Quality analysis device

Abstract

To easily adjust a position where a helical antenna is brought into electrical contact with an outer conductor, in a mass spectroscope comprising an ECR-LICP type radical generation section.SOLUTION: A mass spectroscope comprises: a dielectric tube 410; a helical antenna 411 of a conductor wound around an outer periphery of the tube; an outer conductor 412 in which a magnet is embedded; a frame member 44 which is fixed to the outer conductor and holds the tube; a rotary member 431 to which the position in a center axis direction of the tube is fixed, which is attached to the frame member freely rotatably around the axis and has a through hole in which a screw groove is formed on an inner peripheral surface; and a connection member 42 that is a member inserted into a gap between the helical antenna and the outer conductor and electrically connecting both of them, includes an inner cylinder of which the position in a circumferential direction is fixed with respect to the frame member and an outer cylinder which is coaxial with the inner cylinder and in which a leaf spring part is provided at a distal end of the inner cylinder and the outer cylinder and a thread corresponding to the screw groove is formed at an outer periphery of a proximal end of the inner cylinder.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a mass spectrometer. In particular, it relates to a mass spectrometer that performs an operation of dissociating ions using radicals generated from a source gas.

Background Art

[0002] There is known a mass spectrometer that dissociates ions by attaching radicals such as hydrogen radicals, oxygen radicals, and nitrogen radicals to ions derived from sample components, and then mass-analyzes the product ions generated thereby (for example, Patent Documents 1 and 2). For example, when a dissociation operation using radicals is performed on ions derived from a peptide, various types of product ions reflecting the structure such as the amino acid sequence of the peptide are generated. By analyzing the mass spectrum in which such product ions are observed, the structure of the peptide can be estimated.

[0003] As such a radical generation unit used in such a mass spectrometer, for example, those described in Non-Patent Documents 1 and 2 are known. These radical generation units have a configuration including a helical antenna in which a conductive wire is wound around a capillary tube made of a dielectric such as quartz in a three-dimensional spiral shape. Microwave power is supplied to the helical antenna, and plasma is generated in the source gas passing through the capillary tube by the eddy current, generating radicals of the source gas.

[0004] Further, in the radical generation units described in Non-Patent Documents 1 and 2, a magnet is disposed outside the capillary tube, and the density of the plasma is increased and stabilized by the electron cyclotron resonance (ECR) phenomenon using the magnetic field generated by this magnet. Such a radical generation unit is called an ECR-LICP (Electron Cyclotron Resonance-Localized Inductively Coupled Plasma) type because it uses local inductive discharge and electron cyclotron resonance for the generation and maintenance of plasma.

[0005] In an ECR-LICP type radical generation unit, a substantially cylindrical outer conductor is provided coaxially with the helical antenna, separated by a gap, outside a helical antenna wound around the outer circumference of a capillary tube, and this outer conductor is grounded. A conductive connecting member is inserted into the gap between the helical antenna and the outer conductor, and this connecting member electrically connects the outer conductor to an appropriate part of the helical antenna in the longitudinal direction. This determines the impedance of the helical antenna, and an ECR resonant circuit including this impedance is formed. In such an ECR-LICP type radical generation unit, the position of the connecting member, i.e., the axial position of the helical antenna electrically connected to the outer conductor, needs to be adjusted for each device so that appropriate resonance occurs in the ECR resonant circuit.

[0006] Patent Document 3 describes a connecting member that is inserted into the gap between a helical antenna and an outer conductor. This connecting member has a double cylindrical tube structure composed of an inner cylinder and an outer cylinder, each of which is divided circumferentially by an axially extending slit, and each of the divided pieces has a tapered portion that bulges outward at the outer tip of the divided piece of the inner cylinder.

[0007] When electrically connecting the outer conductor and the helical antenna using this connecting member, the user holds the base end of the inner cylinder with one hand, with the tip of the segmented piece of the outer cylinder in contact with the tapered portion of the inner cylinder, inserts the connecting member into the gap between the helical antenna and the outer conductor, and moves the outer cylinder axially toward the tip with the other hand to determine the position where the helical antenna is electrically connected to the outer conductor and plasma is generated effectively. Once the position where plasma is generated effectively is determined, the user moves the outer cylinder axially toward the inner cylinder with the other hand. This causes the tapered portion of the inner cylinder to press the segmented piece of the outer cylinder outward, causing the segmented piece to bend outward and press against the outer conductor. At the same time, the segmented piece of the outer cylinder presses the tapered portion of the inner cylinder inward, causing the segmented piece to bend inward and press against the helical antenna. The segments of the inner and outer cylinders function as leaf springs, with the segments of the inner cylinder making close contact with the helical antenna and the segments of the outer cylinder making close contact with the inner surface of the outer conductor, thereby fixing the helical antenna and the outer conductor in an electrically connected state. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2019-191081 [Patent Document 2] International Publication No. 2019 / 155725 [Patent Document 3] International Publication No. 2022 / 059247 [Non-patent literature]

[0009] [Non-Patent Document 1] Yuji Simabukuro, et al., "Tandem Mass Spectrometry of Peptide Ions by Microwave Excited Hydrogen and Water Plasmas," Analytical Chemistry, 2018, Vol. 90, No. 12, pp. 7239-7245. [Non-Patent Document 2] Yuji Simabukuro, "Comprehensive Study on the Low-energy Atomic Hydrogen Beam: From Production to Velocity Distribution Measurement" (Doctoral Dissertation), [online], [Retrieved April 8, 2020], Doshisha University Academic Repository, Internet<URL: https: / / doors.doshisha.ac.jp / duar / repository / ir / 27819 / zk1079.pdf> [Overview of the project] [Problems that the invention aims to solve]

[0010] In the ECR resonant circuit described above, the resonance state changes significantly if the contact position between the helical antenna and the outer conductor differs by 1 to several millimeters. Therefore, it is necessary to fine-tune the contact position between the two to within 1 mm or even less. However, when using the above-mentioned connecting member, one hand holds the base end of the inner cylinder while the other hand extends the outer cylinder axially and presses it against the tip of the inner cylinder to fix it in place. This makes it easy for misalignment to occur, such as the inner cylinder extending simultaneously when the outer cylinder is pressed against the tip of the inner cylinder, making it difficult to fine-tune the contact position between the helical antenna and the outer conductor.

