JP2008095504A - Analysis apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an analysis apparatus being improved such that a harmful effect caused by electrical discharge and so on occurred in a chamber of the analysis apparatus can be prevented by efficiently exhausting hydrogen gas from the chamber. <P>SOLUTION: An evacuation system of the analysis apparatus 10 includes a roughing vacuum pump 50, and a turbo molecular pump 30 including a low vacuum side stage 32 and a high vacuum side stage 31. A main body 20 connected to the roughing vacuum pump 50 includes a first chamber 24 substantially decompressed by the roughing vacuum pump 50, a second chamber 25 which is subsequently combined with the low vacuum side stage 32 of the turbo molecular pump 30 and into which the hydrogen gas is introduced, and a third chamber 26 which is subsequently combined with the high vacuum side stage 31. Additional gas which has large molecular weight and does not substantially include light gas such as hydrogen gas is introduced into an intermediate position of the low vacuum side stage 32, thereby partial pressure of hydrogen at a position of an exhaust side end 37 of the low vacuum side stage 32 at a time of exhaust equilibrium is reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an analysis apparatus, and more particularly to an analysis apparatus having a configuration in which a plurality of chambers are depressurized so as to have different degrees of vacuum by a single roughing pump and a turbo molecular pump.

  Conventionally, various analyzers have been commercialized. As an example, an inductively coupled plasma mass spectrometer is known in the industry as a highly sensitive apparatus for detecting a trace amount of metal ions. The apparatus is configured to generate a plasma including the sample to be analyzed, then form an ion beam from the plasma via an interface, and separate predetermined ions in the ion beam by a mass-to-charge ratio.

  As one of the improved techniques related to this analyzer, it is known to introduce a reaction gas having a relatively low molecular weight into the chamber of the analyzer (Non-Patent Document 1). This is to solve the problem that the signal of the polyatomic molecular ion containing the carrier gas element introduced into the apparatus together with the non-analyzed sample interferes with the measurement signal of the predetermined element. Is introduced at an intermediate position to neutralize such ions and prevent signal interference.

  Specifically, such a reactive gas may be a hydrogen gas that includes or does not include helium gas or the like. As an example, such a gas may be introduced into a cell containing a multipole electrode located downstream of an interface consisting of a sampling cone and a skimmer cone. In this case, the chamber containing the sampling cone and skimmer cone is roughed mainly by a roughing pump. On the other hand, the chamber in which the cell is located and the subsequent chamber are decompressed further using a turbo molecular pump.

  The mass analyzing means placed in the chamber subsequent to the chamber in which the cell is located is for separating ions, and the chamber is required to be in a high vacuum. An evacuation system for such an analytical apparatus is designed using, for example, a composite turbo molecular pump having a two-stage (or more multi-stage) configuration, or the chamber is substantially constituted by two separate turbo molecular pumps. According to the design to reduce the pressure separately. In the former case, the chamber including the mass analyzing means requiring high vacuum is decompressed using all stages, while the front chamber including the cell is a part located on the exhaust side or the low vacuum side. It is possible to reduce the pressure using only this stage.

  By the way, it is known that the exhaust performance of a turbo molecular pump is lowered in the case of a gas having a low molecular weight. In the case of hydrogen gas, this phenomenon is particularly remarkable. This is due to the evacuation principle of the turbo molecular pump, and it is difficult to induce molecules having a small mass and a high movement speed in a predetermined direction.

  Usually, the compression ratio of the gas is displayed to show the performance of the turbomolecular pump with respect to gas exhaust. The compression ratio of the gas indicates the ratio of the pressure of the gas on the inlet side and the outlet side when the turbo molecular pump is operated, and it can be said that the higher the compression ratio, the higher the exhaust performance. In particular, the compression ratio for hydrogen gas is also an important index for showing the exhaust performance of hydrogen, but for the above reasons, it does not become a high value as compared with other gases.

