JP2007103300A - Ion guide, and ion guide assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ion guide which has a high ion transport efficiency by the ion guide while preventing reduction of the degree of vacuum in a chamber at the maintenance time or the like of an ion generation source. <P>SOLUTION: In the ion guide 12 which is equipped with a plurality of sets of opposing electrode rods 15 to 18 mutually arranged in parallel, and which guides the ions by applying a voltage between these electrode rods so that these ions incident into the ion guide will be extended in parallel with the electrode rods and advance in the ion transport axial line direction near on the ion transport axial line 14 positioned at the center of the electrode rod of each set, each electrode rod is formed from a plurality of hollow rods, and these hollow rods are telescopically coupled so that the ion guide is expandable and contractable. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ion guide and an ion guide assembly.

  In mass spectrometers that perform mass analysis of clusters, etc., ions are generated by an ion generation source in the atmospheric pressure region, and mass analysis is performed by introducing the generated ions into a mass spectrometer or the like in a high vacuum region. Yes. That is, the generation of ions in the ion generation source must be performed in the atmospheric pressure region, and various analyzes such as mass spectrometry must be performed in the high vacuum region. For this reason, it is necessary to transport the ions generated by the ion generation source from the atmospheric pressure region to the high vacuum region.

  In order to transport ions from the atmospheric pressure region to the high vacuum region, for example, an ion guide is used. The ion guide is composed of a plurality of sets of opposing electrode rods arranged in parallel to each other. A DC power supply voltage and a high-frequency power supply voltage are applied in a superimposed manner between the electrode rods arranged in this manner, whereby ions incident from the ion generation source fly between these electrode rods while vibrating in a complicated manner. In particular, depending on the mass-to-charge ratio, ions fly near the axis located at the center of each set of electrode rods (hereinafter referred to as the “ion transport axis”) with stable vibration, and thus a mass-to-charge ratio within a predetermined range. Ions are guided along the ion transport axis.

  An ion guide is provided for each of the plurality of chambers. Differential evacuation is performed between these chambers so that the degree of vacuum in the chambers increases stepwise in the ion flight direction. Therefore, ions incident on the ion guide from the ion generation source are introduced into the chamber having a higher degree of vacuum as they fly along the ion transport axis, and as a result, ions generated in the atmospheric pressure region are introduced into the high vacuum region. Will be introduced.

  As described above, Patent Document 1 discloses an ion guide used for transporting ions from an atmospheric pressure region to a high vacuum region. In this ion guide, the ion transport axis is bent by bending the electrode rod, and the bent portion of each electrode rod is bent at the cut portion. Accordingly, an ion guide having an ion transport axis bent and in which a gap between electrode rods is maintained with high accuracy is provided.

JP 2000-268770 A JP-A-8-222182 JP-A-6-60847

  By the way, when changing the target substance for mass spectrometry or performing maintenance of the ion source, etc., the ion source is removed from the chamber containing the ion guide, or the adjacent chamber is separated. There is a need to. At this time, in order to prevent a decrease in the degree of vacuum in the chamber that has already been evacuated to a high degree of vacuum, it is necessary to close the opening of the chamber leading to the ion generation source or the like or the opening between adjacent chambers, For this purpose, it is necessary to provide a gate valve or the like in the vicinity of the opening.

  Thus, when a gate valve is provided in the vicinity of the opening, it is necessary to dispose the ion guide so that the gate of the gate valve and the ion guide do not contact or interfere when the gate valve is closed. However, since the gate of the gate valve is generally relatively thick, when the ion guide is arranged in this way, the distance between the end of the ion guide and the opening of the chamber becomes relatively long, and thus the ion generation source. The gap between the ion guides or the ion guides in adjacent chambers is relatively long. In such a gap, ions are not guided in the direction of the ion transport axis by the ion guide, so some ions are separated from the ion transport axis while passing through the gap. The transport efficiency will be reduced.

  Accordingly, an object of the present invention is to provide an ion guide having high ion transport efficiency by an ion guide while preventing a decrease in the degree of vacuum in a chamber that accommodates the ion guide during maintenance of the ion generation source. .

