High-precision detection device for gated high voltage

Abstract

The invention belongs to the technical field of space plasma environment detection, and relates to a high-precision gating high voltage detection device, which comprises a level processing circuit which is realized based on a field effect transistor and is used for filtering a high voltage part of input gating high voltage and only outputting low voltage; the ADC conversion circuit is used for periodically outputting gated high-voltage level data after analog-to-digital conversion at a set frequency under the control of the data processing unit; and the data processing unit is realized on the basis of the FPGA and is used for controlling the ADC conversion circuit, collecting level data output by the ADC conversion circuit, packaging the level data and outputting the packaged level data to a PC (Personal Computer) end through an RS422 interface. By adopting the device provided by the invention, the measuring range of the oscilloscope is reduced from 300V to 3V, and the measuring precision is improved from 50V / div to 0.5 V / div, so that the problem of low measuring precision of gating high-voltage high-low level switching is solved, and the risk of high-voltage discharge caused by direct measurement of high voltage by an oscilloscope meter pen is avoided.

Description

[0001] This application is a divisional of an invention application with the application number "2025101041613", the invention name "A Low-Level High-Precision Detection Device for Gated High Voltage Based on Field-Effect Transistors", and the application date of January 23, 2025. Technical Field

[0002] The present invention belongs to the technical field of space plasma environment detection, and particularly relates to a high-precision detection device for gated high voltage. Background Art

[0003] In space plasma environment detection, ion energy, direction, flux, and mass spectrometry detection are important detection elements. Among them, in the aspects of plasma flux measurement and ion mass spectrometry analysis, there is a wide range of application requirements for gated high voltage. The stable state of the high and low levels after the high and low level switching of the gated high voltage is an important parameter for evaluating the performance of the gated high voltage.

[0004] First, the gated high voltage is mainly used for the flux control of ionospheric ion imaging detection. For a typical ionospheric detection satellite, the orbit is 340 - 450 km, and the total change range of the ion differential flux reaches about 8 orders of magnitude (5×10 6 cm-2s-1sr-1eV-1 - 5×10 14 cm-2s-1sr-1eV-1), with a large absolute value, which is a typical area where large-flux ions exist. The basic working principle of ion imaging detection is to use a microchannel plate (Micro Channel Plate, abbreviated as: MCP) and a fluorescent screen to amplify and image the single-ion charge signal, and then finely analyze the density, temperature, drift velocity of ions, and the spatial distribution of ion components, with the advantages of high spatio-temporal analysis. However, when this type of ion imaging detection instrument measures in an environment with extremely high ionospheric ion flux, if flux control is not performed, it will saturate and cannot work properly. As Figure 1 shown in the design cross-section of the ion imager, a gated electrode is set at the ion entrance to limit the incident ion beam by applying a gated high voltage. When the output of the gated high voltage is at a high level, the door is closed to prevent ions from entering; when the output is at a low level, the door is opened to allow ions to enter, so as to ensure that the microchannel plate (MCP) and the fluorescent screen work within a suitable dynamic range.

[0005] Second, the gated high voltage is a key technology for mass spectrometry analysis based on the time-of-flight measurement system. The basic principle of the mass spectrometer based on the time-of-flight measurement system is: where m is the ion mass (unit: kilogram), and v is the ion velocity (unit: m / s). According to the ion flight time T, the flight velocity v can be deduced, and the ion energy E is deduced through the high voltage amplitude of the electrostatic analyzer; combined with the ion composition information can be deduced.

[0006] As Figure 2 shown in the figure, the gated high voltage is applied in the time-of-flight measurement system. The TDC-GPX is a time-of-flight measurement chip that measures the time interval between the start signal START and the stop signal STOP. The gated high voltage output by the gated high voltage module is used to control the "opening" of the gated electrode: that is, to allow incident ions to enter, and at the same time as the start signal START for the time-of-flight measurement of the TDC-GPX. After the incident ions pass through the free flight region with a distance of L and reach the detector, a digital pulse is output as the stop signal STOP for the time-of-flight measurement of the TDC-GPX. The TDC-GPX finally gives the time of flight of the incident ions.