From this point of view, various devices have been conventionally devised for exhausting hydrogen gas with a turbo molecular pump. In one example, the flow path near the turbo molecular pump is cooled to reduce the movement speed of gas molecules (Patent Document 1), and in another example, a hydrogen storage alloy is disposed inside the vacuum system (Patent Document). 2, Patent Document 3). As another example, there is a method of reducing the partial pressure of hydrogen gas at the intake port of the turbo molecular pump by introducing a gas having a high molecular weight to the intake side of the auxiliary pump (Patent Document 4).
JP-A-5-280465 JP-A-5-280466 JP-A-7-310657 JP-A-7-27089 “Beneficial Ion / Molecule Reactions in Elemental Mass Spectrometry”, Gregory C. Eiden, Charles J. Barinaga and David W. Koppenaal, Rapid Communications in Mass Spectrometry, Vol. 11, 37-42 (1997)

  By the way, in the inductively coupled plasma mass spectrometer, when hydrogen gas is introduced to prevent signal interference caused by carrier gas ions as described above, if the introduction amount is large, the hydrogen gas is converted into a turbo molecular pump. It is conceivable that the exhaust cannot be sufficiently performed. In such a case, the hydrogen gas remaining in the apparatus without causing a reaction causes a discharge by the multi-type electrode in the mass spectrometer, and this discharge has an adverse effect such as a background noise in the mass analysis result. It is also possible.

  In particular, in an inductively coupled plasma mass spectrometer, when analyzing a high matrix sample, such a phenomenon is likely to occur when the occlusion of the orifice of the skimmer cone at the interface portion proceeds to some extent. That is, the pressure at the exhaust side end of the turbo molecular pump becomes a fixed value determined by the performance of the roughing pump, so that when the plasma constituent gas such as argon gas is not supplied due to the clogging of the orifice, the exhaust of the turbo molecular pump The partial pressure of hydrogen gas also increases at the side edges. If so, if the turbo molecular pump is used under exhaust conditions with a margin for exhausting hydrogen gas, it will be exceptional, otherwise it will cause a phenomenon that the exhaust performance of hydrogen gas will deteriorate rapidly, and analysis by the mass spectrometer There is a disadvantage that the analysis cannot be continued due to excessive background noise in the result.

  Therefore, a means for efficiently exhausting hydrogen gas is required in such an analyzer. However, the methods described in Patent Documents 1 to 3 described above cannot exhaust hydrogen gas sufficiently efficiently to the extent that such discharge can be reliably prevented. In the method described in Patent Document 4, the partial pressure of hydrogen gas at the lowest position of the turbo pump cannot be lowered sufficiently, and therefore the partial pressure of hydrogen on the intake port side can be lowered sufficiently. Can not.

  Accordingly, an object of the present invention is to provide an improved analyzer that can efficiently exhaust hydrogen gas from the chamber and prevent adverse effects such as discharge in the analyzer chamber. . In particular, as described above, the present invention includes a vacuum exhaust system that prevents the exhaust performance of hydrogen gas from abruptly decreasing even when the supply of plasma constituent gas is not sufficiently performed. It is an object of the present invention to provide an analyzer. In addition, the object of the present invention is to efficiently perform the operation of the evacuation system in such an improvement so that the analysis result is not adversely affected.

  The present invention relates to a low vacuum chamber in which substantial evacuation is performed by a roughing pump, a high vacuum chamber connected to the low vacuum chamber and decompressed in combination with a turbo molecular pump located upstream of the roughing pump, In the analyzer that introduces hydrogen gas into a part of the high vacuum chamber, the hydrogen gas is not substantially contained in the intermediate position closer to the exhaust side end inside the turbo molecular pump, and the molecular weight than hydrogen gas. The large additional gas is directly introduced to reduce the partial pressure of the hydrogen gas at the exhaust side end of the turbo molecular pump, thereby reducing the partial pressure of the hydrogen gas in the high vacuum chamber and increasing the pressure from within the low vacuum chamber. An analyzer characterized by suppressing an increase in the partial pressure of hydrogen gas in a high vacuum chamber when the flow of gas other than hydrogen gas into the vacuum chamber is reduced. It is intended to provide. The roughing pump can be, for example, an oil rotary pump.