[0011] The problem that this invention aims to solve is to provide a technique that allows for easy fine-tuning of the position in which the helical antenna and the outer conductor are electrically contacted in a mass spectrometer equipped with an ECR-LICP type radical generation unit. [Means for solving the problem]

[0012] The mass spectrometer according to the present invention, which was developed to solve the above problems, A tube made of dielectric material, A helical antenna made of a conductor and wound around the outer circumference of the tube, A cylindrical member provided coaxially with the pipe on the outside of the pipe, comprising an outer conductor in which a magnet is embedded and whose inner surface is made of a conductive material, A frame member fixed to one end of the outer conductor and holding the pipe, A cylindrical member is attached to the frame member at a position opposite one end of the outer conductor, with its position in the axial direction of the central axis of the pipe fixed and rotatable around the central axis, and the rotating member has a through hole through which the pipe is inserted and which has a screw groove formed on its inner circumferential surface, A connecting member that is inserted into the gap between the helical antenna and the outer conductor and electrically connects the helical antenna and the outer conductor, comprising: an inner cylinder provided coaxially with the outside of the tube and fixed in a circumferential position with respect to the frame member; and an outer cylinder provided coaxially with the inner cylinder and on the outside of the inner cylinder, wherein leaf spring portions are provided at the tips of the inner and outer cylinders that bend inward and outward, respectively when pressed against each other, and a screw thread corresponding to the screw groove is formed on the outer circumference of the base end of the inner cylinder. It is equipped with. [Effects of the Invention]

[0013] The mass spectrometer according to the present invention comprises a tube made of a dielectric material (dielectric tube) and a helical antenna made of a conductor wound around its outer circumference. In this mass spectrometer, when in use, a raw material gas is supplied to the inside of the dielectric tube and high-frequency power is supplied to the helical antenna to generate a plasma of the raw material gas and produce radicals. The mass spectrometer according to the present invention also has an ECR-LICP type configuration, which comprises a cylindrical member provided coaxially with the dielectric tube, having a magnet embedded in it and an outer conductor whose inner surface is made of a conductive material. The mass spectrometer according to the present invention further comprises a connecting member for adjusting the position in which the helical antenna and the outer conductor are brought into contact and electrically connected. The resonance state of the ECR resonant circuit is adjusted by grounding the outer conductor and adjusting the position in which the helical antenna and the outer conductor come into contact with this connecting member.

[0014] The mass spectrometer according to the present invention further includes a frame member fixed to one end of the outer conductor and holding a dielectric tube. A cylindrical rotating member is attached to the frame member at a position opposite to one end of the outer conductor, such that its position is fixed in the axial direction of the dielectric tube and it is rotatable around the central axis. The rotating member has a through hole through which the dielectric tube is inserted, and screw grooves are formed on its inner circumferential surface.

[0015] The connecting member in this invention comprises an inner cylinder whose circumferential position is fixed with respect to a frame member fixed to one end of the outer conductor, and an outer cylinder positioned outside the inner cylinder. The tips of the inner and outer cylinders are provided with leaf spring portions that bend inward and outward, respectively, when the two are pressed together. Furthermore, the outer circumference of the inner cylinder has screw threads that correspond to the screw grooves on the inner surface of the rotating member.

[0016] When adjusting the position where the helical antenna contacts the outer conductor, with the tip portions of the outer cylinder and the inner cylinder in contact, the inner cylinder is advanced in the axial direction of the dielectric tube by rotating the rotating member, and the position where the plasma is favorably generated by bringing the helical antenna into electrical contact with the outer conductor is determined. When the position where the plasma is favorably generated is determined, the outer cylinder is advanced axially with respect to the inner cylinder, and the leaf spring portions provided at the tips of both are bent inward and outward, respectively, to bring the inner cylinder into close contact with the helical antenna and the outer cylinder into close contact with the outer conductor and fix them. In the mass spectrometer according to the present invention, the axial position of the inner cylinder is fixed by a rotating member fixed in the central axis direction of the dielectric tube by being held by a frame member fixed to the outer conductor, and the outer cylinder is advanced axially with respect to the inner cylinder. Therefore, the position where the helical antenna and the outer conductor are electrically contacted can be easily finely adjusted without causing a displacement of the inner cylinder during the operation.

Brief Description of the Drawings

[0017] [Figure 1] Schematic configuration diagram of an embodiment of the mass spectrometer according to the present invention. [Figure 2] Cross-sectional view showing a schematic configuration of the upper part of the main body of the radical generation unit in the present embodiment. [Figure 3] Cross-sectional view showing a schematic configuration of the lower part of the main body of the radical generation unit in the present embodiment. [Figure 4] Plan view of the pressing plate in the present embodiment. [Figure 5] Perspective view of the plunger in the present embodiment. [Figure 6] Perspective view of the sleeve in the present embodiment. [Figure 7] Perspective view of the first adjustment knob in the present embodiment. [Figure 8] Side view of the upper part of the main body of the radical generation unit in the present embodiment. [Figure 9] View showing a state where the helical antenna and the outer conductor part are electrically contacted in the present embodiment.

Mode for Carrying Out the Invention

[0018] Embodiments of the mass spectrometer according to the present invention will be described below with reference to the drawings.

[0019] <Outline configuration of mass spectrometer 1> Figure 1 is a schematic diagram of a mass spectrometer 1, which is one embodiment of the present invention. The mass spectrometer 1 of this embodiment is a quadrupole time-of-flight (Q-TOF) mass spectrometer equipped with an atmospheric pressure ion source. This mass spectrometer 1 can also be used as a liquid chromatograph mass spectrometer by connecting a liquid chromatograph (LC) to its preceding stage.

[0020] As shown in Figure 1, the mass spectrometer 1 of this embodiment has an ionization chamber 10 and a vacuum chamber 100. The ionization chamber 10 is in an atmosphere of approximately atmospheric pressure. The inside of the vacuum chamber 100 is divided into several (four chambers in this embodiment) sections, which, in order from the side closest to the ionization chamber 10, are the first intermediate vacuum chamber 11, the second intermediate vacuum chamber 12, the first analysis chamber 13, and the second analysis chamber 14. Each of these chambers is evacuated by a vacuum pump (rotary pump and / or turbomolecular pump) not shown, and the system has a multi-stage differential pumping configuration in which the vacuum level increases sequentially from the ionization chamber 10, which is in an atmosphere of approximately atmospheric pressure, to the second analysis chamber 14, which is in a high vacuum atmosphere.

