A plasma density sampling system and method

Abstract

This invention discloses a plasma density sampling system. A power conversion module converts a first voltage signal input from a power supply module into a second voltage signal with a predetermined peak value. A triangular wave conversion module converts the second voltage signal into a triangular wave driving voltage signal for driving a probe, and drives the probe to generate a detection current. The probe's detection current is then converted into a voltage signal, which is output to a signal conditioning module. The signal conditioning module conditions the voltage signal converted from the detection current into a third voltage signal of 1-5V. An acquisition and frequency adjustment module samples the third voltage signal according to a set sampling frequency to obtain a sampling current signal. This invention also discloses a plasma density sampling method that adjusts the sampling frequency based on the detection current. This invention is applied to plasma density measurement in real flight environments and can adapt to 10e... 10 cm ‑3 up to 10e 14 cm ‑3 Measurement of plasma density within a range.

Description

Technical Field

[0001] This invention relates to the field of plasma measurement technology, specifically to a plasma density sampling system and method. Background Technology

[0002] To investigate the impact of plasma electron density on hypersonic vehicle telemetry, tracking, and command (TT&C) communication, research on plasma electron density measurement technology is necessary. The plasma density generated during flight typically ranges from the 10th to the 14th power level. However, since the telemetry bandwidth of a hypersonic vehicle is generally only a few Mbps, bandwidth resources are limited, making it impossible to adapt to wide-range, long-term plasma density acquisition under these resource constraints. Summary of the Invention

[0003] The purpose of this invention is to overcome the aforementioned shortcomings and provide a plasma density sampling system and method, solving the technical problem that existing technologies cannot adapt to wide-range, long-term plasma density acquisition. This invention is applied to plasma density measurement in real flight environments and can adapt to 10e... 10 cm -3 up to 10e 14 cm -3 Measurement of plasma density within a range.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0005] A plasma density sampling system includes a power supply module, a power conversion module, a triangular wave conversion module, a signal conditioning module, an acquisition and frequency adjustment module, and a probe;

[0006] The power conversion module converts the first voltage signal input from the power supply module into a second voltage signal with a predetermined peak value, and outputs the second voltage signal to the triangular wave conversion module;

[0007] The triangular wave conversion module receives the second voltage signal input from the power conversion module, converts the second voltage signal into a triangular wave driving voltage signal for driving the probe, drives the probe to generate a detection current, converts the probe's detection current into a voltage signal, and outputs the converted voltage signal to the signal conditioning module.

[0008] The signal conditioning module receives the converted voltage signal input from the triangular wave transformation module and conditions the converted voltage signal into a third voltage signal of 1 to 5V.

[0009] The acquisition and frequency adjustment module samples the third voltage signal at a set sampling frequency to obtain the sampled current signal.

[0010] Furthermore, the power supply module includes a power supply and an isolation module;

[0011] The power supply provides DC power, and the isolation module performs isolation and transformation on the DC power to obtain a first voltage signal;

[0012] The power conversion module includes a boost circuit and a buck circuit; the boost circuit converts the first voltage signal input from the power supply module into a second voltage signal with a peak value of +V0, and the buck circuit converts the first voltage signal input from the power supply module into a second voltage signal with a peak value of -V0.

[0013] The triangular wave conversion module includes an analog triangular wave generator circuit, a power amplifier output circuit, and a signal sampling resistor. The analog triangular wave generator circuit receives the second voltage signal with a peak value of +V0 and the second voltage signal with a peak value of -V0, generates a triangular wave voltage signal, and outputs the triangular wave voltage signal to the power amplifier output circuit. The power amplifier output circuit amplifies the triangular wave voltage signal and uses it to drive the probe. The driving current signal of the probe is converted into a voltage signal after passing through the series signal sampling resistor.

[0014] Furthermore, the power supply provides DC power of 28V±4V;

[0015] The boost circuit converts the first voltage signal input from the power supply module into a second voltage signal with a peak value of +50V, and the buck circuit converts the first voltage signal input from the power supply module into a second voltage signal with a peak value of -50V.