In order to solve the above-mentioned problem, in the first invention, an ion guide having a plurality of sets of opposing electrode rods arranged in parallel to each other, the ions incident on the ion guide are In an ion guide that guides these ions by applying a voltage between the electrode rods so as to travel in the direction of the ion transport axis in the vicinity of the ion transport axis that extends in parallel and is located at the center of each pair of electrode rods, The electrode rod is formed of a plurality of hollow rods, and these hollow rods are connected in a nested manner so that the ion guide can be expanded and contracted.
According to the first invention, when the gate valve is opened, the ion guide is extended so that the ion guide enters the opening of the gate valve, and when the gate valve is closed, the ion guide is contracted so that the ion guide is It is possible to prevent contact with the gate.

  In the second invention, in the ion guide assembly using the ion guide of the first invention, each electrode rod is formed by nesting a plurality of stages of hollow rods, It is held by at least one rod holder that maintains the relative positional relationship between these hollow rods.

  According to a third aspect of the present invention, in the ion guide assembly using the ion guide of the first aspect, each electrode rod is formed by nesting three or more hollow rods, and the outermost of each electrode rod. The hollow rods of each step are held by at least one rod holder that maintains the relative positional relationship between these hollow rods, and the innermost hollow rods of each electrode rod maintain the relative positional relationship between these hollow rods. Held by at least one rod holder.

  According to a fourth invention, in the second or third invention, one of the rod holders holding the hollow rods of different stages is moved relative to the other rod holder, and the ion guide is moved. A holder relative movement device for expanding and contracting is further provided.

  According to a fifth invention, in any one of the second to fourth inventions, there is provided a chamber having an opening for accommodating the ion guide and through which ions guided by the ion guide pass, and an opening of the chamber. A gate valve for opening and closing, and when the gate valve is opened, the ion guide extends across the opening of the gate valve, and when the gate valve is closed, the ion guide is gated. It is shrunk out of the valve opening.

  According to the present invention, by closing the gate valve, it is possible to prevent a reduction in the degree of vacuum in the chamber during maintenance of the ion generation source. In addition, when the gate valve is opened, the ion guide is extended so that the ion guide enters the opening of the gate valve, so that the gap between the ion source and the ion guide or the gap between the ion guides in the adjacent chambers. Is relatively short. Accordingly, it is possible to provide an ion guide with high ion transport efficiency by the ion guide while preventing a decrease in the degree of vacuum in the chamber during maintenance of the ion generation source.

  Hereinafter, an ion guide and an ion guide assembly of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a mass spectrometer 1 using an ion guide of the present invention. The mass spectrometer 1 includes an ion generator 2 that ionizes a sample, an ion transport device 3 that transports ions generated by the ion generator 2, and mass spectrometry that performs mass analysis of ions transported by the ion transport device 3. 4 in total. The ion generator 2 may use a sputtering method in which positively charged ions are generated from sample molecules by irradiating the sample with a high-energy ion beam, or a secondary ion of a reagent gas A chemical ionization method that generates positively charged ions by reacting sample molecules may be used. Regardless of which method is used, ionization of the sample in the ion generating apparatus 2 is performed in an atmosphere having a low atmospheric pressure or a low degree of vacuum. The mass spectrometer 4 is a double-focusing mass spectrometer using, for example, a magnetic field analyzer and an electrostatic field analyzer, and needs to be maintained at a high degree of vacuum for accurate mass analysis.

The ion transport device 3 includes three chambers 5, 6, and 7 between the ion generator 2 and the mass spectrometer 4, and these chambers are connected to the low-vacuum chamber 5 from the ion generator 2 toward the mass spectrometer 4. The medium vacuum chamber 6 and the high vacuum chamber 7 are arranged in series in this order. The low vacuum chamber 5 is evacuated to a low degree of vacuum (hereinafter referred to as “low vacuum”) by a turbo molecular pump (TMP) 8, for example, about 10 ⁻³ Torr. The medium vacuum chamber 6 is evacuated by TMP 9 to a medium degree of vacuum (hereinafter referred to as “medium vacuum”), for example, about 10 ⁻⁵ Torr. High vacuum chamber 7 is a high degree of vacuum by TMP10 (hereinafter, referred to as "high vacuum") to be evacuated, for example, about 10 ^-7 Torr. Therefore, the vacuum degree of these vacuum chambers increases in the order of the low vacuum chamber 5, the medium vacuum chamber 6, and the high vacuum chamber 7.

