Analyzing 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

Analyzer

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

[0002] A mass spectrometer comprises an ion source that ionizes a sample, a separation section that separates the ions according to mass, and a measurement section that measures the separated ions. Components contained in the sample are ionized into electromagnetically separable ions and then introduced into the separation section. The separation section is composed of a vacuum chamber to ensure the ion's range, and separates the ions according to their mass-to-charge ratio. In the measurement section, the intensity of the ions separated by mass is detected using an electron multiplier or other device.

[0003] The vacuum chamber is divided into multiple compartments, each of which is differentially evacuated. The upstream vacuum chamber houses a separation section and is connected to a dry pump for rough evacuation. The downstream vacuum chamber houses a separation section and a measurement section and is connected to a turbomolecular pump for main evacuation. An ion introduction electrode is provided between the vessel containing the ion source and the vacuum chamber.

[0004] The ion introduction electrode is provided with a counter plate that generates an electric field on the side of the vessel housing the ion source. A fine hole that passes through the ion introduction electrode connects the vessel housing the ion source to the vacuum chamber. Ions generated from the sample by the ion source are introduced into the vacuum chamber through the fine hole due to the potential difference between the ion source and the counter plate and the pressure difference between the vessel housing the ion source and the vacuum chamber.

[0005] In recent years, there has been a demand for further improvements in the sensitivity of mass spectrometers. The sensitivity of ion detection improves when the amount of ions introduced into the measurement unit housed in a vacuum chamber is increased. However, conventionally, the pores formed in the ion introduction electrode have high flow resistance. It is expected that increasing the pore diameter will reduce the flow resistance and increase the amount of ions introduced. However, increasing the pore diameter also increases the amount of gas flowing in, which reduces the degree of vacuum in the vacuum chamber.

[0006] To improve the sensitivity of ion detection, it is necessary to maintain a high degree of vacuum in the vacuum chamber. A high degree of vacuum can be achieved by using a vacuum pump with a high exhaust speed. However, a vacuum pump with a high exhaust speed requires a large device and is expensive to install. Recently, this problem has been addressed by increasing the diameter of the pores and the number of vacuum pumps.

[0007] In mass spectrometers, if a power outage occurs in the power supply system, the power supply to the vacuum pump will be cut off. If the power supply to the vacuum pump is cut off, differential evacuation becomes impossible, the roughing pump stops, and excessive pressure is applied to the main pump. Since the cutoff of the power supply to the vacuum pump can lead to damage to the vacuum pump, measures are taken to protect the vacuum system.

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

[0009] Patent Document 2 discloses an atmospheric pressure ionization mass spectrometer equipped with a leak valve in the intermediate pressure section. When the vacuum pump that evacuates the intermediate pressure section and the vacuum pump that evacuates the analytical section are stopped, 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 retention valve provided in the second narrow-aperture electrode section or a butterfly valve provided above the turbomolecular pump.

[0010] Patent Document 3 discloses a vacuum device equipped with valves that are opened and closed by an interlock to prevent damage to the vacuum pump. In this vacuum device, the turbomolecular pump is protected by a hard interlock that instantly closes the exhaust-side and intake-side valves when the dry pump stops while the turbomolecular pump is rotating.

[0011] Patent Document 4 discloses an exhaust system equipped with a turbomolecular pump and an electric valve. In this exhaust system, an electric valve provided between the roughing pump and the exhaust port of the turbomolecular pump, and an electric valve provided between the turbomolecular pump and the chamber are closed in the event of a power outage.

[0012] JP 2018-066370, JP 06-068843, JP 08-026857, JP 2002-147386

[0013] When a power outage occurs in the power supply system of an analytical instrument, the power supply to the vacuum pump is cut off and it is no longer driven by electricity. However, the vacuum pump's rotor continues to rotate for a while due to inertia. Until the rotor stops, gas continues to flow into the vacuum pump's intake side. The pressure on the vacuum pump's intake side increases, and excessive pressure is applied to the vacuum pump's rotor, causing damage to the vacuum pump. This can shorten the vacuum pump's service life or cause the vacuum pump's rotor to break or fracture.

[0014] In particular, turbomolecular pumps used as vacuum pumps gradually slow down from full rotation of tens of thousands of rpm when the drive of their rotors is stopped, continuing to rotate for about 10 minutes before stopping. Turbomolecular pumps have a limited operating pressure range and are generally used in conjunction with a roughing vacuum pump. In the event of a power outage, the exhaust on the exhaust side of the turbomolecular pump by the roughing vacuum pump also stops, increasing the load on the rotors of the vacuum pump.

[0015] In recent years, in the field of mass spectrometers and other devices, there has been a trend toward enlarging the diameter of the pore connecting the vessel housing the ion source and the vacuum chamber in order to improve the sensitivity of ion detection. Enlarging the diameter of the pore increases the amount of ions introduced into the vacuum chamber, but also increases the inflow rate and volume of gas flowing into the intake side of the vacuum pump in the event of a power outage. This increases the risk of damage to the vacuum pump due to excessive pressure on the vacuum pump's rotor.

[0016] Generally, the probability of damage to vacuum pumps due to power outages is not that high. However, once damaged, replacement is necessary, which incurs significant equipment costs. Generally, the use of an uninterruptible power supply is considered as a countermeasure against power outages. However, adding an uninterruptible power supply increases the size of the entire analytical equipment and increases the equipment costs. Therefore, a low-cost, simple countermeasure is desired to protect the vacuum pumps of analytical equipment in the event of a power outage.

[0017] In the technology of Patent Document 1, a pressure difference occurs across the pilot valve, which may prevent a sudden decrease in the vacuum level of the vacuum chamber. However, the pilot valve is located between the backing pump and the vacuum pump. With this structure, the pilot valve increases flow path resistance, slowing the pumping speed of the vacuum pump and lowering the vacuum level of the vacuum chamber. When a high vacuum level is required, a vacuum pump with a high pumping speed is required, which increases the size of the entire device and increases the equipment costs.

