Channeltron electron multiplier and ion detector

Abstract

The CEM and ion detector of the present embodiment has a configuration for achieving ion detection with higher sensitivity than the prior art. The channel-type electron multiplier has at least a channel body, an input-side conductive layer, an output-side conductive layer, and an electrode. The channel body contains a channel having a tapered opening portion provided on the input side, and a resistance layer and an electron emission layer formed on the inner wall surface of the channel. The input-side conductive layer is provided on the input end surface of the channel body and a part thereof extends within the tapered opening portion. The output-side conductive layer is provided on the output end surface of the tapered opening portion. The electrode has one or more openings through which charged particles pass, and is disposed on the opposite side of the output end surface with respect to the input end surface. The electrode and the input-side conductive layer are set to the same potential by excluding the influence of an external electric field within the tapered opening portion.

Description

Technical Field

[0001] This invention relates to a channel-type electron multiplier and an ion detector containing the channel-type electron multiplier. Background Technology

[0002] As a detection device that can be used in quality analysis equipment, etc., ion detectors having a channel-type electron multiplier (hereinafter referred to as "CEM"), an input-side electrode (hereinafter referred to as "IN electrode") disposed on the input end face side of the CEM, an output-side electrode (hereinafter referred to as "OUT electrode") disposed on the output end face side of the CEM, and an anode for capturing electrons emitted from the output end face of the CEM are known, for example, as disclosed in Japanese Patent Application Publication No. 52-26150 (Patent Document 1) and Japanese Patent Application Publication No. 3-53443 (Patent Document 2). In addition, the above-mentioned CEM has a continuous (channel-type) multiplier electrode structure in which a resistive layer and an electron emission surface are stacked sequentially on the inner wall surface of the channel. In particular, in the aforementioned Patent Documents 1 and 2, in order to obtain the area of ​​the channel opening where charged particles (ions) guided from the external electrode to the ion detector arrive, an opening on the inner wall surface that is tapered (hereinafter referred to as "tapered opening") is provided at the input end of the channel in such a way that its cross-sectional area gradually decreases along the direction of ion travel.

[0003] Furthermore, Japanese Patent Application Publication No. 2011-181336 (Patent Document 3) discloses a grid electrode that is set in the ground potential (GND) as the aforementioned external electrode. Summary of the Invention

[0004] The inventors' research on the aforementioned prior art revealed the following problem: In recent years, improving detection efficiency has become an important requirement in quality analysis equipment used for counting, and the detection sensitivity obtained by the prior art as described above cannot meet this requirement.

[0005] Specifically, in CEMs, to obtain the area of ​​the channel opening (the possible detection area), it is effective to provide a specially shaped opening (a tapered opening with a cross-sectional area that gradually decreases from the input side to the output side) at the end of the channel. However, if the tapered opening is exposed to an external electric field, the intrusion of this external electric field will disturb the electrostatic field inside the tapered opening. In this case, the efficiency of attracting electrons (secondary electrons) generated inside the tapered opening to the output side of the channel is low, resulting in a decrease in detection sensitivity. In addition, since CEMs have a continuous (channel-type) multiplication electrode structure using a resistive film, a voltage drop also occurs inside the tapered opening. Under such circumstances, when ions reach the input side of the tapered opening, although the voltage that contributes to multiplication can be maximized (high-sensitivity detection), when ions reach the output side of the tapered opening, the voltage that contributes to multiplication is lost (low-sensitivity detection).

[0006] The present invention was implemented to solve the problems described above, and its object is to provide a CEM having a structure for achieving ion detection with higher sensitivity than the prior art, and an ion detector containing the CEM.

[0007] To address the aforementioned problems, the CEM (channel-type electron multiplier) according to this embodiment includes: a channel body, an input-side conductive layer, an output-side conductive layer, and electrodes. The channel body has: an input end face where charged particles (ions) arrive, an output end face opposite to the input end face, and at least one channel connecting the input end face and the output end face. Furthermore, a first resistive layer and a first electron emission layer are formed on the inner wall surface of the channel. The input-side conductive layer is disposed such that it continuously covers a portion of the input end face and the inner wall surface of the channel. The output-side conductive layer is disposed on the output end face such that at least a portion is located at the opening end of the channel. The electrodes are disposed on the opposite side of the output end face relative to the input end face and have at least one opening for allowing charged particles toward the input end face to pass through. Specifically, the channel includes a tapered opening having an opening end aligned with the input end face and an inner wall surface formed such that the cross-sectional area decreases from the input end face toward the output end face. Furthermore, the input-side conductive layer and the electrodes are set to the same potential. In this specification, the "cross-sectional area" of a tapered opening, etc., is defined on a plane perpendicular to the central axis of the channel body extending from the input end face toward the output end face.

[0008] The ion detector according to this embodiment includes at least a channel-type electron multiplier having the structure described above (the channel-type electron multiplier according to this embodiment).

[0009] Furthermore, the various embodiments of the present invention will be more fully understood from the following detailed description and accompanying drawings. These embodiments are merely examples and should not be considered as limiting the present invention.