  In each of the vacuum chambers 5, 6, 7, ion guides 11, 12, 13 are provided. The ion guides 11, 12, and 13 have an axis line (hereinafter referred to as “ion transport axis”) 14 extending in the longitudinal direction of the ion guides 11, 12, and 13 from the ion emission opening 2 a of the ion generator 2. 4 are arranged so as to be coaxial with the straight line connecting the four ion incident apertures 4a, that is, so as to be aligned substantially in a straight line between the ion generator 2 and the mass spectrometer 4. Since these ion guides 11, 12 and 13 have the same form, the ion guide 12 in the medium vacuum chamber 6 will be described below.

  2 is a perspective view of the ion guide 12 of the present invention, and FIG. 3 is a cross-sectional side view of the ion guide 12 as viewed in the longitudinal direction from the cross-sectional line III-III in FIG. As shown in FIGS. 2 and 3, in this embodiment, the ion guide 12 includes two sets of opposing electrode rods 15, 16, 17, 18 arranged in parallel to the ion transport axis 14 and in parallel to each other. It has. The first set of electrode rods is composed of two electrode rods 15 and 16, and the second set of electrode rods is also composed of two electrode rods 17 and 18.

  The two electrode rods of each set are arranged so that the ion transport axis 14 is located at the center thereof. That is, the ion transport axis 14 is positioned at the center of the first pair of two electrode rods 15 and 16, and thus the two electrode rods 15 and 16 constituting the first set are symmetrical with respect to the ion transport axis 14. Be placed. Similarly, the ion transport axis 14 is located at the center of the second electrode rods 17 and 18 in the second set, so that the two electrode rods 17 and 18 constituting the second set are symmetrical with respect to the ion transport axis 14. Be placed. In this embodiment, the distance from each electrode rod 15, 16 constituting the first set to the ion transport axis 14 is equal to the distance from each electrode rod 17, 18 constituting the second set to the ion transport axis 14. Each of the electrode rods 15, 16, 17, 18 is formed so that its cross section is substantially a perfect circle.

  The electrode rods 15, 16, 17, 18 of the ion guide 12 are held by at least two rod holders 20 so that the relative positional relationship between these electrode rods is maintained. The rod holder 20 is made of an insulating material, for example, ceramics, and has a substantially quadrangular prism shape with an opening 21 having a substantially square cross section as shown in FIGS. Each electrode rod 15, 16, 17, 18 is fixed inside the square opening 21 and in the vicinity of each corner by an insulating bolt (not shown) or the like.

A positive DC power supply voltage V _dc and a high frequency power supply voltage V _ac are superimposed and applied to the first set of electrode rods 15 and 16. A negative DC voltage power source V _dc and a high frequency power source voltage V _ac are superimposed and applied to the second set of electrode rods 17 and 18. That is, when the angular frequency of the high frequency is ω and the time is t, a voltage of (V _dc + V _ac cos ωt) is applied to the first set of electrode rods 15 and 16, and the second set of electrode rods 17 and 18 is applied. A voltage of − (V _dc + V _ac cos ωt) is applied.

Thus, by applying a voltage to each pair of electrode rods 15, 16, 17, and 18, an electric field is formed in the space between these electrode rods. Accordingly, ions that have entered the ion guide 12 along the ion transport axis 14 are subjected to a force in a direction perpendicular to the ion transport axis 14 by the electric field formed between the electrode rods while traveling along the ion transport axis 14. . If the DC power supply voltage V _dc , the high frequency power supply voltage V _ac , the angular frequency ω, etc. are appropriately set, ions having a mass-to-charge ratio (m / e) in a specific range do not leave the vicinity of the ion transport axis 14. Force can be applied to ions. That is, according to the ion guide 12, ions having a mass-to-charge ratio in a specific range are guided along the ion transport axis 14 in accordance with the settings of the DC power supply voltage V _dc , the high-frequency power supply voltage V _ac , the angular frequency ω, and the like. be able to.

  In the above description, the ion guide 12 in the medium vacuum chamber 6 has been described as an example, but the ion guide 11 in the low vacuum chamber 5 and the ion guide 13 in the high vacuum chamber 7 are similarly configured and voltage application is similarly performed. Etc. are performed. Therefore, the ion guides 11 and 13 in the low vacuum chamber 5 and the high vacuum chamber 7 also guide ions having a mass-to-charge ratio in a specific range along the ion transport axis 14 in the same manner as the ion guide 12 in the medium vacuum chamber 6. be able to.