[0018] The technology of Patent Document 2 can prevent a decrease in the gain of ion detectors such as multipliers. However, installing a vacuum retention valve at the second aperture electrode not only raises the issue of clogging the aperture of the second aperture electrode with dirt and increases costs, but also leads to problems such as disturbances in the electric field. Furthermore, the operation of the vacuum retention valve can easily cause the aperture to become clogged due to the detachment of dirt. Maintenance work to remove the dirt is required, which hinders mass spectrometry. Disturbances in the electric field can affect the trajectory of charged particles and reduce the ion transmittance in the separation section. On the other hand, installing a butterfly valve above the turbomolecular pump raises equipment costs. With a normal exhaust sequence, the load on the main-evacuation turbomolecular pump can be reduced even with a roughing vacuum pump. Therefore, installing a butterfly valve in case of a power outage has cost-effectiveness issues.

[0019] In the technology of Patent Document 3, valves that are opened and closed by an interlock are provided on the intake and exhaust sides of a turbomolecular pump. However, the piping on the intake and exhaust sides of a turbomolecular pump is generally provided with a relatively large inner diameter. Considering the pumping speed of the turbomolecular pump, providing valves in such locations increases flow path resistance to a non-negligible extent. The combined conductance that takes the valves into account reduces the effective pumping speed. Furthermore, problems arise such as increased power consumption due to the operation of the valves themselves and an increase in the size of the entire device.

[0020] In the technology of Patent Document 4, an electric valve is provided between the roughing pump and the exhaust port of the turbomolecular pump, and between the turbomolecular pump and the chamber. However, as in Patent Document 3, when an electric valve is provided on the intake side or exhaust side of the turbomolecular pump, the effective pumping speed decreases. In addition, problems arise such as increased power consumption due to the operation of the electric valve itself and an increase in the size of the entire device.

[0021] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an analytical device that can reduce the amount of gas that flows into a vacuum pump when power supply to the vacuum pump is stopped, using a simple structure.

[0022] In order to solve the above problems, the analytical apparatus of the present invention includes a charged particle generation source that generates charged particles, a vacuum chamber whose interior is evacuated, a fine hole that introduces the charged particles from the charged particle generation source into the vacuum chamber, and a vacuum pump connected to the vacuum chamber, and further includes a sealing plug that can seal the fine hole, and the sealing plug seals the fine hole when power to the vacuum pump is stopped.

[0023] According to the present invention, it is possible to provide an analytical device that can reduce the amount of gas that flows into a vacuum pump when power supply to the vacuum pump is stopped, using a simple structure.

[0024] 1 is a diagram illustrating the configuration of an analytical device according to an embodiment of the present invention; FIG. 2 is a diagram illustrating the operation of a pressure-type sealing plug in an analytical device; FIG. 3 is a diagram illustrating the operation of a pressure-type sealing plug in an analytical device; FIG. 4 is a diagram explaining a method for forming a plug hole in an analytical device; FIG. 5 is a diagram illustrating an example of the structure of a plug hole in an analytical device; FIG. 6 is a diagram illustrating an example of the structure of a plug hole in an analytical device; FIG. 7 is a diagram illustrating an example of the structure of a plug hole in an analytical device; FIG. 8 is a diagram illustrating the operation of an electromagnetic-type sealing plug in an analytical device; FIG. 9 is a diagram illustrating the operation of an electromagnetic-type sealing plug in an analytical device.

[0025] An analyzer according to one embodiment of the present invention will be described below with reference to the drawings. Note that common components in the following drawings are given the same reference numerals, and duplicated descriptions will be omitted.

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

[0027] 1, an analytical device 100 is shown as a mass spectrometer equipped with an ion source 2 that uses electrospray ionization (ESI). The analytical device 100 performs mass analysis of components contained in a sample solution 1. The sealing plug 41 is a pressure type that operates using a pressure difference and its own weight.

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

[0029] 1, the vacuum chambers 16, 19, and 28 are each divided into a plurality of chambers. In FIG. 1, the vacuum chambers 16, 19, and 28 are each composed of a first differential pumping chamber 16, a second differential pumping chamber 19, and an analysis chamber 28.

[0030] The ion source vessel 9 and the first differential pumping chamber 16 are separated by the ion introduction electrode 6. A first pore 7 is formed through the center of the ion introduction electrode 6. The ion source vessel 9 and the first differential pumping chamber 16 are in communication with each other through the first pore 7.

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

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

[0033] Vacuum pumps 18 and 22 are connected to the vacuum chambers 16, 19, and 28. The intake side of a turbomolecular pump 22 is connected to the second differential pumping chamber 19 and the analysis chamber 28. The intake side of a dry pump 18 is connected to the exhaust side of the first differential pumping chamber 16 and the turbomolecular pump 22. The turbomolecular pump 22 is a pump that exhausts gas molecules by causing its rotors to collide with them, repelling the gas molecules. Under atmospheric pressures where there are many gas molecules, a large load is placed on the rotors, so the exhaust side is evacuated by the dry pump 18.

[0034] The first differential pumping chamber 16 houses an ion guide 11. The second differential pumping chamber 19 houses an ion thermalizer 17. The analysis chamber 28 houses a mass filter 24. The ion guide 11, ion thermalizer 17, and mass filter 24 constitute an ion analysis section that separates ions.

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

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

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

[0038] The ion source 2 may be provided with a nebulizer tube (not shown). The nebulizer tube may be disposed 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, the injection of the inert gas from the nebulizer tube can atomize the liquid droplets into fine droplets.

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

[0040] The sample solution 1 is sprayed as droplets from the tip of the capillary 3 toward the inside of the ion source vessel 9. The spray of inert gas promotes evaporation of the solvent and collisions of the droplets of the sample solution 1. As the droplets become finer due to the evaporation of the solvent and collisions, the electric field on the surface of the droplets increases. When the repulsive force between the charges exceeds the surface tension of the droplets, the droplets split. The sprayed droplets split into smaller droplets through repeated splitting, and ultimately ions 4 at the monomolecular level are generated.

