A multi-layer nested electrostatic analyzer

Abstract

The present application relates to the technical field of space physics and space environment detection, and relates to a multi-layer nested electrostatic analyzer, which comprises a shielding grid, an electrostatic deflection device, a trajectory guiding device, a hemispherical multi-layer concentric grid electrode, a microchannel plate, a position sensitive anode, an electronic processor and a device shell; the device shell is arranged on the electronic processor, the shell opening is covered by the shielding grid, and the electrostatic deflection device, the trajectory guiding device, the hemispherical multi-layer concentric grid electrode, the microchannel plate and the position sensitive anode are arranged in the shell; the present application reduces two-dimensional voltage scanning required by traditional electrostatic analysis type low-energy charged particle measurement to one-dimensional voltage scanning, can greatly save voltage scanning time, improve the time resolution of low-energy charged particle measurement, and has wide application demand in the detection of small-scale structures in space.

Description

Technical Field

[0001] This invention belongs to the field of space physics and space environment detection technology, and specifically relates to a multi-layer nested electrostatic analyzer. Background Technology

[0002] Charged particles are a major component of the space environment and an important subject of research in space physics and space weather. The detection of charged particles can be used to study fundamental physics questions of interest to humanity, such as particle acceleration, heating, and the transport and dissipation of energy and matter in space. Solving these fundamental physics problems helps improve humanity's basic understanding of outer space and the fundamental laws governing the universe. Charged particles can also interact with spacecraft in orbit, causing various space environment effects such as charging and discharging. The detection and research of charged particles in space helps humanity understand the unknown world and provides a guarantee for the safe conduct of various human space activities. The detection of charged particles is an essential part of space environment and space physics satellite projects. For example, the European Space Agency's CLUSTER satellite, the US MMS satellite, the European Space Agency's Mars Express, the US MAVEN satellite, China's Fengyun series satellites, Chang'e-1 / 2, and Tianwen-1 have all conducted charged particle detection for space physics and space weather research.

[0003] Based on their energy levels, charged particles can be categorized into high-energy charged particles and low-energy charged particles. Currently, the common method for measuring low-energy charged particles involves using electrostatic analysis to analyze the direction and energy of the incident particle, then amplifying the charge signal using a microchannel plate, outputting a charge pulse for electronic processing to obtain the particle's energy, direction, and flux information. In space physics research, it is typically necessary to obtain the three-dimensional velocity distribution function of low-energy charged particles across the entire space and energy range. The total time required to obtain a three-dimensional velocity distribution function is called the time resolution. Higher time resolution is more beneficial for the detection and study of small-scale structures. Small-scale structure research is a crucial direction for solving fundamental problems of energy transport and dissipation in space physics. Currently, the US MMS satellite is the most representative project for small-scale structure detection, achieving a fastest electron detection time resolution of 30 ms. However, research on fundamental problems in space physics, such as magnetic reconnection, turbulence, and shock waves, requires detection at the electron cyclotron scale (approximately 5 ms). Currently, no instrument can achieve a time resolution <30 ms, which does not yet meet the basic requirements of space physics. The main reason is that traditional electrostatic analysis methods for detecting low-energy charged particles require voltage scans in both energy and direction dimensions. These two-dimensional voltage scans can only be performed sequentially, which is time-consuming. Reducing voltage scan time and improving detection time resolution are important development directions for low-energy charged particle detection. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing low-energy particle detection instruments in terms of insufficient time resolution. This invention proposes a new multi-layer nested electrostatic analyzer device that breaks through the limitation of traditional instruments requiring voltage scanning in both energy and direction dimensions. It eliminates the need for voltage scanning in the energy dimension and only requires scanning in the direction dimension. This can greatly improve the measurement time resolution of low-energy charged particles to about a few milliseconds, meeting the needs of space physics for electron cyclotron scale detection.

[0005] To achieve the above objectives, this invention provides a multi-layer nested electrostatic analyzer that overcomes the problem of insufficient time resolution in existing space low-energy charged particle detection. It uses an electrostatic deflection device to achieve a large field of view measurement; and utilizes a hemispherical multi-layer concentric grid electrode combined with a microchannel plate at the rear end and a position-sensitive anode to achieve simultaneous particle energy measurement without scanning, which can greatly improve the detection time resolution.

