Microwave reflectometer for measuring plasma waves and measuring method based on microwave reflectometer

Abstract

The invention relates to the technical field of detection, and discloses a microwave reflectometer for measuring plasma waves and a measurement method based on the microwave reflectometer, and the microwave reflectometer comprises a detection signal transmitting module which is used for outputting a first frequency synthesizer source signal, and transmitting a target detection signal obtained by performing frequency multiplication conversion on the first frequency synthesizer source signal to plasma; the local oscillator signal transmitting module is used for outputting a second frequency synthesizer source signal and performing frequency multiplication conversion on the second frequency synthesizer source signal to obtain a target local oscillator signal; the reflection signal reflection module is used for acquiring a target reflection signal reflected after the plasma receives the target detection signal; and the frequency mixing signal modulation module is used for performing frequency mixing modulation on the target local oscillation signal and the target reflection signal to obtain a target intermediate frequency signal. The method has the beneficial effect that the measurement precision of plasma high-frequency waves is improved.

Description

Technical Field

[0001] The present application relates to the field of detection technology, and in particular to a microwave reflectometer for measuring plasma waves and a measurement method based thereon. Background Art

[0002] Density fluctuation microwave reflectometry is widely used in magnetic confinement plasma diagnosis, mainly for density fluctuation detection in the low-frequency band, but it still faces technical bottlenecks in the measurement of high-frequency waves (such as ion Bernstein waves (IBW) and low-hybrid waves (LHW)). High-frequency waves are crucial to fusion plasmas, for example, IBW waves transfer energy to improve fusion efficiency, and LHW waves drive plasma currents.

[0003] However, existing technologies cannot effectively detect these fluctuations, which limits the verification of related theories and experimental research. Therefore, it is urgent to solve how to improve the measurement accuracy of plasma high-frequency waves to provide important support for fusion energy research. Summary of the invention

[0004] The present application provides a microwave reflectometer for measuring plasma waves and a measurement method based thereon, which solves the technical problem of how to improve the measurement accuracy of plasma high-frequency waves and achieves the technical effect of improving the measurement accuracy of plasma high-frequency waves.

[0005] In order to achieve the above objectives, the main technical solutions adopted in this application include: In a first aspect, an embodiment of the present application provides a microwave reflectometer for measuring plasma waves, comprising: A detection signal sending module, used for outputting a first frequency synthesis source signal, and sending a target detection signal obtained by frequency doubling the first frequency synthesis source signal into the plasma; A local oscillator signal transmitting module, used for outputting a second frequency synthesis source signal, and performing frequency doubling conversion on the second frequency synthesis source signal to obtain a target local oscillator signal; A reflection signal reflection module, used for obtaining a target reflection signal reflected by the plasma after receiving the target detection signal; The mixing signal modulation module is used to mix and modulate the target local oscillator signal and the target reflected signal to obtain a target intermediate frequency signal.

[0006] The present embodiment provides a microwave reflectometer for measuring plasma waves. The detection signal sending module increases the first frequency synthesis source signal to a higher frequency through frequency doubling conversion, thereby enhancing the signal's penetration and resolution, and being able to more accurately detect high-density or thicker plasmas. Secondly, the local oscillator signal transmitting module adopts a similar frequency doubling conversion technology to increase the frequency of the second frequency synthesis source signal, so that it can be better coupled with the inherent mode of the plasma, thereby improving the signal's response efficiency and detection capability. The reflected signal reflection module provides important information about the plasma state, such as density, temperature, etc., by receiving the reflected signal. Subsequently, the mixing signal modulation module mixes and modulates the target local oscillator signal and the target reflected signal to generate an intermediate frequency signal that is easy to process. This process not only simplifies signal processing and improves the signal-to-noise ratio of the signal, but also effectively improves the accuracy and response speed of data analysis.

[0007] Optionally, the detection signal sending module includes a first frequency multiplication unit and a sending unit connected end to end in sequence; The first frequency doubling unit is used to frequency-multiply the output first frequency synthesis source signal to the W band to obtain a first W band microwave signal; The sending unit is used to send a target detection signal obtained by attenuation adjustment of the first W-band microwave signal into the plasma.