[0010] Furthermore, the scope of application of this invention becomes clear from the following detailed description. However, while the detailed description and specific examples illustrate suitable embodiments of the invention, they are merely illustrative, and those skilled in the art can discover various modifications and variations within the scope of this invention from the detailed description. Attached Figure Description

[0011] Figure 1 (a) and Figure 1 (b) is a diagram illustrating the construction of a simulation model containing the main parts of the CEM.

[0012] Figure 2 This is a cross-sectional view used to illustrate the first structure of the ion detector involved in this embodiment.

[0013] Figure 3 This is a cross-sectional view used to illustrate the second structure of the ion detector according to this embodiment.

[0014] Figure 4 This is an assembly process diagram illustrating an example of the construction of the channel body in the CEM involved in this embodiment.

[0015] Figure 5 (a)~ Figure 5 (e) A diagram showing the appearance of the channel body and various variations in the CEM according to this embodiment.

[0016] Figure 6 (a) and Figure 6 (b) is a diagram showing the cross-sectional structure near the tapered opening in the channel body of the CEM according to this embodiment.

[0017] Figure 7 (a)~ Figure 7 (c) A diagram illustrating various cross-sectional structures applicable to the IN electrode of a CEM according to this embodiment.

[0018] Figure 8 (a) and Figure 8 (b) To show the applicable Figure 3 The graph shows the results of the measurement of the improvement rate of detection efficiency and the improvement rate of sensitivity for various CEM structures of ion detectors. Detailed Implementation

[0019] Figure 1 (a) and Figure 1(b) A diagram illustrating the construction of a simulation model containing the main components of a CEM (channel-type electron multiplier) prepared for prior art research, based on the inventors' conclusions as shown in the "Technical Problem to be Solved by the Invention" section above. In the simulation of the specific implementation, electrostatic field analysis was performed on three factors to improve the detection efficiency and sensitivity of the CEM: "external potential near the input-side opening," "presence or absence of a metal mesh (electrode) covering the input-side opening," and "presence or absence of an inserted electrode portion (part of the input-side conductive layer) disposed within the input-side opening." Furthermore, Figure 1 (a) is a 3D view of simulation model (basic model) 1. Figure 1 (b) is along as Figure 1 (a) is a cross-sectional view of the simulation model of line II shown in the figure.

[0020] like Figure 1 (a) and Figure 1 (b) shows that the simulation model 1 includes, for example, a model body 2 made of ceramic material. A channel 20 is provided in the model body 2 as the main part of the CEM. This channel 20 has an input end for ion arrival and an output end opposite to the input end, from which electrons multiplied in response to the input of ions are finally emitted. Furthermore, a resistive layer and an electron emission layer are sequentially stacked on the inner wall surface of the channel 20. The resistive layer and the electron emission layer are formed, for example, by atomic layer deposition (ALD). Further, the channel 20 consists of a tapered opening 20c located at the input end, and first and second passages 20a and 20b respectively disposed between the tapered opening 20c and the output end. The tapered opening 20c has an opening end consistent with the input end and an inner wall surface structure formed such that the cross-sectional area decreases from the input end to the output end. The first and second pathways 20a and 20b are two pathways connecting the output port of the conical opening 20c and the output end of the channel 20, respectively, with their respective input ports simultaneously connected to the output port of the conical opening 20c. Furthermore, an input-side conductive layer 21a connected to an IN electrode for setting a predetermined potential is provided on the input end of the channel 20 (coinciding with the opening end of the conical opening 20c), and an output-side conductive layer 21b connected to an OUT electrode is provided on the output end of the channel 20 (coinciding with the output ends of the first and second pathways 20a and 20b). Further, an external electrode 30 for guiding ions to the conical opening 20c of the channel 20 is provided within the model body 2. Additionally, as in... Figure 1 In the example shown in (b), region 40 is a region in the inner wall surface of the conical opening 20c where a portion of the input-side conductive layer 21a can be configured.

[0021] In this simulation model 1, the potential of the external electrode 30 is set to ground potential (GND), the potential of the input-side conductive layer 21a is set to -2000V, and the potential of the output-side conductive layer 21b is set to -100V. The distance from the external electrode 30 to the input end of the channel 20 (the opening end of the conical opening 20c) is 2mm, and the distance from the opening end of the conical opening 20c to the output port of the conical opening 20c (hereinafter referred to as the "cone length") is 6mm. The area of ​​the opening end of the conical opening 20c (the effective area of ​​the CEM) is 8mm × 7.2mm. Furthermore, the cone angle θ is 64°.

[0022] Electrostatic field analysis was performed on the first to third CEM structures derived from the simulation model 1 having the structure described above. Furthermore, in the first CEM structure, no grid electrode is disposed at the opening end of the conical opening 20c. Additionally, a portion of the input-side conductive layer 21a (insertion electrode) is not disposed in region 40. In the second CEM structure, no grid electrode is disposed at the opening end of the conical opening 20c. However, a portion of the input-side conductive layer 21a (insertion electrode) between the inner wall of the conical opening 20c and the resistive layer is disposed in region 40. In the third CEM structure, a grid electrode is disposed at the opening end of the conical opening 20c. However, a portion of the input-side conductive layer 21a (insertion electrode) is not disposed in region 40.

