A rotary multi-stage separated dynode multiplication structure and a multiplier including the same

Abstract

The present invention belongs to the technical field of electron multipliers, and relates to a rotary multi-stage separated dynode multiplication structure, which includes a turntable, a plurality of rotary dynodes, and a fixed dynode arranged outside the turntable; the fixed dynode includes a first cathode plate, a grid, a first upper baffle connected to the upper end of the first cathode plate, and a first lower baffle connected to the lower end of the first cathode plate. The first cathode plate is an arc-shaped plate, and the grid is connected to the side of the first cathode plate; the rotary dynode includes a second cathode plate, a second upper baffle, and a second lower baffle. The second cathode plate has the same shape as the first cathode plate, and both the second upper baffle and the second lower baffle are leaf-shaped plates; the plurality of rotary dynodes includes N working dynodes and a spare dynode, and the turntable is connected with a rotating device. The spare dynode can replace the dynode with deteriorated performance, thereby prolonging the service life of the electron multiplier. By rotation, the problem of too rapid deterioration of the performance of the first-stage and last-stage dynodes can be solved, and the gain of the electron multiplier can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electron multipliers, and relates to a rotary multi-stage separated dynode multiplication structure and a multiplier including the same. Background Art

[0002] An electron multiplier is a vacuum electron device used for signal amplification, and its gain can reach 10 7 ~10 8 , and it has been widely used in mass spectrometry technology, vacuum technology, space exploration, and cesium atomic frequency standards. Electron multipliers are mainly divided into two categories in terms of structure: channel type and separated dynode type. Among them, the separated dynode electron multiplier is the most widely used due to its advantages such as high gain, high reliability, wide dynamic range, and long service life. The separated dynode electron multiplier generally adopts a multi-stage dynode structure. Incident particles bombard the secondary electron emitter on the surface of the dynode through high-voltage acceleration, and the obtained secondary electrons will continue to bombard the next-stage dynode under the action of the inter-stage acceleration electric field, thereby realizing electron multiplication. Omitting the loss of secondary electrons during inter-stage transfer, the total gain G = a*b n-1 , where n is the number of multiplier stages, a is the secondary electron emission coefficient of the first-stage dynode, and b is the secondary electron emission coefficient of other stages of dynodes. Since there is a large pressure difference between the emission source of incident particles and the first-stage dynode, the secondary electron emission coefficient of the first-stage dynode is different from that of other stages.

[0003] During the use of the electron multiplier, on the one hand, the electron beam continuously bombards the secondary electron emission material, causing radiation damage to the material and resulting in a decrease in the secondary electron emission performance of the material. On the other hand, pollutants will be adsorbed on the surface of the secondary electron emission material of the electron multiplier, thereby increasing the work function of the material surface, and the secondary electron emission coefficient will also decrease accordingly. Therefore, the gain of the electron multiplier will continuously decrease during use, and the output stability is not high. And when its gain drops to a certain set threshold, it will completely fail, and the service time before failure is the service life of the multiplier. The first-stage dynode or the last-stage dynode has the shortest service life, and the service life of the first-stage dynode or the last-stage dynode represents the service life of the electron multiplier. Summary of the Invention

[0004] The purpose of the present invention is to provide a rotary multi-stage separated dynode multiplication structure and a multiplier including the same to solve the problem of the short service life of the electron multiplier.

[0005] The present invention is realized through the following technical solutions:

[0006] A rotary multi-stage separated dynode multiplication structure includes a turntable, a plurality of rotary dynodes provided on the turntable, and a fixed dynode provided outside the turntable;

[0007] The rotating dynode includes a second cathode plate, a second upper baffle plate, and a second lower baffle plate. The second cathode plate has the same shape as the first cathode plate. Both the second upper baffle plate and the second lower baffle plate are leaf-shaped plates.

[0008] The plurality of rotating dynodes includes N working dynodes and one spare dynode. The turntable is connected to a rotating device.

[0009] Furthermore, the rotating device includes two working modes:

[0010] Working mode 1: Each time the power supply of the electron multiplier is turned on, the turntable is started to rotate at a preset angle.

[0011] Working mode 2: Only when the gain of the electron multiplier drops to a preset level, the turntable is started to rotate at a preset angle, and the spare dynode is used to replace the first or last dynode with degraded performance.

