A multi-resolution grid compact retarding potential analyzer and detection method

Abstract

The application provides a multi-resolution grid compact retarding potential analyzer and a detection method, which comprises a shell, a plurality of independent and identical branch retarding potential analyzers arranged at intervals in the shell, wherein each branch retarding potential analyzer comprises an outer shell, a circuit board and a multi-layer grid structure in the outer shell, and the circuit board is provided with a control module for controlling the branch retarding potential analyzer. Through the design of the plurality of independent and identical branch retarding potential analyzers, the resolution of the overall sensor can be flexibly adjusted.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of space plasma research and space physics science, and particularly relates to a multi-resolution grid compact retarding potential analyzer and a detection method. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] The retarding potential analyzer is one of the important sensors in the ionosphere plasma in-situ detection project, which is used to detect the ion density and ion temperature, ion composition and ion drift velocity of the sensor normal. The current retarding potential analyzer principle structure is based on the Faraday cage, and the sensor is a cylindrical shape with a multi-layer grid structure inside. By applying potential to each layer of grid, ions at different energy levels in the plasma can be screened. The voltage control of the retarding layer grid is used, and the numerical value of the ion current signal corresponding to the collection layer under different retarding voltages is recorded, thereby drawing the volt-ampere characteristic curve of the retarding potential analyzer. Through the analysis of the volt-ampere characteristic curve, the scientific data of the ionospheric ion parameters that researchers want to obtain can be calculated and obtained.

[0004] The specific implementation principle of the early traditional retarding potential analyzer is that the first layer and the second layer are ground layers, and the potential is at ground potential, which is directly connected to the ground potential of the satellite shell and satellite circuit, and is used to shield the disturbance of the scanning change of the internal retarding grid of the sensor to the external space plasma; the third layer is a retarding layer, which is used to load a scanning retarding bias, and the function is to screen ions at different energy levels. If the ion kinetic energy is greater than the electron volt energy corresponding to the bias potential, the ion can enter the collection layer to be collected, otherwise it will be blocked by the retarding layer and cannot be collected by the collection layer. The fourth layer is an inhibition layer, which is used to resist and inhibit the collection of electrons in the plasma by the collection plate, and to prevent the escape of secondary electrons and photoelectrons on the collection plate, so as to ensure that the current signal collected by the collection layer is formed by ions. This simplified structure has great defects in ion detection and ion drift velocity detection. After research, it is found that the reason why this simple sensor cannot meet the detection requirements is mainly due to the distortion of the grid electric field. In order to obtain the optimal sensor model, domestic and foreign researchers use simulation software to model the grid according to the real size and arrange it in different ways, and use the Monte Carlo method to statistically analyze the influence of each sensor model on the transmission rate of particles.

[0005] The traditional retarding potential analyzer has low ionospheric precision, small dynamic range, large volume, and especially low spatial resolution, which is usually kilometer, and it is difficult to detect small-scale inhomogeneous bodies, which is mainly limited by the bandwidth of the operational amplifier circuit, the bandwidth of the filter, and the loading of the retarding grid layer scanning voltage. If the near-earth orbit satellite speed is 7600 The spatial resolution of the corresponding plasma parameters is one plasma parameter point per 7600 meters, and the fine structure of the ionosphere cannot be characterized from the spatial position, especially the scientific data of the rapid change of the plasma parameters in the small-scale irregular spatial area cannot be well detected, thereby limiting the research needs and research accuracy of researchers. SUMMARY

[0006] To overcome the deficiencies of the prior art, the present application provides a multi-resolution grid compact retarding potential analyzer and a detection method, which realizes flexible adjustment of the resolution of the overall retarding potential analyzer through the design of multiple independent and identical branch retarding potential analyzers.

[0007] To achieve the above object, a first aspect of the present application provides a multi-resolution grid compact retarding potential analyzer, comprising: a casing, a plurality of independent and identical branch retarding potential analyzers arranged at intervals in the casing; wherein each branch retarding potential analyzer comprises a shell, a circuit board and a multi-layer grid structure arranged in the shell, and the circuit board is provided with a control module for separately controlling the branch retarding potential analyzer.