[0016] The peak value of the triangular wave drive voltage is ±50V, the drive load is not less than 3A, and the frequency is not less than 200Hz.

[0017] Furthermore, the maximum detection current is ±3A, the minimum is 0.2mA, and the dynamic range is 83.5dB.

[0018] Furthermore, the signal conditioning module includes multiple signal conditioning circuits, each of which includes an amplifier circuit; the amplification factor of the amplifier circuit is determined according to the magnitude of the converted voltage signal.

[0019] The amplifier circuit includes an amplifying resistor with an accuracy of 1% and a temperature coefficient of 50ppm / ℃.

[0020] Furthermore, the method by which the acquisition and frequency adjustment module samples the third voltage signal according to the set sampling frequency is as follows:

[0021] (1) Set the sampling frequency of the acquisition and frequency adjustment module to low frequency, continuously acquire the third voltage signal for T milliseconds, and obtain the sampled current signal within T milliseconds;

[0022] (2) Determine whether the range of the sampled current signal within T milliseconds is full relative to the first path of the signal conditioning module. If it is not full, proceed to step (3); if it is full, proceed to step (4).

[0023] (3) Determine whether the sampled current signal within T milliseconds is greater than the second threshold. If the sampled current signal is not greater than the second threshold, set the sampling frequency of the acquisition and frequency adjustment module to low frequency. If the sampled current signal is greater than the second threshold, set the sampling frequency to high frequency.

[0024] (4) Determine whether the sampling current signal within T milliseconds is at full scale relative to the second path of the signal conditioning module. If it is at full scale, proceed to step (5); if it is not at full scale, proceed to step (6).

[0025] (5) Switch the signal conditioning module to the third channel and set the sampling frequency of the acquisition and frequency adjustment module to high frequency;

[0026] (6) Set the sampling frequency to high frequency;

[0027] The low-frequency sampling frequency is ≤1kHz, and the high-frequency sampling frequency is ≥30kHz.

[0028] The first channel has a range of 10 mA, the second channel has a range of 100 mA, and the third channel has a range of amperes.

[0029] The second threshold is set based on the system sampling error and is used to determine whether the sampled current signal is a valid signal.

[0030] A plasma density sampling method, comprising:

[0031] S1 uses a probe to obtain the detection current corresponding to the plasma density;

[0032] S2 converts the probe current into a third voltage signal of 1-5V;

[0033] S3 samples the third voltage signal according to the set sampling frequency to generate a sampled current signal. The specific method is as follows:

[0034] S3.1 Set the sampling frequency to low frequency and continuously sample the third voltage signal for T milliseconds to obtain the sampled current signal within T milliseconds;

[0035] S3.2 Determine whether the sampled current signal within T milliseconds is less than the first threshold. If the sampled current signal is less than the first threshold, proceed to step S3.3. If the sampled current signal is not less than the first threshold, proceed to step S3.4.

[0036] S3.3 Determine whether the sampled current signal within T milliseconds is greater than the second threshold. If the sampled current signal is not greater than the second threshold, set the sampling frequency to low frequency. If the sampled current signal is greater than the second threshold, set the sampling frequency to high frequency.

[0037] S3.4 sets the sampling frequency to a high frequency;

[0038] The low-frequency sampling frequency is ≤1kHz, and the high-frequency sampling frequency is ≥30kHz.

[0039] The second threshold is less than the first threshold.

[0040] Furthermore, the first threshold is set to 10 mA;

[0041] The second threshold is set based on the sampling error and is used to determine whether the sampled current signal is a valid signal.

[0042] Furthermore, in step S3.3, when the sampled current signal is not greater than the second threshold, the sampling frequency is set to 1kHz; when the sampled current signal is greater than the second threshold, the sampling frequency is set to 1MHz.

[0043] In step S3.4, the sampling frequency is set to 1MHz.