  On the wall between the low vacuum chamber 5 and the medium vacuum chamber 6 and the wall between the medium vacuum chamber 6 and the high vacuum chamber 7, ion passage openings 22 and 23 are provided. The ion passage openings 22, 23, the ion emission opening 2a, and the ion incident opening 4a are openings having a small diameter, and are aligned with the ion transport axis 14, that is, provided on the ion transport axis 14. Accordingly, a straight line connecting the ion emission opening 2a of the ion generator 2 to the ion incident opening 4a of the mass spectrometer 4 extends without being blocked by the walls that define the chambers 5, 6, and 7.

  In the ion transport device 3 of the mass spectrometer 1 configured as described above, ions incident on the low vacuum chamber 5 from the ion emission opening 2 a of the ion generation device 2 are moved along the ion transport axis 14 by the ion guide 11. The inside of the low vacuum chamber 5 is transported and is incident on the medium vacuum chamber 6 through the ion passage opening 22 between the low vacuum chamber 5 and the medium vacuum chamber 6. The ions incident on the medium vacuum chamber 6 are transported in the medium vacuum chamber 6 along the ion transport axis 14 by the ion guide 12, and are used for passing ions between the medium vacuum chamber 6 and the high vacuum chamber 7. The light enters the high vacuum chamber 7 through the opening 23. The ions incident on the high vacuum chamber 7 are transported in the high vacuum chamber 7 along the ion transport axis 14 by the ion guide 13 and are incident on the mass spectrometer 4 through the ion incident aperture 4a. According to the ion transport device 3 of the present embodiment, ions are transported from the ion generator 2 operating at atmospheric pressure (that is, operating in the low vacuum region) to the mass spectrometer 4 operating in the high vacuum region.

  By the way, the low vacuum chamber and the like of the ion generation device and the ion transport device generally require regular maintenance such as replacement of a sample to be mass analyzed. When performing such maintenance, it is necessary to return the pressure in the low vacuum chamber of the ion generation device and the ion transport device to atmospheric pressure. In this case, a gate valve or the like for opening and closing the ion passage opening between the low vacuum chamber and the medium vacuum chamber or the ion passage opening between the medium vacuum chamber and the high vacuum chamber is provided near the ion passage opening. Otherwise, when the low vacuum chamber is returned to atmospheric pressure, the medium vacuum chamber and the high vacuum chamber will also return to atmospheric pressure.

  Here, since the low vacuum chamber is not evacuated until a high degree of vacuum is reached, even if the low vacuum chamber reaches atmospheric pressure, it can be evacuated to a target degree of vacuum in a relatively short time. . However, since the high vacuum chamber is evacuated until the degree of vacuum is very high, when the high vacuum chamber reaches atmospheric pressure, it takes a considerably long time (for example, several days) to evacuate to the target degree of vacuum. Necessary. Therefore, the medium vacuum chamber and the high vacuum chamber should not be returned to atmospheric pressure when performing the regular maintenance as described above.

  On the other hand, for example, if a gate valve or the like for opening and closing the ion passage opening between the low vacuum chamber and the medium vacuum chamber is provided in the vicinity of the ion passage opening, the ion transport efficiency by the ion guide decreases. . The reason for this will be described with reference to FIG. 4 taking as an example the case where the gate valve is arranged on the middle vacuum chamber side of the ion passage opening. In FIG. 4, the same reference numerals are assigned to the same components as those of the present invention.

When the gate valve 30 (see FIG. 4B) for opening and closing the ion passage opening 22 is not provided, as shown in FIG. 4A, the ion guides 11 in the adjacent chambers 5 and 6 are provided. , the distance L ₁ between the end of the 12 is substantially equal to or slightly greater extent and the thickness W of the wall disposed between the chambers 5,6. On the other hand, if provided, such as gate valve 30 for opening and closing the ion passage aperture 22, as shown in FIG. 4 (b), the distance L ₂ of these chambers between the ends of the ion guide 11, 12 5 , 6 is considerably longer than the thickness W of the wall disposed between the two. This is because the end of the ion guide 12 prevents the gate valve 30 and the electrode rods 15 to 18 of the ion guide 12 from contacting and interfering when the gate valve 30 is closed (broken line in FIG. 4B). This is because a space having a thickness corresponding to the gate 31 of the gate valve 30 must be provided between the chamber and the wall disposed between the chambers 5 and 6. That is, the ion guide 12 must be arranged so that the electrode rods 15 to 18 of the ion guide 12 do not cross the opening of the gate valve 30.