[0023] With the external electrode 30 removed, electrostatic field analysis in the first CEM structure confirms that the voltage inside the conical opening 20c also decreases. In this case, a voltage drop of several hundred volts is foreseeable when ions reach the output port of the conical opening 20c. That is, because the potential difference (hereinafter referred to as the "CEM voltage") from the input to the output of channel 20 cannot be utilized for electron multiplication, the designed gain cannot be obtained. In contrast, with the external electrode 30 removed, in the second CEM structure, a higher gain is expected due to the reduced voltage drop within the conical opening 20c.

[0024] Furthermore, in the first CEM structure with the external electrode 30 configured, the dead zone (the area where electrons generated inside the conical opening 20c cannot be introduced into the first and second pathways 20a and 20b) expands due to the influence of the external electric field on the electrostatic field inside the conical opening 20c (after electrostatic field analysis, it is confirmed that the external electric field penetrates into the conical opening 20c). On the other hand, the effective area shrinks (approximately 1 / 4 of the area at the opening end). In contrast, in the third CEM structure with the external electrode 30 configured, a grid electrode is configured on the opening end of the conical opening 20c. In this case, through electrostatic field analysis, it can be confirmed that the influence of the external electric field is eliminated (the entire conical opening 20c can be utilized as an effective area). That is, in the case of the third CEM structure, it is expected to obtain a detection efficiency four times that of the first CEM structure.

[0025] The above investigation confirms that the combination of voltage loss suppression (high gain) at the conical opening and shielding of the external electric field (ensuring the effective area) is effective for achieving higher sensitivity detection in ion detectors.

[0026] Hereinafter, the contents of each embodiment of the present invention will be described individually.

[0027] (1) The CEM (channel-type electron multiplier) according to this embodiment includes, in one embodiment, a channel body, an input-side conductive layer, an output-side conductive layer, and electrodes. The channel body has an input end face where charged particles (ions) arrive, an output end face opposite to the input end face, and at least one channel connecting the input end face and the output end face. In addition, a first resistive layer and a first electron emission layer are formed on the inner wall surface of the channel. The input-side conductive layer is provided in such a way that it continuously covers a portion of the input end face and the inner wall surface of the channel. The output-side conductive layer is provided on the output end face such that at least a portion is located at the opening end of the channel. The electrodes are disposed on the opposite side of the output end face relative to the input end face and have at least one opening for ions toward the input end face to pass through. In particular, the channel includes a tapered opening portion having an opening end that coincides with the input end face and is shaped such that the cross-sectional area decreases from the input end face to the output end face. In addition, the input-side conductive layer and the electrodes are set to the same potential.

[0028] As described above, in the CEM according to this embodiment, a portion of the input-side conductive layer (a conductor used to set the potential of the channel input terminal via the IN electrode) provided on the input end face is disposed as an insertion electrode within the tapered opening, thus effectively suppressing CEM voltage loss. Furthermore, the tapered opening has an opening at its opening end for ion passage and is equipped with an electrode at the same potential as the input-side conductive layer. Therefore, the influence of the external electric field on the electrostatic field inside the tapered opening is shielded, ensuring a sufficient effective area within the tapered opening.

[0029] (2) As one embodiment of this invention, preferably, a portion of the input-side conductive layer is directly disposed on the inner wall of the conical opening, in the input-side region that includes at least the opening end that coincides with the input end face.

[0030] (3) Alternatively, in one embodiment, the first resistive layer may be directly disposed on the inner wall of the conical opening, in an input-side region that includes at least an opening end aligned with the input end face, and the first electron emission layer may be directly disposed on the first resistive layer, with a portion of the input-side conductive layer directly disposed on the first electron emission layer. In such a cross-sectional structure, further, in one embodiment, the second resistive layer may be directly disposed on the input-side conductive layer, and the second electron emission layer may be directly disposed on the second resistive layer, in an input-side region that includes at least an opening end aligned with the input end face. Furthermore, in one embodiment, the second electron emission layer is preferably made of a high-gamma material. Specifically, in one embodiment, the second electron emission layer is preferably made of magnesium fluoride. Moreover, in the structure where a portion of the input-side conductive layer is directly disposed on the first electron emission layer, the fabrication of the CEM becomes easier because the patterning of the first resistive layer and the first electron emission layer is not required.

[0031] (4) As one embodiment of this invention, the length of a portion of the input-side conductive layer located within the tapered opening (hereinafter referred to as "insertion amount"), defined as the length along the central axis of the channel body extending from the input end to the output end, is preferably less than 1 / 2 of the tapered length of the tapered opening. This is because if the insertion amount of the input-side conductive layer exceeds 1 / 2 of the tapered length, the detection efficiency itself will decrease.

[0032] (5) As one embodiment, the electrode may also be in contact with the input-side conductive layer. In this case, as one embodiment, the electrode is preferably made of an elastic material. On the other hand, as one embodiment, the electrode may also be disposed in the space opposite to the output side of the input side, at a predetermined distance from the input-side conductive layer. Since these electrodes are set to the same potential as the input-side conductive layer, disturbances from the electrostatic field inside the conical opening (influence from external electric fields) can be avoided regardless of the electrode's placement.

[0033] (6) As one embodiment of this invention, the electrode preferably has a grid structure. In particular, the aperture ratio (the occupancy rate of the openings in the effective area where the grid is formed) of the grid electrode suitable for this embodiment is preferably 50% to 95%. In addition, the aperture ratio of the grid electrode may also vary partially (for example, a structure with different aperture ratios near the center and around the perimeter of the grid).