[0044] Furthermore, the aforementioned plasma density sampling method also includes continuously sampling the third voltage signal and sending it to telemetry for telemetry framing.

[0045] Compared with the prior art, the present invention has the following advantages:

[0046] (1) This invention creatively proposes a plasma density sampling system and method, which is applied for the first time to plasma density measurement in a real flight environment and can be adapted to 10e 10 cm -3 up to 10e 14 cm -3 Measurement of plasma density within a range;

[0047] (2) Based on the correspondence between plasma density and current signal magnitude, the present invention divides the conditioning circuit into different levels, which can ensure effective acquisition of signals under different densities.

[0048] (3) Under the condition of limited bandwidth resources, the present invention can save telemetry bandwidth resources to the maximum extent and obtain effective measurement data by dynamically adjusting the sampling frequency in real time, compared with the existing ground direct high-speed sampling method. Attached Figure Description

[0049] Figure 1 This is a block diagram illustrating the principle of the plasma density sampling system of the present invention.

[0050] Figure 2 The circuit portion of the plasma density sampling system of this invention is shown in the block diagram.

[0051] Figure 3 This is a diagram of the boost circuit of the present invention;

[0052] Figure 4 This is a diagram of the step-down circuit of the present invention;

[0053] Figure 5 This is the output circuit diagram of the power amplifier of the present invention;

[0054] Figure 6 This is a flowchart of the plasma density sampling system of the present invention. Detailed Implementation

[0055] The features and advantages of the present invention will become clearer and more apparent from the following detailed description.

[0056] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0057] In plasma measurement methods, a high sampling rate is required to ensure effective acquisition of the probe driving signal in order to obtain an effective current-voltage characteristic curve. Based on the principle of plasma measurement, this invention designs a probe measurement system for real-world flight environments. This system drives a probe to form a saturated electron or ion flow when plasma is generated during flight, and then collects electrical data.

[0058] This invention proposes a plasma density sampling system and method with adjustable base acquisition frequency. First, based on the correspondence between plasma density and current signal magnitude, the conditioning circuit is divided into different levels to ensure effective signal acquisition at different densities and adapt to a wide range of plasma density measurements. Simultaneously, the acquisition frequency is dynamically adjusted according to the real-time magnitude of the plasma signal, maximizing the acquisition of effective measurement data while making reasonable use of telemetry bandwidth resources.

[0059] Plasma density sampling system such as Figure 1 and Figure 2The system includes a power supply, an isolation module, a power conversion module, a triangular wave conversion module, a signal conditioning module, and an acquisition and frequency adjustment module. The isolation module limits, filters, and isolates the input voltage, preventing reverse power connection from affecting the equipment. The power conversion module boosts, bucks, and limits the voltage output after isolation, providing a peak voltage signal of ±50V to the triangular wave conversion module. The triangular wave conversion module generates a triangular wave voltage, driving a triangular wave drive voltage signal with a peak value of ±50V, a load capacity of not less than 3A, and a frequency of not less than 200Hz. This triangular wave drive voltage signal is output to a probe to generate a plasma current signal. Simultaneously, it samples the plasma drive current signal through a sampling resistor and outputs it to the signal conditioning module. The signal conditioning module conditions and outputs a 0-5V voltage signal to the acquisition and frequency adjustment module for processing, and finally outputs the data for telemetry framing.

[0060] The power management module includes a power supply, an isolation module, and a power conversion module. It isolates and converts the externally input DC power (28V±4V), providing high voltage and high load current to the triangular wave drive module and powering all circuits. The triangular wave drive module first generates a triangular wave using a dedicated triangular wave chip. A triangular wave drive amplifier circuit then generates a triangular wave voltage with a peak value of ±50V. This signal is input to the power amplifier output circuit, ultimately outputting a triangular wave drive voltage signal with a peak value of ±50V, a drive load of not less than 3A, and a frequency of not less than 200Hz. Under the action of the triangular wave drive voltage, the probe generates a current signal, which is converted into a voltage signal by a sampling resistor and output to the signal conditioning module. Simultaneously, the triangular wave drive voltage is led out to the input signal conditioning module, which conditions the input signal into a 0-5V voltage signal for system acquisition.