Thus, the longer the distance L ₂ between the ends of the ion guide 11, ion which has been transported by the ion guide 11 of the lower vacuum chamber 5, the gap between the ion guide 11 and the ion guide 12 The ion guides 11 and 12 do not receive force from the ion guides 11 and 12 when passing through the ion guide, so that some of these ions are separated from the ion transport axis 14, so that the ion transport efficiency by the ion guides 11 and 12 is lowered.

  On the other hand, according to the ion guide of the present invention, there is no need to evacuate the middle vacuum chamber and the high vacuum chamber from the atmospheric pressure every time the low vacuum chamber is regularly maintained, and the ion transport efficiency is lowered. Can be prevented. Hereinafter, the configuration of the ion guide of the present invention will be described using the ion guide 12 of the medium vacuum chamber 6 as an example.

  The electrode rods 15 to 18 constituting the ion guide 12 are each formed of a plurality of hollow rods as shown in FIG. For example, the electrode rod 15 includes a first-stage hollow rod 15a having a short outer diameter and a second-stage hollow rod 15b having a larger outer diameter than the first-stage hollow rod 15a. The outer diameter of the first-stage hollow rod 15a is substantially the same as the inner diameter of the second-stage hollow rod 15b, and the first-stage hollow rod 15a is accommodated coaxially in the second-stage hollow rod 15b. That is, the first-stage hollow rod 15a is disposed on the inner side, and the second-stage hollow rod 15b is disposed on the outer side. The first-stage hollow rod 15a is slidable in the axial direction within the second-stage hollow rod 15b. Therefore, the electrode rod 15 can be expanded and contracted by sliding the first-stage hollow rod 15a in a nested manner within the second-stage hollow rod 15b. All the electrode rods 15 to 18 are formed in this way, and therefore all the electrode rods 15 to 18 are formed to be extendable.

  FIG. 5 is a cross-sectional side view schematically showing the medium vacuum chamber 6 in which the ion guide 12 is accommodated. As shown in the figure, the hollow rod of each stage is held by at least one rod holder 20 for each stage. In the present embodiment, each of the electrode rods 15 to 18 is formed of a two-stage hollow rod, and thus is held by at least two rod holders 20a and 20b. That is, as shown in FIG. 5, the first-stage hollow rods 15 a to 18 a of all the electrode rods 15 to 18 are held by the first rod holder 20 a, and the second-stage hollow rods 15 b to 15- 18b is held by the second rod holder 20b.

  As described above, the electrode rods 15 to 18 are fixed to the rod holders 20a and 20b with insulating bolts or the like. That is, the first-stage hollow rods 15a to 18a are fixed to the first rod holder 20a, and the second-stage hollow rods 15b to 18b are fixed to the second rod holder 20b. Thereby, the first-stage hollow rods 15a to 18a and the second-stage hollow rods 15b to 18b cannot move relative to each other.

  On the other hand, the rod holders 20 can move relative to each other. In the present embodiment, as shown in FIG. 5, the first rod holder 20 a is connected to the wall defining the medium vacuum chamber 6 via the rack and pinion mechanism 26 with respect to the medium vacuum chamber 6, and the second rod The holder 20 b is fixed to a wall defining the medium vacuum chamber 6 via a fixing member 27. The rack 28 of the rack and pinion mechanism 26 is fixed to the first rod holder 20a, and the pinion 29a is rotated by a high vacuum rotation introducing machine 29b fixed to the wall defining the medium vacuum chamber 6. The high-vacuum rotation introducing device 29 b can introduce a rotational motion into the medium vacuum chamber 6 manually or automatically from the outside of the medium vacuum chamber 6. The rack and pinion mechanism 26 operates to move the first rod holder 20 a in the axial direction of the electrode rods 15 to 18, that is, in the direction of the ion transport axis 14. Therefore, by operating the rack and pinion mechanism 26, the first rod holder 20a and the second rod holder 20b are moved toward or away from each other.

