to a section 40c extending upward from a medium height are formed by means of lathe work or the like. A sealing plug 41 is inserted into the section 40a extending upward from the middle part of the first pore 7. When a closing member 52 is press-fitted into each through hole, a plug hole 40 is formed.

[0094] As the closing member 52, appropriate materials such as carbon steel and stainless steel can be used as long as heat resistance to a high temperature of about 200 °C and strength to withstand press-fitting are ensured. The ion introduction electrode 6 can be formed of, for example, stainless steel or the like. The space between the ion introduction electrode 6 and the first differential exhaust chamber 16 is hermetically sealed by an O-ring 51.

[0095] The sealing plug 41 can be formed of a metal such as carbon steel or stainless steel, or a ceramic such as silicon nitride. The sealing plug 41 can be provided in an appropriate shape such as a spherical shape, a cylindrical shape, or a weight shape as long as the inflow rate of gas through the first pore 7 can be made smaller than the allowable inflow rate when the vacuum pumps 18 and 22 are decelerating. However, the sealing plug 41 needs to be provided in consideration of the self-weight of the sealing plug 41, the buoyancy due to the pressure difference formed through the bypass pipe 43, the frictional force with the inner wall of the plug hole 40, and the like.

[0096] For example, when the gravity F1 acting on the sealing plug 41 is such that the sealing plug 41 is a carbon steel sphere with a diameter φ = 2 mm, F1 ≒ 0.032 gf. When the vacuum below the sealing plug 41 at the time of a power failure is assumed to be half of the atmospheric pressure, the buoyancy F2 acting on the sealing plug 41 is F2 ≒ 15.7 gf. When the friction coefficient μ between the sealing plug 41 and the inner wall of the plug hole 40 is assumed to be 0.5, the frictional force F3 acting on the sealing plug 41 is F3 ≒ 0.016 gf. It is known that the friction coefficient μ increases even in contact between different metals at a high vacuum.

[0097] Under this condition, F1 + F3 (≈0.048 gf) ≪ F2 (≈15.7 gf). The sealing plug 41 can be provided so as to float under the coefficient of friction μ with the inner wall of the assumed plug hole 40 due to the pressure difference between the first pore 7 and the analysis chamber 28 when a power failure occurs, and to fall by its own weight due to the pressure difference between the first pore 7 and the atmospheric pressure when a power failure occurs.

[0098] A minute gap may be formed between the sealing plug 41 and the inner wall of the plug hole 40. When a gap is formed, gas outflow occurs from the first pore 7 toward the analysis chamber 28. However, if the gap between the sealing plug 41 and the inner wall of the plug hole 40 is about 10 μm or less, the gas outflow rate can be made negligibly small. If it is about 10 μm or less, the sealing plug 41 can be floated by the pressure difference when power is supplied to the analyzer 100.

[0099] For example, if the plug hole 40 is formed with a diameter φ = 2 mm and a tolerance class F8 (tolerance: 0.006 - 0.020 mm), and a precision carbon steel ball with a diameter φ = 2 mm (tolerance: 0 - 0.005 mm) is used as the sealing plug 41, the maximum gap is 20 μm and the average gap is about 10.5 μm (13 μm - 2.5 μm).

[0100] The thermal expansion coefficient of carbon steel is about 12×10 -6 / K. The thermal expansion coefficient of stainless steel is about 17×10 -6 / K. When the ion introduction electrode 6 is heated to 200°C, compared with the case at room temperature of 20°C, the pore diameter of the plug hole 40 becomes about 1.8 μm larger than the diameter of the carbon steel ball. The difference between the pore diameter of the plug hole 40 and the diameter of the sealing plug 41 becomes smaller during thermal expansion than at room temperature. The average gap during thermal expansion is about 12.3 μm (10.5 μm + 1.8 μm). The ratio of the average gap during thermal expansion to the pore diameter of the plug hole 40 is about 163:1, and the gap ratio can be made sufficiently small.