[0034] (7) The ion detector according to this embodiment includes, as one aspect, a CEM (the CEM according to this embodiment) having the structure described above, and an anode for capturing electrons emitted from the output end face of the CEM.

[0035] (8) Alternatively, the ion detector according to this embodiment may also include a CEM, a via, a Faraday cup, and an anode, as described above. The via allows ions to pass through the space where the CEM is disposed (the space defined by the frame of the ion detector). Therefore, the via forms part of the frame of the ion detector. The Faraday cup functions to block ions passing through the via that are directed towards the space other than the input end face of the CEM. The anode is an electrode that captures electrons emitted from the output end face of the CEM.

[0036] The methods listed above in the "[Description of Embodiments of the Invention]" section are applicable to all other methods, or to all combinations of these other methods.

[0037] The specific construction of the channel-type electron multiplier and ion detector according to the present invention will now be described in detail with reference to the accompanying drawings. Furthermore, the present invention is not limited to these examples, and all modifications within the scope of the claims are intended to be identical to or included within that scope. Additionally, the same reference numerals are used for the same elements in the description of the drawings, and repeated descriptions are omitted.

[0038] Figure 2 This is a cross-sectional view used to illustrate the first structure of the ion detector according to this embodiment. Furthermore, Figure 2 The text shows something equivalent to, for example, the text is incomplete and contains errors. A more accurate translation would require the full context. Figure 1(b) shows the cross-sectional structure. The ion detector 100A with the first structure includes a CEM (channel-type electron multiplier) and an anode 400. The CEM 200 has an input end face 210a arranged facing an external electrode 300 (with an opening for ions to pass through) for introducing ions (charged particles) into the CEM 200, and an output end face 210b located on the opposite side of the external electrode 300 relative to the input end face 210a. In addition, the CEM 200 is composed of a channel body 210, an input side electrode (hereinafter referred to as "IN electrode") 150 disposed in the channel body 210 on the ion arrival side (input end face 210a side), and an output side electrode (hereinafter referred to as "OUT electrode") 160 disposed in the channel body 210 on the opposite side of the IN electrode 150 (output end face 210b side). The anode 400 is disposed on the output end side of the channel body 210. Furthermore, when the ion detector 100A is used in a mass analysis device, the external electrode 300 is an electrode of the ion detector that is close to the mass separation section such as a quadrupole or ion trap, an opening provided between these mass separation sections and the ion detector 100A to shield external noise, and a lens that guides charged particles to the ion detector through the mass separation section.

[0039] The channel body 210 contains a channel 220 with a conical opening 230. The opening end of the conical opening 230 is aligned with the input end face 210a of the channel body 210, and the output port of the conical opening 230 is located inside the channel body 210 and connected to the output end face 210b of the channel body 210.

[0040] Additionally, an IN electrode 150 is mounted on one end of the channel body 210 containing the input end face 210a, and an OUT electrode 160 is mounted on the other end of the channel body 210 containing the output end face 210b.

[0041] The IN electrode 150 comprises a metal flange 151, a metal cap 152, a mesh electrode 153 (an electrode having one or more openings), a metal gasket 154, and a metal ring (made of...) for securing the IN electrode 150 itself to the channel body 210. Figure 5 (a) The pair of metal parts 155a and 155b shown in the diagram constitute the structure. One end of the metal flange 151 is fused to a groove near the input end face 210a in a groove provided on the side of the channel body 210 (e.g., Figure 5A metal ring (composed of a pair of metal parts 155a and 155b) is installed on the groove 251 shown in (a), with the other end extending toward the external electrode 300. One end of the metal cover 152 is fused to one end of the metal pad 154, which has a shape that accommodates the front end portion of the input end face 210a in the channel body 210 and is housed within the metal flange 151. Therefore, the input end face 210a of the channel body 210 is covered by the metal cover 152 while in contact with it. In addition, since the metal pad 154 is also fixed while in contact with the inner wall of the metal flange 151, the metal flange 151 and the metal cover 152 are electrically connected. The metal cover 152 is provided with an opening for exposing the opening end of the conical opening 230 of the channel 220, and a metal part (electrode) having one or more openings for ions to pass through the conical opening 230 is provided on the opening. This is because the presence of the external electrode 300 reduces the influence of the electrostatic field inside the conical opening 230. Furthermore, in Figure 2 In the example, these metal components (electrodes) are mesh electrodes 153 made of elastic material and fused to the open ends of the metal cap 152, with an opening ratio preferably of 50% to 95%. Alternatively, the mesh electrode 153 may have multiple types of openings with different areas. In this case, for example, a mesh electrode 153 with a higher opening ratio near the center of the mesh than in the surrounding area can be used.

[0042] Additionally, the IN electrode 150 includes an input-side conductive layer 510 for electrically connecting the metal cover 152 and the input end face 210a of the channel body 210. This input-side conductive layer 510 (forming a part of the IN electrode 150) is disposed on the input end face 210a and the inner wall of the tapered opening 230. Specifically, a portion of the input-side conductive layer 510 (hereinafter referred to as the "insertion electrode") extends continuously from the input end face 210a toward the output port of the tapered opening 230 on the inner wall surface of the tapered opening 230. Furthermore, in the presence of… Figure 2 In the examples shown in the figures, although only the insertion electrode (part of the input-side conductive layer 510) within the conical opening 230 is shown, the inner wall surface of the conical opening 230 is provided with... Figure 6 (a) or Figure 6 (b) shows the specific stacked structure (consisting of a conductive layer, an electron emission layer, and a resistive layer).