[0021] The ionization chamber 10 is equipped with an electrospray ionization (ESI) probe 101 that applies an electric charge to a liquid sample and sprays it. The ESI probe 101 is introduced with a sample solution containing sample components separated by, for example, an LC column (not shown).

[0022] The ionization chamber 10 and the first intermediate vacuum chamber 11 are connected through a small-diameter desolvation tube 102. The first intermediate vacuum chamber 11 is composed of multiple rod electrodes arranged to surround the ion optical axis C, which is the central axis of the ion flight path, and an ion guide 111 is positioned near the ion optical axis C to focus the ions.

[0023] The first intermediate vacuum chamber 11 and the second intermediate vacuum chamber 12 are separated by a skimmer 112 having a small hole at its top. The second intermediate vacuum chamber 12 also has an ion guide 121, which is composed of multiple rod electrodes arranged to surround the ion optical axis C and focuses ions in the vicinity of the ion optical axis C.

[0024] In the first analysis chamber 13, along the ion optical axis C, a quadrupole mass filter 131 for separating ions according to their mass-to-charge ratio (m / z), a collision cell 132 containing a multipole ion guide 133, and an ion transport electrode 134 for transporting ions that have passed through the collision cell 132 are arranged. The quadrupole mass filter 131 and the multipole ion guide 133 are each composed of multiple rod electrodes. The ion transport electrode 134 is composed of multiple ring-shaped electrodes.

[0025] A radical generation unit 4 is connected to the collision cell 132. In the collision cell 132, ions are dissociated by radicals such as oxygen radicals supplied from the radical generation unit 4. The radical generation unit 4 will be described later. In addition to the radical generation unit 4, a gas supply unit can also be connected to the collision cell 132 as needed to supply a collision gas (usually an inert gas such as argon) to cause collision-induced dissociation.

[0026] The second analysis chamber 14 includes an ion transport electrode 141 for transporting ions incident from the first analysis chamber 13, an orthogonal acceleration unit 142 having a pair of extrusion electrodes and retraction electrodes arranged opposite each other across the optical axis C of the ions, an acceleration electrode 143 for accelerating the ions sent out into the flight space by the orthogonal acceleration unit 142, a reflectron electrode 144 that forms the folding trajectory of the ions in the flight space, an ion detector 145, and a flight tube 146 that forms the flight space inside. The ion detector 145 is, for example, an electron multiplier tube or a multichannel plate.

[0027] The mass spectrometer 1 in this embodiment further comprises a control / processing unit 5, an input unit 6, and a display unit 7. The control / processing unit 5 controls the operation of each of the above-mentioned units and has the function of receiving detection signals from the ion detector 145 and performing predetermined data processing. The control / processing unit 5 is configured, for example, by a general-purpose personal computer (PC), and various functions are realized by executing dedicated control / processing software installed on the computer using a processor.

[0028] An example of typical MS / MS analysis operation in the mass spectrometer 1 of this embodiment will be described.

[0029] The ESI probe 101 imparts an electric charge to the supplied liquid sample and sprays the liquid sample into the ionization chamber 10. The sample components in the sprayed charged droplets are ionized as the droplets are atomized and the solvent vaporizes. The ions generated from the sample components are drawn into the desolvation tube 102 by the gas flow formed by the pressure difference between the ionization chamber 10 and the first intermediate vacuum chamber 11 located on both sides of the desolvation tube 102, and sent to the first intermediate vacuum chamber 11. The ions that enter the first intermediate vacuum chamber 11 fly along the ion optical axis C, pass through the ion guide 111, the small holes in the skimmer 112, and the ion guide 121 in sequence, and are sent to the first analysis chamber 13, where they enter the quadrupole mass filter 131.

[0030] Multiple rod electrodes constituting the quadrupole mass filter 131 are subjected to a voltage obtained by superimposing a DC voltage and a high-frequency voltage from a power source (not shown). Only ions (precursor ions) having a specific mass-to-charge ratio (m / z) value corresponding to this applied voltage selectively pass through the quadrupole mass filter 131 and enter the collision cell 132. Radicals are supplied to the collision cell 132 from the radical generation unit 4, and the precursor ions introduced into the collision cell 132 react with the radicals and dissociate. The various product ions generated by dissociation are focused by the electric field formed by the multipole ion guide 133 as they pass through the collision cell 132, then sequentially pass through the ion transport electrode 134 and ion transport electrode 141, and enter the orthogonal acceleration unit 142.

[0031] A pulse voltage is applied to the electrodes of the orthogonal acceleration unit 142 at predetermined timings from a power source (not shown). The electric field formed between the extrusion electrode and the retraction electrode by the application of this pulse voltage causes the ions introduced into the orthogonal acceleration unit 142 to be ejected in a direction approximately perpendicular to the ion optical axis C. The ions ejected from the orthogonal acceleration unit 142 are accelerated by the acceleration electrode 143 and introduced into the flight space within the flight tube 146. Subsequently, the ions fold back due to the reflected electric field formed by the reflectron electrode 144 and reach the ion detector 145. The ion detector 145 outputs a detection signal to the control / processing unit 5 corresponding to the amount of incident ions. The flight time from the time the ions leave the orthogonal acceleration unit 142 until they reach the ion detector 145 depends on the velocity of the ions, and the ion velocity depends on the m / z value of each ion. The control / processing unit 5 creates a time-of-flight spectrum showing the relationship between flight time and ion intensity based on the detection signal obtained by the ion detector 145, and creates a mass spectrum by converting the flight time to a mass-to-charge ratio.

[0032] For example, when performing structural analysis of a known sample component, the mass-to-charge ratio of the precursor ion selected by the quadrupole mass filter 131 is set to the value of the mass-to-charge ratio of a representative ion of the target component. Product ions generated from specific precursor ions having this value are then comprehensively detected while being separated according to their mass-to-charge ratio. The resulting mass spectrum (product ion spectrum) shows product ions corresponding to various substructures of the target sample component molecule. The control and processing unit 5 can then perform structural estimation of the sample component by analyzing this mass spectrum.

[0033] <Configuration of radical generation section 4> Next, the configuration of the radical generation unit 4, which generates radicals to be supplied to the collision cell 132, will be described.

[0034] The radical generation unit 4 is an ECR-LICP type radical generation unit, and as shown in Figure 1, it has a main body 40 including a radical generation chamber 400, a raw material gas supply unit 48, and a microwave power supply 46. A valve 41 for adjusting the flow rate of the raw material gas is provided in the flow path from the raw material gas supply unit 48 to the radical generation chamber 400.

