Orthogonal acceleration time-of-flight mass spectrometer

Abstract

The orthogonal acceleration time-of-flight mass spectrometer (1) of the present invention comprises: a vacuum chamber (100) divided into a first vacuum chamber and a second vacuum chamber; an insulating isolation component (162) configured to span the two vacuum chambers; a front-stage annular electrode (1311) and a rear-stage annular electrode (1312-1314) respectively fixed to the first vacuum chamber side and the second vacuum chamber side of the insulating isolation component; a first fixing component for positioning the insulating isolation component relative to a specified position in the second vacuum chamber, including a first displacement component for displacing the central axes of the front-stage and rear-stage annular electrodes in a specified direction orthogonal to the central axis by thermal expansion; a second fixing component (170) for positioning the rear-stage annular electrode relative to the above-mentioned specified position, including a second displacement component for displacing the central axis in the specified direction by thermal expansion, wherein the difference in thermal expansion per unit temperature between the first displacement component and the second displacement component is less than 30% of the thermal expansion of the first displacement component.

Description

Technical Field

[0001] The present invention relates to an orthogonal acceleration time-of-flight mass analyzer. Background Art

[0002] In a time-of-flight mass spectrometer (TOF-MS), a certain kinetic energy is given to an ion group derived from a sample component so that it flies in a space of a fixed distance, and the mass-to-charge ratio of each ion contained in the ion group is obtained based on the flight time. At this time, if there is a deviation in the initial energy (initial flight velocity) of the ions, the flight time will deviate between ions with the same mass-to-charge ratio, and the mass resolution will be reduced. In order to solve this problem, an orthogonal acceleration time-of-flight mass spectrometer (orthogonal acceleration time-of-flight mass spectrometer) can be used (for example, patent documents 1-4). In an orthogonal acceleration time-of-flight mass spectrometer, an ion group is incident on an orthogonal acceleration section having a repeller electrode and an introduction electrode. By accelerating the ion group in a direction orthogonal to its incident direction, the influence of the deviation of the flight velocity in the incident direction can be eliminated, thereby improving the mass resolution.

[0003] The orthogonal acceleration time-of-flight mass spectrometer comprises an ionization chamber equipped with an ion source, an intermediate vacuum chamber equipped with a transport optical system for transporting ion groups generated in the ion source and a collision cell for fragmenting ions of a specified mass-to-charge ratio contained in the ion group, and an analysis chamber for flying the ion group introduced from the transport optical system. The intermediate vacuum chamber and the analysis chamber are arranged in a vacuum chamber. The ionization chamber, the intermediate vacuum chamber, and the analysis chamber have a differential exhaust type structure in which the vacuum degree increases in this order, and each chamber is divided by a partition wall component having an ion passage portion.

[0004] In an orthogonal acceleration time-of-flight mass spectrometer, in order to transport ions from an intermediate vacuum chamber to an analysis chamber, a transfer electrode is arranged at the boundary between the intermediate vacuum chamber and the analysis chamber (e.g., patent documents 1-4). The transfer electrode is an electrode that connects a plurality of annular electrodes in the direction of the central axis via an insulating isolation component. The annular electrode located at the frontmost stage side (ion source side) is arranged in the intermediate vacuum chamber, and the annular electrode located at the rear stage is arranged in the analysis chamber. The transfer electrode is positioned by fixing the insulating isolation component to the opening formed in the partition wall component that divides the intermediate vacuum chamber and the analysis chamber, and fixing the annular electrode located at the last stage relative to the wall surface of the vacuum chamber in the analysis chamber. When fixing the annular electrode located at the last stage, in order to insulate the annular electrode from the vacuum chamber, a fixing component at least part of which is made of an insulating material is used. The transfer electrode is precisely positioned so that the central axis (ion optical axis) of the plurality of annular electrodes passes through the center of the opposing surfaces of the repeller electrode and the introduction electrode of the orthogonal acceleration section and is parallel to the opposing surfaces.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: International Publication No. 2016 / 042632

[0008] Patent Document 2: International Publication No. 2019 / 220554

[0009] Patent Document 3: International Publication No. 2019 / 224948

[0010] Patent Document 4: International Publication No. 2019 / 229864

[0011] Patent Document 5: International Publication No. 2019 / 220497

[0012] Non-patent literature

[0013] Non-Patent Document 1: “Table of Machinable Ceramics Properties”, [Online], Ferrotec Material Technologies Co., Ltd., [retrieved on October 27, 2020], URL <URL:https: / / ft-mt.co.jp / assets / pdf / jp / machinable_ceramics / machinab le_ceramics_performance.pdf> Summary of the invention

[0014] Technical problem to be solved by the invention

[0015] In an orthogonal acceleration time-of-flight mass spectrometer, the flight path of ions is limited by a flight tube disposed in the analysis chamber. Since the flight tube expands or contracts with temperature changes, if the temperature during mass analysis is different, the length of the flight path is also different, and even for the same ions, the flight time will be different, resulting in poor mass accuracy. In order to prevent such degradation of mass accuracy, Patent Document 3 describes heating and temperature-adjusting the analysis chamber to a specified temperature between 35°C and 50°C.

[0016] The orthogonal acceleration time-of-flight mass spectrometer is assembled in the factory at room temperature (e.g., 25°C). Therefore, if the analysis chamber is heated and temperature-controlled to the above temperature, the various components that fix the transfer electrode will undergo thermal expansion. As described above, the transfer electrode is positioned and fixed relative to the vacuum chamber on the front-stage side and the rear-stage side, respectively. Usually, the material and size of the components used to fix the transfer electrode on the front-stage side are different from the material and size of the components used to fix it on the rear-stage side. In many cases, the vacuum chamber is made of aluminum, and the components that fix the transfer electrode use a combination of, for example, an aluminum conductive component and an insulating component made of PEEK (polyetheretherketone). The thermal expansion coefficient of PEEK resin is greater than that of aluminum. Therefore, when the device is assembled in the factory, even if the transfer electrode is positioned with high precision so that the ion optical axis passes through the center of the opposing surfaces of the repeller electrode and the introduction electrode of the orthogonal acceleration section and is parallel to the opposing surfaces, if the analysis chamber is heated during mass analysis, the thermal expansion of each component is different, and the ion optical axis is offset. If the ion optical axis is shifted, there is a problem that device performance such as mass resolution, ion detection sensitivity, and mass accuracy is reduced.

