High-time-resolution radiation current detector and detection method based on electronic signal stretching

Abstract

The present invention relates to a radiation flux detector and a detection method, and more particularly to a high-time-resolution radiation flux detector and a detection method based on electronic signal stretching, which solves the technical problem of slow time response of existing radiation flux detectors. The radiation flux detector provided by the present invention includes an axial magnetic field, and a photocathode, a grid, a microchannel plate, and a collector anode arranged in sequence along the radial direction within the axial magnetic field. A dynamic decay electric field for accelerating photoelectrons is applied between the photocathode and the grid. The photoelectrons are accelerated by the dynamic decay electric field and subjected to a period of motion stretching in the drift region before being incident on the microchannel plate. The electron stretching is used to convert ultrafast light signals into a longer time scale within a limited time, thereby improving the time resolution of the system. Different stretching magnifications can be obtained by adjusting the dynamic decay electric field to adapt to different system requirements.

Description

Technical Field

[0001] The present invention relates to a radiation flow detector and a detection method, and in particular to a high time resolution radiation flow detector and a detection method based on electronic signal stretching. Background Art

[0002] Photomultiplier tubes (PMTs) with pulse response functions of 100 to 300 ps are commonly used to measure the properties of radiation signals in high-energy-density physics experiments such as laser fusion and Z-pinch experiments. Conventional radiation flux detectors consist of a photocathode, a microchannel plate (MCP), and an anode. Their operation involves the radiation signal being incident on the detector's photocathode, where electrons are accelerated and incident on the MCP, where they are multiplied and amplified before being received by the anode. These systems typically employ close focusing, with the distances between the photocathode and the MCP being approximately 1 mm, and the distances between the MCP and the anode being approximately 1 mm. DC voltages are applied between the photocathode and the MCP, between the MCP input and output surfaces, and between the MCP output and the anode. Limited by the transit time of the MCP, these systems typically achieve a best-case time response of only 200 ps, making them difficult to meet the requirements for ultrafast signal detection. Summary of the Invention

[0003] The purpose of the present invention is to solve the technical problem of slow time response of existing radiation flow detectors and to provide a high time resolution radiation flow detector and detection method based on electronic signal stretching.

[0004] To achieve the above object, the technical solution adopted by the present invention is:

[0005] A high time-resolved radiation flux detector based on electronic signal stretching is characterized in that it comprises an axial magnetic field, and a photocathode, a grid, a microchannel plate and a current collecting anode arranged in sequence within the axial magnetic field from the inlet end to the outlet end of the axial magnetic field;

[0006] The photocathode is used to receive the photon signal of the radiation flow to be detected incident from the entrance end of the axial magnetic field and convert it into photoelectrons;

[0007] The area between the photocathode and the grid is a cathode grid area, to which a dynamic decay electric field is applied, and the dynamic decay electric field is used to accelerate photoelectrons; the photocathode and the grid serve as electrodes for carrying the dynamic decay electric field;

[0008] The area between the grid and the microchannel plate is a drift region, and the photoelectrons are moved and stretched in the drift region before being incident on the microchannel plate. After being multiplied and amplified by the microchannel plate, they are incident on the collecting anode.

[0009] The collector anode is used to collect photoelectrons and output them from the axial magnetic field outlet end;

[0010] The axial magnetic field is used to overcome the space charge effect in the process of photoelectrons drifting from the photocathode to the collector anode, so as to ensure the electron focusing characteristics.

[0011] Furthermore, it also includes a nonlinear high-voltage driving pulse generator, which cooperates with the photocathode and the grid to form a dynamic attenuation electric field.

[0012] Furthermore, the nonlinear high-voltage drive pulse generator is an avalanche pulse generator;

[0013] The avalanche pulse generator includes a trigger splitter, N pulse generators with independently controllable amplitudes and delays, and a multi-channel synthesizer, wherein N is greater than or equal to 2; the amplitude of the pulse generator is achieved by adjusting the power supply voltage, and the delay is achieved by an internal counter;

[0014] The trigger splitter has an input end and N output ends, and the N output ends are respectively connected to the input ends of the N pulse generators; the input end of the trigger splitter is used to connect and receive an external control signal, and perform power amplification and equal power distribution on it;

[0015] The multiplexer has N input terminals and one output terminal, and the N input terminals are respectively connected to the output terminals of the N pulse generators; the input terminals of the multiplexer are used to synthesize the driving pulse signals generated by the N pulse generators, and the output terminal of the multiplexer is connected to the photocathode.