[0006] The multi-layer nested electrostatic analyzer includes: a shielding grid, an electrostatic deflection device, a trajectory guiding device, a hemispherical multi-layer concentric grid electrode, a microchannel plate, a position-sensitive anode, an electronics processor, and a device housing;

[0007] The device housing is mounted on the electronics processor. The opening of the housing is covered by a shielding grid. Inside the housing (1) are an electrostatic deflection device, a trajectory guiding device, a hemispherical multi-layer concentric grid electrode, a microchannel plate, and a position-sensitive anode. The front end of the electrostatic deflection device is equipped with a shielding grid and is connected to the housing. The rear end of the electrostatic deflection device is equipped with a trajectory guiding device and is connected to the front end of the trajectory guiding device. The hemispherical multi-layer concentric grid electrode is located below the rear end of the trajectory guiding device and is connected to the rear end of the trajectory guiding device. The microchannel plate and the position-sensitive anode are sequentially arranged below the hemispherical multi-layer concentric grid electrode. The bottom end of the hemispherical multi-layer concentric grid electrode is attached to the edge of the microchannel plate and is connected to the electronics processor through a connector.

[0008] As one of the improvements to the above technical solutions, the shielding mesh usually covers the opening of the outer shell, either on the outside of the outer shell or close to the inner side of the outer shell.

[0009] As an improvement to the above technical solution, the shielding grid is a conical structure with mesh holes on the surface, which shields the internal electric field while allowing particles to enter through the mesh holes.

[0010] As an improvement to the above technical solution, the electrostatic deflection device includes: an upper deflection plate and a lower deflection plate; the upper deflection plate has a bowl-shaped structure with its rim facing upward and an opening at its bottom; the lower deflection plate has a vase-shaped structure with its rim facing upward; the upper and lower deflection plates are two symmetrically arranged arc plates with a cross-section of 45°, forming an incident channel.

[0011] The upper and lower deflection plates scan charged particles in any direction within a 90° range along the incident channel using the voltage they apply.

[0012] As an improvement to the above technical solution, the trajectory guidance device includes an upper electrode and a lower electrode; the upper electrode is disposed at the bottom opening of the upper deflection plate; the lower electrode is disposed on the hemispherical multilayer concentric grid electrode; the upper electrode and the lower electrode are grounded, so as to introduce the charged particles emitted by the electrostatic deflection device into the hemispherical multilayer concentric grid electrode connected at its rear end.

[0013] As an improvement to the above technical solution, the hemispherical multilayer concentric grid electrode is used to deflect the trajectory of charged particles entering the electrostatic analyzer by applying voltage thereon; the deflection angle varies with different energies.

[0014] The hemispherical multilayer concentric grid electrode comprises five concentric spherical grid electrodes, with the bottom of the innermost spherical grid electrode attached to the outer edge of the microchannel plate. Each spherical grid electrode is supplied with a fixed voltage. The voltage applied to the spherical grid electrodes increases sequentially from the outside in, while the voltage difference between adjacent spherical grid electrodes remains constant. The five layers of spherical grid electrodes form a fixed deflection electric field, deflecting the trajectory of incident charged particles downwards. Higher energy particles exhibit a smaller deflection angle, while lower energy particles exhibit a larger deflection angle. The radial position of the charged particle hitting the microchannel plate is related to the particle's energy.

[0015] As an improvement to the above technical solution, the microchannel plate has a circular structure. Different high voltages are applied to the upper and lower surfaces of the microchannel plate to create a pressure difference, which amplifies the charge signal of the incident charged particles and outputs an electron cloud.

[0016] As an improvement to the above technical solution, the position-sensitive anode has a circular structure that matches the size of the microchannel plate. The position-sensitive anode receives the electron cloud output from the microchannel plate, distinguishes the position of the electron cloud, and outputs a charge pulse signal. This signal is then input to the electronics processor via a connector.