[0035] <Configuration of the main body 40> Next, the configuration of the main body 40 will be described. Figure 2 is a schematic cross-sectional view showing the structure of the upstream portion of the main body 40 (closer to the raw material gas supply section 48). Figure 3 is a schematic cross-sectional view showing the structure of the downstream portion of the main body 40 (closer to the collision cell 132).

[0036] The main unit 40 generates plasma using the raw material gas supplied from the raw material gas supply unit 48, and supplies the radicals generated in the plasma to the collision cell 132. The microwave power supply 46 supplies microwave power for generating the plasma. Examples of raw material gases include water vapor, oxygen gas, dry air, nitrogen gas, and hydrogen gas.

[0037] The main body 40 includes a central cylindrical tube 410 made of an insulator and dielectric such as quartz or alumina, a helical antenna 411 which is a strip-shaped conductor (usually metal) spirally wound around the central cylindrical tube 410, an outer conductor part 412 made of a conductor that is coaxial with the central cylindrical tube 410 and has an inner diameter larger than the outer diameter of the central cylindrical tube 410, magnets 413 and 415, a casing 414 that holds the outer conductor part 412, and a microwave supply connector 416 attached to the casing 414. For the helical antenna 411, for example, a material close to pure copper with high conductivity and formability (such as oxygen-free copper or tough pitch copper) is used. Furthermore, it is preferable that its surface be gold-plated to prevent oxidation.

[0038] A retaining plate 435 is attached to the upper surface of the outer conductor portion 412. The retaining plate 435 is a disc-shaped member as shown in Figure 4, with one opening 4351 in the center into which the central cylindrical tube 410 etc. is inserted, and four openings 4352 around it into which the support members 441 described later are inserted. The central opening 4351 is provided with a projection 4353 that restricts the rotation of the plunger 421 and sleeve 424 described later around the central axis of the central cylindrical tube 410.

[0039] Four support members 441 are erected on the upper surface of the outer conductor section 412, flanking a retaining plate 435, and a disc-shaped top plate member 442 is fixed to the upper end of each support member 441. The upper end of the central cylindrical tube 410 is inserted into the top plate member 442 and is connected to a flow path extending from the raw gas supply section 48. In addition, thrust washers 443 (only one is shown in Figure 2) are fixed at three equal intervals in the circumferential direction on the lower surface of the top plate member 442. In this embodiment, the support members 441, the top plate member 442, and the thrust washers 443 constitute the frame member 44. The top plate member 442 is made of a material that does not transmit light of wavelengths emitted from the light source 417 described later (such as aluminum alloy or stainless steel).

[0040] The interior of the central cylindrical tube 410 serves as a raw material gas introduction tube through which the raw material gas is introduced, and is also used as a radical generation chamber. Specifically, the portion of the internal space of the central cylindrical tube 410 around which the helical antenna 411 is wound and its vicinity becomes the radical generation chamber 400. The microwave supply connector 416 is a coaxial connector and is connected to the microwave power supply 46 via a coaxial cable (not shown). The conductive wire of the coaxial connector is connected to one end of the helical antenna 411. The outer conductor portion 412 is also grounded. As will be described later, a part of the helical antenna 411 and the outer conductor portion 412 are electrically connected, and the connection point becomes the grounding point of the helical antenna 411. The helical antenna 411, the outer conductor portion 412, the plunger 421, and the sleeve 424 (plunger 421 and sleeve 424 will be described later) constitute the resonator of the ECR. The microwave power supply 46 supplies power to this resonator via the coaxial cable and the microwave supply connector 416.

[0041] A light source 417 that irradiates the central cylindrical tube 410 with light of a predetermined wavelength and a photodetector 418 are provided in the casing 414, facing the radical generation chamber 400. The photodetector 418 detects light in a predetermined wavelength band that includes the wavelength of light emitted from the plasma in the radical generation chamber 400. It is preferable to use a photodetector 418 that is not sensitive to the light emitted from the light source 417. For example, an LED light source that emits deep ultraviolet light can be used as the light source 417. Alternatively, a photodiode that is sensitive to the visible light region (and does not detect ultraviolet light) can be used as the photodetector 418. As a result, the photodetector 418 detects plasma emission without being affected by the light emitted from the light source 417.

[0042] A transport pipe 47 is connected to the outlet end of the central cylindrical tube 410 of the main body 40 for transporting radicals generated in the radical generation chamber 400 to the collision cell 132. The transport pipe 47 is an insulating tube, and can be made of, for example, quartz glass or borosilicate glass.

[0043] On the outer circumference of the central cylindrical tube 410, a plunger 421 and a sleeve 424, which are cylindrical members, are arranged coaxially with the central cylindrical tube 410, in order from the inside out.

[0044] Figure 5 is a perspective view of the plunger 421. The plunger 421 has a shape that resembles two cylindrical parts of different diameters combined together. A portion of the outer circumference of the larger diameter cylindrical part located at the top is formed into a flat surface, and a scale 4213 in 1 mm units is engraved on this flat surface. In addition, screw threads (not shown in Figure 5) are formed on the outer circumference other than the flat surface. An elongated opening 4211 extending in the axial direction is provided on the side of the upper region of the smaller diameter cylindrical part located at the bottom. A projection 4353 provided on the retaining plate 435 is inserted into this opening 4211, thereby allowing the plunger 421 to move in the axial direction of the central cylindrical tube 410, but preventing it from rotating around this axis. Furthermore, the lower end of the plunger 421 is divided into multiple (four in this embodiment) slits parallel to the axis, each forming a divided piece 4212. Each segmented piece 4212 has a tapered portion 4213 formed at its tip, which gradually bulges outward from the base towards the tip.

[0045] Figure 6 is a perspective view of the sleeve 424. The sleeve 424 is a cylindrical member with a larger diameter than the plunger 421, and has elongated slits 4241 and 4242 formed at its upper and lower ends, respectively, extending in the direction of the central axis of the central cylindrical tube 410. A projection 4353 of the retaining plate 435 is inserted into the slit 4241 formed at the upper end of the sleeve 424, thereby preventing the sleeve 424 from rotating around the central axis of the central cylindrical tube 410. The lower part of the sleeve 424 is divided into multiple (four in this embodiment) sections by the slit 4242, each forming a segmented piece 4243.