[0016] Furthermore, the pulse generator includes a delay adjustment module and a unit pulse generation module connected to the delay adjustment module;

[0017] The input ends of the N delay adjustment modules are respectively connected to the N output ends of the trigger splitter;

[0018] The output ends of the N unit pulse generation modules are respectively connected to the N input ends of the multiplexer.

[0019] Furthermore, the photocathode is arranged near the entrance of the axial magnetic field, and the collector anode is arranged near the exit of the axial magnetic field;

[0020] The distance between the photocathode and the entrance of the axial magnetic field, and the distance between the collector anode and the exit of the axial magnetic field are equal to the diameter of the axial magnetic field.

[0021] Furthermore, the axial magnetic field is an electron rarefaction confinement magnetic field;

[0022] The electron rarefaction confinement magnetic field is a coil magnetic field wound with a double-layer coil, and four-layer coils are wound at both the entrance and exit positions.

[0023] Furthermore, the distance between the photocathode and the grid is 0.5 mm to 1.5 mm.

[0024] Furthermore, the distance between the microchannel plate and the current collecting anode is 0.5 mm to 1.5 mm.

[0025] The present invention further provides a high time resolution radiation flow detection method, which is based on the above-mentioned high time resolution radiation flow detector based on electronic signal stretching, and is special in that it includes the following steps:

[0026] Step 1: Adjust the position of the radiation flow detector so that the radiation flow photon signal to be detected is incident on the photocathode along the setting direction of the radiation flow detector;

[0027] Step 2: After receiving the incident radiation flow photon signal to be detected, the photocathode converts it into photoelectrons and emits them;

[0028] Step 3: After being emitted from the photocathode, the photoelectrons enter the cathode grid region, are accelerated by the dynamic attenuation electric field, and then pass through the grid into the drift region;

[0029] Step 4: The accelerated photoelectrons are stretched in the drift region at different speeds for a period of time, and then incident on the microchannel plate, which multiplies and amplifies the photoelectrons;

[0030] Step 5: The multiplied and amplified photoelectrons are incident on the collecting anode, which collects the incident photoelectrons and outputs them, completing the detection of the radiation flow photon signal.

[0031] Furthermore, before step 1, the following steps are also included:

[0032] Step A, adjusting the positions of the photocathode, grid, microchannel plate and collector anode in the axial magnetic field, and dynamically attenuating the intensity of the electric field;

[0033] Step A.1: Determine the electron stretching magnification factor based on the time resolution required for radiation flux detection using the following formula:

[0034]

[0035] Among them, T MAG is the time resolution required for radiation flow detection, M is the electron stretching magnification, T MCP is the transit time of the microchannel plate;

[0036] Step A.2: Select the distance between the grid and the microchannel plate, and the slope of the dynamic decay electric field according to the following formula:

[0037]

[0038] Where L is the distance between the grid and the microchannel plate, is the slope of the dynamic decay electric field, V d is the average speed of photoelectrons;

[0039] Step A.3, adjust the positions of the photocathode and the collector anode so that the distance between the photocathode and the entrance of the axial magnetic field and the distance between the collector anode and the exit of the axial magnetic field are equal to the diameter of the axial magnetic field;

[0040] Step A.4: Adjust the position of the grid and the microchannel plate in the axial magnetic field and the intensity of the dynamic attenuation electric field according to the distance between the grid and the microchannel plate and the slope of the dynamic attenuation electric field obtained in step A.2.

[0041] Compared with the prior art, the present invention has the following beneficial technical effects:

[0042] 1. The high-time-resolution radiation flux detector based on electron signal stretching provided by the present invention accelerates photoelectrons through a dynamically decaying electric field, and then stretches them in the drift region for a period of time before being incident on the microchannel plate. The electron stretching is used to convert ultrafast light signals into longer time scales within a limited time, thereby improving the time resolution of the system.