[0017] In order to solve the above problem, it is possible to make the temperature of the mass spectrometer consistent with the temperature during analysis. However, since the heating temperature during analysis varies depending on the environment or the state of the device when the analysis is performed, the target temperature when the mass spectrometer is temperature-controlled can be appropriately changed (for example, Patent Document 5). Therefore, the solution of making the temperature of the mass spectrometer consistent with that during analysis cannot be adopted.

[0018] Furthermore, for example, when an orthogonal acceleration time-of-flight mass spectrometer is transported from a factory to an overseas destination, it is transported by ship or air, but the temperature inside the container loaded therein may vary in a wide range of 5° C. to 50° C. Each component undergoes thermal expansion (or contraction) due to such temperature changes generated during the transport process, and the fixed positions between the components change irreversibly. In such a case, the ion optical axis is shifted as described above, and the device performance such as mass resolution, ion detection sensitivity, and mass accuracy is reduced.

[0019] The technical problem to be solved by the present invention is to provide an orthogonal acceleration time-of-flight mass spectrometer in which the ion optical axis is unlikely to shift even when the temperature during assembly of the device is different from that during use or when the target temperature of the flight tube is changed.

[0020] Solutions for solving the above technical problems

[0021] The orthogonal acceleration time-of-flight mass spectrometer of the present invention, which is completed in order to solve the above-mentioned technical problems, comprises:

[0022] The vacuum chamber has an internal space divided into a first vacuum chamber and a second vacuum chamber;

[0023] an insulating isolation component, arranged to span the first vacuum chamber and the second vacuum chamber;

[0024] A front-stage annular electrode fixed to the first vacuum chamber side of the insulating isolation component;

[0025] A plurality of rear-stage annular electrodes are fixed to the second vacuum chamber side of the insulating isolation member and are connected to each other via an insulating connection member;

[0026] a first fixing member for positioning the insulating isolation member relative to a predetermined position in the second vacuum chamber, and comprising a first displacement member for displacing the central axes of the front-stage annular electrode and the rear-stage annular electrode in a predetermined direction orthogonal to the central axes by thermal expansion;

[0027] The second fixing member positions any one of the plurality of rear-stage side annular electrodes relative to the prescribed position, and includes a second displacement member that displaces the central axis in the prescribed direction orthogonal to the central axis by thermal expansion, and a difference between the amount of thermal expansion of the first displacement member per unit temperature and the amount of thermal expansion of the second displacement member per unit temperature is less than 30% of the amount of thermal expansion of the first displacement member.

[0028] The central axis of the annular electrode on the front stage and the annular electrode on the rear stage is equivalent to the central axis (ion optical axis) of the flight path of the ions. The first displacement component may be the same as the first fixed component, or may be a part of the first fixed component. In addition, the second displacement component may be the same as the second fixed component, or may be a part of the second fixed component. When designing an orthogonal acceleration time-of-flight mass spectrometer, the ion optical axis is determined so that the ions flying from the front stage of the transfer electrode are transported to the specified position of the rear stage of the transfer electrode at a specified angle (typically, straightly in the center between the repeller electrode and the introduction electrode constituting the orthogonal acceleration section). Positioning the insulating isolation component and the annular electrode on the rear stage relative to the specified position in the second vacuum chamber means configuring the insulating isolation component and the annular electrode on the rear stage so that the position of the ion optical axis is as shown in the above design.

[0029] Effects of the Invention

[0030] In the orthogonal acceleration time-of-flight mass spectrometer of the present invention, the insulating isolation component is configured to span the first vacuum chamber and the second vacuum chamber divided in the vacuum chamber. The insulating isolation component is fixed relative to a specified position in the second vacuum chamber by a first fixing component. The first fixing component includes a first displacement component that displaces the central axis of the front-stage side annular electrode and the rear-stage side annular electrode in a specified direction orthogonal to the central axis by thermal expansion. In addition, a front-stage side annular electrode is fixed on the first vacuum chamber side of the insulating isolation component, and a plurality of rear-stage side annular electrodes are fixed on the second vacuum chamber side. And, any one of the plurality of rear-stage side annular electrodes (typically the annular electrode located at the last stage) is fixed relative to the above-mentioned specified position by a second fixing component. The second fixing component also includes a second displacement component that displaces the central axis of the front-stage side annular electrode and the rear-stage side annular electrode in the specified direction orthogonal to the central axis by thermal expansion. Furthermore, the difference between the thermal expansion amount of the first displacement member per unit temperature (1 degree) (the sum of the products of the lengths of the members constituting the first displacement member in the above-mentioned predetermined direction and the thermal expansion coefficient) and the thermal expansion amount of the second displacement member per unit temperature (the sum of the products of the lengths of the members constituting the second displacement member in the above-mentioned predetermined direction and the thermal expansion coefficient) is 30% or less of the thermal expansion amount of the first displacement member. Therefore, even when the temperature at the time of assembly of the device is different from the temperature at the time of use, when the target temperature of the temperature control of the flight tube is changed, or when the temperature changes during the transport process of the device, since the difference between the expansion amount or the contraction amount is small, the deviation of the ion optical axis can be suppressed, and the reduction of the device performance such as mass resolution, ion detection sensitivity, and mass accuracy can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a diagram showing the overall configuration of a mass spectrometer as one embodiment of the orthogonal acceleration time-of-flight mass spectrometer of the present invention.

[0032] Figure 2 This is an enlarged view of the vicinity of the post-stage transfer electrode of the mass spectrometer of this embodiment.

[0033] Figure 3 It is a diagram for explaining the structure of the first fixing member of the mass spectrometer according to the present embodiment.

[0034] Figure 4 It is a diagram for explaining the configuration of a transfer electrode of the mass spectrometer according to the present embodiment.

[0035] Figure 5 It is a diagram for explaining the shape of the opening of the lens electrode constituting the transfer electrode of the mass spectrometer according to the present embodiment.

[0036] Figure 6These are other diagrams for explaining the shape of the opening of the lens electrode constituting the transfer electrode of the mass spectrometer according to the present embodiment.

[0037] Figure 7 It is a diagram for explaining the configuration of an ion acceleration unit of the mass spectrometer according to the present embodiment.

[0038] Figure 8 This is a diagram for explaining the deviation of the ion beam axis in the conventional technology.