[0008] The detection signal sending module of this embodiment significantly improves the frequency, penetration and detection accuracy of the signal by doubling the first frequency synthesis source signal to the W band. The W band signal has strong energy and can effectively penetrate high-density plasma, reduce signal attenuation, and thus improve the detection efficiency. In addition, the attenuation adjustment function in the sending unit can accurately control the signal strength, avoid the influence of too strong or too weak signals on the detection results, and ensure the appropriate intensity of the first frequency synthesis source signal to achieve the best detection effect. It is possible to maintain efficient signal propagation and a stable detection process under different plasma conditions, thereby improving the overall detection accuracy and reliability. Through the coordinated work of the frequency doubling unit and the attenuation adjustment, it not only has stronger adaptability, but also ensures the consistency and stability of the detection results, greatly enhancing the monitoring capability of the plasma state.

[0009] Optionally, the first frequency multiplication unit comprises a first frequency source synthesizer, a first coaxial isolator and a first frequency multiplier connected end to end in sequence; The first frequency source synthesizer is used to output the first frequency synthesizer source signal; The first coaxial isolator is used to unidirectionally transmit the first frequency synthesis source signal to the first frequency multiplier; The first frequency multiplier is used for multiplying the frequency of the first frequency synthesis source signal to the W band to obtain the first W band microwave signal.

[0010] In this embodiment, the first frequency source synthesizer generates a stable and accurate low-frequency signal, providing a reliable signal source for the subsequent frequency doubling process. Then, the first coaxial isolator realizes the unidirectional transmission of the signal and effectively isolates the reverse signal, avoids echo interference, and ensures the purity and transmission stability of the signal. Finally, the first frequency multiplier multiplies the low-frequency signal to the W band, significantly enhancing the signal's penetration and detection accuracy. Therefore, high-precision detection can be performed in complex environments, ensuring that the signal is stable and reliable, and effectively improving the overall performance of the microwave reflectometer.

[0011] Optionally, the transmitting unit comprises a first waveguide isolator, an adjustable attenuator and a first horn antenna connected end to end in sequence; The first waveguide isolator is used to unidirectionally transmit the first W-band microwave signal to the adjustable attenuator; The adjustable attenuator is used to adjust the intensity of the first W-band microwave signal to obtain a target detection signal; The first horn antenna is used to send the target detection signal into the plasma.

[0012] This embodiment effectively isolates the reverse signal through the first waveguide isolator to avoid signal interference and ensure stable signal transmission. Then, the adjustable attenuator adjusts the signal strength as needed to ensure that the signal always maintains the optimal strength under different detection conditions, avoiding the impact of too strong or too weak signals on detection accuracy. Finally, the first horn antenna can efficiently transmit the target detection signal into the plasma, ensuring that the signal propagates at a low attenuation rate and has a strong penetration ability, ensuring that the detection signal can accurately reach the target area.

[0013] Optionally, the local oscillator signal transmitting module comprises a second frequency multiplication unit and a power amplifier connected end to end in sequence; The second frequency multiplication unit is used for multiplying the second frequency synthesis source signal to the W band to obtain a second W band microwave signal; The power amplifier is used to amplify the power of the second W-band microwave signal to obtain the target local oscillator signal.

[0014] The combination of the second frequency multiplication unit and the power amplifier in this embodiment can effectively improve the performance in high-frequency applications. The frequency multiplication unit converts the low-frequency signal to the W band, and by increasing the signal frequency, it has stronger penetration and higher resolution. At the same time, the power amplifier amplifies the power of the converted signal to ensure that the signal maintains sufficient strength during the propagation process, thereby overcoming path loss and external interference, and ensuring that the signal can cover a larger range and remain stable.

[0015] Optionally, the second frequency multiplication unit comprises a second frequency source synthesizer, a second coaxial isolator and a second frequency multiplier connected end to end in sequence; The second frequency source synthesizer is used to output the second frequency synthesizer signal; The second coaxial isolator is used to unidirectionally transmit the second frequency synthesis source signal to the second frequency multiplier; The second frequency multiplier is used for multiplying the frequency of the second frequency synthesis source signal to the W band to obtain the second W band microwave signal.

[0016] In this embodiment, the second frequency source synthesizer generates a stable and accurate low-frequency signal, providing a reliable signal source for the subsequent frequency doubling process. Then, the second coaxial isolator realizes the unidirectional transmission of the signal and effectively isolates the reverse signal, avoiding echo interference, ensuring the purity of the signal and the transmission stability. Finally, the second frequency multiplier multiplies the low-frequency local oscillator signal to the W band to meet the requirements of mixing with the reflected signal, ensuring the signal is stable and reliable, and effectively improving the overall performance of the microwave reflectometer.