[0101] The opening of the plug hole 40 on the side of the first pore 7 is preferably provided on the upstream side of the middle part of the first pore 7 where the ion source container 9 is located. For example, as long as there are no processing problems or interference with the gas flow path, etc., it is preferably provided on the upstream side of the ion introduction electrode 6 provided in a conical shape. The first pore 7 is closer to atmospheric pressure on the upstream side where the ion source container 9 is located. On the other hand, the degree of vacuum becomes higher on the downstream side where the first differential evacuation chamber 16 is located. The pressure difference formed through the bypass pipe 43 becomes larger as the plug hole 40 opens on the upstream side of the first pore 7, so it becomes easier to ensure the buoyancy of the sealing plug 41.

[0102] The sealing plug 41 and the ion introduction electrode 6 can also be formed of the same kind of metal such as stainless steel. When the aperture of the plug hole 40 expands during thermal expansion, there is a possibility that gas may flow out through the gap between the plug hole 40 and the sealing plug 41. However, if the sealing plug 41 and the ion introduction electrode 6 are made of the same material, the difference in thermal expansion is suppressed, so such gas leakage can be prevented. However, when formed of the same kind of metal, the coefficient of friction μ becomes large, so it is preferable to perform lubrication.

[0103] On the inner wall of the plug hole 40 in contact with the sealing plug 41, a liquid lubricant may be applied or a solid lubricant may be formed into a film as necessary. As the liquid lubricant, a type with a low vapor pressure is preferable. As the liquid lubricant, perfluoropolyethers such as Fomblin and fluorine-based lubricants such as polytetrafluoroethylene can be used. As the solid lubricant, molybdenum disulfide, tungsten disulfide, boron nitride, boric acid, polytetrafluoroethylene, chromium, silver, lead alloy, etc. can be used. The solid lubricant can be formed into a film by sputtering, ion plating, plating, etc.

[0104] On the inner wall of the plug hole 40 in contact with the sealing plug 41, a mirror finish for reducing the surface roughness may be applied as necessary. For example, mechanical polishing, electrolytic polishing, chemical polishing, etc. can be performed on the inner wall of the plug hole 40. When the surface roughness of the inner wall of the plug hole 40 is reduced, the coefficient of friction μ with the sealing plug 41 becomes small, and it becomes difficult for dirt to adhere and carry-over is reduced.

[0105] Figures 4, 5, and 6 are diagrams showing structural examples of the stopper holes in the analyzer. Figures 4, 5, and 6 correspond to the cross-sectional view taken along the line I-I in Figure 3. In Figures 4 and 5, reference numeral d1 indicates the pore diameter of the first pore 7, reference numeral d2 indicates the diameter of the sealing plug 41, and reference numeral d3 indicates the pore diameter of the stopper hole 40. In Figures 4, 5, and 6, the left diagram shows the state where the sealing plug 41 has floated, and the right diagram shows the state where the sealing plug 41 has dropped.

[0106] As shown in Figure 4, the diameter d2 of the sealing plug 41 can be made larger than the pore diameter d1 of the first pore 7. That is, the pore diameter d3 of the stopper hole 40 can be made larger than the pore diameter d1 of the first pore 7. Also, the height of the lower end of the sealing plug 41 can be made higher than the height of the upper end of the first pore 7 in the state where the sealing plug 41 has floated.

[0107] The stopper hole 40 can form a stepped wall around the first pore 7 with respect to the traveling direction of ions or the like passing through the first pore 7. At the location where the stopper hole 40 and the first pore 7 are connected, the flow of ions or the like tends to stagnate. At such a place, foreign matter 54 easily adheres to the inner wall of the stopper hole 40. The foreign matter 54 may be the ions 4 obtained by ionizing the sample, or may be neutral particles other than ions.