  As described above, the first-stage hollow rods 15a to 18a are fixed to the first rod holder 20a, and the second-stage hollow rods 15b to 18b are fixed to the second rod holder 20b. When the two-rod holder 20b is moved so as to approach each other, the first-stage hollow rods 15a to 18a enter the second-stage hollow rods 15b to 18b, so that all the electrode rods 15 to 18 are contracted and ions. The guide 12 is in a contracted state. Conversely, when the first rod holder 20a and the second rod holder 20b are moved away from each other, the first-stage hollow rods 15a to 18a are pulled out from the second-stage hollow rods 15b to 18b. All the electrode rods 15-18 are extended and the ion guide 12 will be in the expansion | extension state.

  FIG. 6 is a diagram showing the relationship between expansion and contraction of the ion guide 12 and opening and closing of the gate valve 30. In the state shown in FIG. 6A, the gate valve 30 is open and the ion guide 12 is in the extended state. For this reason, the end portion of the ion guide 12 in the medium vacuum chamber 6 on the low vacuum chamber 5 side is close to the wall between the medium vacuum chamber 6 and the low vacuum chamber 5. The gap between the end of the ion guide 11 and the end of the ion guide 12 in the medium vacuum chamber 6 is very short. Therefore, the ions transported by the ion guide 11 in the low vacuum chamber 5 are transported into the ion guide 12 between the ion guide 11 and the ion guide 12 with little separation from the ion transport axis 14. Therefore, ions can be transported with high efficiency.

  However, at this time, the end of the ion guide 12 on the low vacuum chamber 5 side enters the opening 31 of the gate valve 30. Therefore, if the gate valve 30 is closed while the ion guide 12 is in the extended state, the ion guide 12 and the gate 32 of the gate valve 30 come into contact with each other, and the ion guide 12 and the gate valve 30 are damaged. End up.

  Therefore, as shown in FIG. 6B, when the gate valve 30 should be closed, the ion guide 12 is brought into a contracted state. That is, the ion guide 12 is pulled out from the opening 31 of the gate valve 30 by bringing the ion guide 12 into the contracted state. Thereby, even if the gate 32 of the gate valve 30 is closed, the gate 32 of the gate valve 30 and the ion guide 12 do not contact with each other, and the ion guide 12 and the gate valve 30 are not damaged.

  If the gate 32 of the gate valve 30 is closed, the degree of vacuum in the medium vacuum chamber 6 and the high vacuum chamber 7 is maintained even when the pressure in the low vacuum chamber 5 is returned to the atmospheric pressure due to periodic maintenance. It is maintained as it is. As a result, only the low-vacuum chamber needs to be evacuated after maintenance, so that mass analysis by the mass spectrometer 1 can be resumed relatively early after the maintenance is completed.

  Thus, by using the ion guide of the present invention, there is no need to evacuate the middle vacuum chamber or the high vacuum chamber from the atmospheric pressure every time the low vacuum chamber is regularly maintained, and the ion transport efficiency is lowered. Can be prevented.

  In addition, in the said embodiment, although each electrode rod 15-18 is formed from the two-stage hollow rod, it is not restricted to a two-stage hollow rod, From other multiple-stage hollow rods, such as three stages or four stages. It may be formed. In this case, the hollow rods of each stage are held by at least one rod holder that maintains the relative positional relationship between the hollow rods. That is, the rod holder is arranged so as to hold the hollow rod holder of each stage at least one for every stage. A holder for holding the outermost hollow rod of each electrode rod or a rod holder for holding the innermost hollow rod of each electrode rod is fixed to the wall defining the chamber, and the other holders are It can move relative to the rod holder fixed to the wall.

  Alternatively, when each electrode rod is formed of a three-stage or four-stage hollow rod, at least one rod holder that maintains the relative positional relationship between the hollow rods of the outermost stages of each electrode rod. And the innermost hollow rods of each electrode rod are held by at least one rod holder that maintains the relative positional relationship between the hollow rods, and the hollow rods of the other steps, that is, located in the middle The hollow rod may not be held by the rod holder. In this case, in the same manner as in the above embodiment, either the rod holder that holds the outermost hollow rods or the rod holder that holds the innermost hollow rods defines a wall that defines the chamber. And the other can be moved relative to the rod holder fixed to the wall.