[0017] Optionally, the reflected signal reflection module comprises a second horn antenna, a second waveguide isolator and a low noise amplifier connected end to end in sequence; The second horn antenna is used to send a reflection signal reflected by the plasma after receiving the target detection signal to the second waveguide isolator; The second waveguide isolator is used to unidirectionally transmit the reflected signal to the low noise amplifier; The low noise amplifier is used to amplify the reflection signal to obtain the target reflection signal.

[0018] This embodiment can significantly improve the quality and stability of the signal through the synergistic effect of the second horn antenna, the second waveguide isolator and the low-noise amplifier. The second horn antenna effectively receives the reflected signal and transmits it to the second waveguide isolator; the second waveguide isolator ensures unidirectional transmission of the signal to avoid reverse signal interference, thereby improving the anti-interference ability; while amplifying the signal, the low-noise amplifier minimizes the introduction of additional noise and ensures a high signal-to-noise ratio of the signal. Overall, the coordination of the three modules not only optimizes the signal reception and processing process, but also improves the detection accuracy, ensures the quality of the reflected signal, and provides an accurate basis for subsequent analysis and target detection.

[0019] Optionally, the mixed signal modulation module includes a mixer, a first low-pass filter, a gain amplifier, a second low-pass filter and a third low-pass filter connected in sequence; The mixer is used to mix the target local oscillator signal and the target reflected signal to obtain a mixed signal; The first low-pass filter is used to perform a first filtering on the mixed signal to obtain a first mixed signal; The gain amplifier is used to amplify the first mixing signal to obtain an amplified first mixing signal; The second low-pass filter is used to perform a second filtering on the amplified first mixed signal to obtain a second mixed signal; The third low-pass filter is used to perform a third filtering on the second mixing signal to obtain the target intermediate frequency signal.

[0020] This embodiment mixes the target local oscillator signal with the target reflected signal through a mixer, and converts the high-frequency signal into an intermediate frequency signal suitable for processing. Then, the first low-pass filter removes the high-frequency clutter in the mixed signal, retains the frequency difference part of the target reflected signal, and reduces noise interference. The gain amplifier further amplifies the amplitude of the signal, enhances the signal-to-noise ratio of the signal, and improves the processability of the signal. The second and third low-pass filters gradually clean up the high-frequency noise in the signal to ensure that the output target intermediate frequency signal is purer. Through these multi-stage processing, the signal quality is significantly improved, the noise and interference of the signal are effectively suppressed, and a basis is provided for subsequent target recognition and signal analysis.

[0021] Optionally, the frequencies of the first frequency synthesis source signal and the second frequency synthesis source signal are 12.5GHz-18.33GHz; the frequencies of the target detection signal and the target local oscillator signal are 75GHz-110GHz; the frequency of the target detection signal, the frequency of the target local oscillator signal and the frequency of the plasma wave need to meet the following conditions: |F1+f-F2|≤100MHz, wherein F1 is the frequency of the target detection signal, f is the frequency of the plasma wave, and F2 is the frequency of the target local oscillator signal.

[0022] In a second aspect, an embodiment of the present application provides a measurement method of the microwave reflectometer according to the above-mentioned method, the method comprising: The detection signal sending module outputs a first frequency synthesis source signal, and sends a target detection signal obtained by frequency doubling the first frequency synthesis source signal to the plasma; The local oscillator signal transmitting module outputs a second frequency synthesis source signal, and performs frequency doubling conversion on the second frequency synthesis source signal to obtain a target local oscillator signal; The reflection signal reflection module obtains the target reflection signal reflected by the plasma after receiving the target detection signal; The mixing signal modulation module mixes and modulates the target local oscillator signal and the target reflected signal to obtain a target intermediate frequency signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 A schematic diagram of a microwave reflectometer for measuring plasma waves, showing a specific scenario example; Figure 2 A block diagram of a microwave reflectometer for measuring plasma waves provided in an embodiment of the present application; Figure 3 A block diagram of a first frequency multiplication unit provided in an embodiment of the present application; Figure 4 A block diagram of a sending unit provided in an embodiment of the present application; Figure 5 A block diagram of a second frequency multiplication unit provided in an embodiment of the present application; Figure 6 A block diagram of a reflection signal reflection module provided in an embodiment of the present application; Figure 7 A block diagram of a mixing signal modulation module provided in an embodiment of the present application; Figure 8 A flow chart of a microwave reflectometer measurement method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0026] Density fluctuation microwave reflectometry is an important tool in the diagnosis of magnetically confined plasmas. It mainly obtains density fluctuation information in plasma by emitting microwave signals and receiving reflected signals. At present, this technology is mainly used in the detection of fluctuations in lower frequency bands (tens of kHz to hundreds of kHz), such as the toroidal Alfvén local oscillator mode (TAE). However, with the deepening of fusion research, the study of high-frequency waves in the frequency band of tens of MHz to several GHz (such as ion Bernstein waves (IBW) and low-hybrid waves (LHW)) has become increasingly important, but the existing reflectometry technology still faces significant challenges in the measurement of high-frequency waves.