[0008] A second aspect of the present application provides a detection method of a multi-resolution grid compact retarding potential analyzer, comprising:

[0009] The scanning voltage of the multiple branch retarding potential analyzers is different;

[0010] The ion current of the multiple branch retarding potential analyzers under the corresponding scanning voltage is collected;

[0011] The volt-ampere characteristic curve of the retarding potential analyzer is obtained based on the ion current and the corresponding scanning voltage;

[0012] The detection result is obtained based on the obtained volt-ampere characteristic curve.

[0013] The above one or more technical solutions have the following beneficial effects:

[0014] In the present application, the compact retarding potential analyzer comprises a casing, a plurality of independent and identical branch retarding potential analyzers arranged at intervals in the casing, and the branch retarding potential analyzers are independently controlled to realize multiple spatial resolution adjustable modes of the multiple branch retarding potential analyzers, the spatial resolution under different modes is increased by 4 to 50 times compared with the conventional retarding potential analyzer, the fine structure of the ionosphere is flexibly detected under the premise of accurately characterizing the volt-ampere characteristic curve, and the detection time is shortened.

[0015] Advantages of the present application additional aspects will become apparent in the following description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings, which form a part of this specification, are included to provide a further understanding of the application, and are incorporated by reference herein. The embodiments depicted herein are provided by way of example only, and together with the description serve to explain the application.

[0017] Figure 1 The existing internal grid structure of the retardation potential analyzer is shown in the schematic diagram.

[0018] Figure 2(a) is a total assembly diagram of the compact retardation potential analyzer in the first embodiment of the present application.

[0019] Figure 2(b) is a structure schematic diagram of the branch retardation potential analyzer in the first embodiment of the present application.

[0020] Figure 3 The grid structure of the branch retardation potential analyzer in the first embodiment of the present application is shown in the schematic diagram.

[0021] Figure 4 The retardation grid scanning voltage configuration of the four branch retardation potential analyzers under the voltage range mode 0 in the first embodiment of the present application is shown in the schematic diagram.

[0022] Figure 5 The retardation grid scanning voltage configuration of the four branch retardation potential analyzers under the voltage range mode 1 in the first embodiment of the present application is shown in the schematic diagram.

[0023] Figure 6 The retardation grid scanning voltage configuration of the four branch retardation potential analyzers under the voltage range mode 2 in the first embodiment of the present application is shown in the schematic diagram.

[0024] Figure 7 The retardation grid scanning voltage configuration of the four branch retardation potential analyzers under the voltage range mode 3 in the first embodiment of the present application is shown in the schematic diagram.

[0025] Figure 8 The retardation grid scanning voltage configuration of the four branch retardation potential analyzers under the voltage range mode 4 in the first embodiment of the present application is shown in the schematic diagram.

[0026] Figure 9 The principle schematic diagram of the transimpedance amplification circuit in the first embodiment of the present application is shown in the schematic diagram.

[0027] Figure 10 The modeling schematic diagram of the transimpedance amplification noise analysis in the first embodiment of the present application is shown in the schematic diagram.

[0028] Figure 11 The typical retardation potential analyzer volt-ampere characteristic curve in the first embodiment of the present application is shown in the schematic diagram.

[0029] Figure 12Figure 6 is a comparison chart of the fitted curve and the measured curve in the voltage range mode 0 in Example 1;

[0030] Figure 13 Figure 7 is a comparison chart of the fitted curve and the measured curve in the voltage range mode 1 in Example 1;

[0031] Figure 14 Figure 8 is a comparison chart of the fitted curve and the measured curve in the voltage range mode 2 in Example 1;

[0032] Figure 15 Figure 9 is a comparison chart of the fitted curve and the measured curve in the voltage range mode 3 in Example 1;

[0033] Figure 16 Figure 10 is a comparison chart of the fitted curve and the measured curve in the voltage range mode 4 in Example 1.

[0034] In the figure, 1 is a first ground grid, 2 is an aluminum alloy metal support plate, 3 is a second ground grid, 4 is a retarding grid, 5 is a suppression grid, 6 is a third ground grid, 7 is a collector, and 8 is a circuit board. DETAILED DESCRIPTION

[0035] It should be noted that the following detailed description is merely exemplary in nature and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0036] It is to be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments consistent with the present application.