[0043] The grid electrode 153 is an electrode made of the elastic material described above. One end of the metal cover 152 is fused to a metal gasket 154 housed in the metal flange 15. The grid electrode 153, fused to the opening of the metal cover 152, is pressed into the input end face 210a of the channel body 210 (at the same potential as the grid electrode 153 and the inserted electrode portion constituting part of the input-side conductive layer 510). Specifically, the grid electrode 153 is made of an elastic material, and due to the restoring force of the grid electrode 153, it is tightly connected to the input-side conductive layer 510 (a stable contact state is maintained).

[0044] On the other hand, the OUT electrode 160 consists of a metal flange 161, a metal cap 162, a metal container for housing the anode 400 (composed of a hollow component 163a and a base 163b), a metal gasket 164, and a metal ring for fixing the OUT electrode 160 itself to the channel body 210 (composed of a metal flange 161, a metal cap 162, a metal container for housing the anode 400 (composed of a hollow component 163a and a base 163b), a metal gasket 164, and a metal ring for fixing the OUT electrode 160 itself to the channel body 210. Figure 5 (a) is composed of a pair of metal parts 165a and 165b shown.

[0045] One end of the metal flange 161 is fused to a groove in the side of the channel body 210 that is close to the output end face 210b (e.g., Figure 5 (a) The metal ring installed on the groove 252) shown in (a) is made of Figure 5 (a) A pair of metal parts 165a and 165b constitute the structure. One end of the metal cover 162 is fused to one end of the metal pad 164, which has a shape capable of receiving the front end portion of the channel body 210 having the output end face 210b and is fixed in contact with the metal flange 161. Furthermore, the metal cover 162 has an opening on the output end face 210b for exposing the output port of the channel 220. Further, with the front end portion of the channel body 210 including the output end face 210b received, one end of the metal cover 162 is fused to the metal pad 164 fixed to the metal flange 161. Therefore, the output-side conductive layer 520 and the metal cover 162 are tightly connected (the output-side conductive layer 520 and the metal cover 162 are set to the same potential).

[0046] A housing defining the receiving space for the anode 400 is fused to the metal flange 161 of the OUT electrode 160. This housing consists of a hollow component 163a and a base 163b. One end of the hollow component 163a is directly fused to the metal flange 161, and the other end is fixed to the base 163b. The base 163b holds the pin 131 by an insulating material 132, and the anode 400 is fused to one end of the pin 131 extending within the hollow component 163a.

[0047] Figure 3This is a cross-sectional view used to illustrate the second structure of the ion detector according to this embodiment. Furthermore, Figure 3 It also shows the equivalent of, for example Figure 1 (b) shows the cross-sectional structure. The second-structured ion detector 100B includes a perforated component 110, a Faraday cup 120, a CEM 200, and an anode 400. The perforated component 110 forms part of the container of the ion detector 100B and has an opening for allowing ions to pass from the outside of the container to the inside. The Faraday cup 120 functions to prevent ions absorbed through the perforated component 110 from moving to the outside of the ion detector 100B. The CEM 200 is disposed in the space between the Faraday cup 120 and the anode 400, and... Figure 2 The example is the same, consisting of an IN electrode 150, a channel body 210, and an OUT electrode 160. More specifically, the CEM200 includes a metal mesh electrode 153 that forms part of the IN electrode 150, an input-side conductive layer 510 (forming part of the IN electrode 150) disposed on the input end face 210a of the channel body 210 and on the inner wall surface of the tapered opening 230, and an output-side conductive layer 520 (forming part of the OUT electrode 160) disposed on the output end face 210b of the channel body 210 when in contact with the output end (opening end) of the channel 220.

[0048] In addition, the Faraday cup 120, CEM 200, and anode 400 are housed within the container (including the orifice component 110) of the ion detector 100B.

[0049] Figure 4 For the purpose of illustrating the CEM involved in this embodiment ( Figure 2 and Figure 3 An assembly process diagram of an example of the construction of the channel body 210 on the CEM200 is shown.

[0050] like Figure 4 As shown, the channel body 210 is made of, for example, ceramic material and consists of n (an integer) parallel plates 2121-212n and a pair of auxiliary components 210A and 210B. The parallel plates 2121-212n and the auxiliary components 210A and 210B are integrally formed by stamping and sintering. Furthermore, after stamping and sintering, the unwanted peripheral portions of each of the parallel plates 2121-212n are removed along the shear line 250, indicated by the dashed line. Additionally, the parallel plates 2121-212n are each provided with a pattern of channels 220 containing tapered openings 230. This pattern is defined by the cross-sectional shape of a hole penetrating each parallel plate from one main surface to the other.

[0051] Figure 5 (a)~ Figure 5(e) A diagram illustrating the appearance and various variations of the channel body 210 in CEM200. Specifically, Figure 5 (a) shows the contents as described above Figure 4 The assembly process shown represents the main part of the CEM200 of the channel body 210 obtained.