[0007] As Figure 3 shown, the characteristic of the gated high voltage is that the output voltage periodically switches between the high level and the low level at a fixed frequency, and the pulse widths of the high level and the low level are fixed. In the application of the plasma detector, there are index requirements for the high and low level amplitudes, the switching time between the high level and the low level, the minimum pulse width, and the stable state of the level after switching of the gated high voltage. The gated high voltage for ion flux control requires a high level of +300V (closed door), a low level of 0V (open door), adjustable pulse width, a minimum width of 10us, and a switching time between the high level and the low level of 100ns. It is required that the output of the low level of 0V and the effective holding time of the level be accurate, otherwise it will affect the flux control accuracy. The gated high voltage for the mass spectrometer requires a high level of +300V (closed door), a low level of 0V (open door), adjustable pulse width, a minimum width of 30ns, and the switching time between the high level and the low level should be less than 20ns. It is required that the output of the low level of 0V and the effective holding time of the level be accurate, otherwise it will affect the mass spectrometry resolution.

[0008] Due to the charging and discharging of the parasitic capacitance in the gated high voltage circuit, an overshoot phenomenon will occur when the gated high voltage is turned on. This phenomenon will cause damage to the devices in the gated high voltage circuit and affect the service life of the devices. This overshoot phenomenon can be eliminated by adjusting the internal resistance-capacitance matching of the circuit, but it is necessary to be able to accurately measure the stable process of the level after the high and low level switching.

[0009] In different application scenarios, the stable state of the level after the high and low level switching of the gated high voltage is an important parameter for evaluating the performance of the gated high voltage. The level state directly affects the detection index of the detector on the one hand and the reliability of the gated high voltage on the other hand. However, during the debugging process of the gated high voltage circuit, due to the limitation of measurement technology, the measurement accuracy of the stable state of the level after the high and low level switching of the gated high voltage is relatively low.

[0010] Since the high level output by the gated high voltage is +300V, the voltage amplitude is high, the amplitude difference between the high level and the low level reaches 300V, the amplitude difference is large, the switching frequency between the high level and the low level is greater than 10kHz, and the low level holding time is less than 10us.

[0011] At present, an oscilloscope is used to measure the high and low level switching process of the gated high voltage output. The oscilloscope needs to cover a range of +300V, and its measurement resolution can only reach 50V / div, with low accuracy. The stable state of the level after switching cannot be accurately measured. In addition, the high level of the gated high voltage output is +300V high voltage. If the oscilloscope probe is used for direct measurement, there is a risk of high voltage discharge, posing a safety hazard to the test personnel. Summary of the Invention

[0012] The purpose of the present invention is to overcome the defects of the prior art and propose a high-precision detection device for gated high voltage.

[0013] In view of this, the present invention discloses a high-precision detection device for gated high voltage, including: a level processing circuit, an ADC conversion circuit, and a data processing unit. Among them,

[0014] The level processing circuit, implemented based on a field effect transistor, is used to filter the high voltage part of the input gated high voltage and only output a low voltage;

[0015] The ADC conversion circuit is used to periodically output the gated high voltage level data after analog-to-digital conversion at a set frequency under the control of the data processing unit;

[0016] The data processing unit, implemented based on an FPGA, is used to control the ADC conversion circuit, collect the level data output by the ADC conversion circuit, and package and output it to the PC side through an RS422 driver circuit;

[0017] The high level value of the input gated high voltage is +300V, and the low level value is 0V.

[0018] In the level processing circuit, the breakdown voltage V of the field effect transistor DS is 500V, the gate-source conduction threshold voltage V GS is greater than 2V, the rated voltage range that the gate-source can withstand is ±20V, the gate voltage V G is fixed at 5V, the source voltage V S is within the range of 0V to 3V, the drain-source D-S of the field effect transistor conducts, and when the source voltage V S is greater than 3V, the drain-source D-S of the field effect transistor is cut off.

[0019] Preferably, the ADC conversion circuit uses a 16-bit high-precision ADC converter.

[0020] Preferably, the data processing unit includes an FPGA and an RSS422 driver circuit. Among them,

[0021] The FPGA controls the ADC conversion circuit to periodically collect the level data output by the level processing circuit at a frequency of 100 kHz and transmit it to the RS422 driver circuit;

[0022] The RS422 driver circuit converts the level data from a single-ended signal to a differential signal and outputs it to the PC side.