[0037] In the case of no conflict, the embodiments in the application and the features in the embodiments can be combined with each other.

[0038] Example 1

[0039] The present embodiment discloses a multi-resolution grid compact retarding potential analyzer, comprising: a casing, a plurality of independent and identical branch retarding potential analyzers arranged at intervals in the casing; wherein each branch retarding potential analyzer comprises a shell, a circuit board and a multi-layer grid structure arranged in the shell, and a control module for adjusting the spatial resolution of the branch retarding potential analyzer is arranged on the circuit board.

[0040] As Figure 1As shown, the existing retarding potential analyzer is difficult to detect small-scale inhomogeneous bodies in the grid structure, mainly limited by the bandwidth of the operational amplifier circuit, the bandwidth of the filter, and the loading of the retarding grid layer scanning voltage, especially unable to detect scientific data of the rapid change of plasma parameters in small-scale irregular spatial regions, thereby limiting the research needs and research accuracy of researchers. The embodiment improves the structure design of the traditional single-grid retarding potential analyzer to a combination of multiple independent branch retarding potential analyzers. Through the multi-mode configuration of the retarding grid voltage of multiple branch retarding potential analyzers, spatial multi-resolution adjustment is realized. The spatial resolution in different modes is improved by 4 to 50 times compared with the traditional retarding potential analyzer.

[0041] It should be noted that the number of branch retarding potential analyzers is not limited to four, and the number of branch retarding potential analyzers can be two or more.

[0042] The embodiment takes four branch retarding potential analyzers as an example for illustration, as shown in FIG. 2(a), the internal part of the retarding potential analyzer in the embodiment is divided into multiple branch retarding potential analyzers of the same size of regular octagon, and the diameter of the inscribed circle of each regular octagonal grid is 40 mm; in order to avoid the influence of the scanning of the four retarding grids on the internal electric field of each other, a reasonable distance is set between the two branch retarding potential analyzers, and a regular octagonal metal shell is sleeved on the outer surface of each branch retarding potential analyzer, the lead wire of the metal shell is grounded to the housing to form an electrostatic shielding shell.

[0043] Preferably, the distance between the two branch retarding potential analyzers is 15 mm.

[0044] The diameter of the grid cylinder of the traditional retarding potential analyzer is 80 mm, and the outer dimension is 100 mm*100 mm; the embodiment adopts four regular octagonal inscribed circles with a diameter of 40 mm, and the total area is distributed in the structure of the number of regular octagons inscribed in the circle being four, the total effective area of the grid is slightly improved, the space utilization is higher, and the grid is horizontally and vertically distributed. The symmetrical regular octagon can ensure that the grid has good consistency, the grid can be easily aligned during installation, and the overall multi-layer grid has high transmittance.

[0045] In addition, the larger the area of the retarding potential analyzer grid is, the larger the minimum current of the collecting electrode is, and the area design of the retarding potential analyzer is too small, which will increase the difficulty of detecting the minimum current. It is beneficial to detect the current as large as possible, and the diameter is too small, and the circuit cannot detect such a small current. The smaller the design is, the higher the requirement for the circuit is.

[0046] The grid diameter in the embodiment is 40mm (i.e. half of the original single large retarding potential analyzer, and the area is one fourth), which meets the requirements. The 40mm is selected so that the four branch retarding potential analyzers combined together have a size basically consistent with the conventional total area, and thus can realize the multi-resolution adjustable function compared with the conventional retarding potential analyzer under the same size.

[0047] It should be noted that in the embodiment, the diameter of the inscribed circle in the retarding grid of the branch retarding potential analyzer can be above 20mm, and the shape of the branch retarding potential analyzer can also be other shapes, such as regular pentagon, regular hexagon, etc.

[0048] As shown in Fig. 2(b), each branch retarding potential analyzer has five layers of gold-plated metal grids which are completely the same. Specifically, the branch retarding potential analyzer includes first ground potential grid 1, aluminum alloy metal support plate 2, second ground potential grid 3, retarding grid 4, suppression grid 5, third ground potential grid 6, collecting layer 7 and circuit board 8 which are sequentially arranged.