[0039] Fig. 9 This is another configuration example of the first displacement member in the mass spectrometer according to the present embodiment.

[0040] Fig.10 This is an enlarged view of the vicinity of the rear-stage transfer electrode of the orthogonal acceleration time-of-flight mass spectrometer according to a modified example. DETAILED DESCRIPTION

[0041] Hereinafter, an embodiment of the orthogonal acceleration time-of-flight mass spectrometer of the present invention will be described with reference to the drawings. Hereinafter, the orthogonal acceleration time-of-flight mass spectrometer of this embodiment will also be simply referred to as a "mass spectrometer."

[0042] Figure 1 The schematic structure of the mass spectrometer 1 of the present embodiment is shown. The mass spectrometer 1 is configured by connecting an ionization device having an ionization chamber 10 disposed therein and a vacuum chamber 100. A first intermediate vacuum chamber 11, a second intermediate vacuum chamber 12, and an analysis chamber 13 are disposed in the vacuum chamber 100. The ionization chamber 10 is substantially at atmospheric pressure, and the first intermediate vacuum chamber 11, the second intermediate vacuum chamber 12, and the analysis chamber 13 have a differential exhaust system structure in which the vacuum degree increases stepwise in this order.

[0043] In the ionization chamber 10, an electrospray ion (ESI) source 101 is arranged to ionize the liquid sample by giving an electric charge to the liquid sample and spraying the liquid sample. Here, the ion source is set as an ESI source, but other ion sources can also be used. Alternatively, it can also be an ion source that ionizes a gas sample or a solid sample. The ions generated in the ionization chamber 10 are incident on the first intermediate vacuum chamber 11 through a capillary 102 arranged in a partition wall member with the first intermediate vacuum chamber 11. The capillary 102 is heated by a heat source not shown.

[0044] The ions generated in the ionization chamber 10 are introduced into the first intermediate vacuum chamber 11 by the pressure difference between the ionization chamber 10 (approximately atmospheric pressure) and the first intermediate vacuum chamber 11. At this time, the ions pass through the interior of the heated capillary 102, thereby removing the solvent. A multipole ion guide 111 is arranged in the first intermediate vacuum chamber 11, and the ion beam is converged near the ion optical axis C by the multipole ion guide 111. The ion beam converged in the first intermediate vacuum chamber 11 is incident on the second intermediate vacuum chamber 12 through the hole provided at the top of the skimmer 112 of the partition wall member with the second intermediate vacuum chamber 12.

[0045] The second intermediate vacuum chamber 12 is provided with a quadrupole mass filter 121 for separating ions according to their mass-to-charge ratio, a collision cell 123 having a multipole ion guide 122 therein, and a front-stage transfer electrode 124 for transporting ions released from the collision cell 123 (a front-stage portion of the transfer electrode 130 for transporting ions from the collision cell 123 to the orthogonal acceleration section 132). Collision-induced dissociation (CID) gas such as argon gas and nitrogen gas is continuously or intermittently supplied inside the collision cell 123. In addition, the multipole ion guide 122 disposed inside the collision cell 123 is disposed in a manner that the space surrounded by a plurality of rod electrodes gradually expands toward the exit of the collision cell 123 (end expansion). By adopting such a configuration, a potential gradient for transporting ions to the exit of the collision cell 123 can be formed simply by applying a high-frequency voltage to each rod electrode.

[0046] A partition wall 164 is provided between the second intermediate vacuum chamber 12 and the analysis chamber 13. The partition wall 164 is composed of an extension 1641 protruding from the inner wall surface of the vacuum chamber 100 and a partition wall member 1642 adjacent to the analysis chamber 13 side of the extension 1641 and fixed by screws 1643 (see Figure 2 to Figure 4 ). Here, for the sake of convenience, the vacuum chamber 100 and the extension portion 1641 are described as separate components, but the extension portion 1641 may be integrated with the vacuum chamber 100 .

[0047] The analysis chamber 13 is provided with: a post-stage transfer electrode 131 (a post-stage part of the transfer electrode 130 that transfers ions from the collision cell 123 to the orthogonal acceleration section 132) that transfers ions incident from the second intermediate vacuum chamber 12 to the orthogonal acceleration section 132; the orthogonal acceleration section 132 is composed of a repeller electrode 1321 and an introduction electrode 1322 that are arranged opposite to each other with the ion optical axis C (orthogonal acceleration region) sandwiched therebetween; the second acceleration section 133 that accelerates ions sent from the orthogonal acceleration section 132 to the flight space; a reflector 134 that forms a return track of the ions in the flight space; a detector 135; and a flight tube 136 and a back plate 137 located at the outer edge of the flight space. The flight space of the ions is limited by the reflector 134, the flight tube 136 and the back plate 137.

[0048] The multipole ion guide 111 disposed in the first intermediate vacuum chamber 11, the quadrupole mass filter 121 disposed in the second intermediate vacuum chamber 12, and the collision cell 123 are fixed and positioned on the wall surface of the vacuum chamber 100. In addition, the front transfer electrode 124 disposed in the second intermediate vacuum chamber 12 is fixed and positioned on the collision cell 123.

[0049] The mass spectrometer 1 of the present embodiment is characterized in the arrangement of the components in the analysis chamber 13 , and in particular, in the mechanism for fixing the subsequent-stage transfer electrode 131 .

[0050] Figure 2 It is an enlarged view of the vicinity of the transfer electrode 130 (upper view), a configuration diagram of the second fixing member 170 described later (middle view), and a diagram showing the configuration of the second insulating member 168 on the upper surface of the substrate 167 described later (lower view). Figure 3 is from Figure 2 A is a view showing the structure of the first fixing member 160 described later. The transfer electrode 130 is composed of a front transfer electrode 124 arranged in the second intermediate vacuum chamber 12 and a rear transfer electrode 131 arranged so as to straddle the second intermediate vacuum chamber 12 and the analysis chamber 13 .

[0051] like Figure 4 As shown, the front-stage transfer electrode 124 is composed of two annular electrodes 1241 and 1242. The two annular electrodes 1241 and 1242 are fixed to each other via an insulating component 161. The annular electrode 1241 located at the front-stage side of the front-stage transfer electrode 124 is fixed to the collision cell 123 via the insulating component 161, thereby the front-stage transfer electrode 124 is positioned. The collision cell 123 is fixed to the vacuum chamber 100 via a fixing component 150. An opening 151 for allowing ions to pass through is provided at the center of each of the annular electrodes 1241 and 1242. Figure 5 As shown, an opening 151 having a larger diameter than the opening of the annular electrode 1242 is provided in the annular electrode 1241 .