[0041] In FIG. 1, the ion source 2 is an electrospray ionization (ESI) ion source. ESI can detect positive and negative ions contained in a small amount of liquid. It is possible to perform mass analysis of polymers without causing fragmentation. However, the ion source 2 may also be a device that uses another ionization method.

[0042] Other ionization methods include atmospheric pressure chemical ionization (APCI), chemical ionization (CI), electron impact ionization (EI), etc. The ion source 2 may include an electron cyclotron resonance (ECR) plasma ion source using microwaves, an inductively coupled plasma (ICP) ion source, a Penning ion source, a laser ion source, etc.

[0043] An ion introduction electrode 6 is provided between the ion source vessel 9 and the first differential pumping chamber 16. The ion introduction electrode 6 has a conical shape on the upstream side and a cylindrical shape on the downstream side. A first narrow hole 7 is formed near the central axis of the ion introduction electrode 6. The first narrow hole 7 connects the ion source vessel 9 and the first differential pumping chamber 16.

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

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

[0046] A gas flow path is formed between the counter plate 5 and the ion introduction electrode 6. A counter gas 8 flows through the gas flow path from the inlet side of the first aperture 7 toward the inside of the ion source vessel 9. The counter gas 8 may be an inert gas such as nitrogen gas. By injecting the counter gas 8 in the reverse direction, neutral particles other than ions and droplets of the sample solution 1 are prevented from entering the first aperture 7.

[0047] The counter plate 5 and the iontophoretic electrode 6 are heated to a high temperature by a heater (not shown), for example, to about 200°C. When the counter plate 5 and the iontophoretic electrode 6 are at a high temperature, droplets of the sample solution 1 approaching them can be vaporized. Since the amount of sample solution 1 adhering to the counter plate 5 and the iontophoretic electrode 6 is reduced, measurement errors due to carryover of contaminants can be reduced.

[0048] Ions 4 generated by the ion source 2 are introduced into the first differential pumping chamber 16 through the first aperture 7 and the axis shifting unit 10 provided downstream of the first aperture 7 by the electric field and pressure difference. The first aperture 7 is provided, for example, as a through-hole with a circular cross section. The diameter of the first aperture 7 can be set to approximately 0.5 mm or more and 1.5 mm or less. The length of the first aperture 7 can be set to several tens of mm.

[0049] The axis-shifting unit 10 has a pore that communicates with the first pore 7 and the first differential pumping chamber 16. The central axis of the pore in the axis-shifting unit 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 that intersects with the central axis of the first pore 7. The pore in the axis-shifting unit 10 opens offset from the collision wall. The axis-shifting unit 10 can separate heavy components such as droplets of the sample solution 1 from light components such as ions. The heavy components collide with the collision wall and cannot pass through the axis-shifting unit 10, while the light components can pass through the axis-shifting unit 10 and flow into the first differential pumping chamber 16.

[0050] The first differential pumping chamber 16 is evacuated by a dry pump 18. The first differential pumping chamber 16 is maintained at a vacuum level of approximately several hundred Pa when the dry pump 18 is in operation. The first differential pumping chamber 16 houses an ion guide 11.

[0051] The ion guide 11 is composed of multipole electrodes and the like, and allows the ions 4 to pass through while converging them. The multipole electrodes are formed from round rods made of metal, ceramic, or the like. Radio frequency voltages with opposite positive and negative polarities are applied between adjacent electrode rods. The ions 4 pass through the space surrounded by the electrode rods, where they are converged by the electric field and unwanted components are removed.

[0052] The ion guide 11 can be configured with, for example, an octapole on the upstream side and a quadrupole on the downstream side. The central axes of the upstream electrode group and the downstream electrode group can be offset in a direction perpendicular to the ion traveling direction. By providing an offset of several millimeters, it is possible to transmit the desired ions 4 while efficiently removing neutral particles other than ions.

[0053] The ions 4 and the like focused in the first differential pumping chamber 16 are introduced into the second differential pumping chamber 19 through the second aperture by the electric field and pressure difference. The second aperture is provided, for example, as a through-hole penetrating the first aperture electrode 15 provided in a flat plate shape. The diameter of the second aperture can be set to several mm. The thickness of the first aperture electrode 15 can be set to several mm.

[0054] The second differential pumping chamber 19 is evacuated by a turbomolecular pump 22. The exhaust side of the turbomolecular pump 22 is evacuated by a dry pump 18. The second differential pumping chamber 19 is maintained at a vacuum level of about several Pa when the turbomolecular pump 22 is operating. The second differential pumping chamber 19 houses an ion thermalizer 17.

[0055] The ion thermalizer 17 is composed of multipole electrodes and the like, and attenuates the kinetic energy of the ions 4 while focusing them. The multipole electrodes are formed of round rods made of metal, ceramic, or the like. High-frequency voltages with opposite polarities are applied between adjacent electrode rods. A neutral gas such as helium or nitrogen is also introduced. The ions 4 pass through the space surrounded by the electrode rods and collide with neutral gas molecules, and are then focused by the electric field. Because the kinetic energy of the ions 4 is reduced by collisions with neutral gas molecules, noise due to spectral interference is reduced, and sensitivity to low-mass components is improved.

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

[0057] The analysis chamber 28 is evacuated by the turbomolecular pump 22. The exhaust side of the turbomolecular pump 22 is evacuated by the dry pump 18. When the turbomolecular pump 22 is operating, the analysis chamber 28 is evacuated to a vacuum. －３ The analysis chamber 28 is maintained at a vacuum level of about 100 Pa. The analysis chamber 28 houses the mass filter 24, the conversion dynode 30, the scintillator 31, and the photomultiplier tube 32.