[0012] Furthermore, the leaf-shaped plate is formed by two arc-shaped plates with the straight line formed by the two end points of the arc where the second cathode plate is located as the center line.

[0013] Furthermore, the rotating device is arranged above the turntable. The turntable is connected to a rotating shaft, and the motor drives the turntable to rotate through the rotating shaft.

[0014] Furthermore, a contact electrode is provided below the turntable, an insulating substrate is provided below the contact electrode, the contact electrode is connected to a voltage dividing circuit, and the potential difference between every two consecutive working dynodes is the same.

[0015] The contact electrode includes a fixed contact electrode and a rotating contact electrode. The fixed contact electrode is arranged below the rotating contact electrode, and the rotating contact electrode is connected to the turntable.

[0016] Both the fixed contact electrode and the rotating contact electrode are hemispherical. The plane of the fixed contact electrode is arranged downward, and the plane of the rotating contact electrode is arranged upward.

[0017] Furthermore, the rotating dynode further includes a common grid, and the common grid is fixed on the turntable.

[0018] Furthermore, the fixed dynode includes a first cathode plate, a grid, a first upper baffle plate connected to the upper end of the first cathode plate, and a first lower baffle plate connected to the lower end of the first cathode plate. The first cathode plate is an arc-shaped plate, and the grid is connected to the side of the first cathode plate.

[0019] The first upper baffle plate and the first lower baffle plate have the same structure and are both fan-shaped plates.

[0020] The inner sides of the first cathode plate and the second cathode plate are both coated with a secondary electron emitter.

[0021] The present invention also discloses a linear multi-stage rotary separated dynode multiplier, which includes a collector, the rotary separated dynode multiplier structure, and a plurality of extended dynodes;

[0022] The rotary separated dynode multiplier structure is arranged at the incident end of the electron multiplier. The extended dynodes have the same structure as the fixed dynodes, and the collector is arranged at the outlet of the last extended dynode.

[0023] The present invention also discloses a linear multi-stage rotary separated dynode multiplier, which includes a collector, the rotary multi-stage separated dynode multiplier structure, and a plurality of extended dynodes;

[0024] The rotary multi-stage separated dynodes are arranged at the collection end of the electron multiplier. The extended dynodes have the same structure as the fixed dynodes, and the collector is arranged at the outlet of the rotary dynode at the last stage.

[0025] The present invention also discloses a linear multi-stage rotary separated dynode multiplier, which includes a collector, the rotary multi-stage separated dynode multiplier structure, and a plurality of extended dynodes;

[0026] The rotary multi-stage separated dynodes are arranged at the incident end and the collection end of the electron multiplier. The extended dynodes have the same structure as the fixed dynodes, and the collector is arranged at the outlet of the rotary dynode at the last stage.

[0027] Compared with the prior art, the present invention has the following beneficial technical effects:

[0028] The present invention discloses a rotary multi-stage separated dynode, which includes a turntable, a plurality of rotary dynodes arranged on the turntable, and fixed dynodes arranged outside the turntable. The rotary dynodes on the turntable can change their positions by rotation, and spare dynodes are arranged on the turntable. By adopting the rotary dynodes, the electron emission coefficient of each dynode is made more stable, improving the output stability of the electron multiplier; by adopting the spare dynodes, the dynodes with deteriorated performance can be replaced, prolonging the service life of the electron multiplier. Through rotation, the problem that the performance of the first-stage and last-stage dynodes deteriorates too fast during use can be solved, and the gain of the electron multiplier can be increased.

[0029] Furthermore, the rotation device includes two working modes: Working mode one, each time the power supply of the electron multiplier is turned on, the turntable is started to rotate by a certain angle, so that the first-stage and last-stage dynodes are different each time the multiplier works. In this way, the gain reduction of each rotary dynode is very weak, improving the output stability and prolonging the service life of the electron multiplier; in working mode two, only when the gain of the multiplier drops to a certain degree, the bottom disc is rotated to replace the severely deteriorated first-stage or last-stage dynode with a spare dynode, improving the service life of the multiplier.