[0052] The rear transfer electrode 131 is composed of four annular electrodes 1311, 1312, 1313, and 1314. These four annular electrodes 1311, 1312, 1313, and 1314 are also fixed to each other via insulating components 162 and 163. The annular electrode 1311 located on the front side (the ionization chamber 10 side) is arranged in the second intermediate vacuum chamber 12, and the remaining annular electrodes 1312, 1313, and 1314 are arranged in the analysis chamber 13. In addition, the insulating component 162 connecting the two annular electrodes 1311 and 1312 on the front side has an outer shape corresponding to the opening portion of the partition wall component 1642 that divides the second intermediate vacuum chamber 12 and the analysis chamber 13, and the insulating component 162 is inserted into the opening portion. As a result, the insulating component 162 is fixed so as to be slidable only in the direction of the ion light axis C. The outer shape of the insulating component 162 in this embodiment is circular. In addition, the insulating member 162 corresponds to the insulating spacer member in the present invention, and the insulating member 163 corresponds to the connecting member in the present invention.

[0053] The annular electrode 1311 disposed in the second intermediate vacuum chamber 12 is provided with a circular opening 151 having a diameter larger than the opening 151 of the annular electrode 1242. The annular electrodes 1312, 1313, and 1314 disposed in the analysis chamber 13 are provided with rectangular openings 152 (slits). Figure 6 As shown, the size of the opening 152 increases in the order of the annular electrodes 1312, 1314, and 1313. The rectangular opening 152 is a rectangle corresponding to the shape of the opening of the ion incident surface of the orthogonal acceleration unit 132 located in the subsequent stage.

[0054] A plate-like substrate 167 having a rectangular opening formed in the center is fixed at a predetermined position 169 (equivalent to a predetermined position in the second vacuum chamber in the present invention) on the side wall of the vacuum chamber 100 in the analysis chamber 13. Here, for the sake of convenience, the vacuum chamber 100 and the substrate 167 are described as separate components, but the substrate 167 may be integrated with the vacuum chamber 100. In addition, on the upper surface of the substrate 167, three cylindrical second insulating components 168 are fixed on each side with the opening of the substrate 167 sandwiched therebetween, for a total of six. Furthermore, a substrate 138 made of a conductive material and having two ion passage openings formed therein is fixed on the upper portion of these six second insulating components 168. Furthermore, a rectangular plate-like positioning plate 140 made of a conductive material and having an ion passage opening formed therein is fixed on the upper surface of the substrate 138. The annular electrode 1314 located at the last stage among the subsequent-stage transfer electrodes 131 is fixed to the positioning plate 140 via the conductive component 165 and the first insulating component 166 .

[0055] like Figure 7As shown, an ion acceleration unit including an orthogonal acceleration unit 132 composed of a repeller electrode 1321 and an intake electrode 1322 and a second acceleration unit 133 is also fixed to the positioning plate 140. In addition, a detector 135 is also fixed to the substrate 138.

[0056] In the ion acceleration unit, a second acceleration part 133 formed by alternately arranging a plurality of groups of four ring-shaped insulating parts 144 (one by one on each rod-shaped part 139 described later) and an accelerating electrode 1331 is arranged on a positioning plate 140, and an introduction electrode 1322 is arranged on the upper part thereof via four ring-shaped insulating parts 145 and four ring-shaped elastic parts 146 (all arranged on each rod-shaped part 139), and a repelling electrode 1321 is arranged on the upper part thereof via four ring-shaped insulating parts 142 (one by one on each rod-shaped part 139). The accelerating electrode 1331 is in the shape of a rectangular plate, and a circular opening for passing ions is provided in the center, and openings for inserting the rod-shaped part 139 and the isolation part 141 are provided at the four corners. Rod-shaped members 139 are respectively provided at the four corners of the positioning plate 140, and the position (height) of the electrode 1322 is limited by the isolation members 141 disposed on the periphery of each rod-shaped member 139. Insulation members 144 and 145 are disposed on the periphery of each isolation member 141, and insulation members 142 are disposed on the periphery of each rod-shaped member 139.

[0057] The mass analyzer is assembled in a factory at room temperature (e.g., 25°C). On the other hand, when performing mass analysis, the analysis chamber 13 is heated and temperature-controlled to a predetermined temperature (e.g., 45°C). As a result, each component expands according to the thermal expansion coefficient of the material constituting the component. In addition, when the target temperature of the temperature control is changed or when the temperature changes during the transportation of the device, each component also expands and contracts according to the thermal expansion coefficient of the material constituting the component.

[0058] In the mass spectrometer 1 of the present embodiment, the transfer electrode 130 is positioned with high precision during manufacturing in the factory so that the central axis (ion optical axis C) of the transfer electrode 130 (the front transfer electrode 124 and the rear transfer electrode 131) passes between the opposing surfaces of the repeller electrode 1321 and the introduction electrode 1322 constituting the orthogonal acceleration section 132 and is parallel to the opposing surfaces. In the rear transfer electrode 131 of the mass spectrometer 1 of the present embodiment, the insulating member 162 arranged so as to straddle the second intermediate vacuum chamber 12 and the analysis chamber 13 (equivalent to the first vacuum chamber and the second vacuum chamber in the present invention) with the partition wall 164 sandwiched therebetween is positioned (fixed so as to be slidable only in the direction of the ion optical axis C) relative to the predetermined position 169 of the vacuum chamber 100 via the partition wall member 1642, the extension 1641, and a portion of the vacuum chamber 100 (a portion from the base of the extension 1641 to the predetermined position 169. This portion is hereinafter referred to as a "partial vacuum chamber 110"). That is, in this embodiment, the partition wall member 1642 , the extension portion 1641 , and the partial vacuum chamber 110 constitute the first fixing member 160 , and the ion optical axis C is positioned at the center position of the insulating member 162 by these.