[0058] The mass filter 24 is composed of a first mass filter 25, a collision cell 26, and a second mass filter 27. The first mass filter 25 and the second mass filter 27 are composed of multipole electrodes, and are controlled by a radio frequency voltage or a direct current voltage. The collision cell 26 is composed of a cell containing the multipole electrodes, and is introduced with a neutral gas such as helium or nitrogen.

[0059] The first mass filter 25 controls the voltage to allow only precursor ions with a specific mass-to-charge ratio (m / Z) to pass through. The collision cell 26 causes the precursor ions to collide with neutral gas molecules. The precursor ions are cleaved at weak chemical bonds by collision-induced dissociation, resulting in specific product ions. The second mass filter 27 controls the voltage to allow only product ions with a specific mass-to-charge ratio (m / Z) to pass through.

[0060] The multiple mass filter 24 separates only specific product ions dissociated from precursor ions. Because it can eliminate the influence of ions with similar masses that are not the target of detection, highly sensitive quantitative analysis of the target product ions becomes possible. The product ions separated by the mass filter 24 are incident on 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 opposite to that of the ions to be detected is applied to it. The secondary electron multiplier electrode generates secondary electrons when ions collide with it. The conversion dynode 30 allows secondary electrons to be generated from product ions with high efficiency.

[0062] The scintillator 31 converts electrons into light. The electrons generated by the conversion dynode 30 are converted into light by inverse photoelectron spectroscopy using the scintillator 31. The scintillator 31 converts the detection signal of the product ions from secondary electrons into light. By performing light conversion, the influence of ions and the like that are not the detection target and are present 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 multiple electron multiplier electrodes. The analog signal of the amplified electrons is converted into a digital signal by the analog / digital converter 33.

[0064] The detection results of the ions detected by the ion detector are 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 ion detection results with known data obtained in advance, qualitative and quantitative analysis of the components contained in the sample solution 1 becomes possible.

[0065] 1 , in the analysis device 100 according to this embodiment, the iontophoretic electrode 6 is provided with a plug hole 40 that connects to the middle of the first pore 7. One end of the plug hole 40 opens to the middle of the first pore 7. The other end of the plug hole 40 opens to the top of the iontophoretic electrode 6. A sealing plug 41 that can seal the first pore 7 is inserted into the plug hole 40.

[0066] The other end of the stopper hole 40 is connected to a bypass pipe 43 via a vacuum joint 42 above the iontophoretic electrode 6. The other end of the bypass pipe 43 is connected to the analysis chamber 28 via a vacuum joint 42. The bypass pipe 43 may be a resin pipe or a metal pipe that is pressure-resistant and flexible enough to be used in a vacuum. A vacuum valve 44 is provided in the middle 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. A pressure difference is formed between the first narrow hole 7 and the analysis chamber 28 through the bypass pipe 43. The first narrow hole 7 has an intermediate pressure between the ion source vessel 9, which is at atmospheric pressure, and the first differential evacuation chamber 16, regardless of whether the vacuum pumps 18 and 22 are energized. The analysis chamber 28 is maintained at the highest degree of vacuum among the vacuum chambers 16, 19, and 28.

[0068] When a power outage occurs and the vacuum pumps 18, 22 are de-energized, the sealing plug 41 falls from the inside of the plug hole 40 into the first narrow hole 7 due to its own weight, thereby closing the first narrow hole 7. On the other hand, when the vacuum pumps 18, 22 are energized, the sealing plug 41 floats from the first narrow hole 7 into the inside of the plug hole 40 due to the pressure difference created through the bypass pipe 43, thereby opening the first narrow hole 7.

[0069] In the event of a power outage, when the power supply to the vacuum pumps 18, 22 is stopped, the vacuum pumps 18, 22 stop being driven by electricity. However, even after the power supply to the vacuum pumps 18, 22 is stopped, the rotors of the vacuum pumps 18, 22 continue to rotate for a while due to inertia. The ion source vessel 9 is in an atmospheric pressure atmosphere, while the first differential evacuation chamber 16 is in a vacuum atmosphere. Therefore, there is a risk that gas will flow from the ion source vessel 9 toward the first differential evacuation chamber 16 until the rotors of the vacuum pumps 18, 22 stop.

[0070] When gas flows from the ion source vessel 9 toward the first differential pumping chamber 16, the pressure gradually increases in the first differential pumping chamber 16, the second differential pumping chamber 19, and the analysis chamber 28, in that order. When the pressure in the first differential pumping chamber 16, the second differential pumping chamber 19, and the analysis chamber 28 increases, the pressure on the intake side of the vacuum pumps 18 and 22 increases. Excessive pressure is applied to the rotors of the vacuum pumps 18 and 22, which may damage the vacuum pumps 18 and 22.

[0071] In particular, the turbomolecular pump 22 has a limited operating pressure range and is used in conjunction with the dry pump 18 for roughing. The exhaust side of the turbomolecular pump 22 is exhausted by the dry pump 18. However, in the event of a power outage, exhaust by the dry pump 18 also stops, which tends to increase the load on the rotor of the turbomolecular pump 22.

[0072] If the speed at which the suction side of the vacuum pump 18, 22 is pressurized or the pressure difference between the suction side and the exhaust side of the vacuum pump 18, 22 exceeds a certain threshold, the rotor blades will be severely damaged. This may shorten the service life of the vacuum pump 18, 22 or damage or break the rotor blades of the vacuum pump 18, 22. This may require replacement of the vacuum pump 18, 22, resulting in significant costs. The damage and cost problems are more pronounced in the turbomolecular pump 22 than in the dry pump 18.

[0073] In contrast to this, if the sealing plug 41 is provided, the first aperture 7 can be sealed without power when the power supply to the vacuum pumps 18, 22 is stopped, thereby significantly reducing the inflow of gas from the ion source vessel 9 toward the first differential evacuation chamber 16. When power supply to the vacuum pumps 18, 22 is stopped, the amount of gas that flows into the vacuum pumps 18, 22 can be reduced with a simple structure. Even when the power supply to the vacuum pumps 18, 22 is stopped, the load on the rotor blades can be reduced, thereby reducing damage to the vacuum pumps 18, 22 and extending their service life.