[0052] The channel body 210, in which parallel plates 2121-212n and auxiliary components 210A and 210B are integrated, has a groove 251 on its side for fixing the IN electrode 150 near the input end face 210a located at the opening end of the tapered opening 230. On the other hand, the channel body 210 has a groove 252 on its side for fixing the OUT electrode 160 near the output end face 210b. Here, a metal ring for fixing the IN electrode 150 to the channel body 210 is embedded in the groove 251. Figure 5 In example (a), the metal ring is composed of a pair of metal parts 155a and 155b. Additionally, a metal ring for securing the OUT electrode 160 to the channel body 210 is embedded in the groove 252. Figure 5 In example (a), the metal ring is composed of a pair of metal parts 165a and 165b.

[0053] In addition, multiple channels can be set up within the main channel body 210. Figure 5 (b)~ Figure 5 (e) To observe the above as follows Figure 5 (a) is a front view of the input end face 210a of the channel body 210 shown, which shows various channel configuration patterns on the input end face 210a. Figure 5 (b) shows that in such Figure 5 (a) shows a channel body 210 with a channel configuration pattern, and a tapered opening 230 of a channel 220 is provided on the input end face 210a. Figure 5 In example (b), the opening end of the conical opening 230 is rectangular, and there are no technical restrictions on its shape (the shape can be chosen arbitrarily). Furthermore, Figure 5 (c) shows a configuration pattern in which two channels are provided in the channel body 210, and conical openings 231a and 231b with square opening ends are provided on the input end face 210a. Figure 5 (d) also shows a configuration pattern in which two channels are provided within the channel body 210, with tapered openings 232a and 232b, each having a rectangular opening end, disposed on the input end face 210a. Furthermore, Figure 5 (e) shows a configuration pattern in which three channels are provided in the channel body 210, and conical openings 233a, 233b, and 233c with rectangular opening ends are provided on the input end face 210a.

[0054] Figure 6 (a) and Figure 6 (b) is a diagram showing the cross-sectional structure near the tapered opening 230 in the channel body 210 of the CEM according to this embodiment. Furthermore, Figure 6 (a) and Figure 6 (b) shows the equivalent of Figure 1 Construction on the cross section shown in (b).

[0055] The first stacked structure applicable to the CEM200 involved in this embodiment is as follows: Figure 6 As shown in (a), an insertion electrode (part of the input-side conductive layer 510) is directly disposed on the inner wall of the tapered opening 230, extending from the input end face 210a toward the output port of the tapered opening 230. A first resistive layer 610 is disposed on the insertion electrode. This first resistive layer 610 is also directly disposed on the inner wall of the channel 220, which extends from the front end of the insertion electrode to the output port of the channel 220 located on the output end face 210b. Furthermore, a first electron emission layer 620 covering the entire first resistive layer 610 is disposed on the first resistive layer 610.

[0056] On the other hand, it can be applied to the second stacked structure of CEM200 involved in this embodiment, such as Figure 6 (b) The first resistive layer 610 shown is directly disposed on the inner wall of the channel 220 from the input end face 210a to the output end face 210b. Further, a first electron emission layer 620 is disposed on the first resistive layer 610 in such a manner that it covers the entire first resistive layer 610. The insertion electrode (a part of the input-side conductive layer 510) is disposed directly on the first electron emission layer 620 from the input end face 210a toward the output port of the conical opening 230. A second resistive layer 710 is disposed on the insertion electrode, and further, a second electron emission layer 720 is disposed on the second resistive layer 710. Here, the second electron emission layer 720 is preferably made of, for example, a high-gamma material such as MgF2 (magnesium fluoride). (High gamma refers to a high gamma value (calculated as "number of secondary electrons emitted / number of incident ions") when ions accelerated at a specified voltage are incident. Figure 6 In the example of (b), the first resistive layer 610 is constructed to directly cover the entire inner wall surface of the channel 220. Therefore, patterning of the layers (conductive and resistive layers) disposed on the inner wall surface of the channel 220 becomes unnecessary. As a result, as... Figure 6 (b) shows a stacked structure, such as Figure 6 The fabrication of the layered structure shown in (a) becomes easier.

[0057] exist Figure 6 (a) and Figure 6In any of the examples in (b), the insertion depth of the inserted electrode (similar to the tapered length, the length defined along the central axis of the tapered opening 230 through the output port) is preferably less than 1 / 2 of the tapered length. Furthermore, the tapered length is as follows: Figure 1 As shown in (b), the distance from the opening end of the tapered opening (which coincides with the input end face 210a of the channel body 210) to the output port of the tapered opening is defined.

[0058] Figure 7 (a)~ Figure 7 (c) A diagram illustrating various cross-sectional structures that can be applied to the CEM involved in this embodiment near the IN electrode. Furthermore, in Figure 7 (a)~ Figure 7 (c) shows the equivalent of, as in Figure 1 The construction on the cross-section shown in (b). Additionally, in Figure 7 In example (a), due to the substantial detail as... Figure 2 The structure near IN electrode 150 shown illustrates the assembly process diagram.