[0061] Specifically, the power management module includes a DC-DC isolation converter circuit, a boost circuit, a buck circuit, and a component power supply circuit. The DC-DC isolation converter circuit limits, filters, and isolates the input 28V±4V voltage, outputting a stable 28V voltage to the boost, buck, and component power supply circuits. The DC-DC converter is selected to meet the 160W drive power requirement, while also considering conversion efficiency. If a single power module is insufficient, multiple power modules are connected in parallel. The boost circuit boosts the +28V voltage to +55V (the boost circuit outputs +55V, but there will be a voltage drop at the probe end; it is given as +50V above). The buck circuit buckes the +28V voltage to -55V. The component power supply circuit converts the +28V voltage to ±5V to power the chips within the converter.

[0062] like Figure 3 and Figure 4The diagram shows the boost and buck circuits. Both circuits are designed with current limiting circuits, with a current threshold of 3.2A. When the current exceeds this threshold, the boost and buck circuits will cut off the output to protect the external probe sensor from damage due to excessive power. The circuits will automatically recover when the current returns to below the threshold. Compared to existing plasma measurement load drive circuits, these boost and buck circuits have strong load driving capability (maximum driving current up to 3A, corresponding to plasma density measurements from the 10th to 14th powers), high safety (automatic power cut-off in case of external short circuit to protect the internal system, and automatic recovery after fault resolution), and strong adaptability to both the measurement itself and external interference.

[0063] The triangular wave conversion module includes an analog triangular wave generator circuit, a power amplifier output circuit, and a signal sampling resistor. The analog triangular wave generator circuit uses a dedicated triangular wave chip to generate a signal at a frequency of 200Hz, with an output amplitude of -1V to +1V, which is then output to the power amplifier driver circuit. A current signal sampling resistor is designed in the signal output path to convert the current signal into a voltage signal of a few millivolts to tens of millivolts, which is then output to the signal conditioning module. Simultaneously, a triangular wave voltage is drawn from the triangular wave driver circuit and output to the signal conditioning module. Specifically, the +55V voltage boosted by the power amplifier output circuit is connected to the +VB and +VS terminals of the triangular wave chip, and the -55V voltage stepped down is connected to the -VB and -VS terminals of the triangular wave chip. Two 0.5-ohm sampling resistors are connected in series at the OUT terminal of the dedicated triangular wave chip for output. Figure 5 The power amplifier output circuit amplifies the voltage amplitude to -55V to +55V. The power amplifier circuit is designed with a current threshold of ±3A, and this signal is directly output to drive the probe. A current signal sampling resistor is designed in the signal output path. The maximum current generated by the drive probe is ±3A, and the minimum is 0.2mA, with a dynamic range of 83.5dB. To meet the system's 8-bit sampling requirements, different sampling resistors R47 and R48 need to be designed. All sampling resistors use 1% accuracy and a 50ppm / ℃ temperature coefficient resistor to ensure acquisition accuracy, converting the current signal into a voltage signal of a few millivolts to tens of millivolts, which is then output to the signal conditioning module. This acquisition path design can guarantee a sampling capability of a minimum 0.2mA and a maximum 3A current, and features a large dynamic range.

[0064] The signal conditioning module conditions multiple acquisition signals into 0-5V signals for system acquisition. The amplification resistor is a high-precision resistor with 1% accuracy and a temperature coefficient of 50ppm / ℃. The circuit conditioning eliminates common-mode voltage through differential operational amplifier. The cutoff frequency of the second-order low-pass filter circuit is designed to be 16kHz. The amplification factor is designed according to the magnitude of the input differential voltage. The amplified voltage meets the input voltage requirements of the external system.