[0023] Preferably, the interface signals between the ADC conversion circuit and the FPGA include: an ADC data bus, an ADC chip select signal, an ADC conversion enable flag signal, and an ADC conversion complete flag signal.

[0024] Preferably, the PC side stores the data of the high and low level switching process of the gated high voltage and the low level stable state for later data analysis and comparison.

[0025] Compared with the prior art, the advantages of the present invention are as follows:

[0026] 1. The present invention utilizes the conduction and cut-off characteristics of the field effect transistor to design a gated high voltage level processing circuit, filters the high voltage part of the gated high voltage, and only outputs a low voltage. After using the present invention, the measurement range of the oscilloscope is reduced from 300 V to 3 V, and the measurement accuracy is improved from 50 V / div to 0.5 V / div, overcoming the problem of low measurement accuracy in the high and low level switching of the gated high voltage and avoiding the risk of high voltage discharge caused by directly measuring the high voltage with the oscilloscope probe.

[0027] 2. The present invention outputs an integrated analog output interface and an RS422 digital output interface after level processing. The detected level can be viewed in real time through an oscilloscope or the data stored in the PC can be used to achieve data analysis, comparison, and research. Brief Description of the Drawings

[0028] Figure 1 is the design sectional view of the ion imager;

[0029] Figure 2 is the schematic diagram of the time-of-flight measurement principle based on the gated high voltage;

[0030] Figure 3 is the schematic diagram of the gated power supply working;

[0031] Figure 4 is the schematic block diagram of the low level high precision detection device for the gated high voltage of the present invention;

[0032] Figure 5 is Figure 4 the schematic diagram of the level processing circuit;

[0033] Figure 6 is Figure 4 the schematic diagram of the ADC conversion circuit;

[0034] Figure 7 is Figure 4 the schematic circuit diagram of the data processing unit;

[0035] Figure 8 is the input / output waveform diagram of the low-level high-precision detection device for the gated high voltage of the present invention. Detailed implementation manners

[0036] The present invention discloses a low-level high-precision detection device for gated high voltage, including: a level processing circuit, an ADC conversion circuit, and a data processing unit, wherein,

[0037] The level processing circuit, implemented based on a field effect transistor, is used to filter the high-voltage part of the input gated high voltage and only output a low voltage;

[0038] The ADC conversion circuit is used to periodically output the analog-to-digital converted gated high voltage level data at a set frequency under the control of the data processing unit;

[0039] The data processing unit, implemented based on an FPGA (Field-Programmable Gate Array), is used to control the ADC (Analog to Digital Converter) conversion circuit, collect the level data output by the ADC conversion circuit, and package and output it to the PC side through the RS422 driver circuit.

[0040] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0041] Embodiment

[0042] An embodiment of the present invention provides a low-level high-precision detection device for gated high voltage. As Figure 4 is a schematic block diagram of the low-level high-precision detection device for gated high voltage. The detection device includes a level processing circuit, an ADC conversion circuit, and a data processing unit. Its analog input is the gated high voltage, and the output is the low-voltage part of the processed gated high voltage. It can be measured by an oscilloscope and has an RS422 interface to package and output the collected data.

[0043] As Figure 5 shows the schematic circuit diagram of the level processing circuit of the low-level high-precision detection device for gated high voltage. In the present invention, the high-level value of the input gated high voltage is +300V, and the low-level value is 0V. GND represents ground. In one embodiment, the specification model of the key component, the field effect transistor, is RCS7464ET2, and the breakdown voltage V of the field effect transistor DSIt is 500V. Due to the charging and discharging of parasitic capacitors in the gated high-voltage circuit, an overshoot phenomenon will occur in the gated high-voltage at the moment of opening the door. This phenomenon will cause damage to the devices in the gated high-voltage circuit and affect the service life of the devices. This overshoot phenomenon can be eliminated by debugging the internal resistance-capacitance matching of the circuit, but it is necessary to be able to measure the level stabilization process after the high and low level switching with high precision.