[0043] 2. In the high-time-resolution radiation flux detector based on electronic signal stretching provided by the present invention, the avalanche pulse generator includes multiple pulse generators with independently controllable amplitudes and delays, which can output cathode gate drive pulses with different leading and trailing edges and different shapes, thereby obtaining different stretching magnifications M;

[0044] 3. In the high-time-resolution radiation flow detector based on electronic signal stretching provided by the present invention, the coil at the axial magnetic field outlet position is four-layered, which can improve the magnetic field strength at the outlet position and the uniformity of the entire magnetic field;

[0045] 4. In the high-time-resolution radiation flow detector based on electronic signal stretching provided by the present invention, the distance between the photocathode collecting anode and the axial magnetic field outlet is equal to the diameter of the axial magnetic field, which can ensure that the non-uniformity of the magnetic field intensity at the magnetic field outlet relative to the magnetic field center is better than 10%, thereby ensuring the spatial resolution of the photocathode and the collection efficiency of the collecting anode. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a schematic diagram of the structure of the high time resolution radiation flow detector based on electronic signal stretching provided by the present invention;

[0047] Figure 2 This is a schematic diagram of the structure of an avalanche pulse generator in a high-time-resolution radiation flow detector based on electronic signal stretching provided by the present invention;

[0048] The following are the descriptions of the reference numerals:

[0049] 1-photocathode, 2-grid, 3-microchannel plate, 4-collecting anode, 5-axial magnetic field;

[0050] 6-trigger splitter, 7-delay adjustment module, 8-unit pulse generation module, 9-multiplexer, 10-pulse generator. DETAILED DESCRIPTION

[0051] In order to make the purpose, advantages and features of the present invention clearer, the high time resolution radiation flow detector and detection method based on electronic signal stretching proposed by the present invention are further described in detail below with reference to the accompanying drawings and specific embodiments.

[0052] like Figure 1 As shown, a high time-resolved radiation flow detector based on electronic signal stretching includes an axial magnetic field 5, and a photocathode 1, a grid 2, a microchannel plate 3 and a collecting anode 4 arranged in sequence from the entrance end to the exit end in the axial magnetic field 5.

[0053] The photocathode 1 receives photon signals from the radiation stream to be detected, incident from the entrance of the axial magnetic field 5, and converts them into photoelectrons. The area between the photocathode 1 and the grid 2 is the cathode grid region, where a dynamically decaying electric field is applied, accelerating the photoelectrons. The photocathode 1 and the grid 2 act as electrodes, carrying the dynamically decaying electric field. The distance between the photocathode 1 and the grid 2 is 0.5 mm to 1.5 mm. The area between the grid 2 and the microchannel plate 3 is the drift region. After acceleration, the photoelectrons undergo motion and stretching in the drift region before entering the microchannel plate 3. After being multiplied and amplified by the microchannel plate 3, they enter the collecting anode 4. The collecting anode 4 collects the photoelectrons and outputs them from the exit of the axial magnetic field 5. The distance between the microchannel plate 3 and the collecting anode 4 is 0.5 mm to 1.5 mm. The axial magnetic field 5 is used to overcome the space charge effect during the photoelectron drift from the photocathode to the collecting anode, thereby ensuring electron focusing properties.

[0054] To ensure that electron stretching exhibits linear time-conversion characteristics, the modulation of electron velocity in the cathode-grid region must be linear over time, which means that the voltage variation in the cathode-grid region must be nonlinear. Therefore, a sub-nanosecond nonlinear high-voltage drive pulse generator is required for cathode-grid drive. In this embodiment, an avalanche pulse generator is used, which cooperates with the photocathode 1 and grid 2 to form a dynamically decaying electric field.

[0055] like Figure 2As shown, the avalanche pulse generator includes a trigger splitter 6, N pulse generators 10 with independently controllable amplitudes and delays, and a multiplexer 9, where N ≥ 2. The trigger splitter 6 has one input and N outputs. The input of the trigger splitter 6 is used to receive an external control signal and amplify and distribute the power equally. The N outputs are respectively connected to the inputs of the N pulse generators 10. The multiplexer 9 has N inputs and one output. The N inputs are respectively connected to the outputs of the N pulse generators 10. The output of the multiplexer 9 is connected to the photocathode 1.

[0056] The amplitude of pulse generator 10 is achieved by adjusting the power supply voltage, and the delay is achieved by an internal counter. Pulse generator 10 includes a delay adjustment module 7 and a unit pulse generation module 8 connected to the delay adjustment module 7. The inputs of the N delay adjustment modules 7 serve as the inputs of pulse generator 10 and are respectively connected to the N outputs of trigger splitter 6. The outputs of the N unit pulse generation modules 8 serve as the outputs of pulse generator 10 and are respectively connected to the N inputs of multiplexer 9.