[0108] The foreign matter 54 varies for each sample solution 1 and for each ion to be analyzed, and becomes a factor of cross-contamination. When the sealing plug 41 operates, the foreign matter 54 is rubbed and peeled off from the inner wall of the stopper hole 40. The peeled foreign matter 54 reaches the detection unit and becomes noise in the mass spectrum, which may deteriorate the analysis accuracy. The amount of adhesion of such foreign matter 54 increases as the surface area of the inner wall of the stopper hole 40 is larger below the sealing plug 41.

[0109] Therefore, as shown in FIG. 5, it is preferable that the diameter d2 of the sealing plug 41 is slightly larger than the pore diameter d1 of the first pore 7. That is, it is preferable that the pore diameter d3 of the plug hole 40 is slightly larger than the pore diameter d1 of the first pore 7. For example, the difference between the diameter d2 of the sealing plug 41 and the pore diameter d1 of the first pore 7 is preferably 1 mm or less, more preferably 500 μm or less, and even more preferably 100 μm or less. The diameter d2 of the sealing plug 41 is preferably set to a length such that the sealing plug 41 does not enter the first pore 7 at normal temperature and during thermal expansion.

[0110] Further, the height of the lower end of the sealing plug 41 is preferably close to the height of the upper end of the first pore 7 in a state where the sealing plug 41 floats. For example, the difference between the height of the lower end of the sealing plug 41 and the height of the upper end of the first pore 7 is preferably 5 mm or less, and more preferably 1 mm or less.

[0111] With such a structure, the amount of foreign matter 54 adhering to the inner wall of the plug hole 40 can be reduced. Therefore, high analysis accuracy can be ensured. Even when the sealing plug 41 operates, since a large amount of foreign matter 54 does not peel off from the inner wall of the plug hole 40, carry-over can be suppressed not only when analysis is resumed after a power failure but also when power is supplied to the analyzer 100.

[0112] As shown in FIG. 6, the sealing plug 41 can also be provided in a shape such that the lower surface of the sealing plug 41 and the upper surface of the first pore 7 are substantially flush in a floating state. In FIG. 6, the sealing plug 41 is provided in a cylindrical shape with a concave notch at the lower part. The lower part of the sealing plug 41 is notched in an arc shape with the same curvature as the first pore 7 in a cross-sectional view.

[0113] With such a structure, when the sealing plug 41 floats, the amount of foreign matter 54 adhering to the inner wall of the plug hole 40 can be reduced. When a power outage occurs, although the first pore 7 cannot be completely blocked, the inflow of gas can be suppressed to the extent that damage to the turbo molecular pump 22 can be prevented. In such a structure, a counterbore may or may not be provided at the bottom of the plug hole 40. From the viewpoint of making it difficult for the flow of ions or the like to stagnate, it is preferable not to provide a counterbore.

[0114] In addition, in FIGS. 4, 5, and 6, although the bottom of the plug hole 40 has a rectangular shape, the bottom of the plug hole 40 can also be made to coincide with the bottom surface of the first pore 7. When restarting the analysis after a power outage, as long as the buoyancy acting on the dropped sealing plug 41 can be ensured, it can also be provided with a structure in which the sealing plug 41 lands on the bottom surface of the first pore 7.

[0115] FIGS. 7A and 7B are diagrams showing the operation of the electromagnetic sealing plug in the analyzer. FIG. 7A shows the state during energization of the vacuum pumps 18 and 22 when power is supplied to the analyzer 100. FIG. 7B shows the state during a power outage of the vacuum pumps 18 and 22 when power supply to the analyzer 100 is stopped. As shown in FIGS. 7A and 7B, the sealing plug 41 provided in the analyzer 100 can also be provided in an electromagnetic type driven by an electromagnetic actuator 55.

[0116] In FIGS. 7A and 7B, a straight-hole-shaped plug hole 40 is provided in the ion introduction electrode 6 so as to be connected to the first pore 7. One end of the plug hole 40 opens in the middle of the first pore 7. The other end of the plug hole 40 opens above the ion introduction electrode 6. A sealing plug 41 supported by the electromagnetic actuator 55 is inserted into the straight-hole-shaped plug hole 40.