[0059] Figure 7 (a) shows the state before and after the metal cap 152 is fused to the metal flange 151 constituting the IN electrode 150. That is, at the front end of the channel body 210 containing the input end face 210a (the position where the groove 251 is provided), the metal flange 151 is fixed to the channel body 210 by fusing one end of the metal flange 151 to a metal ring composed of a pair of metal parts 155a and 155b. At this time, the metal liner 154 inside the metal flange 151 is fixed (conductive state). An input-side conductive layer 510 is provided on the input end face 210a of the channel body 210 and the inner wall surface of the conical opening 230 (from the input end face 210a to near the center of the inner wall of the conical opening 230). A portion of the input-side conductive layer 510 located on the inner wall of the conical opening 230 functions as an insertion electrode.

[0060] The metal cap 152 has an opening for exposing the conical opening 230. The grid electrode 153, made of an elastic material, is fused to the opening end of the metal cap 152 when bent so as to protrude toward the output port of the conical opening 230. Here, the opening ratio of the grid electrode 153 is preferably 50% to 95%. Alternatively, the grid electrode 153 may have multiple types of openings with different areas. For example, a grid electrode 153 with a higher opening ratio near the center of the grid than in the surrounding area can also be used. Furthermore, one end of the metal cap 152 with the bent grid electrode 153 is fused to a metal gasket 154 fixed inside the metal flange 151. At this time, the metal cap 152 is pressed into the input-side conductive layer 510 provided on the input end face 210a. Therefore, the grid electrode 153 deforms, and through the restoring force of the grid electrode 153, the grid electrode 153 and the input-side conductive layer 510 are tightly connected.

[0061] In addition, Figure 7 In example (a), although the grid electrode 153 is directly disposed on the input end face 210a of the channel body 210 through the input-side conductive layer 510, the grid electrode 153 may also not be directly disposed on the input end face 210a of the channel body 210. That is, Figure 7 In example (b), in the aspect that the grid electrode 153 is positioned at a distance offset from the input end face 210a only by a predetermined distance, compared with Figure 7 The example in (a) is different. Figure 7 In example (b), the metal plate 156, on which the grid electrode 153 is provided at the open end, is not fused to the opening of the metal cover 152 but is fused to the other end of the metal flange 151. Since either the metal flange 151 or the metal cover 152 is also a metal component constituting part of the IN electrode 150, ... Figure 7 Similar to example (a), the grid electrode 153 and the input-side conductive layer 510 are set to the same potential. Therefore, the electrostatic field inside the tapered opening 230 becomes difficult to be affected by an external electric field through the grid electrode 153. Furthermore, as... Figure 7 (b) The construction of the IN electrode 150 shown, except for the arrangement of the grid electrode 153, is similar to that of... Figure 7 The IN electrode 150 shown in (a) has the same structure.

[0062] exist Figure 7 In example (c), the alternative Figure 7(a) The grid electrode 153 uses a hole component 157 having an opening 157a for ion passage. This hole component 157 is fused to the metal cap 152 in a manner that covers the opening of the metal cap 152, and the hole component 157 is set to the same potential as the input-side conductive layer 510. In particular, when the ion trajectory reaching the conical opening 230 is restricted (when the beam diameter of the input ion beam is smaller than the opening diameter of the conical opening 230), since the ion permeability is better than that of the grid electrode 153, such a hole component 157 is preferably used as the construction of the IN electrode 150. Furthermore, as... Figure 7 (c) shows the IN electrode 150, which differs from the mesh electrode 153 and the hole component 157 in its construction, as shown in the figure. Figure 7 The IN electrode 150 shown in (a) has the same construction.

[0063] Figure 8 (a) and Figure 8 (b) is about Figure 3 The various configurations used in the ion detectors are shown, along with graphs illustrating the measurement results of the improvement in detection efficiency and sensitivity. Furthermore, in this specification, "detection efficiency" is defined as output current / (input ion current × CEM gain) × 100. Additionally, "sensitivity" refers to the substantial gain obtained by the ion detector.

[0064] Figure 8 (a) shows that Figure 3 Measurement results for the ion detector 100B shown, regarding the configuration in which no insertion electrode (part of the input-side conductive layer 510) is provided within the conical opening 230. Figure 8 In (a), graph G810A shows the measurement results for the reference structure without the grid electrode 153 (equivalent to the first CEM structure described above), and graph G810B shows the measurement results for the structure with the grid electrode 153 disposed at the opening end of the tapered opening 230 (equivalent to the third CEM structure described above). Furthermore, Figure 8 (a) The vertical axis shows the magnification based on the measurement results shown in Chart G810A.

[0065] On the other hand Figure 8 (b) shows that Figure 3 Measurement results regarding the structure of the ion detector 100B shown, in which a grid electrode 153 is provided within the opening end of the conical opening 230. Figure 8In (b), Figure G820A shows the measurement results for a reference structure with only the grid electrode 153 (equivalent to the third CEM structure described above), while Figures G820B to G820D show the measurement results for a structure with an insertion electrode provided in the input-side conductive layer 510 (a structure combining the second and third CEM structures described above). Specifically, Figure G820B shows the measurement results for a structure where the insertion amount of the insertion electrode is set to 3 / 4 of the tapered length, Figure G820C shows the measurement results for a structure where the insertion amount of the insertion electrode is set to 1 / 4 of the tapered length, and Figure G820D shows the measurement results for a structure where the insertion amount of the insertion electrode is set to 1 / 2 of the tapered length. Furthermore, Figure 8 (b) The vertical axis shows the graph G820A (which is essentially the same as...) Figure 8 The measurement results shown in (a) (consistent with Chart G810B) are the benchmark magnification.