[0030] Further, the rotary dynodes at various positions on the turntable are connected to the voltage dividing circuit by means of rotary contact electrodes and fixed contact electrodes to achieve a constant potential. The rotating disc drives the hemispherical rotary contact electrode below it to rotate. The fixed contact electrode is located below the rotary contact electrode. The reason for designing it as a hemispherical shape is that good electrical contact needs to be achieved between the upper rotary electrode and the lower fixed electrode to form a circuit. However, the contact area between the upper and lower electrodes should not be too large, otherwise the rotational friction will be very large, which is not conducive to rotation. Designing it as a hemispherical shape enables the two to have contact at the top of the sphere, and the contact area is very small.

[0031] Furthermore, adding a common grid to the rotary dynode will help focus the electrons. When the electron movement is too divergent, this structure can be used for improvement. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is the planar distribution diagram of the eight-stage rotary separation dynode of the present invention;

[0033] Figure 2 is the structure of the fixed dynode;

[0034] Figure 3 is the structure of the rotary dynode;

[0035] Figure 4 is the schematic diagram of the electrode connection of the rotary dynode on the disc;

[0036] Figure 5 is the three-dimensional solid diagram of the eight-stage rotary separation dynode electron multiplier of the present invention;

[0037] Figure 6 is the electron trajectory diagram of the eight-stage rotary separation dynode electron multiplier;

[0038] Figure 7 is the structure diagram of the linear multi-stage rotary separation dynode multiplier with the first-stage rotation;

[0039] Figure 8 is the structure diagram of the linear multi-stage rotary separation dynode multiplier with the last-stage rotation;

[0040] Figure 9 is the structure diagram of the linear multi-stage rotary separation dynode multiplier with the first-stage and last-stage rotations;

[0041] Figure 10 is the schematic diagram of the structure of adding a common grid to the rotary dynode.

[0042] Among them, 1 is the turntable, 2 is the rotary dynode, 3 is the fixed dynode, 4 is the collector, 5 is the rotating shaft, 6 is the rotary contact electrode, 7 is the fixed contact electrode, and 8 is the insulating substrate;

[0043] 21 is the second cathode plate, 22 is the second upper baffle, 23 is the second lower baffle, and 24 is the common grid;

[0044] 31 is the first cathode plate, 32 is the grid, 33 is the first upper baffle, and 34 is the first lower baffle. Detailed implementation mode

[0045] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following further elaborates in detail in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the described embodiments are only some embodiments of the present invention, rather than all embodiments.

[0046] The components described and illustrated in the drawings and embodiments of the present invention can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of the present invention provided in the following drawings is not intended to limit the scope of the present invention claimed, but only represents a selected embodiment of the present invention. Based on the drawings and embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts fall within the protection scope of the present invention.

[0047] It should be noted that: the term "comprising", "including" or any other variant is intended to cover non-exclusive inclusion, so that a process, element, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to the process, element, method, article or device. In addition, the terms "horizontal" and "vertical" are based on the orientation and positional relationship of the devices or components shown in the drawings, and are only for better describing the present invention, rather than requiring the devices, components or devices shown to have a specific orientation, so it cannot be understood as a limitation to the present invention.

[0048] The features and performance of the present invention are further elaborated in detail in combination with the following embodiments.

[0049] Embodiment 1

[0050] Taking an eight-stage rotary separated dynode as an example for illustration, as Figure 1 the planar distribution diagram of the eight-stage rotary separated dynode shown in Figure 5 and the three-dimensional solid diagram of the eight-stage rotary separated dynode electron multiplier shown in

[0051] In operating mode 1, each time the multiplier is started, the bottom disk will be rotated 90 degrees, thereby enabling the control of the four dynodes on the disk to alternately serve as the first dynode and the last dynode. In operating mode 2, the multiplier can operate normally for a long time. Only after the gain drops to a certain level, the bottom disk is rotated to rotate the dynode with degraded performance to the spare dynode position.

[0052] Refer to Figure 2 , which represents the fixed dynode structure outside the turntable 1, including: the first cathode plate 31, the first upper baffle 33, the first lower baffle 34, and the grid 32. The first cathode plate 31 is in the shape of an arc-shaped sheet and is made of stainless steel. The secondary emitter is made of a thin film material with a high secondary electron emission coefficient and covers the surface of the first cathode plate 31. The upper and lower baffles are fan-shaped thin sheets made of stainless steel to limit the longitudinal movement of electrons. The grid 32 is made of a good conductor. The voltage difference between adjacent grids 32 will accelerate the electrons to bombard the secondary emitter. At the same time, the grid 32 plays a role in focusing electrons and preventing the electrons from scattering.