[0046] Both the plunger 421 and the sleeve 424 are made of an elastically deformable conductive material (or a material whose surface is coated with a conductive material), and the segmented piece 4212 at the lower end of the plunger 421 and the segmented piece 4243 at the lower end of the sleeve 424 each function as a leaf spring. As such a material, for example, a copper alloy for springs (beryllium copper, phosphor bronze, etc.) can be used. In addition, it is preferable to gold plate the surfaces of the plunger 421 and the sleeve 424 in order to reduce contact resistance.

[0047] Furthermore, on the outer circumference of the central cylindrical tube 410, a first adjustment knob 431, a first anti-rotation nut 432, a second anti-rotation nut 433, and a second adjustment knob 434 are arranged coaxially with the central cylindrical tube 410, in order from the side closest to the top plate member 442 (upper side). In this embodiment, the first adjustment knob 431 corresponds to the rotating member in the present invention. The second adjustment knob 434 corresponds to the adjustment member in the mass spectrometer described in Section 3 below.

[0048] Figure 7 is a perspective view of the first adjustment knob 431 from below. The first adjustment knob 431 has a cylindrical body portion 4311 and a fixing portion 4312 extending from the upper surface of the body portion and having an L-shaped cross-section. The upper end of the fixing portion 4312 (the portion having a cross-section corresponding to the short side of the L-shape) is inserted between the top plate member 442 and three thrust washers 443. In this way, the first adjustment knob 431 is attached to the frame member 44 such that the position in the axial direction of the central cylindrical tube 410 is fixed and it is rotatable around the central axis. The first adjustment knob 431 is provided with a through hole 4313 into which the central cylindrical tube 410 and the plunger 421 are inserted, and a screw groove is formed on the inner surface of the through hole 4313 that engages with the screw threads formed on the outer circumference of the plunger 421.

[0049] The first anti-rotation nut 432, the second anti-rotation nut 433, and the second adjustment knob 434 also have screw grooves formed on their inner surfaces that engage with the screw threads formed on the outer circumference of the plunger 421. The first anti-rotation nut 432, the second anti-rotation nut 433, and the second adjustment knob 434 are not restricted from moving in the direction of the central axis of the central cylindrical tube 410. Therefore, when they are rotated, they move up and down in the direction of the central axis of the central cylindrical tube 410 relative to the plunger 421.

[0050] In this radical generation unit 4, radicals are generated as follows. The raw material gas supply unit 48 supplies the raw material gas to the central cylindrical tube 410. The microwave power supply 46 supplies a microwave current having a center frequency in the range of, for example, 2.4 GHz to 2.5 GHz to the helical antenna 411. Subsequently, with microwave power supplied from the microwave power supply 46 to the raw material gas in the radical generation chamber 400, deep ultraviolet light is irradiated onto the central cylindrical tube 410 from the light source 417. Upon receiving deep ultraviolet light, electrons are emitted from the wall surface of the central cylindrical tube 410, which is made of quartz, alumina, etc., and these electrons promote the generation of plasma in the radical generation chamber 400. At this time, if the resonator is adjusted so that the electron cyclotron frequency of electrons moving around the magnetic field formed by magnets 413 and 415 matches the microwave frequency, the plasma density increases and stabilizes due to the ECR. Radicals such as oxygen radicals generated inside the central cylindrical tube 410 are released from the open end of the central cylindrical tube 410 and supplied to the collision cell 132 through the transport pipe 47.

[0051] Deep ultraviolet light can harm the human eye. In this embodiment, the space from which deep ultraviolet light is irradiated from the light source 417 is covered by the casing 414. Furthermore, since the upper end of the central cylindrical tube 410 is covered by the top plate member 442, even if the deep ultraviolet light irradiated from the light source 417 is repeatedly reflected on the inner surface of the central cylindrical tube 410 and reaches the upper end of the central cylindrical tube 410, the reflected light does not leak to the outside of the main body 40. Therefore, the safety of the user's eyes from deep ultraviolet light emitted from the light source 417 can be ensured.

[0052] In this embodiment, as shown in Figure 9, the outer conductor portion 412 and the helical antenna 411 are electrically connected by a connecting member 42 having a plunger 421 and a sleeve 424, which is inserted between the helical antenna 411 and the outer conductor portion 412. The resonance state in the ECR resonator changes significantly depending on the position of the helical antenna 411 that is electrically connected to the grounded outer conductor portion 412. Therefore, it is required to adjust the connection position of the helical antenna 411 in millimeter units, more preferably in sub-millimeter units.

[0053] The following describes the procedure for adjusting the position in which the helical antenna 411 and the outer conductor portion 412 are electrically connected in this embodiment.

[0054] In the mass spectrometer 1 of this embodiment, a scale sticker 4314 is attached to the first adjustment knob 431 (see Figure 8) before use. This may be done, for example, by the manufacturer of the mass spectrometer, or by the user of the mass spectrometer 1 before starting to use the mass spectrometer 1. The scale sticker 4314 is the same length as the outer circumference of the first adjustment knob 431, and has the numbers 0 to 9 marked at equal intervals. For example, at the mass spectrometer manufacturer, with the plunger 421 rotated so that it is in a predetermined reference position (the position where the lower end of the first adjustment knob 431 coincides with the reference marked on the scale 4313), the scale sticker 4314 is attached so that the "0" on the scale sticker 4314 is positioned on the front of the top plate member 442. As described above, the plunger 421 has a scale 4213 marked in 1 mm increments. Furthermore, in this embodiment, the plunger 421 is designed to move 1 mm up or down by rotating the first adjustment knob 431 once. Therefore, by rotating the first adjustment knob 431 so that the number on the scale sticker 4314 attached to the first adjustment knob 431 changes by 1, the position of the plunger 421 in the axial direction of the central cylindrical tube 410 can be adjusted in increments of 0.1 mm.

[0055] To adjust the position where the helical antenna 411 and the outer conductor portion 412 are electrically connected, first, the first adjustment knob 431 is rotated. As described above, the first adjustment knob 431 is rotatable around the central axis of the central cylindrical tube 410 and is held by the frame member 44 so as not to move in the direction of the central axis. In addition, a screw groove is formed inside the through hole of the first adjustment knob 431 that engages with the screw threads formed on the outer circumference of the plunger 421. Furthermore, the projection 4353 of the retaining plate 435 is inserted into the opening 4211 provided in the plunger 421, so that the plunger 421 does not rotate around the central axis of the central cylindrical tube 410. In other words, each of these parts forms a feed screw mechanism, and by rotating the first adjustment knob 431 in a predetermined direction, the plunger 421 can be moved downward.