[0059] like Figure 3 As shown, the partition wall component 1642 is fixed to the extension part 1641 by screws 1643 at four positions symmetrical around the ion optical axis C. Therefore, if the partition wall component 1642 expands or contracts, the size of the central opening changes, but the ion optical axis C does not shift. In addition, the displacement of the ion optical axis C refers to the change of the position of the ion optical axis C relative to the reference position, with the specified position 169 as the reference position. Therefore, in the present embodiment, in the first fixed component 160, the extension part 1641 and the partial vacuum chamber 110 constitute the first displacement component.

[0060] The annular electrode 1314 located at the last stage of the rear transfer electrode 131 is fixed to the substrate 167 fixed at the predetermined position 169 of the vacuum chamber 100 via the conductive component 165, the first insulating component 166, the positioning plate 140, the substrate 138, and the second insulating component 168. That is, in the present embodiment, the conductive component 165, the first insulating component 166, the positioning plate 140, the substrate 138, the second insulating component 168, and the substrate 167 constitute the second fixing component 170, and the ion optical axis C is positioned at the center position of the annular electrode 1314 by these components. These components all displace the ion optical axis C by expansion or contraction. Therefore, in the present embodiment, the second fixing component 170 is the same as the second displacement component.

[0061] In the conventional mass spectrometer, the vacuum chamber 100 (partial vacuum chamber 110), the extension 1641, the conductive member 165, and the substrate 138 are made of aluminum, and the first insulating member 166 and the second insulating member 168 are made of PEEK. Figure 2 and Figure 4 Compared with the thermal expansion in the vertical direction (the specified direction orthogonal to the ion beam axis C in the present invention), the thermal expansion of the second displacement component composed of the aluminum component and the PEEK component in this direction is greater. As a result, Figure 8 As shown in FIG. 1 , the ion optical axis C is offset, the efficiency of introducing ions into the orthogonal acceleration unit 132 is reduced, the detection sensitivity is reduced, and the mass resolution or mass accuracy is reduced. Figure 8 In order to clearly show the displacement of the ion optical axis C, the thermal expansion amount of each component is set to be larger than the actual amount. In addition, the partition wall component 1642 of this embodiment is made of polyacetal resin, but as mentioned above, the thermal expansion of the partition wall component 1642 does not cause the ion optical axis C to shift, so it is not included in the first displacement component.

[0062] In this embodiment, the vacuum chamber 100 (partial vacuum chamber 110), the conductive component 165, the positioning plate 140, and the substrate 138 are made of the same type of conductive material. For example, aluminum is used as in the past for the conductive material. However, it is not a necessary condition of the present invention that all conductive components are made of the same conductive material, and different types of conductive materials may be used. For example, stainless steel (SUS) may be used instead of aluminum.

[0063] Furthermore, a first insulating material having a smaller thermal expansion coefficient than the conductive material is used in the first insulating member 166, and a second insulating material having a larger thermal expansion coefficient than the conductive material is used in the second insulating member 168. For example, when the conductive material is aluminum, PEEK can be used as the second insulating material, and nitride-based machinable ceramics, which are one of machinable ceramics with good machinability, can be used as the first insulating material. As the first insulating material, for example, boron nitride can be used, but it is preferable to use machinable ceramics such as nitride-based machinable ceramics and mica-based machinable ceramics.

[0064] As described above, in the mass spectrometer 1 of the present embodiment, the first insulating material having a smaller thermal expansion coefficient than the conductive material is used in the first insulating member 166, and the second insulating material having a larger thermal expansion coefficient than the conductive material is used in the second insulating member 168. Therefore, the lengths of the two insulating members are appropriately adjusted according to the thermal expansion coefficients of the two insulating members ( Figure 2Specifically, the difference between the thermal expansion amount of the first displacement component per unit temperature (the sum of the product of the length of each component constituting the first displacement component in the above-mentioned predetermined direction and the thermal expansion coefficient) and the thermal expansion amount of the second displacement component per unit temperature is suppressed to less than 30% of the thermal expansion amount of the first displacement component. Figure 2 The displacement amount of the ion optical axis C in the vertical direction caused by the thermal expansion of the first displacement member and the displacement amount of the ion optical axis C in the vertical direction caused by the thermal expansion of the second displacement member are set to the same level, and even if the temperature is different during manufacturing and mass analysis, the offset of the ion optical axis C can be suppressed. In addition, even if the target temperature of the temperature control of the flight tube 136 is changed, the offset of the ion optical axis C can be suppressed. Furthermore, even if thermal expansion and contraction occur due to temperature changes in the transport stroke of the mass analyzer 1, the displacement of the ion optical axis C caused by the thermal expansion and contraction of the first displacement member and the displacement of the ion optical axis C caused by the thermal expansion and contraction of the second displacement member are also the same level, so that an irreversible large offset of the ion optical axis C will not occur.

[0065] Example

[0066] Hereinafter, a specific embodiment will be described. In the present embodiment, the vacuum chamber 100 (partial vacuum chamber 110), the extension 1641, the conductive component 165, the positioning plate 140, the substrate 138 and the base material 167 are made of aluminum, the second insulating component 168 is made of a component made of PEEK, and the first insulating component 166 is made of Photoveel II (a registered trademark of Ferrotec Material Technologies Co., Ltd.) described in non-patent document 1. Photoveel II is a nitride-based machinable ceramic that is a type of machinable ceramic. In addition, as in the past, the first insulating component 166 is made of a component made of PEEK as a comparative example (prior art). In addition, in any of the embodiments and comparative examples, the partition wall component 1642 is made of a component made of POM (polyacetal resin).

[0067] Table 1 shows the materials and lengths of the various components constituting the first displacement member that are common to the embodiment and the comparative example. Figure 2 The design length in the up and down directions), thermal expansion coefficient and thermal expansion amount.

[0068] [Table 1]

[0069]

[0070] Table 2 shows the raw materials and lengths of the components constituting the second displacement member in the comparative example. Figure 2 The values ​​shown in the bottom layer are the length, thermal expansion coefficient and thermal expansion amount of the second displacement member as a whole.

[0071] [Table 2]

[0072]

[0073] Table 3 shows the raw materials and lengths of the components constituting the second displacement member in the embodiment. Figure 2 The values ​​shown in the bottom layer are the length, thermal expansion coefficient and thermal expansion amount of the second displacement member as a whole.