[0057] When multiple pulses with different amplitudes or different delay conditions are synthesized together, different leading and trailing edges, as well as cathode drive pulses with different shapes can be output, thereby obtaining different stretching magnifications M.

[0058] The axial magnetic field 5 is an electron rarefaction confinement field, constructed using a double-layer coil. To compensate for the attenuated magnetic field at the coil outlet, four layers of coil are wound at both ends to improve the magnetic field strength at the outlet and the uniformity of the entire magnetic field. Furthermore, to reduce stray magnetic fields and improve system excitation efficiency, the coils are shielded with metal.

[0059] The electron rarefaction confinement magnetic field is used to overcome the electron space charge effect. It is a long, uniform magnetic field, with the intensity decreasing toward the field outlet. To ensure the spatial resolution of the photocathode 1 and the collection efficiency of the collector anode 4, the non-uniformity of the magnetic field intensity at the cathode and anode relative to the center of the field is less than 10%.

[0060] The high time-resolved radiation flow detector based on electron signal stretching provided by the present invention is a non-imaging device, so the magnetic field strength required to overcome the space charge effect is greatly reduced compared to the imaging type, and only a few hundred gauss is needed. If the cathode position is selected appropriately, it can play a role in compensating for the uniformity of the magnetic field. In the present invention, the photocathode 1 is arranged at a position close to the entrance of the electron sparse confinement magnetic field 5, and the collecting anode 4 is arranged at a position close to the exit of the electron sparse confinement magnetic field. The distance between the photocathode 1 and the entrance of the electron sparse confinement magnetic field and the distance between the collecting anode 4 and the exit of the electron sparse confinement magnetic field are equal to the diameter of the electron sparse confinement magnetic field. At this time, it can be ensured that the magnetic field non-uniformity is better than 10%.

[0061] The working principle of the high time resolution radiation flow detector based on electronic signal stretching provided by the present invention is as follows:

[0062] The incident radiation flow photon signal is converted into photoelectrons by the photocathode 1, and the photoelectrons are accelerated by the dynamic decay electric field between the photocathode 1 and the grid 2. Since the electric field between the photocathode 1 and the grid 2 is a dynamic decay electric field, the speed of the photoelectrons that first pass through the cathode grid area is large, and the speed of the photoelectrons that pass through the cathode grid area later is small. After the speed dispersion, the photoelectrons enter the drift area. Due to the different speeds, the photoelectrons that enter the drift area are stretched for a period of time and then incident on the microchannel plate 3. The photoelectrons are multiplied and amplified by the microchannel plate 3 and then incident on the collecting anode 4 and output.

[0063] According to the working principle of the system, the system time resolution can be expressed as:

[0064]

[0065] Among them, T MAG is the time resolution of the high-resolution radiation flux detector based on electronic signal stretching, M is the electron stretching magnification, T MCP is the MCP transit time.

[0066] According to the above formula, the high time-resolution radiation flow detector based on electronic signal stretching provided by the present invention can increase the system time resolution by M times.

[0067] Assuming that photoelectrons are emitted from the photocathode 1 and enter the cathode region at time t0 and t1 respectively, the magnification of the two photoelectrons with an incident time interval of t1-t0 after stretching can be expressed as:

[0068]

[0069] Wherein, L is the distance between the grid 2 and the microchannel plate 3, is the slope of the dynamic decay electric field, V d is the average speed of photoelectrons.

[0070] It can be seen from the above formula that the electron stretching magnification M of the high time-resolved radiation flow detector based on electron signal stretching provided by the present invention depends on the average speed of photoelectron movement, the slope of the dynamic decay electric field and the distance of electron stretching movement.

[0071] The electron stretching magnification M is determined according to the time resolution required by the system, and the slope of the dynamic decay electric field The distance L between the grid 2 and the microchannel plate 3 is adaptively selected according to the determined electron stretching magnification M as well as the application scenario and implementation difficulty.

[0072] The high-time-resolution radiation flux detector based on electron signal stretching proposed in this paper can increase the time resolution of the original system by a factor of M, effectively increasing the detector system bandwidth in a short period of time. Its core technology uses electron stretching to convert ultrafast optical signals to longer timescales within a limited timeframe. This technology will play a significant role in laser fusion (ICF) experiments and may even help advance the overall state of ultrafast diagnostics.