[0049] Specifically, the first ground potential grid 1 and the second ground potential grid 3 are connected to the ground potential, and are directly connected to the reference ground of the branch retarding potential analyzer shell and the circuit, which is used to suppress the influence of the scanning voltage generated by the retarding grid on the space plasma; the retarding grid 4 is connected to the output retarding scanning voltage of the digital-to-analog converter, which is used to screen ions of different energies; the suppression grid 5 is connected to -15V, which is used to resist the electrons in the ionosphere plasma; and the third ground potential grid 6 is connected to the ground, which can prevent the secondary electrons of the collecting layer from escaping, and shield the interference of the scanning bias loaded by each layer of grid on the rear-end circuit of the instrument.

[0050] In the embodiment, the grids in the first ground potential grid 1, the second ground potential grid 3, the retarding grid 4, the suppression grid 5 and the third ground potential grid 6 are all regular octagonal gold-plated grids, and the upper and lower parts of the grid are clamped by polyimide insulating pads, i.e. polyimide insulating pads are arranged between the branch retarding potential analyzer shell and the first ground potential grid 1, between the first ground potential grid 1 and the aluminum alloy metal support plate 2, between the aluminum alloy metal support plate 2 and the second ground potential grid 3, between the second ground potential grid 3 and the retarding grid 4, between the retarding grid 4 and the suppression grid 5, between the suppression grid 5 and the third ground potential grid 6, and between the third ground potential grid 6 and the collecting layer 7.

[0051] In the embodiment, the circuit board 8 is provided with a control module, which includes an operational amplifier circuit, a filter circuit, a digital-to-analog conversion circuit, a power supply circuit and an MCU circuit.

[0052] The key to realizing the multi-resolution switching of the retarding potential analyzer is the parallel control of the scanning voltage of the retarding grid of the four branch retarding potential analyzers.

[0053] Specifically, the digital-to-analog conversion circuit adopts a multi-channel voltage output digital-to-analog converter, which is used for parallel control of scanning voltages of barrier grids of four independent branch retarding potential analyzers.

[0054] Since the average area of the grid of the compact retarding potential analyzer in the embodiment is about one fourth of that of a traditional retarding analyzer, the detection of weak current is more stringent, and in the embodiment, a fA-level operational amplifier is selected to construct a transimpedance amplification circuit for a key device, i.e., an operational amplifier circuit, of the circuit part.

[0055] The transimpedance amplification circuit is shown in FIG. 2, and is used for converting a detected current signal into a voltage output signal. Figure 9 The transimpedance amplification circuit includes a feedback resistor Rf connected between input and output terminals of the operational amplifier.

[0056] The principle of the transimpedance amplification circuit utilizes the virtual short and virtual open properties of the operational amplifier. According to the virtual open property, the input current signal measured by the circuit will all flow through the feedback resistor Rf. The formula (1) is an output voltage formula of the output terminal of the transimpedance amplification circuit, and at this time, the value of the output voltage of the output terminal measured by the analog-to-digital converter can be used to inversely deduce the value of the measured weak current signal.

[0057] (1) According to the above analysis, in an ideal case, the measured current will all flow through the feedback resistor Rf, and the gain multiple value of the circuit is

[0058] , which can be conveniently adjusted and calculated, and therefore the structure is very suitable for measurement of extremely weak current and can stably realize large-gain signal amplification. In the circuit for detecting the weak ionospheric current, noise analysis is essential. Whether passive devices such as resistors and capacitors or active devices such as operational amplifiers and instrument amplifiers are used, noise is ubiquitous, and the construction of an operational amplifier model for quantitative analysis of noise is a key to improving the detection accuracy of weak current.

[0059] In the embodiment, as shown in FIG. 3, noise analysis is performed on the transimpedance amplification circuit, and noise sources can be equivalent to three external noise sources plus an ideal noiseless operational amplifier in modeling.