[0074] 2A and 2B are diagrams illustrating the operation of a pressure-type sealing plug in an analytical device. Fig. 2A shows a state when the vacuum pumps 18 and 22 are energized and power is supplied to the analytical device 100. Fig. 2B shows a state when the vacuum pumps 18 and 22 are energized and power supply to the analytical device 100 is stopped and a power outage occurs to the vacuum pumps 18 and 22. As shown in Figs. 2A and 2B, the pressure-type sealing plug 41 can be configured to operate by switching the pressure difference formed through the bypass piping 43 using a vacuum valve 44.

[0075] The plug hole 40 is preferably provided in an L-shaped bent structure. In Figures 2A and 2B, the plug hole 40 has a section 40a extending upward from the middle of the first narrow hole 7, a section 40b extending horizontally at about an intermediate height, and a section 40c extending upward from about an intermediate height. Sections 40a and 40b are connected at the L-shaped bent portion. Sections 40b and 40c are connected at the inverted L-shaped bent portion.

[0076] The diameter of section 40a extending upward from the middle of first narrow hole 7 is set to be equal to the outer diameter of sealing plug 41. The diameter of section 40b extending horizontally at about an intermediate height is set to be smaller than the diameter of section 40a extending upward from the middle of first narrow hole 7 and the outer diameter of sealing plug 41. The diameter of section 40c extending upward from about an intermediate height is set to be such that gas flow is not impeded.

[0077] The sealing plug 41 is inserted in a section 40a extending upward from the middle of the first micropore 7. With this structure, the sealing plug 41 can be moved up and down by the pressure difference and its own weight in the section 40a extending upward from the middle of the first micropore 7. In the structure and arrangement of the existing iontophoretic electrode 6, the plug hole 40 can be opened to the middle of the first micropore 7 while ensuring the connection of the bypass piping 43 to the plug hole 40.

[0078] In the event of a power outage, the vacuum valve 44 has the function of switching the flow path of the bypass piping 43 by stopping the supply of electricity. 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 element 45 is provided movably and has a plurality of ports and flow paths that connect the ports to one another. The coil housing 46 houses a 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 is magnetic and movable by electromagnetic force. The tip of the movable magnetic member 48 supports the valve element 45. The base end of the movable magnetic member 48 is inserted into the inside of the solenoid coil 47 so that it can move back and forth freely. The spring 49 elastically connects the valve element 45 to the coil housing 46. The spring 49 biases the valve element 45 toward the coil housing 46 so that the valve element 45 is in a communication position that connects the bypass pipe 43.

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

[0082] One inlet port is switchable between open and closed with respect to the section of the bypass piping 43 on the analysis chamber 28 side. The other inlet port is switchable between open and closed with respect to the space in the atmospheric pressure environment. One outlet port communicates with one inlet port within the valve body 45, and is switchable between open and closed with respect to the section of the bypass piping 43 on the stopper hole 40 side. The other outlet port is communicated with the other inlet port within the valve body 45, and is switchable between open and closed with respect to the section of the bypass piping 43 on the stopper hole 40 side.

[0083] 2A , when power is supplied to the analytical device 100, the solenoid coil 47 is energized. When energized, the solenoid coil 47 generates an electromagnetic force, which attracts and pulls up the movable magnetic member 48. The valve element 45 supported by the movable magnetic member 48 resists the bias of the spring 49 and is maintained in a communication position that allows communication with the bypass pipe 43.

[0084] In the communication position, the plug hole 40 and the analysis chamber 28 communicate with each other through the bypass pipe 43. In the event of a power outage, the first narrow hole 7 is at an intermediate pressure between the ion source vessel 9 and the first differential pumping chamber 16. On the other hand, the analysis chamber 28 is maintained at a higher degree of vacuum than the first differential pumping chamber 16. Therefore, in the plug hole 40, the area below the sealing plug 41 is at a low vacuum level close to atmospheric pressure, and the area above the sealing plug 41 is at a high vacuum level.

[0085] When switched to the communicating position, a large pressure difference is applied to both sides of the sealing plug 41. As a result, the sealing plug 41 rises against its own weight due to the pressure difference, is held inside the plug hole 40, and opens the first pore 7. The sealing plug 41 hits the inner wall of the bent portion of the plug hole 40 and is stopped.

[0086] 2B , when power supply to the analytical device 100 is stopped, the solenoid coil 47 is de-energized. The solenoid coil 47 does not generate electromagnetic force and does not pull up the movable magnetic member 48. The valve element 45 supported by the movable magnetic member 48 is biased by the spring 49 and maintained in the open position that opens the bypass pipe 43 to the atmospheric pressure environment.

[0087] In the open position, the plug hole 40 and the analysis chamber 28 do not communicate with each other through the bypass piping 43, and the plug hole 40 is open to the space under atmospheric pressure. In the event of a power outage, the first narrow hole 7 has an intermediate pressure between that of the ion source vessel 9 and the first differential pumping chamber 16. Meanwhile, air 50 flows into the plug hole 40 from the space under atmospheric pressure. Therefore, in the plug hole 40, the area below the sealing plug 41 becomes a low vacuum close to atmospheric pressure, and the area 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 to both sides of the sealing plug 41. Therefore, the sealing plug 41 falls under its own weight and closes the first narrow hole 7. When power supply to the analytical device 100 is then resumed, the solenoid coil 47 is energized, thereby reopening the first narrow hole 7. The vacuum pumps 18 and 22 can be restarted, and the analytical device 100 can resume analysis.