  In this case, the additional gas may be a gas having an atmospheric component, or may be argon gas, nitrogen gas, or helium gas. In other cases, a gas obtained by mixing at least two of these gases may be used. The additional gas may include a gas flow rate of 20% to 90%, preferably 40% to 80%, in a flow rate ratio, with respect to the displacement at the position of the exhaust side end of the turbo molecular pump.

  The intermediate position where the additional gas is introduced can be a position close to the exhaust side end in the low vacuum side stage. A dedicated port may be provided as an additional gas introduction port, or an existing vent port may be used. In other cases, the degree of the effect is slightly reduced, but the same gas as the above gas may be introduced not at the intermediate position of the low vacuum side stage but at the exhaust side end. In this case, an existing purge port can be used in addition to the dedicated port.

  In other cases, instead of introducing an additional gas from an external gas source, a pipe for roughing decompression extending from the first chamber is connected to an intermediate position of the turbo molecular pump to add a gas guided from the first chamber. It can also be used as a gas.

  In addition, the high vacuum chamber may include a gas introduction chamber into which hydrogen gas is introduced immediately after the low vacuum chamber, and an analysis chamber provided with analysis means further downstream of the gas introduction chamber.

  In this case, as an example, the turbo molecular pump has a single-type composite configuration including a low vacuum side stage on the side coupled to the roughing pump and a high vacuum side stage overlapping the low vacuum side stage. The gas introduction chamber may be coupled to the inlet portion of the low vacuum side stage downstream of the high vacuum side stage of the turbo molecular pump, and the analysis chamber may be coupled to the high vacuum side stage of the turbo molecular pump.

  As another example, the turbo molecular pump includes first and second turbo molecular pumps coupled to each of the gas introduction chamber and the analysis chamber and coupled to a common roughing pump, the first and second turbo pumps. Additional gas may be introduced into both molecular pumps.

  Further, in another example, the turbo molecular pump includes first and second turbo molecular pumps coupled to the gas introduction chamber and the analysis chamber, respectively, and the exhaust side of the second turbo molecular pump is connected to the first turbo molecular pump. The intermediate position coupled to the intermediate position of the molecular pump for introducing additional gas may be a position further downstream than the intermediate position closer to the exhaust side end of the second turbo molecular pump.

  Further, in the analyzer of the present invention, even when hydrogen gas is not introduced into the chamber of the analyzer, additional gas can be continuously introduced from the inlet into the turbo molecular pump. That is, an equilibrium state of the vacuum exhaust system is realized by the additional gas continuously introduced during the analysis.

  According to the analyzer of the present invention, it is possible to further greatly reduce the partial pressure of the hydrogen gas on the intake side as compared with the prior art, thereby reducing the possibility of inconvenience such as discharge in the chamber. be able to. In addition, even when the inflow of gas other than hydrogen gas from the low vacuum chamber into the high vacuum chamber is inadvertently reduced, an increase in the partial pressure of hydrogen gas can be suppressed, and the partial pressure of hydrogen gas can be reduced. It can be prevented that the analysis operation cannot be continued due to a sudden rise.

  In particular, according to the analyzer of the present invention, it is possible to introduce additional gas into the turbo molecular pump even when hydrogen gas is not introduced into the chamber. A plurality of analyzes with different gas introduction conditions can be performed stably and continuously, with the effect of on / off being minimized. Further, the heat generated in the turbo molecular pump can be effectively released through the additional gas, and the service life of the turbo molecular pump can be extended.

  With reference to the accompanying drawings, an analyzer according to a preferred embodiment of the present invention will be described in detail below. In this embodiment, for the sake of illustration, an example of an inductively coupled plasma mass spectrometer is shown as an analyzer, but the present invention can also be applied to other analyzers having a similar basic configuration.

  FIG. 1 shows an inductively coupled plasma mass spectrometer according to a first embodiment of the present invention, and is a schematic configuration diagram mainly showing a portion that performs an action of mass spectrometry. An inductively coupled plasma mass spectrometer 10 shown in FIG. 1 includes a main body 20 including mass analyzing means, and a plasma torch 11 for generating inductively coupled plasma P at a high vacuum side stage thereof. Although not shown, a coil connected to a high frequency power source is disposed in the vicinity of the plasma torch 11, and plasma P is generated in the plasma torch 11 by the operation of the coil.