  In the above embodiment, the ion guide 12 in the medium vacuum chamber 6 can be extended and contracted, but the ion guide 11 in the low vacuum chamber 5 or the ion guide 13 in the high vacuum chamber 7 instead of the ion guide 12. It is good also as a structure which can be expanded-contracted. Alternatively, the ion guides in all the vacuum chambers may be configured to be extendable / contractable.

  In the above embodiment, the first rod holder 20a can be moved using the rack and pinion mechanism 26. However, the first rod holder 20a can be moved using another mechanism. You may be able to do it. For example, a high-vacuum linear introduction machine capable of introducing linear motion into the medium vacuum chamber 6 manually or automatically from the outside of the medium vacuum chamber 6 is fixed to the wall defining the medium vacuum chamber 6 and the high vacuum. The first rod holder 20a may be connected to the linear introduction machine, and the first rod holder 20a may be moved directly in the direction of the ion transport axis 14 by this high vacuum linear introduction machine.

  Moreover, although the said embodiment showed the example which used the ion guide in order to transport ion in the mass spectrometer 1, the apparatus using the ion guide of this invention is not restricted to a mass spectrometer. Alternatively, the ion guide of the present invention may be used as a quadrupole of a quadrupole mass spectrometer.

  Furthermore, in the above embodiment, the ion guide is formed of four electrode rods, but the number of electrode rods forming the ion guide is not limited to four, and other numbers such as 6, 8, 10, and the like. An ion guide may be formed from the electrode rod. The electrode rod is not limited to a cylindrical rod, and may be an electrode having another shape such as a hollow hyperbolic electrode or a square bar electrode capable of forming an electric field.

It is a figure which shows the mass spectrometer using the ion guide of this invention. It is a perspective view of the ion guide of this invention. FIG. 3 is a cross-sectional side view of the ion guide as viewed in the longitudinal direction from a cross-sectional line III-III in FIG. 2. It is a figure for demonstrating the reason that the transport efficiency of the ion by an ion guide falls when a gate valve is provided in the opening vicinity of ion passage. It is the cross-sectional side view which showed schematically the inside vacuum chamber which accommodated the ion guide of this invention. It is a figure which shows the relationship between expansion / contraction of an ion guide and opening / closing of a gate valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mass spectrometer 2 Ion generator 3 Ion transport device 4 Mass spectrometer 5 Low vacuum chamber 6 Medium vacuum chamber 7 High vacuum chamber 8-10 Turbo molecular pump (TMP)
11-13 Ion guide 15-18 Electrode rod

Claims (5)

An ion guide comprising a plurality of sets of opposing electrode rods arranged in parallel to each other, wherein the ions incident on the ion guide extend parallel to the electrode rod and are located at the center of each set of electrode rods In an ion guide that guides these ions by applying a voltage between these electrode rods so as to travel in the direction of the ion transport axis in the vicinity of the ion transport axis,
Each electrode rod is formed from a plurality of hollow rods, and the hollow rods are connected in a nested manner so that the ion guides can be expanded and contracted.   The ion guide assembly using the ion guide according to claim 1, wherein each electrode rod is configured by nesting a plurality of stages of hollow rods, and the hollow rods of each stage are disposed between the hollow rods. An ion guide assembly held by at least one rod holder that maintains a relative positional relationship.   2. An ion guide assembly using the ion guide according to claim 1, wherein each electrode rod is formed by nesting three or more hollow rods, and the outermost hollow rod of each electrode rod. They are held by at least one rod holder that maintains the relative positional relationship between these hollow rods, and the innermost hollow rods of each electrode rod are at least one rod that maintains the relative positional relationship between these hollow rods. An ion guide assembly held by a holder.   The apparatus further comprises a holder relative movement device that moves one of the rod holders holding the hollow rods of different stages relative to the other rod holders to expand and contract the ion guide. 4. The ion guide assembly according to 3.   A chamber having an opening for accommodating the ion guide and through which ions guided by the ion guide pass; and a gate valve for opening and closing the opening of the chamber, and when the gate valve is opened 5. The ion guide according to claim 2, wherein the ion guide extends across the opening of the gate valve, and the ion guide is shrunk out of the opening of the gate valve when the gate valve is closed. An ion guide assembly according to claim 1.

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