[0065] Based on the plasma density ranging from the 10th to the 14th power, corresponding to currents ranging from a few milliamps to a few amperes, with a dynamic range of 83.5 dB, the real-time online acquisition system divides the conditioning circuit into different ranges to achieve the acquisition of a large dynamic signal range. The conditioning paths are divided according to the 10-mA range (1mA to tens of milliamps), the 100-mA range (tens of milliamps to hundreds of milliamps), and the ampere range (several amperes). This can cover plasma density measurements from the 10th to the 14th power, and the signal resolution can reach tens of microamps. It is applied to plasma density measurements in the first real flight environment.

[0066] like Figure 6 The conditioned probe signal is processed by the acquisition and frequency conversion module. It first maintains low-frequency sampling, then acquires measurement data in real-time over T milliseconds for analysis, and switches the sampling frequency in real-time. Compared to existing methods of direct high-speed sampling from the ground, this method maximizes the saving of telemetry bandwidth resources and obtains effective measurement data. The processing procedure is as follows:

[0067] 1) First, determine whether the 10 mA range is at full scale. If it is not at full scale, further determine whether the sampled value is greater than the threshold (which can be set according to the system acquisition error, the purpose of which is to determine whether there is a valid signal, preferably set to 0.1 mA). If it is not greater than the threshold, maintain low frequency sampling (not higher than 1 kHz). If it is greater than the threshold, switch to high sampling frequency (not lower than 30 kHz) for signal sampling. If it is determined to be at full scale, switch to step 2).

[0068] 2) Determine if the 100mA range is at full scale. If it is not at full scale, it is a valid signal. Then switch to a high sampling frequency (not less than 30kHz, this solution uses 1MHz) for signal sampling. If it is at full scale, switch to the ampere range.

[0069] 3) If the range is determined to fall directly within a certain number of amperes, then switch to a higher sampling frequency (1MHz in this solution);

[0070] 4) During the generation of a valid signal, sampling is maintained and sent to telemetry for telemetry framing to form a valid telemetry information code stream for transmission.

[0071] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

[0072] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A plasma density sampling system, characterized by, It includes a power supply module, a power conversion module, a triangular wave conversion module, a signal conditioning module, an acquisition and frequency adjustment module, and a probe; The power conversion module converts the first voltage signal input from the power supply module into a second voltage signal with a predetermined peak value, and outputs the second voltage signal to the triangular wave conversion module; The triangular wave conversion module receives the second voltage signal input from the power conversion module, converts the second voltage signal into a triangular wave driving voltage signal for driving the probe, drives the probe to generate a detection current, converts the probe's detection current into a voltage signal, and outputs the converted voltage signal to the signal conditioning module. The signal conditioning module receives the converted voltage signal from the triangular wave conversion module and conditions the converted voltage signal into a third voltage signal of 1~5V. The acquisition and frequency adjustment module samples the third voltage signal according to the set sampling frequency to obtain the sampled current signal; The method by which the acquisition and frequency adjustment module samples the third voltage signal according to the set sampling frequency is as follows: (1) Set the sampling frequency of the acquisition and frequency adjustment module to low frequency, continuously acquire the third voltage signal for T milliseconds, and obtain the sampled current signal within T milliseconds; (2) Determine whether the range of the sampled current signal within T milliseconds is full relative to the first path of the signal conditioning module. If it is not full, proceed to step (3); if it is full, proceed to step (4). (3) Determine whether the sampled current signal within T milliseconds is greater than the second threshold. If the sampled current signal is not greater than the second threshold, set the sampling frequency of the acquisition and frequency adjustment module to low frequency. If the sampled current signal is greater than the second threshold, set the sampling frequency to high frequency. (4) Determine whether the range of the sampled current signal within T milliseconds is full relative to the second path of the signal conditioning module. If it is full, proceed to step (5); if it is not full, proceed to step (6). (5) Switch the signal conditioning module to the third channel and set the sampling frequency of the acquisition and frequency adjustment module to high frequency; (6) Set the sampling frequency to high frequency; The low-frequency sampling frequency is ≤1kHz, and the high-frequency sampling frequency is ≥30kHz; The first channel has a range of 10 mA, the second channel has a range of 100 mA, and the third channel has a range of amperes. The second threshold is set based on the system sampling error and is used to determine whether the sampled current signal is a valid signal.