[0117] The electromagnetic actuator 55 has a function of closing the first pore 7 with the sealing plug 41 when power supply stops during a power outage. The electromagnetic actuator 55 includes a coil housing 56, a solenoid coil 57, a movable magnetic member 58, a spring 59, a shaft seal member 60, and an O-ring 61.

[0118] The sealing plug 41 is fixed to one end of the movable magnetic member 58. The sealing plug 41 supported by the electromagnetic actuator 55 can be provided in an appropriate shape such as spherical, cylindrical, or conical. The coil housing 56 houses the solenoid coil 57. The solenoid coil 57 is connected to a power source (not shown) and generates an electromagnetic force when energized.

[0119] The movable magnetic member 58 has magnetism and is provided with mobility by an electromagnetic force. The tip of the movable magnetic member 58 is inserted into the plug hole 40 and supports the sealing plug 41. The base end of the movable magnetic member 48 is inserted into the inside of the solenoid coil 57 so as to be able to move forward and backward. The spring 59 elastically connects between the coil housing 56 and the movable magnetic member 58. The spring 59 biases the movable magnetic member 58 toward the first pore 7 so that a reaction force against the electromagnetic force is applied to the movable magnetic member 58.

[0120] The shaft seal member 60 is provided with an opening at the upper part of the plug hole 40. The shaft seal member 60 seals the plug hole 40 into which the movable magnetic member 58 is inserted, with the movable magnetic member 58 being able to move forward and backward. The O-ring 61 is housed in the shaft seal member 60. The O-ring 61 hermetically seals the sliding part with the movable magnetic member 58. The shaft seal member 60 and the O-ring 61 prevent leakage of gas through the plug hole 40.

[0121] The sealing plug 41 supported by the electromagnetic actuator 55 closes the first pore 7 when a power failure occurs or when the power supply to the vacuum pumps 18, 22 is stopped. On the other hand, the sealing plug 41 supported by the electromagnetic actuator 55 is pulled up from the first pore 7 into the inside of the plug hole 40 by the electromagnetic force of the electromagnetic actuator 55 and opens the first pore 7 when there is power supply to the vacuum pumps 18, 22.

[0122] As shown in Fig. 7A, when power is supplied to the analyzer 100, the solenoid coil 57 is energized. The solenoid coil 57 generates an electromagnetic force by being energized, and attracts and pulls up the movable magnetic member 58 with the electromagnetic force. The sealing plug 41 supported by the movable magnetic member 58 is pulled up from the first pore 7, held inside the plug hole 40, and the first pore 7 is opened.

[0123] On the other hand, as shown in Fig. 7B, when power supply to the analyzer 100 is stopped, the energization of the solenoid coil 57 is stopped. The solenoid coil 57 does not generate an electromagnetic force and does not pull up the movable magnetic member 58. The sealing plug 41 supported by the movable magnetic member 58 enters the first pore 7 from the plug hole 40 according to the repulsive force of the spring 59 applied to the movable magnetic member 58, and closes the first pore 7.

[0124] The electromagnetic actuator 55 is preferably provided with heat resistance when the ion introduction electrode 6 is heated to a high temperature. As the heat-resistant O-ring 61, a perfluoropolyether rubber such as Viton or a fluorine-based elastomer such as a vinylidene fluoride copolymer rubber can be used. Further, it is preferable to provide the movable magnetic member 58, the proximity portion between the movable magnetic member 58 and the coil housing 56, and the joint portion between the movable magnetic member 58 and the spring 59 with a structure having high thermal resistance. For example, a heat-resistant material having a high thermal conductivity such as ceramics or a heat-resistant resin can be provided between the intermediate portion of the movable magnetic member 58, between the movable magnetic member 58 and the coil housing 56, and between the movable magnetic member 58 and the spring 59.