[0060] The three external noise sources mainly include a voltage noise source Figure 10 appearing in differential form at the input terminal, a current noise at the input terminal, and a thermal noise of the feedback resistor of the operational amplifier ​​​The noise of the operational amplifier is simulated by LT spice software. For the trans-impedance amplifier, the main noise source is the thermal noise of the feedback resistor.

[0061] The total noise of the trans-impedance amplifier is calculated by the following formula:

[0062] (2)

[0063] The thermal noise of the trans-impedance amplifier is calculated by the following formula:

[0064] (3)

[0065] The gain of the trans-impedance amplifier is related to the feedback resistor by the following formula:

[0066] (4)

[0067] If the noise caused by the semiconductor intrinsic noise is not considered, the signal gain of the trans-impedance amplifier is positively correlated with the feedback resistor, and the output noise voltage is positively correlated with the feedback resistor. Therefore, increasing the value of the feedback resistor can effectively improve the signal-to-noise ratio of the detection system. Therefore, increasing the value of the feedback resistor can effectively improve the signal-to-noise ratio of the detection system.

[0068] In this embodiment, the circuit of the trans-impedance amplifier is simulated. When the feedback resistor is 10G, the minimum current signal can be recognized as 0.1pA. In order to have a certain redundancy, the feedback resistor is reduced by one order of magnitude. Through actual measurement, the current signal of 1pA can be accurately detected, solving the problem of weak current caused by the reduction of mesh area. It is very suitable for the demand of weak current detection in small size and compact ion detection.

[0069] In this embodiment, the scanning voltage of the four independent branch barrier potential analyzers in different modes is shown in Table 1. Only five voltage scanning modes are set here, but in fact, it is not limited to these five modes.

[0070] Table 1: Different mode scanning voltage configuration of four sensor barrier grids

[0071]

[0072] ​​Voltage range mode 0: The same scan voltage is configured for the barrier grid of the retardation potential analyzer, and the voltage time is 1 s. The barrier grids of the branch retardation potential analyzers 1, 2, 3 and 4 are simultaneously scanned from 0 V to 16 V. Mode 0 is a low spatial resolution mode, and the spatial resolution is consistent with that of the traditional retardation potential analyzer. The sample points of the volt-ampere characteristic curve are the most and the curve is the most delicate. It is suitable for detecting large-scale spatial displacement plasma structure. The specific voltage configuration is shown in Figure 4 .

[0073] Voltage range mode 1: The scan voltage of the barrier grid of the branch retardation potential analyzer 1 is configured for 0.25 s, and the scan voltage of the barrier grid of the branch retardation potential analyzer 2 is configured for 0.25 s. The scan voltage of the barrier grid of the branch retardation potential analyzer 3 is configured for 0.25 s, and the scan voltage of the barrier grid of the branch retardation potential analyzer 4 is configured for 0.25 s. The scan voltage of the barrier grid of the branch retardation potential analyzer 1 is scanned from 0 to 4 V, the scan voltage of the barrier grid of the branch retardation potential analyzer 2 is scanned from 4 V to 8 V, the scan voltage of the barrier grid of the branch retardation potential analyzer 3 is scanned from 8 V to 12 V, and the scan voltage of the barrier grid of the branch retardation potential analyzer 4 is scanned from 12 V to 16 V. Mode 1 is also a low spatial resolution mode. If the same number of sample points is collected as the traditional retardation potential analyzer, the volt-ampere characteristic curve is described. The spatial resolution of mode 1 is 4 times that of the traditional retardation potential analyzer. The specific voltage configuration is shown in Figure 5 .

[0074] Voltage range mode 2: The scan voltage of the barrier grid of the branch retardation potential analyzer 1 is fixed at 1 V, the scan voltage of the barrier grid of the branch retardation potential analyzer 2 is fixed at 4 V, the scan voltage of the barrier grid of the branch retardation potential analyzer 3 is fixed at 12 V, and the scan voltage of the barrier grid of the branch retardation potential analyzer 4 is fixed at 16 V. In this mode, the period of the scan voltage is not relied on, but only depends on the sampling rate of the analog-to-digital converter. In order to consider the data quantity and the quantization noise of the analog-to-digital converter, the sampling rate is set to 7.6k. At this time, the spatial resolution reaches microns. Since the number of sample points of a curve drawn by four points is small, a data processing method based on cubic spline interpolation is used to draw the volt-ampere characteristic curve of the retardation potential analyzer. The specific voltage configuration is shown in Figure 6 .