[0073] The present invention also provides a high time resolution radiation flow detection method, based on the above-mentioned high time resolution radiation flow detector based on electronic signal stretching, comprising the following steps:

[0074] Step A, adjusting the positions of the photocathode 1, the grid 2, the microchannel plate 3 and the collector anode 4 in the axial magnetic field 5, and the intensity of the dynamically attenuated electric field;

[0075] Step A.1: Determine the electron stretching magnification factor according to the time resolution required for radiation flux detection using the following formula:

[0076]

[0077] Among them, T MAG is the time resolution required for radiation flow detection, M is the electron stretching magnification, T MCP is the transit time of the microchannel plate 3;

[0078] Step A.2: Select the distance between the grid 2 and the microchannel plate 3 and the slope of the dynamic attenuation electric field according to the following formula:

[0079]

[0080] Wherein, L is the distance between the grid 2 and the microchannel plate 3, is the slope of the dynamic decay electric field, V d is the average speed of photoelectrons;

[0081] Step A.3, adjust the positions of the photocathode 1 and the collector anode 4 so that the distance between the photocathode 1 and the entrance of the axial magnetic field 5 and the distance between the collector anode 4 and the exit of the axial magnetic field 5 are equal to the diameter of the axial magnetic field 5;

[0082] Step A.4: Adjust the positions of the grid 2 and the microchannel plate 3 in the axial magnetic field 5 and the intensity of the dynamic attenuation electric field according to the distance between the grid 2 and the microchannel plate 3 and the slope of the dynamic attenuation electric field obtained in step A.2.

[0083] Step 1: Adjust the position of the radiation flow detector so that the radiation flow photon signal to be detected is incident on the photocathode 1 along the setting direction of the radiation flow detector.

[0084] Step 2: After receiving the incident photon signal of the radiation flow to be detected, the photocathode 1 converts it into photoelectrons and emits them.

[0085] Step 3: After being emitted from the photocathode 1, the photoelectrons enter the cathode grid region, are accelerated by the dynamic attenuation electric field, and then pass through the grid 2 into the drift region.

[0086] Step 4: The accelerated photoelectrons are stretched in the drift region at different speeds for a period of time and then incident on the microchannel plate 3, and the microchannel plate 3 multiplies and amplifies the photoelectrons.

[0087] Step 5: The multiplied and amplified photoelectrons are incident on the collecting anode 4, which collects the incident photoelectrons and outputs them, thereby completing the detection of the radiation flow photon signal.

Claims

1. A high time-resolved radiation flow detector based on electronic signal stretching, characterized by: It comprises an axial magnetic field (5), a nonlinear high-voltage driving pulse generator for generating a dynamic attenuation electric field, and a photocathode (1), a grid (2), a microchannel plate (3) and a current collecting anode (4) arranged in sequence from an inlet end to an outlet end in the axial magnetic field (5); The photocathode (1) is used to receive photon signals of the radiation flow to be detected incident from the entrance end of the axial magnetic field (5) and convert them into photoelectrons; The area between the photocathode (1) and the grid (2) is a cathode grid area, to which a dynamic decay electric field is applied, and the dynamic decay electric field is used to accelerate photoelectrons; the photocathode (1) and the grid (2) serve as electrodes for carrying the dynamic decay electric field; The area between the grid (2) and the microchannel plate (3) is a drift region, and the photoelectrons are moved and stretched in the drift region before being incident on the microchannel plate (3). After being multiplied and amplified by the microchannel plate (3), they are incident on the collector anode (4); The collector anode (4) is used to collect photoelectrons and output them from the outlet end of the axial magnetic field (5); The axial magnetic field (5) is used to overcome the space charge effect during the process of photoelectrons drifting from the photocathode (1) to the collector anode (4); The nonlinear high-voltage drive pulse generator is an avalanche pulse generator; The avalanche pulse generator includes a trigger splitter (6), N pulse generators (10) with independently controllable amplitudes and delays, and a multiplexer (9), wherein N ≥ 2; The trigger splitter (6) has an input end and N output ends, and the N output ends are respectively connected to the input ends of the N pulse generators (10); the input end of the trigger splitter (6) is used to connect an external control signal and perform power amplification and equal power distribution on it; The multiplexer (9) has N input terminals and one output terminal, and the N input terminals are respectively connected to the output terminals of the N pulse generators (10); the multiplexer (9) is used to synthesize the driving pulse signals generated by the N pulse generators (10), and the output terminal of the multiplexer (9) is connected to the photocathode (1).