[0074] [Table 3]

[0075]

[0076] As calculated from the numerical values ​​shown in Tables 1 and 2, in the comparative example, the thermal expansion coefficient of the first displacement member is 2.37×10 -5 (1 / K), the thermal expansion coefficient of the second displacement member is 3.10×10 -5 (1 / K), the ratio of the thermal expansion coefficient of the second displacement member to the thermal expansion coefficient of the first displacement member (thermal expansion coefficient of the second displacement member / thermal expansion coefficient of the first displacement member) is 1.31. That is, the thermal expansion coefficient of the second displacement member is 31% greater than that of the first displacement member. In addition, the thermal expansion amount of the first displacement member per unit temperature (1 degree) is 3.72×10 -3 mm, and the thermal expansion of the second displacement member per unit temperature is 4.87×10 -3 mm, the difference is 1.15×10 -3 mm is 31% of the thermal expansion of the first displacement member. Figure 2 The difference between the thermal expansion amount of the second displacement component in the up and down directions (the displacement amount of the ion optical axis C caused by the thermal expansion of the second displacement component) and the thermal expansion amount of the first displacement component (the displacement amount of the ion optical axis C caused by the thermal expansion of the first displacement component) is 0.035 mm.

[0077] On the other hand, in the embodiment, as calculated from the numerical values ​​shown in Table 1 and Table 3, the thermal expansion coefficient of the first displacement member is 2.37×10 -5 (1 / K), the thermal expansion coefficient of the second displacement member is 2.63×10 -5(1 / K), the ratio of the thermal expansion coefficient of the second displacement member to the thermal expansion coefficient of the first displacement member (thermal expansion coefficient of the second displacement member / thermal expansion coefficient of the first displacement member) is 1.11. That is, the thermal expansion coefficient of the second displacement member is suppressed to a value 11% greater than the thermal expansion coefficient of the first displacement member. In addition, the thermal expansion amount of the first displacement member per unit temperature (1 degree) is 3.72×10 -3 mm, and the thermal expansion of the second displacement member per unit temperature is 4.13×10 -3 mm, the difference is 0.41×10 -3 mm is 11% of the thermal expansion of the first displacement member. In addition, it can be seen that the difference between the thermal expansion of the second displacement member (the displacement of the ion optical axis C caused by the thermal expansion of the second displacement member) and the thermal expansion of the first displacement member (the displacement of the ion optical axis C caused by the thermal expansion of the first displacement member) when the temperature rises by 30°C is also suppressed to 0.013 mm. By adopting the structure of the embodiment, the deviation of the ion optical axis C is suppressed to about 1 / 3 compared with the comparative example. By adjusting the length of each component more finely, the difference can also be suppressed to substantially 0.

[0078] The above-described embodiment and examples are merely examples and can be modified as appropriate in accordance with the spirit of the present invention.

[0079] In the above-mentioned embodiments and examples, Figure 3 As shown, the partition wall component 1642 is fixed to the extension portion 1641 by screws 1643 at a position symmetrical to the ion optical axis C. Even if the partition wall component 1642 is thermally expanded, the ion optical axis C does not shift. Therefore, the partition wall component 1642 is not included in the first displacement component. However, depending on the position where the partition wall component 1642 is fixed to the extension portion 1641, the ion optical axis C can be shifted by the thermal expansion of the partition wall component 1642. For example, in the case where the partition wall component 1642 is fixed to the extension portion 1641 at only one position by screws 1643, the first displacement component is composed of the partial vacuum chamber 110, the extension portion 1641, and the partition wall component 1642. Fig. 9 As shown, the thermal expansion of these components needs to be considered separately.

[0080] Furthermore, in the above-described embodiment and examples, the subsequent-stage transfer electrode 131 is configured to be supported and fixed from below, but it is also possible to adopt a configuration in which the subsequent-stage transfer electrode 131 is suspended and fixed from above.

[0081] exist Fig.10The configuration of the orthogonal acceleration time-of-flight mass spectrometer 2 of a modified example in which the rear-stage transfer electrode 131, the ion acceleration unit, and the detector 135 are suspended and fixed from above is shown. In the modified example, the annular electrode 1314 located at the last stage of the rear-stage transfer electrode 131 is fixed from the upper wall surface of the vacuum chamber 100 via the first insulating member 266, the second insulating member 267, and the conductive member 265. That is, the second fixing member is composed of the first insulating member 266, the second insulating member 267, and the conductive member 265. In addition, the second fixing member is the same as the second displacement member. The first fixing member and the first displacement member are the same as those in the above-mentioned embodiment and example (the first displacement member is different depending on the position of fixing the partition wall member 1642 to the extension part 1641, etc.). The acceleration unit is fixed to the upper wall surface of the vacuum chamber 100 through the insulating member 261, and the ion detector 135 is fixed to the upper wall surface of the vacuum chamber 100 through the insulating member 262.

[0082] In a modified example, the second insulating component 267 is composed of a material (e.g., PEEK) having a larger thermal expansion coefficient than the material of the extension portion 1641 or the conductive component 265 (e.g., aluminum), and the first insulating component 266 is composed of a material (e.g., Photoveel II) having a smaller thermal expansion coefficient than the material of the extension portion 1641 or the conductive component 265, thereby achieving the same effect as the above-mentioned embodiment.

[0083] In addition, it is also possible to only suspend and hold the rear transfer electrode 131 from above, but if the component or detector defining the ion optical axis C is fixed relative to a different predetermined position, there is a possibility that a deviation occurs on the ion optical axis C or a deviation occurs in the flight path of the ions and the position of the detector. Therefore, when the rear transfer electrode 131 is fixed relative to the upper wall surface of the vacuum chamber 100, it is preferable to also fix the ion acceleration unit and the ion detector relative to the upper wall surface of the vacuum chamber 100 as in the above-mentioned modification.

[0084] In the above embodiment, the transfer electrode is a ring electrode, but a segmented multipole electrode (a multipole electrode divided into multiple segments along the ion optical axis C) may also be used. In addition, in the above embodiment, an ion trap (including LIT or PLIT) may also be used as an orthogonal acceleration unit.

[0085] The number of components constituting the first fixing member 160 or the second fixing member 170 , 270 and the type of material constituting each component are not limited to those described in the above-mentioned embodiment, examples and modified examples, and can be appropriately changed as long as the requirements of the present invention are met.

[0086] [plan]

[0087] Those skilled in the art will appreciate that the above-mentioned multiple exemplary embodiments are specific examples of the following schemes.