[0017] As one of the improvements to the above technical solution, the electronic processor includes: a signal preamplifier circuit, a high-voltage circuit, a low-voltage circuit, a power supply circuit, an interface circuit, and an FPGA processor.

[0018] The signal preamplifier circuit is used to amplify the corresponding charge pulse signal output by the position-sensitive anode of the connected connector to obtain the amplified charged particle electrical signal.

[0019] The FPGA processor is used to calculate the energy, direction, and flux information of the charged particles by combining the pulse count per unit time with the voltage data applied by the electrostatic analyzer and the voltage data applied by the electrostatic deflection device based on the obtained amplified charged particle electrical signal.

[0020] The high-voltage circuit is used to provide the required multiple high voltages; wherein, the multiple high voltages further include: positive high voltage and negative high voltage;

[0021] The low-voltage circuit is used to cooperate with the FPGA to control the operation of the entire electronics processor, including communicating with the outside world through the FPGA control interface circuit, which can be used to communicate with the satellite bus; and controlling the high-voltage circuit to output the required high voltage through the FPGA and DA converter.

[0022] The power supply circuit is used to supply power.

[0023] The advantages of this invention compared to the prior art are as follows:

[0024] This invention reduces the two-dimensional voltage scan required for traditional electrostatic analysis-based low-energy charged particle measurement to a one-dimensional voltage scan, which can greatly save voltage scan time and improve the temporal resolution of low-energy charged particle measurement. It has wide application potential in the detection of small-scale structures in space. Attached Figure Description

[0025] Figure 1 This is a schematic cross-sectional view of a multi-layer nested electrostatic analyzer according to the present invention.

[0026] Figure 2 This is a schematic diagram of a multi-layer nested electrostatic analyzer of the present invention installed on a satellite platform;

[0027] Figure 3 This is a schematic diagram of the electronic processor of a multi-layer nested electrostatic analyzer according to the present invention.

[0028] Figure label:

[0029] 1. Device housing; 2. Shielding grid; 3. Upper deflection plate; 4. Lower deflection plate; 5. Upper electrode; 6. Lower electrode; 7. Hemispherical multilayer concentric grid electrode; 8. Microchannel plate; 9. Position-sensitive anode; 10. Connector; 11. Electronic processor. Detailed Implementation

[0030] The present invention will now be further described with reference to the accompanying drawings.

[0031] like Figure 1As shown, this invention provides a multi-layer nested electrostatic analyzer that overcomes the problem of insufficient time resolution in existing space low-energy charged particle detection. It uses an electrostatic deflection device to achieve a large field of view measurement; and utilizes a hemispherical multi-layer concentric grid electrode combined with a microchannel plate at the rear end and a position-sensitive anode to achieve simultaneous particle energy measurement without scanning, which can greatly improve the detection time resolution.

[0032] The multi-layer nested electrostatic analyzer includes: a shielding grid 2, an electrostatic deflection device, a trajectory guiding device, a hemispherical multi-layer concentric grid electrode 7, a microchannel plate 8, a position-sensitive anode 9, an electronics processor 11, and a device housing 1;

[0033] The device housing 1 is mounted on the electronics processor 11, and contains a shielding grid 2, an electrostatic deflection device, a trajectory guiding device, a hemispherical multilayer concentric grid electrode 7, a microchannel plate 8, and a position-sensitive anode 9. The shielding grid 2 is located at the front end of the electrostatic deflection device and is connected to the housing. The trajectory guiding device is located below the rear end of the electrostatic deflection device and is connected to the front end of the trajectory guiding device. The hemispherical multilayer concentric grid electrode 7 is located below the rear end of the trajectory guiding device and is connected to the rear end of the trajectory guiding device. The microchannel plate 8 and the position-sensitive anode are sequentially arranged below the hemispherical multilayer concentric grid electrode 7, and the bottom end of the hemispherical multilayer concentric grid electrode 7 is attached to the edge of the microchannel plate 8 and connected to the electronics processor 11 through a connector 10.