[0027] High-frequency waves play a critical role in fusion plasma. For example, IBW waves transfer energy to ions by exciting high-energy alpha particles, thereby increasing the energy output of fusion reactors. LHW waves can also drive plasma currents and promote steady-state operation. However, current reflectometers cannot effectively detect these fluctuations, which limits the verification of related theories and the in-depth experimental research.

[0028] Solving these problems requires breakthroughs in high-frequency wave signal reception and processing technology, including improving the sensitivity of reflected signals, signal demodulation capabilities, and noise suppression levels. At the same time, it is also necessary to develop new reflectometers adapted to high-frequency wave measurements and provide experimental data support for the theories of IBW, LHW, and other waves. This will promote the progress of fusion energy research and promote a better understanding and application of the role of high-frequency waves in the fusion process.

[0029] Based on this, in order to solve the above technical problems, please refer to Figure 1 In a specific scenario example, the detection signal sending module includes a first frequency multiplication unit and a sending unit connected end to end in sequence. Among them, the first frequency multiplication unit includes a first frequency source synthesizer, a first coaxial isolator and a first frequency multiplier connected end to end in sequence; the first frequency source synthesizer outputs a first frequency synthesis source signal, and transmits the first frequency synthesis source signal unidirectionally to the first frequency multiplier through the first coaxial isolator, and the first frequency multiplier multiplies the first frequency synthesis source signal to the W band to obtain a first W-band microwave signal. The sending unit includes a first waveguide isolator, an adjustable attenuator and a first horn antenna connected end to end in sequence; the first W-band microwave signal is unidirectionally transmitted to the adjustable attenuator through the first waveguide isolator; the adjustable attenuator adjusts the intensity of the first W-band microwave signal to obtain a target detection signal; the first horn antenna sends the target detection signal to the plasma.

[0030] The reflected signal reflection module includes a second horn antenna, a second waveguide isolator and a low-noise amplifier which are connected end to end in sequence; the second horn antenna sends the reflected signal reflected by the plasma after receiving the target detection signal to the second waveguide isolator; the second waveguide isolator transmits the reflected signal unidirectionally to the low-noise amplifier; the low-noise amplifier amplifies the reflected signal to obtain the target reflected signal.

[0031] The local oscillator signal transmitting module includes a second frequency multiplication unit and a power amplifier connected end to end in sequence; the second frequency multiplication unit includes a second frequency source synthesizer, a second coaxial isolator and a second frequency multiplier connected end to end in sequence; the second frequency source synthesizer outputs a second frequency synthesis source signal; the second coaxial isolator transmits the second frequency synthesis source signal unidirectionally to the second frequency multiplier; the second frequency multiplier multiplies the second frequency synthesis source signal to the W band to obtain a second W band microwave signal. The reflected signal reflection module includes a second horn antenna, a second waveguide isolator and a low noise amplifier connected end to end in sequence; the second horn antenna sends the reflected signal reflected by the plasma after receiving the target detection signal to the second waveguide isolator; the second waveguide isolator transmits the reflected signal unidirectionally to the low noise amplifier; the low noise amplifier amplifies the reflected signal to obtain the target reflected signal.