[0088] (Item 1)

[0089] An orthogonal acceleration time-of-flight mass spectrometer of one embodiment comprises:

[0090] The vacuum chamber has an internal space divided into a first vacuum chamber and a second vacuum chamber;

[0091] an insulating isolation component, arranged to span the first vacuum chamber and the second vacuum chamber;

[0092] A front-stage annular electrode fixed to the first vacuum chamber side of the insulating isolation component;

[0093] A plurality of rear-stage annular electrodes are fixed to the second vacuum chamber side of the insulating isolation member and are connected to each other via an insulating connection member;

[0094] a first fixing member for positioning the insulating isolation member relative to a predetermined position in the second vacuum chamber, and comprising a first displacement member for displacing the central axes of the front-stage annular electrode and the rear-stage annular electrode in a predetermined direction orthogonal to the central axes by thermal expansion;

[0095] The second fixing member positions any one of the plurality of rear-stage side annular electrodes relative to the prescribed position, and includes a second displacement member that displaces the central axis in the prescribed direction orthogonal to the central axis by thermal expansion, and a difference between the amount of thermal expansion of the first displacement member per unit temperature and the amount of thermal expansion of the second displacement member per unit temperature is less than 30% of the amount of thermal expansion of the first displacement member.

[0096] In the orthogonal acceleration time-of-flight mass spectrometer described in the first item, the insulating isolation component is arranged so as to span the first vacuum chamber and the second vacuum chamber divided in the vacuum chamber. The insulating isolation component is fixed relative to a prescribed position in the second vacuum chamber by a first fixing component. The first fixing component includes a first displacement component that displaces the central axes of the front-stage side annular electrode and the rear-stage side annular electrode in a prescribed direction orthogonal to the central axis by thermal expansion. In addition, a front-stage side annular electrode is fixed on the first vacuum chamber side of the insulating isolation component, and a plurality of rear-stage side annular electrodes are fixed on the second vacuum chamber side. Furthermore, any one of the plurality of rear-stage side annular electrodes (typically the annular electrode located at the last stage) is fixed relative to the above-mentioned prescribed position by a second fixing component. The second fixing component also includes a second displacement component that displaces the central axes of the front-stage side annular electrode and the rear-stage side annular electrode in the prescribed direction orthogonal to the central axis by thermal expansion. Furthermore, the difference between the thermal expansion amount of the first displacement member per unit temperature (1 degree) (the sum of the products of the lengths of the members constituting the first displacement member in the above-mentioned predetermined direction and the thermal expansion coefficient) and the thermal expansion amount of the second displacement member per unit temperature (1 degree) (the sum of the products of the lengths of the members constituting the second displacement member in the above-mentioned predetermined direction and the thermal expansion coefficient) is 30% or less of the thermal expansion amount of the first displacement member. Therefore, even when the temperature at the time of assembly of the device is different from the temperature at the time of use, when the target temperature of the temperature control of the flight tube is changed, or when the temperature changes during the transport stroke of the device, since the difference between the expansion amount or the contraction amount is small, the deviation of the ion optical axis can be suppressed, and the reduction of the device performance such as mass resolution, ion detection sensitivity, and mass accuracy can be suppressed.

[0097] (Item 2)

[0098] The orthogonal acceleration time-of-flight mass spectrometer according to item 1 further comprises:

[0099] A partition wall component that divides the first vacuum chamber and the second vacuum chamber;

[0100] The extension part is arranged on the inner wall surface of the vacuum chamber and fixed with the partition wall component.

[0101] The first fixing member includes the partition wall member, the extending portion, and a portion of the vacuum chamber located from the extending portion to the predetermined position.

[0102] In the orthogonal acceleration time-of-flight mass spectrometer of the second aspect, the insulating spacer member is fixed by the extension portion and the partition wall member provided to partition the first vacuum chamber and the second vacuum chamber, so the number of components can be minimized.

[0103] (Item 3)

[0104] In the orthogonal acceleration time-of-flight mass spectrometer described in item 2,

[0105] The first displacement member is a part of the extension portion and the vacuum chamber.

[0106] As a solution of the orthogonal acceleration time-of-flight mass spectrometer of item 2, a configuration can be adopted in which the partition wall component is fixed to the extension part at a position symmetrical around the ion optical axis. In this case, the first displacement component of the orthogonal acceleration time-of-flight mass spectrometer of item 3 is composed of the extension part and a part of the vacuum chamber. In the orthogonal acceleration time-of-flight mass spectrometer of item 3, since it is not affected by the thermal expansion of the partition wall component, the displacement of the ion optical axis can be suppressed.

[0107] (Item 4)

[0108] In the orthogonal acceleration time-of-flight mass spectrometer described in any one of items 1 to 3,

[0109] A difference between a thermal expansion coefficient of the first displacement member and a thermal expansion coefficient of the second displacement member is 30% or less of the thermal expansion coefficient of the first displacement member.

[0110] In the orthogonal acceleration time-of-flight mass spectrometer described in Item 4, the difference between the thermal expansion coefficient of the first displacement member and the thermal expansion coefficient of the second displacement member is 30% or less of the thermal expansion coefficient of the first displacement member. In many cases, the lengths of the first displacement member and the second displacement member in the prescribed direction are approximately the same. In these cases, by using the orthogonal acceleration time-of-flight mass spectrometer described in Item 4, even when the temperature during assembly of the device is different from the temperature during use, when the target temperature of the temperature control of the flight tube is changed, or when the temperature changes during transportation of the device, the difference between the expansion or contraction of the first fixing member and the second fixing member can be suppressed to be small, thereby suppressing the deviation of the ion optical axis.

[0111] (Item 5)

[0112] In the orthogonal acceleration time-of-flight mass spectrometer described in any one of items 1 to 4,

[0113] The second displacement member includes a member made of an insulating material.

[0114] In the orthogonal acceleration time-of-flight mass spectrometer of item 5, the vacuum chamber and the subsequent-stage annular electrode are insulated by the second displacement member (the member made of an insulating material included therein).

[0115] (Item 6)

[0116] In the orthogonal acceleration time-of-flight mass spectrometer described in any one of items 1 to 5,

[0117] The second displacement member includes a first insulating member formed of a first insulating material, a second insulating member formed of a second insulating material, and a conductive member formed of a conductive material.