[0034] The shielding grid 2 is used to shield the electric field inside the device and allow charged particles to pass through the mesh.

[0035] The electrostatic deflection device is used to expand the field of view for pitch angle detection and to guide low-energy charged particles incident from space into the trajectory guidance device.

[0036] The electrostatic deflection device includes an upper deflection plate 3 and a lower deflection plate 4; the upper deflection plate 3 has a bowl-shaped structure with its rim facing upward and an opening at its bottom; the lower deflection plate 4 has a vase-shaped structure with its rim facing upward.

[0037] The upper deflecting plate 3 and the lower deflecting plate 4 are two symmetrically arranged arc plates with a cross-section of 45°, forming an incident channel. Low-energy charged particles are introduced along the incident channel by scanning a 90° range of arbitrary directions using the voltage applied to the upper deflecting plate 3 and the lower deflecting plate 4. The incident channel formed by the upper deflecting plate 3 and the lower deflecting plate 4 has a circumferentially funnel-shaped structure, with the opening of this circumferentially funnel-shaped structure facing outwards from the device housing 1, for introducing low-energy charged particles.

[0038] The angle between the center line of symmetry of the upper deflection plate 3 and the lower deflection plate 4 and the upper edge of the electronics processor 11 is 30°, which can realize the measurement of charged particles with a field of view greater than 2π.

[0039] The trajectory guiding device is used to introduce charged particles incident from the electrostatic deflection device and guide them into the hemispherical multilayer concentric grid electrode 7.

[0040] The trajectory guidance device includes an upper electrode 5 and a lower electrode 6. The upper electrode 5 is disposed at the bottom opening of the upper deflection plate 3. The lower electrode 6 is disposed on the hemispherical multilayer concentric grid electrode 7. The upper electrode 5 and the lower electrode 6 are grounded, so as to guide the charged particles emitted by the electrostatic deflection device into the hemispherical multilayer concentric grid electrode connected at its rear end.

[0041] The hemispherical multilayer concentric grid electrode 7 includes five concentric hemispherical grid electrodes, with the bottom end of the innermost spherical grid electrode attached to the outer edge of the microchannel plate 8. It is used to deflect the trajectory of charged particles entering the electrostatic analyzer by applying voltage, and the deflection angle is different depending on the energy.

[0042] In this system, each of the five concentric spherical grid electrodes is subjected to a fixed voltage. The voltage increases sequentially from the outside in, while the voltage difference between adjacent spherical grid electrodes remains constant. The five layers of spherical grid electrodes form a fixed deflection electric field, deflecting the trajectory of incident charged particles downwards. Higher energy particles exhibit a smaller deflection angle, while lower energy particles exhibit a larger deflection angle. The radial position of the charged particle hitting the microchannel plate 8 is related to the particle's energy.

[0043] The microchannel plate 8 has a circular structure. Different high voltages are applied to the upper and lower surfaces of the microchannel plate 8 to create a pressure difference, which amplifies the charge signal of the incident charged particles and outputs a cloud of electrons.

[0044] The position-sensitive anode 9 has a circular structure that matches the size of the microchannel plate 8. The position-sensitive anode 9 receives the electron cloud output from the microchannel plate 8, distinguishes the position of the electron cloud, and outputs a charge pulse signal. This signal is input to the electronics processor 11 via connector 10.

[0045] The electronic processor 11 is used to process the corresponding charge pulse signals output by the signal preamplifier, and obtain the direction, energy and flux information of the charged particles respectively.

[0046] like Figure 3 As shown, the electronic processor 11 includes: a signal preamplifier circuit, a high-voltage circuit, a low-voltage circuit, a power supply circuit, an interface circuit, and an FPGA processor;

[0047] The signal preamplifier circuit is used to amplify the corresponding charge pulse signal output by the position sensitive anode 9 of the connected connector 10 to obtain the amplified charged particle electrical signal.

[0048] The FPGA processor is used to calculate the energy, direction, and flux information of the charged particles by combining the pulse count per unit time with the voltage data applied by the electrostatic analyzer and the voltage data applied by the electrostatic deflection device based on the obtained amplified charged particle electrical signal.