[0053] Figure 3 It represents the structure of the rotating dynode 2, including three parts: the second cathode plate 21, the second upper baffle 22, and the second lower baffle 23. The second cathode plate 21 and the secondary emitter are the same in shape and material as the cathode plate and the secondary emitter of the fixed dynode 3. The upper and lower baffles of the rotating dynode 2 are in the shape of leaves, approximately elliptical thin sheets, and the material is stainless steel. The leaf-shaped plate is formed by two arc-shaped plates with the straight line formed by the two end points of the arc where the second cathode plate 21 is located as the center line.

[0054] Figure 4 It represents the electrode connection of the rotating dynode 2 on the disk. The lower part of the turntable 1 is a hemispherical rotating contact electrode 6, which is connected to a hemispherical fixed contact electrode 7 with the same sphere diameter. The fixed contact electrode 7 is connected to a specific voltage-dividing resistor in the circuit to ensure that the potentials of the dynodes at each position on the turntable 1 remain unchanged before and after rotation. Dynodes other than those on the turntable 1 can be directly connected to the corresponding voltage-dividing resistors through wires or conductors because their positions are fixed. Both the rotating contact electrode 6 and the fixed contact electrode 7 are made of good conductors.

[0055] Figure 6 It represents the electron trajectory diagram of the eight-stage rotary separated dynode electron multiplier, which is the schematic diagram of the electron movement in the first embodiment and also illustrates the rationality or feasibility of the first embodiment.

[0056] Embodiment 2

[0057] Such as Figure 10As shown, it is a structure similar to that of the first embodiment, but a grid is also designed for the rotating dynode, which is called the shared grid 24. The shared grid 24 of the rotating dynode is fixed and does not rotate with the bottom disk. After each rotating dynode rotates into place, the shared grid 24 will exactly fit with each rotating dynode. The spare dynode does not need to be designed with the shared grid 24 and only needs to follow the rotation. Adding the shared grid 24 to the rotating dynode will help focus the electrons. When the electron movement is too divergent, this structure can be used for improvement.

[0058] Embodiment Three

[0059] As Figure 7 shown, it is a linear multi-stage rotary separated dynode multiplier structure with the first-stage rotation. One end of the particle incident source is designed as the rotary structure of the first embodiment, which can slow down the performance degradation of the first-stage dynode of the electron multiplier and can conveniently expand the dynode to improve the multiplier gain, enabling more extensive applications.

[0060] Embodiment Four

[0061] As Figure 8 shown, it is a linear multi-stage rotary separated dynode multiplier structure with the last-stage rotation. One end of the collector 4 is designed as the rotary structure of the first embodiment, which can expand the dynode and slow down the performance degradation of the last-stage multiplier of the electron multiplier.

[0062] Embodiment Five

[0063] As Figure 9 shown, it is a linear multi-stage rotary separated dynode multiplier structure with the first-stage and last-stage rotation. Both the incident end and the collection end are designed as the rotary structures of the first embodiment, which can expand the dynode and simultaneously slow down the performance degradation of the first-stage and last-stage of the electron multiplier.

[0064] More preferably, the area of the middle turntable 1 can be enlarged so that more than four rotating dynodes 2 can be symmetrically placed thereon. By this method, the expansion of the dynode can also be achieved.

[0065] The electron multiplier proposed by the present invention has the following advantages:

[0066] (1) By using the turntable 1, the problem of rapid performance degradation of the first-stage and last-stage dynodes during use can be solved through rotation, and the gain of the electron multiplier can be improved.

[0067] (2) By using the rotating dynode 2, the electron emission coefficient of each dynode is made more stable, improving the output stability of the electron multiplier.