[0089] With this type of pressure-type sealing plug 41, when power supply to the analytical device 100 is stopped and power supply to the vacuum pumps 18 and 22 is stopped, power supply to the solenoid coil 47 is also stopped, so that the first aperture 7 can be closed without power. Closing the first aperture 7 prevents gas from flowing into the intake side of the vacuum pumps 18 and 22. Even if the first aperture 7 is not completely closed, inserting the sealing plug 41 into the first aperture 7 makes it possible to reduce the gas inflow rate below the allowable inflow rate when the turbomolecular pump 22 is decelerating. This reduces the load on the rotors of the vacuum pumps 18 and 22, protecting the vacuum pumps 18 and 22.

[0090] 1, 2A, and 2B, the sealing plug 41 is configured to operate due to the pressure difference between the ion source vessel 9 and the analysis chamber 28. The analysis chamber 28 is the space that is maintained at the highest 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 floated by the pressure difference.

[0091] However, as long as the pressure difference required for operation is ensured, the sealing plug 41 may be configured to operate due to the pressure difference between the ion source vessel 9 and the second differential pumping chamber 19, or may be configured to operate due to the pressure difference between the ion source vessel 9 and the first differential pumping chamber 16. The bypass piping 43 may be connected between the plug hole 40 and the second differential pumping chamber 19 or between the plug hole 40 and the first differential pumping chamber 16, instead of between the plug hole 40 and the analysis chamber 28.

[0092] 3 is a diagram illustrating a method for forming a plug hole in an analytical device. As shown in FIG. 3, the plug hole 40 can be formed by drilling a hole in the iontophoretic electrode 6. By combining linear through-holes, sections 40a, 40b, and 40c that are connected to each other at a curved portion can be formed.

[0093] In the iontophoretic electrode 6, a through-hole corresponding to section 40a extending upward from the middle of the first micropore 7, a through-hole corresponding to section 40b extending horizontally at about mid-height, and a through-hole corresponding to section 40c extending upward from about mid-height are formed by lathe machining or the like. A sealing plug 41 is inserted into section 40a extending upward from the middle of the first micropore 7. A blocking member 52 is press-fitted into each through-hole to form a plug hole 40.

[0094] The blocking member 52 may be made of any suitable material, such as carbon steel or stainless steel, as long as it has heat resistance to temperatures as high as about 200°C and strength sufficient to withstand press-fitting. The ion introduction electrode 6 may be made of stainless steel, for example. An O-ring 51 provides an airtight seal between the ion introduction electrode 6 and the first differential evacuation chamber 16.

[0095] The sealing plug 41 can be made of metal such as carbon steel or stainless steel, or ceramic such as silicon nitride. The sealing plug 41 can be provided in any suitable shape, such as a sphere, a cylinder, or a cone, as long as it can make the inflow rate of the gas through the first narrow hole 7 smaller than the allowable inflow rate when the vacuum pumps 18 and 22 are decelerating. However, the sealing plug 41 must be provided in consideration of its own weight, buoyancy due to the pressure difference generated through the bypass pipe 43, friction with the inner wall of the plug hole 40, etc.

[0096] For example, when the sealing plug 41 is a carbon steel sphere with a diameter φ of 2 mm, the gravity F1 acting on the sealing plug 41 is approximately 0.032 gf. When the degree of vacuum below the sealing plug 41 during a power outage is assumed to be half of atmospheric pressure, the buoyancy F2 acting on the sealing plug 41 is approximately 15.7 gf. When the coefficient of friction μ between the sealing plug 41 and the inner wall of the plug hole 40 is assumed to be 0.5, the friction force F3 acting on the sealing plug 41 is approximately 0.016 gf. It is known that the coefficient of friction μ increases even when dissimilar metals come into contact with each other at high vacuum levels.

[0097] Under these conditions, F1 + F3 (≈0.048 gf) <<F2 (≈15.7 gf). The sealing plug 41 can be configured so that, under an assumed coefficient of friction μ with the inner wall of the plug hole 40, it floats up due to the pressure difference between the first narrow hole 7 and the analysis chamber 28 in the event of a power outage, and falls under its own weight due to the pressure difference between the first narrow hole 7 and atmospheric pressure in the event of a power outage.

[0098] A minute gap may be formed between the sealing plug 41 and the inner wall of the plug hole 40. If a gap is formed, gas will flow out 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 amount of gas that flows out can be made negligible. If the gap is about 10 μm or less, the sealing plug 41 can be floated by a pressure difference when power is supplied to the analysis device 100.

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

[0100] The thermal expansion coefficient of carbon steel is approximately 12 x 10 －６ / K. The thermal expansion coefficient of stainless steel is approximately 17 x 10 －６ / K. When the iontophoretic electrode 6 is heated to 200°C, the diameter of the plug hole 40 becomes approximately 1.8 μm larger than the diameter of the carbon steel ball compared to when the electrode is at room temperature (20°C). The difference between the 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 approximately 12.3 μm (10.5 μm + 1.8 μm). The ratio of the average gap during thermal expansion to the diameter of the plug hole 40 is approximately 163:1, which allows the gap ratio to be sufficiently small.

[0101] The opening of the plug hole 40 on the first orifice 7 side is preferably provided in the middle of the first orifice 7 on the upstream side where the ion source vessel 9 is located. For example, it is preferably provided upstream of the ion introduction electrode 6, which is provided in a conical shape, as long as there are no processing problems or interference with the gas flow path, etc. The first orifice 7 is closer to atmospheric pressure on the upstream side where the ion source vessel 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 piping 43 becomes larger the closer the plug hole 40 opens upstream of the first orifice 7, making it easier to ensure the buoyancy of the sealing plug 41.

[0102] The sealing plug 41 and the iontophoretic electrode 6 can also be made of the same metal, such as stainless steel. When the diameter of the plug hole 40 expands due to thermal expansion, gas may leak through the gap between the plug hole 40 and the sealing plug 41. However, if the sealing plug 41 and the iontophoretic electrode 6 are made of the same material, the difference in thermal expansion is suppressed, preventing such gas leakage. However, when they are made of the same metal, the coefficient of friction μ increases, so lubrication is preferable.