[0049] The directional information of the charged particles includes their azimuth and elevation angles. Since the position-sensitive anode is circular, the azimuth angle is obtained from the circumferential position of the electrical signal on the anode, and the elevation angle is calculated from the voltage difference applied by the upper deflection plate 3 and lower deflection plate 4 of the electrostatic deflection device. The energy information of the charged particles is obtained from the radial position of the electrical signal on the anode. The flux information of the charged particles can be obtained from the count value of the electrical signal collected on the anode per unit time. All the above calculations are performed using existing techniques known in the art.

[0050] The high-voltage circuit is used to provide the required multiple high voltages; wherein, the multiple high voltages further include: positive high voltage and negative high voltage;

[0051] The low-voltage circuit is used to cooperate with the FPGA to control the operation of the entire electronics processor 11, including communicating with the outside world through the FPGA control interface circuit, which can be used to communicate with the satellite bus; and controlling the high-voltage circuit to output the required high voltage through the FPGA and DA converter.

[0052] The power supply circuit is used to supply power to the entire device.

[0053] The device housing 1 is used to provide an installation platform.

[0054] The upper deflection plate 3, lower deflection plate 4, hemispherical multilayer concentric grid electrode 7, microchannel plate 8, and position-sensitive anode 9 can all be insulated with polyimide material.

[0055] The upper deflection plate 3, lower deflection plate 4, hemispherical multilayer concentric grid electrode 7, microchannel plate 8, and position-sensitive anode 9 are fixed to the device housing 1 by polyimide material.

[0056] The shielding grid 2, upper electrode 5, lower electrode 6, and connector 10 can be directly fixed to the device housing 1.

[0057] The shielding grid 2, the hemispherical multi-layer concentric grid electrode 7, and the position-sensitive anode 9 are made of beryllium copper.

[0058] The measuring device based on the above structure, in addition to the shielding grid 2, the hemispherical multilayer concentric grid electrode 7, the microchannel plate 8, the position-sensitive anode 9, the connector 10, and the electronics processor 11, Figure 1 All other components shown are made of aluminum.

[0059] like Figure 2 As shown, the multi-layer nested electrostatic analyzer for charged particle measurement of the present invention is embedded in the satellite surface, and the portion above the hemispherical multi-layer concentric grid electrode (including the hemispherical multi-layer concentric grid electrode) extends out of the satellite surface, keeping the detection window as far away from the satellite surface as possible to reduce the interference of the charged state of the satellite surface on the measurement. At the same time, the electronics processor 11 is placed inside the satellite cabin, which is beneficial for temperature control of the working environment of the electronics processor.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A multi-layer nested electrostatic analyzer, characterized in that, The outer casing (1) is mounted on the electronic processor (11). The opening of the outer casing (1) is covered by a shielding grid (2). The outer casing (1) contains an electrostatic deflection device, a trajectory guiding device, a hemispherical multilayer concentric grid electrode (7), a microchannel plate (8), and a position-sensitive anode (9). A shielding grid (2) is provided at the front end of the electrostatic deflection device and connected to the outer shell (1); a trajectory guiding device is provided at the rear end of the electrostatic deflection device and connected to the front end of the trajectory guiding device; a hemispherical multilayer concentric grid electrode (7) is provided at the rear end of the trajectory guiding device and connected to the rear end of the trajectory guiding device; a microchannel plate (8) and a position-sensitive anode (9) are arranged sequentially below the hemispherical multilayer concentric grid electrode; and the bottom end of the hemispherical multilayer concentric grid electrode (7) is attached to the edge of the microchannel plate (8) and connected to the electronics processor through a connector (10); The hemispherical multilayer concentric grid electrode (7) is used to deflect the trajectory of charged particles entering the electrostatic analyzer by applying voltage thereon; the deflection angle varies with different energies. The hemispherical multilayer concentric grid electrode consists of 5 concentric spherical grid electrodes, with the bottom of the innermost spherical grid electrode attached to the outer edge of the microchannel plate (8). Each spherical grid electrode is given a fixed voltage. The voltage applied to the spherical grid electrode increases sequentially from the outside to the inside. The voltage difference between two adjacent spherical grid electrodes is fixed. The 5 layers of spherical grid electrodes form a fixed deflection electric field, which deflects the trajectory of the incident charged particle downward. The higher the energy, the smaller the deflection angle, and the lower the energy, the larger the deflection angle. The radial position of the charged particle hitting the microchannel plate (8) is related to the particle energy.