[0118] In the orthogonal acceleration time-of-flight mass spectrometer described in Item 6, the thermal expansion amount of the second displacement member can be appropriately adjusted by using two different insulating materials. Of course, three or more insulating materials with different thermal expansion coefficients can also be used. In addition, for the conductive material, multiple materials with different thermal expansion coefficients can also be used.

[0119] (Item 7)

[0120] In the orthogonal acceleration time-of-flight mass spectrometer described in item 6,

[0121] The first insulating material has a smaller thermal expansion coefficient than the conductive member, and the second insulating material has a larger thermal expansion coefficient than the conductive member.

[0122] The orthogonal acceleration time-of-flight mass spectrometer described in Item 6 can be constructed, like the orthogonal acceleration time-of-flight mass spectrometer described in Item 7, by including a component composed of a first insulating material having a smaller thermal expansion coefficient than a conductive material constituting the conductive component, and a component composed of a second insulating material having a larger thermal expansion coefficient than the conductive material.

[0123] (Item 8)

[0124] In the orthogonal acceleration time-of-flight mass spectrometer described in item 6 or 7,

[0125] The first insulating material is a machinable ceramic.

[0126] In the orthogonal acceleration time-of-flight mass spectrometer described in Item 8, by using a member made of machinable ceramics having good machinability as the first insulating member, the second fixing member can be manufactured more simply and with high precision.

[0127] (Item 9)

[0128] In the orthogonal acceleration time-of-flight mass spectrometer described in any one of items 6 to 8,

[0129] The first insulating material is nitride-based ceramics.

[0130] In mass spectrometers, vacuum chamber components made of aluminum are often used. Therefore, as in the orthogonal acceleration time-of-flight mass spectrometer described in Item 9, nitride-based ceramics can be preferably used as the first insulating material.

[0131] Description of Reference Numerals

[0132] 1.2 Quality analysis device

[0133] 100 Vacuum chamber

[0134] 110 Partial Vacuum Chamber

[0135] 10Ionization chamber

[0136] 101 Electrospray Ion Source

[0137] 1111st intermediate vacuum chamber

[0138] 111 Multipole Ion Guide

[0139] 12The 2nd intermediate vacuum chamber

[0140] 121 quadrupole mass filter

[0141] 122 Multipole ion guide

[0142] 123 Collision Cell

[0143] 124 Pre-stage transfer electrode

[0144] 1241, 1242 Ring Electrode

[0145] 13Analysis Room

[0146] 131 Post-stage transfer electrode

[0147] 1311 ring electrode (front stage ring electrode)

[0148] 1312, 1313, 1314 annular electrodes (rear stage annular electrodes)

[0149] 132 Orthogonal Acceleration Unit

[0150] 1321 Repeller Electrode

[0151] 1322Introduction of electrodes

[0152] 133 Second Acceleration Unit

[0153] 134 reflector

[0154] 135 detector

[0155] 136 Flight Tube

[0156] 137 Back Panel

[0157] 138 substrate

[0158] 140 positioning plate

[0159] 160 1st fixed part

[0160] 161, 162, 163 Insulation parts

[0161] 164 partition wall

[0162] 1641 extension

[0163] 1642 Partition wall components

[0164] 165, 265 conductive parts

[0165] 166, 266 No. 1 insulating part

[0166] 167 Base Material

[0167] 168, 267 Second insulation part

[0168] 169 specified position (fixed position of substrate 167)

[0169] 170Second fixing part

[0170] 261, 262 Insulation parts

[0171] C ion optical axis.

Claims

1. An orthogonal acceleration time-of-flight mass spectrometer, characterized in that: have: The vacuum chamber has an internal space divided into a first vacuum chamber and a second vacuum chamber; an insulating isolation component, arranged to span the first vacuum chamber and the second vacuum chamber; A front-stage annular electrode fixed to the first vacuum chamber side of the insulating isolation component; A plurality of rear-stage annular electrodes are fixed to the second vacuum chamber side of the insulating isolation member and are connected to each other via an insulating connection member; a first fixing member for positioning the insulating isolation member relative to a predetermined position in the second vacuum chamber, and comprising a first displacement member for displacing the central axes of the front-stage annular electrode and the rear-stage annular electrode in a predetermined direction orthogonal to the central axes by thermal expansion; The second fixing member positions any one of the plurality of rear-stage side annular electrodes relative to the prescribed position, and includes a second displacement member that displaces the central axis in the prescribed direction orthogonal to the central axis by thermal expansion, and a difference between the amount of thermal expansion of the first displacement member per unit temperature and the amount of thermal expansion of the second displacement member per unit temperature is less than 30% of the amount of thermal expansion of the first displacement member.

2. The orthogonal acceleration time-of-flight mass spectrometer according to claim 1, characterized in that: Also available: A partition wall component that divides the first vacuum chamber and the second vacuum chamber; The extension part is arranged on the inner wall surface of the vacuum chamber and fixed with the partition wall component. The first fixing member includes the partition wall member, the extending portion, and a portion of the vacuum chamber located from the extending portion to the predetermined position.

3. The orthogonal acceleration time-of-flight mass spectrometer according to claim 2, characterized in that: The first displacement member is a part of the extension portion and the vacuum chamber.

4. The orthogonal acceleration time-of-flight mass spectrometer according to claim 1, characterized in that: A difference between a thermal expansion coefficient of the first displacement member and a thermal expansion coefficient of the second displacement member is 30% or less of the thermal expansion coefficient of the first displacement member.

5. The orthogonal acceleration time-of-flight mass spectrometer according to claim 1, characterized in that: The second displacement member includes a member made of an insulating material.

6. The orthogonal acceleration time-of-flight mass spectrometer according to claim 1, characterized in that: The second displacement member includes a first insulating member formed of a first insulating material, a second insulating member formed of a second insulating material, and a conductive member formed of a conductive material.

7. The orthogonal acceleration time-of-flight mass spectrometer according to claim 6, characterized in that: The first insulating material has a smaller thermal expansion coefficient than the conductive member, and the second insulating material has a larger thermal expansion coefficient than the conductive member.

8. The orthogonal acceleration time-of-flight mass spectrometer according to claim 6, characterized in that: The first insulating material is a machinable ceramic.

9. The orthogonal acceleration time-of-flight mass spectrometer according to claim 6, characterized in that: The first insulating material is nitride-based ceramics.

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