[0103] If necessary, a liquid lubricant may be applied to the inner wall of the plug hole 40 that comes into contact with the sealing plug 41, or a film of a solid lubricant may be formed. Liquid lubricants with low vapor pressure are preferable. Examples of liquid lubricants that can be used include perfluoropolyethers such as Fomblin and fluorine-based lubricants such as polytetrafluoroethylene. Examples of solid lubricants that can be used include molybdenum disulfide, tungsten disulfide, boron nitride, boric acid, polytetrafluoroethylene, chromium, silver, and lead alloys. A film of a solid lubricant can be formed by sputtering, ion plating, plating, or the like.

[0104] The inner wall of the plug hole 40 that comes into contact with the sealing plug 41 may be subjected to a mirror finish to reduce the surface roughness, if necessary. For example, the inner wall of the plug hole 40 may be subjected to mechanical polishing, electrolytic polishing, chemical polishing, or the like. Reducing the surface roughness of the inner wall of the plug hole 40 reduces the coefficient of friction μ with the sealing plug 41, and also makes it difficult for dirt to adhere, thereby reducing carryover.

[0105] Figures 4, 5, and 6 are diagrams showing examples of the structure of a stopper hole in an analytical device. Figures 4, 5, and 6 correspond to cross-sectional views taken along line II in Figure 3. In Figures 4 and 5, reference numeral d1 denotes the diameter of the first pore 7, reference numeral d2 denotes the diameter of the sealing plug 41, and reference numeral d3 denotes the diameter of the stopper hole 40. In Figures 4, 5, and 6, the left figures show a state in which the sealing plug 41 has floated up, and the right figures show a state in which the sealing plug 41 has fallen down.

[0106] 4, the diameter d2 of the sealing plug 41 can be set larger than the diameter d1 of the first narrow hole 7. That is, the diameter d3 of the plug hole 40 can be set larger than the diameter d1 of the first narrow hole 7. Furthermore, the height of the lower end of the sealing plug 41 can be set higher than the height of the upper end of the first narrow hole 7 when the sealing plug 41 is in a floated state.

[0107] The plug hole 40 can form a stepped wall around the first pore 7 in the direction of travel of ions and the like passing through the first pore 7. The flow of ions and the like is likely to stagnate at the point where the plug hole 40 and the first pore 7 connect. In such a location, foreign matter 54 is likely to adhere to the inner wall of the plug hole 40. The foreign matter 54 may be ions 4 formed by ionizing the sample, or may be neutral particles other than ions.

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

[0109] 5, the diameter d2 of the sealing plug 41 is preferably set slightly larger than the diameter d1 of the first micropore 7. That is, the diameter d3 of the plug hole 40 is preferably set slightly larger than the diameter d1 of the first micropore 7. For example, the difference between the diameter d2 of the sealing plug 41 and the diameter d1 of the first micropore 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 that prevents the sealing plug 41 from entering the first micropore 7 at room temperature and during thermal expansion.

[0110] Furthermore, it is preferable that the height of the lower end of the sealing plug 41 be close to the height of the upper end of the first narrow hole 7 when the sealing plug 41 is in the floated state. For example, the difference in height between the lower end of the sealing plug 41 and the upper end of the first narrow hole 7 is preferably 5 mm or less, and more preferably 1 mm or less.

[0111] With this structure, it is possible to reduce the amount of foreign matter 54 adhering to the inner wall of the stopper hole 40, thereby ensuring high analytical accuracy. Even when the sealing plug 41 operates, a large amount of foreign matter 54 does not peel off from the inner wall of the stopper hole 40, so carryover can be suppressed not only when analysis is resumed after a power outage, but also when power is being supplied to the analysis device 100.

[0112] As shown in Fig. 6, the sealing plug 41 may be shaped so that, in the raised state, the lower surface of the sealing plug 41 is substantially flush with the upper surface of the first narrow hole 7. In Fig. 6, the sealing plug 41 is shaped like a cylinder with a concave cutout at the bottom. The cutout at the bottom of the sealing plug 41 is an arc with the same curvature as the first narrow hole 7 in cross section.

[0113] With this structure, when the sealing plug 41 is in a floating state, the amount of foreign matter 54 adhering to the inner wall of the plug hole 40 can be reduced. In the event of a power outage, the first narrow hole 7 cannot be completely blocked, but the inflow of gas can be suppressed to an extent that damage to the turbomolecular pump 22 can be prevented. In this 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 and the like to stagnate, it is preferable not to provide a counterbore.

[0114] 4, 5, and 6, the bottom of the plug hole 40 is rectangular, but the bottom of the plug hole 40 can also be made to coincide with the bottom surface of the first micropore 7. When analysis is resumed after a power outage, the sealing plug 41 can also be configured to land on the bottom surface of the first micropore 7, as long as buoyancy acting on the dropped sealing plug 41 can be ensured.

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

[0116] 7A and 7B , the iontophoretic electrode 6 is provided with a straight plug hole 40 that connects to the first micropore 7. One end of the plug hole 40 opens to the middle of the first micropore 7. The other end of the plug hole 40 opens to the top of the iontophoretic electrode 6. A sealing plug 41 supported by an electromagnetic actuator 55 is inserted into the straight plug hole 40.

[0117] In the event of a power outage, the electromagnetic actuator 55 has the function of closing the first narrow hole 7 with the sealing plug 41 by stopping the supply of current to the electromagnetic actuator 55. The electromagnetic actuator 55 includes a coil housing 56, a solenoid coil 57, a movable magnetic member 58, a spring 59, a shaft sealing 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 formed in any suitable shape, such as a sphere, a cylinder, or a cone. The coil housing 56 houses a 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 is magnetic and movable by 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 58 is inserted into the inside of the solenoid coil 57 so that it can move back and forth. The spring 59 elastically connects the coil housing 56 and the movable magnetic member 58. The spring 59 biases the movable magnetic member 58 toward the first narrow hole 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 at the opening at the top of the plug hole 40. The shaft seal member 60 seals the plug hole 40, into which the movable magnetic member 58 is inserted, in a state in which the movable magnetic member 58 can move back and forth freely. The O-ring 61 is housed in the shaft seal member 60. The O-ring 61 airtightly seals the sliding portion with the movable magnetic member 58. The shaft seal member 60 and the O-ring 61 prevent gas from leaking through the plug hole 40.