  The main body 20 has an interface structure including a sampling cone 12 and a skimmer cone 13 at the front end thereof. Part of the plasma P generated by the plasma torch 11 is extracted in the form of an ion beam through the interface structure.

  Three chambers that can communicate with each other are provided in the main body 20. The first chamber 24 includes the interface structure described above, and includes a space sandwiched between the sampling cone 12 and the skimmer cone 13. A part of the plasma P enters the chamber 24 through the orifice 12 a of the sampling cone 12. Part of the plasma passes through the orifice 13a of the skimmer cone 13 and is further guided to the subsequent stage in the form of an ion beam. Although not shown, an ion optical component for guiding the ion beam can be disposed behind the skimmer cone 13.

  In the state where the plasma P is ignited, the outside of the sampling cone 12 has a pressure of about atmospheric pressure, and therefore the inside of the chamber 24 has a relatively high pressure. The chamber 24 is configured to be decompressed by the roughing pump 50 via the port 21 and the exhaust pipe 53. The valve 51 located in the middle of the exhaust pipe 53 is operated when the apparatus is started and stopped, and is kept open during the analysis operation. In this state, the chamber 24 has a pressure of about 300 to 1000 Pa. As the roughing pump 50, for example, an oil rotary pump can be used.

  A second chamber 25 that is separated from the first chamber 24 by the gate valve 14 is provided at the subsequent stage of the first chamber 24. A cell 15 is placed in the second chamber 25. The cell 15 is reluctant to cause interference with the mass spectrum from the ion beam taken out through the orifice 13a of the skimmer cone 13 and containing the elements of the carrier gas or the plasma gas and auxiliary gas provided to the plasma torch. In order to remove a polyatomic molecular ion, a reaction such as a charge transfer reaction is caused with a reagent gas (or reaction gas) molecule. In the figure, a reagent gas inlet 18 is shown. Although not shown, the cell 15 can include a multipole electrode or the like.

  A third chamber 26 that is separated from the second chamber by a partition wall 19 is provided at a further stage of the second chamber 25. In the third chamber 26, separation means for extracting ions having a predetermined mass-to-charge ratio is provided. In this embodiment, the means is a multipole electrode 16 such as a quadrupole. In the chamber 26, a detector 17 for detecting the extracted ions is disposed behind the multipole electrode 16. As illustrated, the detector 17 outputs a detection signal toward signal processing means provided outside the main body 20.

  As illustrated, both the second chamber 25 and the third chamber 26 are depressurized by the turbo molecular pump 30. The second chamber 25 is connected to the turbo molecular pump 30 through the exhaust port 22, and the third chamber 26 is connected through the exhaust port 23. As illustrated, the turbo molecular pump 30 includes a high vacuum side stage 31 and a low vacuum side stage 32 that are continuous in the axial direction (or length direction), and further includes a high vacuum side stage and a low vacuum side stage 31, 32. A number of rotor blades 36 placed therethrough. In the illustrated example, the rotor blade 36 is rotatable in a horizontal plane. In another example, some turbo molecular pumps have a configuration in which the axial direction thereof is directed horizontally, and in such a pump device, the rotor blades rotate in a vertical plane.

  The second chamber 25 of the main body 20 is connected to an intermediate position between the high vacuum side stage 31 and the low vacuum side stage 32 via a passage chamber 33 formed integrally with the high vacuum side stage 31 and the low vacuum side stage 32. The That is, the third chamber 26 is depressurized by the action of both the rotary blade group 36a located in the high vacuum side stage 31 and the rotary blade group 36b located in the low vacuum side stage 32, whereas the second chamber 25 is decompressed only by the rotary blade group 36 b located in the low vacuum side stage 32.

When no gas is introduced by the operation of the evacuation system, the second chamber has a pressure of about 3.0 × 10 ^{−2 to} 1.0 × 10 ⁻¹ Pa, and the third chamber 26 has 1 having a pressure of about .5 × ^{10 -4} to 5.0 × ^{10 -4.} When the gas is introduced, the second chamber has a pressure of about 0.7 × 10 ^{−1 to} 1.3 × 10 ⁻¹ Pa, and the third chamber 26 has a pressure of 3.0 × 10 ⁻³ Pa to It has a pressure of about 2.0 × 10 ⁻² Pa.