[0056] Next, the second adjustment knob 434 is rotated and moved downward. Since the outer shape of the sleeve 424 is larger than the diameter of the through hole of the second adjustment knob 434, when the second adjustment knob 434 moves downward, the lower surface of the second adjustment knob 434 also pushes down the sleeve 424. At this time, the divided piece 4243 provided at the lower end of the sleeve 424 pushes down the sleeve 424 to a position where it contacts the tapered portion 4213 at the tip of the divided piece 4212 provided at the lower end of the plunger 421. At this time, as shown in Figure 9, by pressing the lower end of the divided piece 4243 of the sleeve 424 against the tapered portion 4213 formed at the lower end of the divided piece 4212 of the plunger 421, both are elastically deformed outward and inward, respectively, causing the divided piece 4243 of the sleeve 424 to contact the outer conductor portion 412 and the divided piece 4212 of the plunger 421 to contact the helical antenna 411. As a result, the helical antenna 411 and the outer conductor portion 412 make electrical contact via the plunger 421 and the sleeve 424.

[0057] At this time, whether the matching is appropriate is determined by detecting the plasma emission state with the photodetector 418 when the raw material gas and microwave power are supplied to the radical generation chamber 400. In the mass spectrometer 1 of this embodiment, the position of the plunger 421 is adjusted by the first adjustment knob 431 and the sleeve 424 is moved by the second adjustment knob 434 to bring the helical antenna 411 into electrical contact with the outer conductor portion 412 at various points, and the optimal grounding position of the helical antenna 411 (the position in which it is electrically contacted with the outer conductor portion 412) is determined based on the plasma emission state (output signal from the photodetector 147) at each position.

[0058] Once the optimal grounding position for the helical antenna 411 is determined, the sleeve 424 is pushed down slightly further to elastically deform the segmented piece 4243 of the sleeve 424 further outward, bringing it into close contact with the outer conductor portion 412, and the segmented piece 4212 of the plunger further elastically deforms inward, bringing it into close contact with the helical antenna 411. As a result, the helical antenna 411 and the outer conductor portion 412 make electrical contact via the plunger 421 and sleeve 424, holding the helical antenna 411 in a grounded state.

[0059] Next, the first anti-rotation nut 432 is moved upward and brought into contact with the lower surface of the first adjustment knob 431. This fixes the first adjustment knob 431 so that it cannot rotate, thereby fixing the position of the plunger 421. Furthermore, the second anti-rotation nut 433 is moved downward and brought into contact with the upper surface of the second adjustment knob 434. This also fixes the second adjustment knob 434 so that it cannot rotate, thereby fixing the position of the sleeve 424.

[0060] Even when using the resonator adjustment mechanism described in Patent Document 3, it is possible to adjust the position in which the helical antenna electrically contacts the outer conductor. However, in the configuration of Patent Document 3, one hand holds the fixing knob provided at the base end of the inner cylinder (a component corresponding to the plunger 421 in this embodiment), while the other hand holds the movable knob provided at the base end of the outer cylinder (a component corresponding to the sleeve 424 in this embodiment), and the outer cylinder is advanced axially and pressed against the tip of the inner cylinder to fix it. As a result, when the outer cylinder is pressed against the tip of the inner cylinder, the inner cylinder is also advanced at the same time, which can easily cause misalignment, making it difficult to fine-tune the contact position between the helical antenna and the outer conductor.

[0061] In contrast, in this embodiment, when the sleeve 424 is moved downward, the plunger 421 is held in place by the first adjustment knob 431, and even when the sleeve 424 is pressed against the plunger 421, the plunger 421 does not move in the direction of the central axis of the central cylindrical tube 410. Therefore, the position adjusted in sub-millimeter increments according to the scale of the first adjustment knob 431 can be maintained.

[0062] Furthermore, in the configuration described in Patent Document 3, the contact between the helical antenna and the inner cylinder, and between the outer conductor and the outer cylinder, was maintained solely by frictional force. Therefore, vibrations caused by transporting the mass spectrometer would easily dissipate the contact between the two. In addition, when adjusting the grounding position of the helical antenna again, there was no reference point, so the grounding position of the helical antenna had to be adjusted through trial and error each time.

[0063] In contrast, in this embodiment, after the plunger 421 and sleeve 424 are brought into close contact with the helical antenna 411 and the outer conductor portion 412, respectively, at the optimal grounding position of the helical antenna 411, the first locking nut 432 and the second locking nut 433 are moved to contact the first adjustment knob 431 and the second adjustment knob 434, respectively, thereby fixing the first adjustment knob 431 and the second adjustment knob 434 in a non-rotatable state. Therefore, even if vibration occurs after the optimal grounding position of the helical antenna 411 has been determined, such as by moving the mass spectrometer, the contact state between the helical antenna 411 and the outer conductor portion 412 can be maintained. Furthermore, even if it becomes necessary to readjust the grounding position of the helical antenna, the grounding position of the helical antenna can be easily and reproducibly adjusted based on the millimeter scale 4213 engraved on the outer circumference of the plunger 421 and the sub-millimeter numbers inscribed on the scale sticker 4314 attached to the first adjustment knob 431.

[0064] Furthermore, in the configuration described in Patent Document 3, it was necessary to manufacture the fixing knob and male screw portion for holding the inner cylinder when adjusting its position integrally with the inner cylinder, which incurred significant costs for processing.

[0065] In contrast, in this embodiment, the plunger 421 and the first adjustment knob 431 and first anti-rotation nut 432 used for adjusting it are each made as separate components, so they can be manufactured at a low cost.

[0066] The above embodiments are merely examples and can be modified as appropriate in accordance with the spirit of the present invention. The shapes of the plunger 421, sleeve 424, first adjustment knob 431, second adjustment knob 434, first anti-rotation nut 432, second anti-rotation nut 433, and other parts in the above embodiments are merely examples, and parts of appropriate shapes made of appropriate materials can be used as long as they can realize the functions described in the above embodiments.

[0067] In the above embodiment, the rotation of both the plunger 421 and the sleeve 424 around the central axis of the central cylindrical tube 410 was restricted. However, it is sufficient that the rotation of at least the plunger 421 is restricted, and the rotation of the sleeve 424 does not need to be restricted. However, by restricting the rotation of both the plunger 421 and the sleeve 424 as in the above embodiment, the positions of the divided piece 4212 of the plunger 421 and the divided piece 4243 of the sleeve 424 can be aligned, allowing the helical antenna 411 and the outer conductor portion 412 to be in closer and more stable contact.