[0121] In the event of a power outage, when the vacuum pumps 18, 22 are de-energized, the sealing plug 41 supported by the electromagnetic actuator 55 closes the first narrow hole 7. On the other hand, when the vacuum pumps 18, 22 are energized, the sealing plug 41 supported by the electromagnetic actuator 55 is pulled up from the first narrow hole 7 into the plug hole 40 by the electromagnetic force of the electromagnetic actuator 55, thereby opening the first narrow hole 7.

[0122] 7A , when power is supplied to the analytical device 100, current is passed through the solenoid coil 57. When current is passed through the solenoid coil 57, an electromagnetic force is generated, which attracts and pulls up the movable magnetic member 58. The sealing plug 41 supported by the movable magnetic member 58 is pulled up from the first fine hole 7 and held inside the plug hole 40, opening the first fine hole 7.

[0123] 7B , when power supply to the analyzer 100 is stopped, the power supply to 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 micropore 7 from the plug hole 40 in accordance with the repulsive force of the spring 59 acting on the movable magnetic member 58, and closes the first micropore 7.

[0124] The electromagnetic actuator 55 is preferably heat-resistant when the iontophoretic electrode 6 is heated to a high temperature. The heat-resistant O-ring 61 can be made of perfluoropolyether rubber such as Viton or a fluorine-based elastomer such as polyvinylidene fluoride copolymer rubber. The movable magnetic member 58, the portion adjacent to the coil housing 56, and the joint between the movable magnetic member 58 and the spring 59 are preferably configured to have high thermal resistance. For example, a heat-resistant material with high thermal conductivity, such as ceramics or heat-resistant resin, can be provided in the middle of the movable magnetic member 58, between the movable magnetic member 58 and the coil housing 56, or between the movable magnetic member 58 and the spring 59.

[0125] With this type of electromagnetic sealing plug 41, when power supply to the analytical device 100 is stopped and power supply to the vacuum pumps 18, 22 is stopped, power supply to the solenoid coil 57 is also stopped, so that the first narrow hole 7 can be closed without power. Because the first narrow hole 7 is closed, it is possible to prevent gas from flowing into the intake sides of the vacuum pumps 18, 22. Compared to the pressure-type sealing plug 41, the electromagnetic sealing plug 41 has restrictions on the arrangement and structure of the electromagnetic actuator 55, but it offers greater freedom in designing the sealing plug 41 and the plug hole 40.

[0126] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the present invention. For example, the present invention is not necessarily limited to those having all of the configurations of the above-described embodiments. It is possible to replace part of the configuration of an embodiment with another configuration, add part of the configuration of an embodiment to another form, or omit part of the configuration of an embodiment.

[0127] For example, the analytical device 100 is a mass spectrometer. However, the analytical device having a sealing plug capable of sealing a fine hole through which charged particles are introduced from a charged particle generation source into a vacuum chamber may be applied to other analytical devices as long as it includes a charged particle generation source that generates charged particles, a vacuum chamber whose interior is evacuated, a fine hole through which charged particles are introduced from the charged particle generation source into the vacuum chamber, and a vacuum pump connected to the vacuum chamber. Examples of other analytical devices include a scanning electron microscope (SEM), a transmission electron microscope (TEM), and a focused ion beam (FIB) device.

[0128] 100 Analytical apparatus 2 Ion source (charged particle generation source) 6 Ion introduction electrode 7 First aperture 7 (aperture) 9 Ion source container 11 Ion guide 15 First aperture electrode 16 First differential pumping chamber (vacuum chamber) 17 Ion thermalizer 18 Dry pump (vacuum pump) 19 Second differential pumping chamber (vacuum chamber) 20 Second aperture electrode 22 Turbomolecular 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 piping 44 Vacuum valve 45 Valve body 46 Coil housing 47 Solenoid coil 48 Movable magnetic member 49 Spring 50 Atmosphere 51 O-ring 52 Closure member 55 Electromagnetic actuator 56 Coil housing 57 Solenoid coil 58 Movable magnetic member 59 Spring 60 Shaft seal member 61 O-ring

Claims

1. An analytical apparatus including a charged particle generation source that generates charged particles, a vacuum chamber whose inside is evacuated, a fine hole that introduces the charged particles from the charged particle generation source into the vacuum chamber, and a vacuum pump connected to the vacuum chamber, a sealing plug capable of sealing the pore; The sealing plug operates due to the pressure difference between the fine hole and the vacuum chamber when the vacuum pump is energized, and seals the fine hole when the vacuum pump is deenergized.

2. (delete)

3. The analysis device according to claim 1 , a plug hole connected to an intermediate portion of the pore; a bypass pipe connecting the plug hole and the vacuum chamber, The sealing plug is held in the plug hole of the analytical device.

4. The analysis device according to claim 3, a valve for switching between a connection between the plug hole and the vacuum chamber and a connection between the plug hole and a space under atmospheric pressure; The valve opens the connection between the plug hole and the space of the atmospheric pressure environment when the power supply to the vacuum pump is stopped, and opens the connection between the plug hole and the vacuum chamber when the power supply to the vacuum pump is turned on.

5. The analysis device according to claim 4, The vacuum chamber is composed of a plurality of chambers that are differentially evacuated, The bypass piping is connected to the plug hole and to a room having the highest vacuum among the vacuum chambers.

6. (delete)

7. (delete)

8. The analysis device according to claim 1 , The analytical instrument, wherein the vacuum pump is a turbomolecular pump.