[0075] Voltage range mode 3: The barrier grid voltage time of the retardation potential analyzer is set to 0.125 s. The fixed voltage of the barrier grid of the branch retardation potential analyzer 1 is 1 V, the scan voltage of the barrier grid of the branch retardation potential analyzer 2 is scanned from 4 V to 6 V, the scan voltage of the barrier grid of the branch retardation potential analyzer 3 is scanned from 9 V to 11 V, and the fixed voltage of the barrier grid of the branch retardation potential analyzer 4 is 15 V. At this time, the spatial resolution is 8 times that of the traditional retardation potential analyzer. The barrier grid voltages of two of the grids are fixed at 1 V and 15 V, and the scan voltages of the other two barrier grids are set at the inflection points of the volt-ampere curve, respectively. Then, the current values of the two fixed grid voltages are used to describe the trend of the volt-ampere curve. In this mode, the data quantity storage occupation can be reduced. The specific voltage configuration is shown inFigure 7 as shown.

[0076] Voltage range mode 4: set the retarding grid voltage time of the retarding potential analyzer to t, the retarding grid fixed bias voltage of branch retarding potential analyzer 1 is 1V, the retarding grid of branch retarding potential analyzer 2 is scanned from 4V to 4 plus 16t V, the retarding grid of branch retarding potential analyzer 3 is scanned from 8V to 10 plus 16t V, the retarding grid of branch retarding potential analyzer 4 is fixed bias voltage of 14V. At this time t is a variable that can be freely set, at this time the spatial resolution is 1 / t times of the traditional retarding potential analyzer. At this time the size of t will be adjusted according to the spatial position, the larger t is, the longer the scanning voltage period is, the more sample points there are, and the more detailed the curve is, but it also brings the disadvantage of large amount of data, the smaller t is, the shorter the scanning voltage period is, the higher the spatial sampling rate is, but the fewer the sample points are, which brings the disadvantage of not enough stable fitting of the volt-ampere characteristic curve. The embodiment sets t to 0.05s, which can accurately depict the volt-ampere characteristic curve while ensuring a high sampling rate of 20 times, and the amount of curve data will be greatly reduced. The specific voltage configuration is as shown in Figure 8 as shown.

[0077] The voltage configuration of each mode of the retarding grid of the four-branch retarding potential analyzer is flexibly adjusted to ensure the accuracy of the volt-ampere characteristic curve of the retarding potential analyzer, and the spatial resolution is increased to 4 to 50 times adjustable compared with the traditional retarding potential analyzer, which solves the problem that the traditional retarding potential analyzer is limited by long continuous scanning voltage period and not steep voltage time curve, thereby affecting the low spatial resolution, and can detect the fine structure of spatial non-uniform bodies of different scales by switching multiple modes. In order to verify the mutual influence of the retarding grids of the four-branch retarding potential analyzer on the electric field, the internal space potential of the branch retarding potential analyzer with different intervals of four independent space electric fields is simulated by using COMSOL6.0 software, the interval between the compact meshes in different planes is set to 15mm, the vertical upper and lower mesh spacing is 4mm insulating pad, and the outer surface is nested with a metal shell grounded. The simulation results show that the spatial potential distribution of the independent compact retarding potential analyzer is relatively uniform, there is no sharp potential mutation disturbance, and the potential of the retarding grid does not change. Due to the ground treatment of the outer surface and the increase of the distance between the retarding grids, the influence of the mutual spatial potential change of the retarding grid electric field is greatly reduced.

[0078] The standard curve diagram of the overall retarding potential analyzer is as shown in Figure 11The horizontal axis is the scanning voltage and the vertical axis is the collected ion current. In the plasma environment, as the scanning voltage of the retarding grid increases, more and more low-energy ions cannot pass through, and the ion current value decreases. The voltage and current values recorded during the entire scanning process are obtained to obtain the volt-ampere characteristic curve of the retarding potential analyzer.