2. The multi-layer nested electrostatic analyzer according to claim 1, characterized in that, The shielding grid (2) has a conical structure with mesh holes on its surface, which shields the internal electric field while allowing particles to enter through the mesh holes.

3. The multi-layer nested electrostatic analyzer according to claim 1, characterized in that, The electrostatic deflection device includes: an upper deflection plate (3) and a lower deflection plate (4); the upper deflection plate (3) has a bowl-shaped structure with its rim facing upward and an opening at its bottom; the lower deflection plate (4) has a vase-shaped structure with its rim facing upward; the upper deflection plate (3) and the lower deflection plate (4) are two symmetrically arranged arc plates with a cross-section of 45°, forming an incident channel; Among them, the upper deflection plate (3) and the lower deflection plate (4) scan charged particles in any direction within a 90° range along the incident channel by applying voltage.

4. The multi-layer nested electrostatic analyzer according to claim 3, characterized in that, The incident channel formed by the upper deflection plate (3) and the lower deflection plate (4) has a circumferential horn-shaped structure, and the opening of the horn-shaped structure faces the outer shell (1) of the device; the angle between the center line of symmetry of the upper deflection plate (3) and the lower deflection plate (4) and the upper edge of the electronics processor (17) is 30°.

5. The multi-layer nested electrostatic analyzer according to claim 1, characterized in that, The trajectory guiding device includes an upper electrode (5) and a lower electrode (6); the upper electrode (5) is disposed at the bottom opening of the upper deflection plate (3); the lower electrode (6) is disposed on the hemispherical multilayer concentric grid electrode; the upper electrode (5) and the lower electrode (6) are grounded, and the charged particles emitted by the electrostatic deflection device are introduced into the hemispherical multilayer concentric grid electrode connected at its rear end.

6. The multi-layer nested electrostatic analyzer according to claim 1, characterized in that, The microchannel plate (8) has a circular structure. Different high voltages are applied to the upper and lower surfaces of the microchannel plate to form a pressure difference, which amplifies the charge signal of the incident charged particles and outputs a cloud of electrons.

7. The multi-layer nested electrostatic analyzer according to claim 1, characterized in that, The position-sensitive anode (9) has a circular structure that matches the size of the microchannel plate (8). The position-sensitive anode (9) is used to receive the electron cloud output by the microchannel plate (8), distinguish the position of the electron cloud, and output a charge pulse signal, which is input to the electronics processor (11) through the connector (10).

8. The multi-layer nested electrostatic analyzer according to claim 1, characterized in that, The electronic processor (11) includes: a signal preamplifier circuit, a high-voltage circuit, a low-voltage circuit, a power supply circuit, an interface circuit, and an FPGA processor; The signal preamplifier circuit is used to amplify the corresponding charge pulse signal output by the position sensitive anode (9) of the connected connector (10) to obtain the amplified charged particle electrical signal. The FPGA processor is used to calculate the energy, direction, and flux information of the charged particles by combining the pulse count per unit time with the voltage data applied by the electrostatic analyzer and the voltage data applied by the electrostatic deflection device based on the obtained amplified charged particle electrical signal. The high-voltage circuit is used to provide the required multiple high voltages; wherein, the multiple high voltages further include: positive high voltage and negative high voltage; The low-voltage circuit is used to cooperate with the FPGA to control the operation of the entire electronics processor (11), including communicating with the outside world through the FPGA control interface circuit, and can be used to communicate with the satellite bus; and controlling the high-voltage circuit to output the required high voltage through the FPGA and DA converter. The power supply circuit is used to supply power.

Images