[0068] In the above embodiment, a mass spectrometer 1 equipped with a Q-TOF type mass separation unit was used, but any mass separation unit can be used. Also, in the above embodiment, an ion source equipped with an ESI probe 20 that generates ions from a liquid sample was used, but other atmospheric pressure ion sources can also be used. Alternatively, an ion source that generates ions in a vacuum atmosphere may be used. Furthermore, an ion source that generates ions from gaseous or solid samples can also be used. In addition, in the above embodiment, a collision cell 132 was used to react precursor ions with radicals, but other reaction chambers such as a three-dimensional ion trap may be used.

[0069] Furthermore, in the above embodiment, a light source 417 that irradiates a central cylindrical tube 410 made of quartz or aluminum oxide with ultraviolet light was used, but plasma may be generated without using the light source 417.

[0070] [Pattern] It will be obvious to those skilled in the art that the exemplary embodiments described above are specific examples of the following embodiments.

[0071] (Section 1) A mass spectrometer according to one aspect of the present invention is: A tube made of dielectric material, A helical antenna made of a conductor and wound around the outer circumference of the tube, A cylindrical member provided coaxially with the pipe on the outside of the pipe, comprising an outer conductor in which a magnet is embedded and whose inner surface is made of a conductive material, A frame member fixed to one end of the outer conductor and holding the pipe, A cylindrical member is attached to the frame member at a position opposite one end of the outer conductor, with its position in the axial direction of the central axis of the pipe fixed and rotatable around the central axis, and the rotating member has a through hole through which the pipe is inserted and which has a screw groove formed on its inner circumferential surface, A connecting member that is inserted into the gap between the helical antenna and the outer conductor and electrically connects the helical antenna and the outer conductor, comprising: an inner cylinder provided coaxially with the outside of the tube and fixed in a circumferential position with respect to the frame member; and an outer cylinder provided coaxially with the inner cylinder and on the outside of the inner cylinder, wherein leaf spring portions are provided at the tips of the inner and outer cylinders that bend inward and outward, respectively when pressed against each other, and a screw thread corresponding to the screw groove is formed on the outer circumference of the base end of the inner cylinder. It is equipped with.

[0072] The mass spectrometer according to paragraph 1 comprises a tube made of a dielectric material (dielectric tube) and a helical antenna made of a conductor wound around its outer circumference. In this radical generation unit, when in use, a raw material gas is supplied to the inside of the dielectric tube and high-frequency power is supplied to the helical antenna to generate a plasma of the raw material gas and generate radicals. The mass spectrometer according to paragraph 1 also has an ECR-LICP type configuration, which comprises a cylindrical member provided coaxially with the dielectric tube, having a magnet embedded in it and an outer conductor whose inner surface is made of a conductive material. The mass spectrometer according to paragraph 1 further comprises a connecting member for adjusting the position in which the helical antenna and the outer conductor are brought into contact and electrically connected. The resonance state of the ECR resonant circuit is adjusted by grounding the outer conductor and adjusting the position in which the helical antenna and the outer conductor come into contact with this connecting member.

[0073] The mass spectrometer according to paragraph 1 further has a frame member fixed to one end of the outer conductor and holding a dielectric tube. A cylindrical rotating member is attached to the frame member at a position opposite to one end of the outer conductor, such that its position is fixed in the axial direction of the dielectric tube and it is rotatable around the central axis. The rotating member has a through hole through which the dielectric tube is inserted, and screw grooves are formed on its inner circumferential surface.

[0074] The connecting member according to paragraph 1 comprises an inner cylinder whose circumferential position is fixed with respect to a frame member fixed to one end of the outer conductor, and an outer cylinder positioned outside the inner cylinder. The tips of the inner and outer cylinders are provided with leaf spring portions that bend inward and outward, respectively, when pressed together. Furthermore, screw threads corresponding to the screw grooves on the inner surface of the rotating member are formed on the outer circumference of the inner cylinder.

[0075] When adjusting the position where the helical antenna and the outer conductor come into contact, the base end of the inner cylinder is first attached to the through-hole of the rotating member. Then, with the tips of the outer and inner cylinders in contact, the inner cylinder is advanced in the axial direction of the dielectric tube by rotating the rotating member, and the position in which the helical antenna comes into electrical contact with the outer conductor and plasma is generated efficiently is determined. Once the position in which plasma is generated efficiently is determined, the outer cylinder is advanced axially relative to the inner cylinder, and the leaf spring portions provided at the tips of both are bent inward and outward, respectively, to bring the inner cylinder into close contact with the helical antenna and the outer cylinder into close contact with the outer conductor and fix them in place. In the mass spectrometer according to paragraph 1, the axial position of the inner cylinder is fixed by a rotating member that is fixed in the central axis direction of the dielectric tube by being held by a frame member fixed to the outer conductor, and the outer cylinder is advanced axially relative to the inner cylinder. Therefore, the position in which the helical antenna and the outer conductor come into electrical contact can be easily fine-tuned without causing displacement of the inner cylinder during the process.

[0076] (Section 2) The mass spectrometer relating to paragraph 2 is, in addition to the mass spectrometer relating to paragraph 1, A first anti-rotation member, which is positioned on the side of the rotating member where the connecting member is located, and which has a through hole in which a screw groove corresponding to the screw thread is formed. It is equipped with.

[0077] In the mass spectrometer described in paragraph 2, after determining the position of the inner cylinder by the rotating member, the first anti-rotation member is moved relative to the inner cylinder and brought into contact with the rotating member, thereby fixing the rotating member in a non-rotatable state and thereby permanently fixing the position of the inner cylinder.

[0078] (Section 3) The mass spectrometer relating to paragraph 3 is a mass spectrometer relating to paragraph 1 or 2, further comprising: An adjustment member is provided which is positioned on the side of the rotating member where the connecting member is located, and which has a screw groove corresponding to the screw thread and a through hole with a diameter smaller than the outer diameter of the outer cylinder, A second anti-rotation member is a member positioned on the opposite side of the adjusting member from the side where the connecting member is located, and is provided with a through hole having a screw groove corresponding to the screw threads. It is equipped with.

[0079] In the mass spectrometer described in paragraph 3, the outer cylinder is moved by moving the adjustment member to fix the position (grounding position) in which the helical antenna electrically contacts the outer conductor. Furthermore, the second anti-rotation member is moved relative to the inner cylinder and brought into contact with the adjustment member, thereby fixing the adjustment member in a non-rotatable position, and thereby permanently fixing the position of the outer cylinder. As a result, the grounding position of the helical antenna can be maintained even if vibrations occur in the mass spectrometer due to transportation or other reasons.