  As shown in the figure, the exhaust side port 34 of the turbo molecular pump 30 extends toward the roughing pump 50 via the exhaust pipe 54 and is coupled to the exhaust pipe 53. The valve 52 provided in the middle of the exhaust pipe 54 is operated when the apparatus is started and stopped, and is kept open during the analysis operation.

  A characteristic point in the present embodiment is that the turbo molecular pump 30 is configured to be directly supplied with a predetermined flow rate of additional gas. As shown in the figure, the turbo molecular pump 30 has an additional gas introduction port 35 at a position overlapping the low vacuum side stage 32. The additional gas inlet 35 is coupled to the valve 41 via a resistor 42. The valve 41 is coupled to the gas source 40. Since the inside of the turbo molecular pump 30 is in a decompressed state, when the valve 41 is opened, a constant flow of gas is introduced from the additional gas inlet 35 into the low vacuum side stage 32 of the turbo molecular pump 30. . In other cases, the valve 41 may be a needle valve to control a very small flow rate.

  As the additional gas, hydrogen gas or other atmospheric component gas that does not contain molecules having a small molecular weight, argon gas, nitrogen gas, helium gas, or the like may be used. Two or more kinds of these can also be used. The additional gas is continuously introduced after the plasma is ignited while the analysis is performed.

  As described in relation to the prior art, a reactive gas is introduced into the cell 15 as needed during analysis. As the reaction gas, for example, a gas containing hydrogen is used. A molecule of a gas having a low molecular weight such as hydrogen gas diffuses outside the cell 15 in the second chamber 25 and can also diffuse into the third chamber 26. The second chamber 25 and the third chamber 26 are depressurized via the turbo molecular pump 30, but as described above, the performance of the turbo molecular pump 30 is limited when exhausting a gas having a small molecular weight. The

  In this case, if a gas such as hydrogen having a small molecular weight diffused in the second and third chambers 25 and 26 is left undisturbed, the sensitivity of the analysis is adversely affected by the discharge around the multipole electrode 16 in the third chamber 26 in particular. There is also a risk. Conversely, if the exhaust speed is simply increased so as not to cause such a phenomenon, a large burden is generated on the turbo molecular pump 30.

  Therefore, when an additional gas not containing hydrogen gas is introduced as in the present embodiment, the pressure of the gas that can exist at the exhaust side end 37 of the turbo molecular pump 30, that is, the total number of gas molecules is determined by the equilibrium state. Therefore, the residual ratio of the hydrogen gas located at the exhaust side end 37 is relatively reduced. Then, since the hydrogen compression ratio for the turbo molecular pump 30 is determined, the existence ratio of hydrogen gas molecules existing in the second chamber 25 and the third chamber 26 on the intake side is also reduced.

  FIG. 2 is a table showing measured pressure in an experimental example using the apparatus of the first preferred embodiment, (a) is a table showing the pressure of the second chamber, and (b) is a table showing the third chamber. It is a table | surface which shows no pressure. Air is used as the additional gas. As can be understood from these tables, the pressure in any chamber does not change even if additional gas is introduced when hydrogen gas is not introduced, but when hydrogen gas is introduced. By introducing additional gas into the chamber, the pressure in the chamber is reduced by 20% or more or 30% or more.

  In the present embodiment, since the supply of additional gas is continuously performed throughout the analysis time after the operation of the turbo molecular pump 30 is started, the rotor blades of the turbo molecular pump 30 can be used even when hydrogen gas is not introduced. The heat generated in 36 can be released. Further, the additional gas is always supplied during the analysis time, so that a stable equilibrium state is realized in the vacuum system, and highly accurate analysis is possible.

  FIG. 3 is a schematic configuration diagram similar to FIG. 1 showing an inductively coupled plasma mass spectrometer according to a second embodiment of the present invention. Elements having the same functions as those shown in FIG. 1 are indicated by adding 100 to the reference numerals, and description thereof is omitted below.