[0079] Assuming that the space plasma conforms to the Maxwell distribution, the current contribution of the i-th ion to the data curve is:

[0080] (5)

[0081] wherein is the total passage rate, is the window area, is the unit charge, is the ion density of the i-th ion, is the overall speed of the plasma along the sensor axis relative to the satellite, is the absolute potential of the satellite relative to the space plasma, is the scanning bias value, is the mass of the i-th ion, , , is the temperature of the i-th ion. Therefore, the i-th ion current curve data is summed to obtain the current curve formula, which is the measured total current curve, and the total contribution current of all ions is:

[0082] (6)

[0083] By fitting the above formula with the measured volt-ampere characteristic curve, the ion density, ion temperature, ion drift speed, ion composition ratio, satellite absolute potential and other parameter data can be obtained.

[0084]

[0085] ​​Regarding the difference in the number of sample points, the number of sample points in voltage range mode 0, voltage range mode 1, and voltage range mode 3 is significantly greater than that in voltage range mode 2. For the data fitting model of the hindrance potential analyzer under voltage range mode 2, its data relationship corresponds to a specific functional relationship. Therefore, an interpolation algorithm can be used to approximate its current-voltage characteristic curve, aiming to reconstruct the current-voltage characteristic curve containing ionospheric ion movement data using a relatively small number of data points. This reduces the number of measurement points, saving hardware and software resources, and improves the resolution of the measured data by using the interpolation algorithm. Common interpolation methods include nearest neighbor interpolation, linear interpolation, cubic spline interpolation, and cubic convolution interpolation. Based on the two main characteristics of the hindrance potential analysis data fitting model—a small number of data points and inflection points—this embodiment will use cubic spline interpolation. Cubic spline interpolation can better estimate the values ​​between data points, thus obtaining a more continuous curve. At the same time, when there are inflection points in the data points, cubic spline interpolation can approximate the curve at the inflection point through multiple continuous cubic functions, thereby better reflecting the changes in the data points. Data from other models are fitted nonlinearly using the least squares method, such as... Figure 12 , Figure 13 , Figure 14 , Figure 15 , Figure 16 The figures shown correspond to the comparison between the fitting results and the measured hindrance potential analysis of the source meter under voltage range modes 0, 1, 2, 3, and 4, respectively.

[0086] Among them, Figures 13-16 In this context, RPA stands for Restriction Potential Analyzer, and RPA1234 is the Branch Restriction Potential Analyzer 1234.

[0087] This embodiment improves the traditional single-grid hindrance potential analyzer structure by combining four independent, compact octagonal hindrance potential analyzers. Compared to the traditional square profile with a central circular opening, this design improves the space utilization of the grid. By configuring the voltage of the hindrance grid in each of the four branch hindrance potential analyzers, multiple spatial resolution adjustable modes are achieved. In low-resolution mode, the traditional scanning voltage curve is sliced, enabling the acquisition of a more detailed volt-ampere characteristic curve with a higher spatial resolution than traditional hindrance potential analyzers. In high-resolution mode, the hindrance grids of the four branch hindrance potential analyzers are controlled to simultaneously and continuously scan the voltage of local inflection point regions, acquiring a number of sample points with key characteristics to accurately fit a more robust volt-ampere characteristic curve. Combined with corresponding data processing and analysis methods for different spatial resolution modes, different resolutions can be switched in different scenarios to achieve high- and low-speed measurements of parameters such as ion density, ion temperature, and ion drift velocity. Simultaneously, the designed pA-level high-precision, low-noise front-end amplifier circuit enables flexible detection of the fine structure of the ionosphere while maintaining accurate volt-ampere characteristic curves.

[0088] It is of great significance to detect ionospheric small-scale inhomogeneities for communication, navigation, power transmission and aerospace. Retarding potential analyzer is one of the important means for plasma detection. Retarding potential analyzer is constantly advancing towards miniaturization, low power consumption and high spatial resolution. In order to make up for the low spatial resolution of in-situ detection of space plasma, and to reduce the cost and facilitate flexible transplantation for micro-nano satellites, this embodiment proposes a multi-resolution mode four-grid compact retarding potential analyzer design to realize the research of small-scale inhomogeneous plasma. The analyzer can switch different spatial resolutions in different scenarios to detect different spatial scales, especially the fine structure of small-scale ionosphere, improve the comprehensive efficiency of the detection system, and can be very conveniently transplanted to various cubic small satellite payloads, which has broad market and application prospects.