[0068] (3) By using the spare dynode, the dynode with performance degradation can be replaced, extending the life of the electron multiplier.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications or equivalent substitutions can still be made to the specific implementation manners of the present invention, and any modification or equivalent substitution that does not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A multiplier structure of a rotary multi-stage separated dynode, characterized in that, It includes a turntable (1), a plurality of rotation dynodes (2) with the same structure arranged on the turntable (1), and a fixed dynode (3) arranged outside the turntable (1); The fixed dynode (3) includes a first cathode plate (31), a grid (32), a first upper baffle (33) connected to the upper end of the first cathode plate (31), and a first lower baffle (34) connected to the lower end of the first cathode plate (31). The first cathode plate (31) is an arc-shaped plate, and the grid (32) is connected to the side of the first cathode plate (31); The rotation dynode (2) includes a second cathode plate (21), a second upper baffle (22), and a second lower baffle (23). The second cathode plate (21) has the same shape as the first cathode plate (31), and both the second upper baffle (22) and the second lower baffle (23) are leaf-shaped plates; The plurality of rotation dynodes (2) includes N working dynodes and one spare dynode, and the turntable (1) is connected with a rotating device; N = 3; The rotating device includes two working modes: Working mode 1: Each time the power supply of the electron multiplier is turned on, the turntable (1) is started to rotate at a preset angle; the next working dynode rotates to the electron source incident position and serves as the primary dynode; Working mode 2: Only when the gain of the electron multiplier drops to a preset level, the turntable (1) is started to rotate at a preset angle, and the spare dynode is used to replace the primary or final dynode with degraded performance; The preset angle is 90°; A contact electrode is arranged below the turntable (1), an insulating substrate (8) is arranged below the contact electrode, the contact electrode is connected with a voltage dividing circuit, and the potential difference between every two consecutive working dynodes is the same; The contact electrode includes a fixed contact electrode (7) and a rotating contact electrode (6). The fixed contact electrode (7) is arranged below the rotating contact electrode (6), and the rotating contact electrode (6) is connected with the turntable (1); Both the fixed contact electrode (7) and the rotating contact electrode (6) are hemispherical. The plane of the fixed contact electrode (7) is arranged downward, and the plane of the rotating contact electrode (6) is arranged upward.

2. The multiplier structure of a rotary multi-stage separated dynode according to claim 1, characterized in that The leaf-shaped plate is formed by two arc-shaped plates with the straight line formed by the two end points of the arc where the second cathode plate (21) is located as the center line.

3. A multiplier structure of a rotary multi-stage separated dynode according to claim 1, characterized in that, The rotating device is arranged above the turntable (1). The turntable (1) is connected with a rotating shaft (5), and the motor drives the turntable (1) to rotate through the rotating shaft (5).

4. A multiplier structure of a rotary multi-stage separated dynode according to claim 1, characterized in that, The rotation dynode (2) further includes a common grid (24), and the common grid (24) is fixed on the turntable (1).

5. A multiplier structure of a rotary multi-stage separated dynode according to claim 1, characterized in that, The first upper baffle (33) and the first lower baffle (34) have the same structure and are both sector-shaped plates; Both the inner sides of the first cathode plate (31) and the second cathode plate (21) are coated with a secondary electron emitter.

6. A linear multi-stage rotary discrete dynode multiplier, characterized in that, It includes a collector (4), the rotary separation dynode multiplication structure according to any one of claims 1 - 5, and a plurality of extended dynodes; The rotary separation dynode multiplication structure is arranged at the incident end of the electron multiplier. The extended dynode has the same structure as the fixed dynode (3), and the collector (4) is arranged at the outlet of the last extended dynode.

7. A linear multi-stage rotary type separating dynode multiplier, characterized in that, It includes a collector (4), the rotary multi-stage separation dynode multiplication structure according to any one of claims 1 - 5, and a plurality of extended dynodes; The rotary multi-stage separated dynode is arranged at the collection end of the electron multiplier. The extended dynode has the same structure as the fixed dynode (3), and the collector (4) is arranged at the outlet of the rotary dynode (2) at the last stage.

8. A linear multi-stage rotary type separating dynode multiplier, characterized in that, It includes a collector (4), the rotary multi-stage separated dynode multiplication structure according to any one of claims 1-5, and a plurality of extended dynodes; The rotary multi-stage separated dynode is arranged at the incident end and the collection end of the electron multiplier. The extended dynode has the same structure as the fixed dynode (3), and the collector (4) is arranged at the outlet of the rotary dynode (2) at the last stage.

Images