  The main body 120 of the inductively coupled plasma mass spectrometer 110 in the present embodiment has the same configuration as the apparatus of FIG. The difference from the apparatus 10 according to the first embodiment is the configuration of the evacuation system located below the main body 120. That is, in the apparatus 10 shown in FIG. 1, the exhaust pipe 53 extending from the first chamber 24 of the main body 20 is directly connected to the roughing pump 50, whereas in the apparatus 110 shown in FIG. Is coupled to a port 135 that communicates with a low vacuum side stage 132 located downstream of the turbomolecular pump 110.

  That is, in this embodiment, the gas exhausted from the first chamber 124 is used instead of the additional gas introduced in the embodiment of FIG. The main component of the gas provided from the first chamber 124 is argon, which is the main component of the plasma P. Argon gas is a monoatomic molecule, but has a larger mass number than hydrogen. Further, since the first chamber 124 has a higher pressure than the second chamber 125, hydrogen gas does not diffuse from the second chamber into the first chamber. Hydrogen gas is not substantially contained.

  Therefore, by using such a gas as an additional gas, as in the first embodiment, the partial pressure of hydrogen gas can be reduced on the exhaust side of the turbo-molecular pump 130, and accordingly, the second and third on the intake side. The partial pressure of hydrogen gas in the chambers 125 and 126 can also be reduced.

  FIG. 4 is a diagram showing an analysis apparatus according to another preferred embodiment of the present invention. An example of an apparatus provided with separate turbo molecular pumps to depressurize two chambers on the high vacuum side is shown in FIG. It is shown in two different aspects of (b). In these drawings, although the valves and the like shown in FIGS. 1 and 3 exist, the description is omitted.

  In the apparatus 210 shown in (a), the second chamber 225 into which hydrogen gas is introduced and the third chamber 226 including the mass analyzing means are decompressed by separate turbo molecular pumps 230A and 230B, respectively. The turbo molecular pumps 230A, 230B are coupled in parallel to a roughing chamber that depressurizes the relatively low vacuum first chamber 224.

  In this example, an additional gas, that is, a gas that does not include the hydrogen gas described above and has a molecular weight larger than that of the hydrogen gas, is introduced into the intermediate positions A1 and A2 that are closer to the exhaust side ends of the turbo molecular pumps 230A and 230B. The

  Also in the apparatus 310 shown in (b), the second chamber 325 into which hydrogen gas is introduced and the third chamber 326 including the mass analyzing means are decompressed by separate turbo molecular pumps 330A and 330B, respectively. The difference from the apparatus 210 is that the exhaust port of the turbo molecular pump 330B is coupled to an intermediate position of the turbo molecular pump 330A, thereby creating a partial series connection relationship. The roughing pump 350 includes a turbo molecular pump 330A. Only is directly coupled.

  In this example, the additional gas can be introduced downstream from the intermediate position closer to the exhaust side end of the upstream turbo molecular pump 330B, that is, downstream from B1. In the drawing, in addition to FIG. 1, the introduction positions are illustrated as B2 and B3 exemplarily. B2 indicates an intermediate position of the exhaust pipe 335 that couples the turbo molecular pump 330B and the turbo molecular pump 330A, and B3 indicates an intermediate position on the downstream side of the turbo molecular pump 330A where the exhaust pipe 335 is coupled. ing. Additional gas can be introduced from one or more of these locations.

  As described above, the analyzer according to the preferred embodiment of the present invention has been described in detail, but various modifications and changes can be further made by those skilled in the art. For example, as described above, the present invention can be applied to other analysis apparatuses such as a gas chromatograph apparatus into which hydrogen gas is introduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an inductively coupled plasma mass spectrometer as a first preferred embodiment according to the present invention, and in particular, a schematic configuration diagram mainly showing a portion that performs mass analysis. In the experiment example by the apparatus of 1st preferred embodiment, it is a table | surface which shows the measured pressure, (a) is a table | surface which shows the pressure of a 2nd chamber, (b) shows the pressure of a 3rd chamber. It is a table. It is a schematic block diagram similar to FIG. 1 which shows the inductively coupled plasma mass spectrometer which becomes the 2nd preferred embodiment by this invention. FIG. 6 is a diagram showing an example in which separate turbo molecular pumps are provided to depressurize two chambers on the high vacuum side as another preferred embodiment of the present invention, and two different modes (a) and (b) are shown. FIG.