[0089] Embodiment two

[0090] The purpose of this embodiment is to provide a detection method of multi-resolution grid compact retarding potential analyzer, comprising:

[0091] Different modes of scanning voltage are used for multiple branch retarding potential analyzers;

[0092] Ion currents of multiple branch retarding potential analyzers under corresponding scanning voltages are collected;

[0093] Based on the ion current and the corresponding scanning voltage, the volt-ampere characteristic curve of the retarding potential analyzer is obtained;

[0094] Based on the obtained volt-ampere characteristic curve, the detection result is analyzed and obtained.

[0095] Although the specific embodiments of the present application are described above with reference to the accompanying drawings, it is not a limitation on the protection scope of the present application. Those skilled in the art should understand that various modifications or changes made on the basis of the technical solutions of the present application without creative labor are still within the protection scope of the present application.

Claims

1. A multi-resolution grid compact retarding potential analyser characterised in that, The shell, a plurality of independent and identical branch block potential analyzers arranged at intervals in the shell, and a reasonable spacing distance between each two branch block potential analyzers; wherein each branch block potential analyzer comprises a shell, a circuit board and a multilayer grid structure arranged in the shell, the circuit board is provided with a control module for realizing a plurality of spatial resolution adjustable modes of the branch block potential analyzer, and a plurality of independent branch block potential analyzers are controlled in parallel by using different voltage scanning modes; the control module further comprises a transimpedance amplification circuit; the transimpedance amplification circuit is used for converting the detected current signal into a voltage output signal, and the transimpedance amplification circuit comprises a feedback resistor connected between the input terminal and the output terminal of the amplifier.

2. A compact retarding potential analyser of a multi-resolution grid according to claim 1, characterised in that, The multilayer grid structure comprises a first ground potential grid, a metal support plate, a second ground potential grid, a block grid, an inhibition grid, a third ground potential grid and a collection layer arranged in sequence.

3. A compact retarding potential analyser of a multi-resolution grid according to claim 2, characterised in that, The upper and lower sides of the ground potential grid, the ground potential grid, the block grid, the inhibition grid and the ground potential grid are provided with insulating spacers.

4. A compact retarding potential analyser of a multi-resolution grid according to claim 2, characterised in that, The first ground potential grid and the second ground potential grid are connected with the sensor shell, and the block grid is connected with a digital-to-analog conversion circuit.

5. A compact retarding potential analyser of a multi-resolution grid according to claim 4, characterised in that, The digital-to-analog conversion circuit adopts a multi-channel voltage output digital-to-analog converter, and the multi-channel voltage output digital-to-analog converter controls the scanning voltage of the block grid in a plurality of independent and identical sensors in parallel.

6. A method of probing a multi-resolution grid compact retarding potential analyser according to any one of claims 1 to 5, characterised in that, Comprise: Different modes of scanning voltage are used for a plurality of branch block potential analyzers; Collecting ion currents of a plurality of branch block potential analyzers under corresponding scanning voltages; Based on the ion current and the corresponding scanning voltage, the volt-ampere characteristic curve of the block potential analyzer is obtained; Based on the obtained volt-ampere characteristic curve, the detection result is analyzed and obtained.

7. The method of claim 6, wherein the method is performed by a multi-resolution grid compacted retarding potential analyzer. Under different scanning voltage modes, different data processing methods are used for the collected ion currents and corresponding scanning voltages, and the data processing methods include least square method and interpolation method.

8. The method of claim 6, wherein the multi-resolution grid compacted retarding potential analyzer is a compacted retarding potential analyzer (C-RPA) having a plurality of grids, and the method further comprises: applying a voltage to the plurality of grids to generate a plurality of electric fields; and applying a voltage to the plurality of grids to generate a plurality of electric fields. The scanning voltages of the block grids of a plurality of branch block potential analyzers are controlled in parallel.

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