[0044] As Figure 6 、 Figure 7 shown are the schematic diagram of the ADC conversion circuit and the schematic diagram of the data processing unit circuit of the low-level high-precision detection device for gated high-voltage. In one embodiment, the ADC converter uses AD976, a 16-bit high-precision ADC converter. The interface signals between it and the data processing unit FPGA include: ADC data bus, ADC chip select signal, ADC conversion enable flag signal, and ADC conversion complete flag signal. In one embodiment, the data processing unit FPGA in this device controls the ADC to periodically collect the analog level curve output by the level processing circuit at a frequency of 100kHz, and packages and outputs the collected data to the PC through the RS422 interface. The data of the high and low level switching process and the low-level stable state of the gated high-voltage are stored at the PC end, which can be used for later data analysis and comparison.

[0045] As Figure 8 shown is the input-output voltage waveform diagram of the level processing circuit. The input voltage range is 0 to +300V, and the output voltage range is 0 to +3V. The highest output voltage is +3V. The output end is connected to the ADC conversion circuit in this device, and at the same time, an external analog quantity output is led out, which can be measured with high precision using an oscilloscope. The output voltage of this device is 0 to +3V, within the human body safety voltage range, and there is no safety problem for the test personnel.

[0046] By using the device of the present invention to detect the output of the gated high-voltage, the low-level stable process, low-level amplitude, and low-level holding time after the high and low level switching can be measured with high precision. The overshoot phenomenon can be effectively avoided by adjusting the relevant resistance-capacitance matching state in the gated high-voltage circuit. The accurate measurement of the low-level amplitude and low-level holding time can effectively ensure the high-precision measurement of flux control and mass spectrometry analysis instruments.

[0047] The present invention overcomes the problem of low measurement accuracy in the high and low level switching of the gated high-voltage, avoids directly measuring the high voltage with the oscilloscope probe, and can effectively prevent the risk of high-voltage discharge. The present invention utilizes the on-off characteristics of the field effect transistor to design a gated high-voltage level measurement circuit, filters the high-voltage part of the gated high-voltage, and only outputs a low voltage. After using this invention, the oscilloscope measurement range is reduced from 300V to 3V, and the measurement accuracy is improved from 50V / div to 0.5V / div. The specific performance indicators are shown in Table 1:

[0048] Table 1

[0049]

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the embodiments, those of ordinary skill in the art should understand that any modification or equivalent replacement of the technical solutions of the present invention does not depart from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A high-precision detection device for gated high voltage, characterized in that, Including: a level processing circuit, an ADC conversion circuit and a data processing unit, wherein the level processing circuit, implemented based on a field effect transistor, is used to filter the high-voltage part of the input gated high voltage and only output a low voltage; the ADC conversion circuit is used to periodically output the level data of the gated high voltage after analog-to-digital conversion under the control of the data processing unit at a set frequency; the data processing unit, implemented based on an FPGA, is used to control the ADC conversion circuit, collect the level data output by the ADC conversion circuit, and package and output it to the PC side through the RS422 interface; the high-level value of the input gated high voltage is +300V, and the low-level value is 0V; In the described level processing circuit, the breakdown voltage V of the field effect transistor DS is 500V, the gate-source conduction threshold voltage V GS is greater than 2V, the rated voltage range that the gate-source can withstand is ±20V, the gate voltage V G is fixed at 5V, the source voltage V S is in the range of 0V to 3V, the drain-source D-S of the field effect transistor conducts, and when the source voltage V S is greater than 3V, the drain-source D-S of the field effect transistor is cut off.

2. The high-precision detection device for gated high voltage according to claim 1, characterized in that, the ADC conversion circuit uses a 16-bit high-precision ADC converter.

3. The high-precision detection device for gated high voltage according to claim 1, wherein, the data processing unit includes an FPGA and an RSS422 driver circuit, wherein the FPGA controls the ADC conversion circuit to periodically collect the level data output by the level processing circuit at a frequency of 100 kHz and transmit it to the RS422 driver circuit; the RS422 driver circuit converts the level data from a single-ended signal to a differential signal and outputs it to the PC side.

4. The high-precision detection device for gated high voltage according to claim 3, wherein, The interface signals between the ADC conversion circuit and the FPGA include: an ADC data bus, an ADC chip select signal, an ADC conversion enable flag signal, and an ADC conversion completion flag signal.

5. The high-precision detection device for gated high voltage according to claim 3, characterized in that, The PC side stores the data of the high and low level switching process of the gated high voltage and the low level stable state for later data analysis and comparison.

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