[0080] (Section 4) The mass spectrometer according to paragraph 4 is a mass spectrometer according to any of paragraphs 1 to 3, wherein the outer circumference of the inner cylinder is marked with a scale in the direction of the central axis.

[0081] According to the mass spectrometer described in paragraph 4, the inner cylinder can be moved in the central axis direction of the central cylindrical tube with good reproducibility based on the scale engraved on the outer circumference of the inner cylinder.

[0082] (Section 5) The mass spectrometer according to paragraph 5 is a mass spectrometer according to any of paragraphs 1 to 4, wherein the side surface of the rotating member has markings at positions that divide the outer circumference of the rotating member into two or more equal integers.

[0083] The distance the inner cylinder moves in the direction of the central axis of the central cylindrical tube by one rotation of the rotating member is constant. In the mass spectrometer according to paragraph 5, the inner cylinder can be moved in the direction of the central axis of the central cylindrical tube with good reproducibility in units of integer fractions of the said length, based on the scale attached to the side of the rotating member.

[0084] (Section 6) The mass spectrometer relating to paragraph 6 is a mass spectrometer relating to any of paragraphs 1 to 5, further comprising: A light source that irradiates light of a predetermined wavelength into the internal space of the portion of the tube around which the helical antenna is wound. Equipped with, The portion of the aforementioned pipe located closer to the raw material gas supply section than the portion surrounded by the inner cylinder is covered with a material that does not transmit light emitted from the light source.

[0085] In the mass spectrometer described in paragraph 6, light of a predetermined wavelength is irradiated into the inside of the tube, generating electrons from the tube and promoting plasma generation. Furthermore, since the light emitted from the light source does not leak out of the tube, there is no concern about harming the user's eyes.

[0086] (Section 7) The mass spectrometer relating to paragraph 7 is a mass spectrometer relating to any of paragraphs 1 to 6, wherein the rotating member, the inner cylinder, and the outer cylinder are each independent members.

[0087] In the mass spectrometer described in paragraph 7, the rotating member, inner cylinder, and outer cylinder are each made as independent components, eliminating the need to process parts into a complex structure and thus reducing manufacturing costs. [Explanation of Symbols]

[0088] 1...Mass spectrometer 100... Vacuum Chamber 10... Ionization Chamber 101…ESI probe 102... Desolvation tube 11…First intermediate vacuum chamber 111... Aeon Guide 112...Skimmer 12…Second intermediate vacuum chamber 121... Aeon Guide 13…1st analysis room 131... Quadrupole Mass Filter 132...Collision cell 133...Multipole Ion Guide 134... Ion transport electrode 14…Second analysis room 141... Ion transport electrode 142... Orthogonal acceleration section 143...acceleration electrode 144...Reflectron electrodes 145... Ion detector 146... Flight Tube 4…Radical generation section 40...Main body 400... Radical generation chamber 41… Valve 410...Central cylindrical tube 411... Helical antenna 412...Outer conductor section 413, 415... Magnets 414...Casing 416... Microwave supply connector 417...Light source 418... Photodetector 42…Connecting member 421... Plunger 4211…Aperture 4212...Split piece 4213...Tapered section 424... Sleeves 4241, 4242... Slit 4243…divided piece 431...First adjustment knob 4311...Main body 4312…Fixed part 4313... Through hole 4314... Seal 432...First anti-rotation nut 433...Second anti-rotation nut 434... Second adjustment knob 435... Retaining plate 4351, 4352…Aperture 4353…Protrusion 44…Frame members 441... Support member 442... Top panel component 443... Thrust washer 46... Microwave power supply 47...transport pipe 48… Raw material gas supply department 5…Control and Processing Unit 6...Input section 7…Display section C...Ion optical axis

Claims

1. A tube made of dielectric material, A helical antenna made of a conductor and wound around the outer circumference of the tube, A cylindrical member provided coaxially with the pipe on the outside of the pipe, comprising an outer conductor in which a magnet is embedded and whose inner surface is made of a conductive material, A frame member fixed to one end of the outer conductor and holding the pipe, A cylindrical member is attached to the frame member at a position opposite one end of the outer conductor, with its position in the axial direction of the central axis of the pipe fixed and rotatable around the central axis, and the rotating member has a through hole through which the pipe is inserted and which has a screw groove formed on its inner circumferential surface, A connecting member that is inserted into the gap between the helical antenna and the outer conductor and electrically connects the helical antenna and the outer conductor, comprising: an inner cylinder provided coaxially with the outside of the tube and fixed in a circumferential position with respect to the frame member; and an outer cylinder provided coaxially with the inner cylinder and on the outside of the inner cylinder, wherein leaf spring portions are provided at the tips of the inner and outer cylinders that bend inward and outward when pressed together, and a screw thread corresponding to the screw groove is formed on the outer circumference of the base end of the inner cylinder; A mass spectrometer equipped with the following features.

2. moreover, A first anti-rotation member, which is positioned on the side of the rotating member where the connecting member is located, and which has a through hole in which a screw groove corresponding to the screw thread is formed. The mass spectrometer according to claim 1, comprising:

3. moreover, An adjustment member is provided which is positioned on the side of the rotating member where the connecting member is located, and which has a screw groove corresponding to the screw thread and a through hole with a diameter smaller than the outer diameter of the outer cylinder, A second anti-rotation member is a member positioned on the opposite side of the adjusting member from the side where the connecting member is located, and is provided with a through hole having a screw groove corresponding to the screw threads. The mass spectrometer according to claim 1, comprising:

4. The mass spectrometer according to claim 1, wherein the outer circumference of the inner cylinder is marked with a scale in the direction of the central axis.

5. The mass spectrometer according to claim 1, wherein the side surface of the rotating member is marked with a scale at positions that divide the outer circumference of the rotating member into two or more equal integers.

6. moreover, A light source that illuminates the internal space of the portion of the tube around which the helical antenna is wound. Equipped with, The mass spectrometer according to claim 1, wherein the portion of the tube located closer to the raw material gas supply section than the portion surrounded by the inner cylinder is covered with a material that does not transmit light emitted from the light source.

7. The mass spectrometer according to claim 1, wherein the rotating member, the inner cylinder, and the outer cylinder are each independent members.

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