2. The high time-resolved radiation flow detector based on electronic signal stretching according to claim 1, characterized in that: The pulse generator (10) comprises a delay adjustment module (7) and a unit pulse generation module (8) connected to the delay adjustment module (7); The input ends of the N delay adjustment modules (7) are respectively connected to the N output ends of the trigger splitter (6); The output ends of the N unit pulse generation modules (8) are respectively connected to the N input ends of the multiplexer (9).

3. The high time-resolved radiation flow detector based on electronic signal stretching according to claim 1 or 2, characterized in that: The photocathode (1) is arranged at a position close to the entrance of the axial magnetic field (5), and the collector anode (4) is arranged at a position close to the exit of the axial magnetic field (5); The distance between the photocathode (1) and the entrance of the axial magnetic field (5), and the distance between the collector anode (4) and the exit of the axial magnetic field (5) are equal to the diameter of the axial magnetic field (5).

4. The high time-resolved radiation flow detector based on electronic signal stretching according to claim 3, characterized in that: The axial magnetic field (5) is an electron sparse confinement magnetic field; The electron rarefaction confinement magnetic field is a coil magnetic field wound with a double-layer coil, and four-layer coils are wound at both the entrance and exit positions.

5. The high time-resolution radiation flow detector based on electronic signal stretching according to claim 4, characterized in that: The distance between the photocathode (1) and the grid (2) is 0.5 mm to 1.5 mm.

6. The high time-resolution radiation flow detector based on electronic signal stretching according to claim 5, characterized in that: The distance between the microchannel plate (3) and the current collecting anode (4) is 0.5 mm to 1.5 mm.

7. A high time resolution radiation flow detection method, based on the high time resolution radiation flow detector based on electronic signal stretching according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: Adjust the position of the radiation flow detector so that the radiation flow photon signal to be detected is incident on the photocathode (1) along the setting direction of the radiation flow detector; Step 2: After receiving the incident radiation flow photon signal to be detected, the photocathode (1) converts it into photoelectrons and emits them; Step 3: After being emitted from the photocathode (1), the photoelectrons enter the cathode grid region, are accelerated by the dynamic attenuation electric field, and then pass through the grid (2) into the drift region; Step 4: The accelerated photoelectrons are stretched in the drift region at different movement speeds for a period of time, and then incident on the microchannel plate (3), and the microchannel plate (3) multiplies and amplifies the photoelectrons; Step 5: The multiplied and amplified photoelectrons are incident on the collecting anode (4), and the collecting anode (4) collects the incident photoelectrons and outputs them, thereby completing the detection of the radiation flow photon signal.

8. The high time resolution radiation flow detection method according to claim 7, characterized in that: Before step 1, also include: Step A, adjusting the positions of the photocathode (1), the grid (2), the microchannel plate (3) and the collector anode (4) in the axial magnetic field (5), as well as the intensity of the dynamically attenuated electric field; Step A.1: Determine the electron stretching magnification factor based on the time resolution required for radiation flux detection using the following formula: in, T MAG The time resolution required for radiation flow detection is M is the electronic stretching magnification, T MCP is the transit time of the microchannel plate (3); Step A.2: Select the distance between the grid (2) and the microchannel plate (3), and the slope of the dynamic decay electric field according to the following formula: in, L is the distance between the grid (2) and the microchannel plate (3), is the slope of the dynamic decay electric field, V d is the average speed of photoelectrons; Step A.3, adjusting the positions of the photocathode (1) and the collector anode (4) so that the distance between the photocathode (1) and the entrance of the axial magnetic field (5), and the distance between the collector anode (4) and the exit of the axial magnetic field (5) are equal to the diameter of the axial magnetic field (5); Step A.4: Adjust the position of the grid (2) and the microchannel plate (3) in the axial magnetic field (5), and the intensity of the dynamic attenuation electric field according to the distance between the grid (2) and the microchannel plate (3) and the slope of the dynamic attenuation electric field obtained in step A.2.

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