2. The plasma density sampling system according to claim 1, characterized in that, The power supply module includes a power supply and an isolation module; The power supply provides DC power, and the isolation module performs isolation and transformation on the DC power to obtain a first voltage signal; The power conversion module includes a boost circuit and a buck circuit; the boost circuit converts the first voltage signal input from the power supply module into a second voltage signal with a peak value of +V0, and the buck circuit converts the first voltage signal input from the power supply module into a second voltage signal with a peak value of -V0. The triangular wave conversion module includes an analog triangular wave generator circuit, a power amplifier output circuit, and a signal sampling resistor. The analog triangular wave generator circuit receives the second voltage signal with a peak value of +V0 and the second voltage signal with a peak value of -V0, generates a triangular wave voltage signal, and outputs the triangular wave voltage signal to the power amplifier output circuit. The power amplifier output circuit amplifies the triangular wave voltage signal and uses it to drive the probe. The driving current signal of the probe is converted into a voltage signal after passing through the series signal sampling resistor.

3. The plasma density sampling system according to claim 2, characterized in that, The power supply provides 28V±4V DC. The boost circuit converts the first voltage signal input from the power supply module into a second voltage signal with a peak value of +50V, and the buck circuit converts the first voltage signal input from the power supply module into a second voltage signal with a peak value of -50V. The peak value of the triangular wave drive voltage is ±50V, the drive load is not less than 3A, and the frequency is not less than 200Hz.

4. The plasma density sampling system according to claim 3, characterized in that, The maximum current to be detected is ±3A, the minimum is 0.2mA, and the dynamic range is 83.5dB.

5. A plasma density sampling system according to claim 1, characterized in that, The signal conditioning module includes multiple signal conditioning circuits, and each signal conditioning circuit includes an amplifier circuit; the amplification factor of the amplifier circuit is determined according to the magnitude of the converted voltage signal. The amplifier circuit includes an amplifying resistor with an accuracy of 1% and a temperature coefficient of 50ppm / ℃.

6. A plasma density sampling method, characterized in that, include: S1 uses a probe to obtain the detection current corresponding to the plasma density; S2 converts the probe current into a third voltage signal of 1~5V; S3 samples the third voltage signal according to the set sampling frequency to generate a sampled current signal. The specific method is as follows: S3.1 Set the sampling frequency to low frequency and continuously sample the third voltage signal for T milliseconds to obtain the sampled current signal within T milliseconds; S3.2 Determine whether the sampled current signal within T milliseconds is less than the first threshold. If the sampled current signal is less than the first threshold, proceed to step S3.

3. If the sampled current signal is not less than the first threshold, proceed to step S3.

4. S3.3 Determine whether the sampled current signal within T milliseconds is greater than the second threshold. If the sampled current signal is not greater than the second threshold, set the sampling frequency to low frequency. If the sampled current signal is greater than the second threshold, set the sampling frequency to high frequency. S3.4 sets the sampling frequency to a high frequency; The low-frequency sampling frequency is ≤1kHz, and the high-frequency sampling frequency is ≥30kHz; The second threshold is less than the first threshold.

7. The plasma density sampling method according to claim 6, characterized in that, The first threshold is set to 10 mA; The second threshold is set based on the sampling error and is used to determine whether the sampled current signal is a valid signal.

8. A plasma density sampling method according to claim 6, characterized in that, In step S3.3, if the sampled current signal is not greater than the second threshold, the sampling frequency is set to 1kHz; if the sampled current signal is greater than the second threshold, the sampling frequency is set to 1MHz. In step S3.4, the sampling frequency is set to 1MHz.

9. A plasma density sampling method according to claim 6, characterized in that, It also includes continuously sampling the third voltage signal and sending it to telemetry for telemetry framing.

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