Explanation of symbols

10; 110; 210; 310 Analyzer 15; 115 Cell 24; 124; 224; 324 First chamber (low vacuum chamber)
25; 125; 225; 325 Second chamber (high vacuum chamber)
26; 126; 226; 326 Third chamber (high vacuum chamber)
30; 130; 230A, 230B; 330A, 330B Turbo molecular pump 31; 131 High vacuum side stage of turbo molecular pump 32; 132 Low vacuum side stage of turbo molecular pump 40 Gas source 50; 150; 250; 350 Roughing pump

Claims (12)

A low vacuum chamber in which substantial evacuation is performed by the roughing pump, and a high vacuum chamber connected to the low vacuum chamber and decompressed in combination with a turbo molecular pump located upstream of the roughing pump. In an analyzer for introducing hydrogen gas into a part of the high vacuum chamber,
Inside the turbo molecular pump, an additional gas substantially free of hydrogen gas and having a molecular weight larger than hydrogen gas is directly introduced at an intermediate position closer to the exhaust side end, and at the exhaust side end of the turbo molecular pump. By reducing the hydrogen gas partial pressure, the hydrogen gas partial pressure in the high vacuum chamber is reduced, and the amount of gas other than hydrogen gas flowing from the low vacuum chamber into the high vacuum chamber is reduced. An analysis apparatus characterized in that an increase in the partial pressure of hydrogen gas in the high vacuum chamber at the time is suppressed.   The analyzer according to claim 1, wherein the additional gas is any one of a gas having an atmospheric component, nitrogen gas, argon gas, helium gas, or a gas obtained by mixing at least two of these. .   The additional gas is added in an amount that provides a flow rate ratio of 20% to 90% with respect to the total displacement at the exhaust side end of the turbo molecular pump. The analyzer according to claim 1.   The additional gas is added in an amount that makes the additional gas have a flow rate ratio of 40% to 80% with respect to the total displacement at the position of the exhaust side end of the turbo molecular pump. The analyzer according to claim 3.   2. The analyzer according to claim 1, wherein the introduction of the additional gas is turned on / off in accordance with the operation of the roughing pump and the turbo molecular pump, and is continuously provided at the time of analysis.   The rough vacuum decompression pipe extending from the low vacuum chamber is connected to the low vacuum side stage of the turbo molecular pump, and a gas guided from the low vacuum chamber is used as the additional gas. 2. The analyzer according to 1.   The high vacuum chamber includes a gas introduction chamber that is located immediately after the low vacuum chamber and into which hydrogen gas is introduced, and an analysis chamber that is provided with analysis means at a further stage of the gas introduction chamber. The analyzer according to claim 1.   The turbo molecular pump has a composite configuration including a single low vacuum side stage coupled to the roughing pump and a high vacuum side stage overlapping the low vacuum side stage, and A gas introduction chamber is coupled to the inlet portion of the low vacuum side stage downstream of the high vacuum side stage of the turbo molecular pump, and the analysis chamber is coupled to the high vacuum side stage of the turbo molecular pump. The analyzer according to claim 7, characterized in that:   The turbo molecular pump includes first and second turbo molecular pumps coupled to the gas introduction chamber and the analysis chamber, respectively, and coupled to the common roughing pump. The analysis apparatus according to claim 7, wherein the additional gas is introduced into both turbomolecular pumps.   The turbo molecular pump includes first and second turbo molecular pumps coupled to the gas introduction chamber and the analysis chamber, respectively, and an exhaust side of the second turbo molecular pump is connected to the first turbo molecular pump. The intermediate position for introducing the additional gas is further downstream than the intermediate position closer to the exhaust side end of the second turbomolecular pump. The analyzer according to claim 7.   The analyzer according to claim 1, wherein the roughing pump is an oil rotary pump. The analyzer according to claim 1, wherein the introduction position of the additional gas is changed to the position of the exhaust side end instead of the intermediate position.

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