[0066] In the absence of a structure for inserting electrodes within the conical opening 230, by Figure 8 (a) It can be seen that in the structure using the grid electrode 153, the detection efficiency is improved by an average of 3.1 times compared to the structure without the grid electrode 153. Furthermore, in the case of the structure using the grid electrode 153, such as Figure 8 As shown in (b), in the structure where the insertion depth of the insert electrode is set to 1 / 2 of the cone length, the sensitivity is improved by 7.4 times compared to the structure without an insert electrode in the cone opening 230. Based on the above measurement results, by employing "the introduction of insert electrodes" and "the use of grid electrodes (electrodes with more than one opening)," the sensitivity can be improved by up to approximately 23 times compared to existing structures without these insert electrodes and grid electrodes.

[0067] As described above, according to this embodiment, by arranging a portion (insertion electrode) of the input-side conductive layer provided on the input end face within the tapered opening on the input side of the channel, the loss of the CEM voltage defined by the voltage difference between the IN electrode (input-side electrode) and the OUT electrode (output-side electrode) can be reduced (gain improvement). Furthermore, by arranging electrodes having one or more openings at the same potential as the input-side conductive layer at the opening end of the tapered opening, it becomes possible to ensure that there is a sufficient effective area within the tapered opening (avoiding the influence of external electric fields).

[0068] From the foregoing description of the present invention, it is evident that various modifications can be made to the invention. Such modifications do not depart from the spirit and scope of the invention, and all improvements that will be apparent to those skilled in the art are within the scope of the following claims.

Claims

1. A channel-type electron multiplier comprising: a channel body having an input face to which a charged particle arrives, an output face opposite to the input face, at least one channel connecting the input face and the output face, and a first resistance layer and a first electron emission layer formed on an inner wall surface of the channel; an input-side conductive layer provided so as to continuously cover the input face and a part of the inner wall surface of the channel; an output-side conductive layer provided on the output face so that at least a part thereof is located at an opening end of the channel; and an electrode disposed on the opposite side of the output face with respect to the input face and having at least one opening through which the charged particle toward the input face passes, wherein the channel includes a tapered opening portion having an opening end coinciding with the input face and an inner wall surface shaped so as to decrease in cross-sectional area from the input face toward the output face, and wherein the input-side conductive layer and the electrode are set to the same potential.

2. The channel-type electron multiplier according to claim 1, wherein a part of the input-side conductive layer is directly provided on the inner wall of the tapered opening portion in an input-side region of the tapered opening portion at least including the opening end coinciding with the input face.

3. The channel-type electron multiplier according to claim 1, wherein the first resistance layer is directly provided on the inner wall of the tapered opening portion in an input-side region of the tapered opening portion at least including the opening end coinciding with the input face, the first electron emission layer is directly provided on the first resistance layer, and a part of the input-side conductive layer is directly provided on the first electron emission layer.

4. The channel-type electron multiplier according to claim 3, wherein a second resistance layer is directly provided on the input-side conductive layer in an input-side region of the tapered opening portion at least including the opening end coinciding with the input face, and a second electron emission layer is directly provided on the second resistance layer.

5. The channel-type electron multiplier according to claim 4, wherein the second electron emission layer is composed of a high gamma material.

6. The channel-type electron multiplier according to claim 5, wherein the second electron emission layer is composed of magnesium fluoride.

7. The channel-type electron multiplier according to any one of claims 1 to 6, wherein a length of a part of the input-side conductive layer located within the tapered opening portion is 1 / 2 or less of a tapered length of the tapered opening portion, as a length defined along a central axis of the channel body extending from the input face toward the output face.

8. The channel-type electron multiplier according to any one of claims 1 to 6, wherein the electrode is in contact with the input-side conductive layer.

9. The channel-type electron multiplier according to claim 8, wherein the electrode is composed of an elastic material.

10. The channel-type electron multiplier according to any one of claims 1 to 6, wherein ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The electrode is arranged in a space on the opposite side of the output surface from the input surface and at a position separated by a prescribed distance from the input-side conductive layer.

11. The channel electron multiplier according to any one of claims 1 to 6, wherein The electrode has a mesh configuration.

12. The channel electron multiplier according to claim 7, wherein The electrode has a mesh configuration.

13. The channel electron multiplier according to claim 8, wherein The electrode has a mesh configuration.

14. The channel electron multiplier according to claim 9, wherein The electrode has a mesh configuration.

15. The channel electron multiplier according to claim 10, wherein The electrode has a mesh configuration.

16. An ion detector comprising: The channel electron multiplier according to any one of claims 1 to 15; and An anode for capturing electrons emitted from the output surface of the channel electron multiplier.

17. An ion detector comprising: The channel electron multiplier according to any one of claims 1 to 15; An aperture member for passing the charged particles toward a space in which the channel electron multiplier is arranged; A Faraday cup for shielding charged particles among the charged particles that pass through the aperture member toward a space other than the input surface of the channel electron multiplier; and An anode for capturing electrons emitted from the output surface of the channel electron multiplier.

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