[0125] According to such an electromagnetic sealing plug 41, when power supply to the analyzer 100 is stopped and the energization of the vacuum pumps 18 and 22 is stopped, the energization of the solenoid coil 57 is also stopped, so that the first pore 7 can be closed without power. Since the first pore 7 is closed, the inflow of gas to the intake side of the vacuum pumps 18 and 22 can be prevented. Although the electromagnetic sealing plug 41 has restrictions on the arrangement and structure of the electromagnetic actuator 55 compared with the pressure-type sealing plug 41, the degree of freedom in the design of the sealing plug 41 and the plug hole 40 is expanded.

[0126] As described above, the embodiments of the present invention have been explained. However, the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention. For example, the present invention is not necessarily limited to having all the configurations provided in the above-described embodiments. A part of the configuration of a certain embodiment can be replaced with another configuration, a part of the configuration of a certain embodiment can be added to another form, or a part of the configuration of a certain embodiment can be omitted.

[0127] For example, the above-described analyzer 100 is a mass spectrometer. However, an analyzer provided with a sealing plug capable of sealing a pore for introducing charged particles from a charged particle source into a vacuum chamber includes a charged particle source that generates charged particles, a vacuum chamber whose interior is evacuated, a pore for introducing charged particles from the charged particle source into the vacuum chamber, and a vacuum pump connected to the vacuum chamber, and may be applied to other analyzers as long as it has these components. Examples of other analyzers include a Scanning Electron Microscope (SEM), a Transmission Electron Microscope (TEM), a Focused Ion Beam (FIB) apparatus, and the like.

Explanation of Reference Numerals

[0128] 100 Analyzer 2 Ion source (charged particle source) 6 Ion introduction electrode 7 First pore 7 (pore) 9 Ion source container 11 Ion guide 15 First pore electrode 16 First differential evacuation chamber (vacuum chamber) 17 Ion thermalizer 18 Dry pump (vacuum pump) 19 Second differential evacuation chamber (vacuum chamber) 20 Second pore electrode 22 Turbo molecular pump (vacuum pump) 24 Mass filter 25 First mass filter 26 Collision chamber 27 Second mass filter 28 Analysis chamber (vacuum chamber) 30 Conversion dynode 31 Scintillator 32 Photomultiplier tube 40 Plug hole 41 Sealing plug 42 Vacuum joint 43 Bypass pipe 44 Vacuum valve 45 Valve body 46 Coil housing 47 Solenoid coil 48 Movable magnetic member 49 Spring 50 Atmosphere 51 O-ring 52 Blocking member 55 Electromagnetic actuator 56 Coil housing 57 Solenoid coil 58 Movable magnetic member 59 Spring 60 Shaft sealing member 61 O-ring

Claims

1. In an analyzer comprising a charged particle source for generating charged particles, a vacuum chamber with a vacuum inside, a pore for introducing the charged particles from the charged particle source into the vacuum chamber, and a vacuum pump connected to the vacuum chamber, comprising a sealing plug capable of sealing the pore, the sealing plug operates due to the pressure difference between the pore and the vacuum chamber when the vacuum pump is energized, opening the pore, and seals the pore when the energization of the vacuum pump stops. An analyzer.

2. (Deleted)

3. The analyzer according to claim 1, a plug hole connected to the middle part of the pore, and a bypass pipe connecting the plug hole and the vacuum chamber, wherein the sealing plug is held in the plug hole. An analyzer.

4. The analyzer according to claim 3, comprising a valve for switching the connection between the plug hole and the vacuum chamber and the connection between the plug hole and the space in the atmospheric pressure environment, the valve opens the connection between the plug hole and the space in the atmospheric pressure environment when the energization of the vacuum pump stops, and opens the connection between the plug hole and the vacuum chamber when the vacuum pump is energized. An analyzer.

5. The analyzer according to claim 4, wherein the vacuum chamber is composed of a plurality of differentially evacuated rooms, and the bypass pipe is connected to the plug hole and the room with the highest degree of vacuum in the vacuum chamber. An analyzer.

6. (Deleted)

7. (Deleted)

8. The analyzer according to claim 1, wherein the vacuum pump is a turbo molecular pump. An analyzer.

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