[0032] The mixing signal modulation module includes a mixer, a first low-pass filter, a gain amplifier, a second low-pass filter and a third low-pass filter connected in sequence; the mixer mixes the target local oscillator signal and the target reflected signal to obtain a mixing signal; the first low-pass filter performs a first filtering on the mixing signal to obtain a first mixing signal; the gain amplifier amplifies the first mixing signal to obtain an amplified first mixing signal; the second low-pass filter performs a second filtering on the amplified first mixing signal to obtain a second mixing signal; the third low-pass filter performs a third filtering on the second mixing signal to obtain a target intermediate frequency signal. Finally, the target intermediate frequency signal is collected for subsequent research on the propagation and structural characteristics of high-frequency waves inside the plasma, such as the position and amplitude of the high-frequency waves and the relationship between them and the distribution of fast ions.

[0033] In this embodiment, a microwave reflectometer for measuring plasma waves is provided. Figure 2 A block diagram of a microwave reflectometer for measuring plasma waves provided in an embodiment of the present application, such as Figure 2 As shown, the microwave reflectometer comprises: The detection signal sending module is used to output the first frequency synthesis source signal, and send the target detection signal obtained by frequency doubling the first frequency synthesis source signal to the plasma.

[0034] Specifically, the task of the detection signal sending module is to output the first frequency synthesis source signal, which is usually a high-frequency microwave signal used to irradiate the target area such as plasma. Then, this signal will be further processed to obtain the target detection signal through frequency doubling conversion. Among them, frequency doubling conversion is to increase the frequency of the input signal to an integer multiple of the original. Frequency doubling is achieved through nonlinear circuits such as secondary modulators, frequency multipliers, etc. After the first frequency synthesis source signal is multiplied, the frequency will be raised to a new frequency range in order to interact with the target more effectively. Preferably, the first frequency synthesis source signal is multiplied 6 times to the W band (75-110GHz), and the selected frequency multiplier output power is 6-7dBm.

[0035] The local oscillator signal transmitting module is used to output a second frequency synthesis source signal and perform frequency doubling conversion on the second frequency synthesis source signal to obtain a target local oscillator signal.

[0036] Specifically, the local oscillator signal transmitting module is responsible for outputting the second frequency synthesis source signal, which is used to monitor the state of the target plasma through reflection. Similarly, the second frequency synthesis source signal will obtain the target local oscillator signal through frequency doubling conversion. This processing can increase the frequency of the signal so that it matches the frequency of the first frequency synthesis source signal, which is convenient for subsequent signal processing. Preferably, the second frequency synthesis source signal is multiplied 6 times to the W band (75-110GHz), and the selected frequency multiplier output power is 6-7dBm.

[0037] The reflection signal reflection module is used to obtain the target reflection signal reflected by the plasma after receiving the target detection signal.

[0038] Specifically, when the target plasma receives the target detection signal, reflection occurs, and the reflection signal is acquired by the reflection signal module. This reflection signal carries the information of the target plasma, and its intensity, frequency, phase and other characteristics are affected by the physical characteristics of the target plasma such as shape, size, material, etc. and its motion state. By analyzing these reflection signals, the propagation and structural characteristics of high-frequency waves inside the target plasma can be studied.

[0039] The mixing signal modulation module is used to mix and modulate the target local oscillator signal and the target reflected signal to obtain a target intermediate frequency signal.

[0040] Specifically, the mixing signal modulation module mixes and modulates the target local oscillator signal with the target reflected signal to obtain a target intermediate frequency signal. The intermediate frequency signal is a low-frequency signal obtained by mixing two signals. This process helps to reduce processing complexity while maintaining sufficient signal information. Mixing modulation generates two new frequency components by multiplying two frequency signals, one of which is the sum of the original frequencies (high-frequency mixing) and the other is the frequency difference (intermediate frequency). Usually, the frequency difference part is selected as the output signal because it can retain the key information of the target plasma and is more convenient to process.

[0041] In some embodiments, the frequencies of the first frequency synthesis source signal and the second frequency synthesis source signal are 12.5 GHz-18.33 GHz; the frequencies of the target detection signal and the target local oscillator signal are 75 GHz-110 GHz; the frequencies of the target detection signal, the target local oscillator signal and the plasma wave need to meet the following conditions: |F1+f-F2|≤100 MHz, where F1 is the frequency of the target detection signal, f is the frequency of the plasma wave, and F2 is the frequency of the target local oscillator signal.

[0042] Specifically, by controlling the output signal, the frequency f1 of the first frequency synthesis source signal and the frequency f2 of the second frequency synthesis source signal are multiplied to the W band, so that the electromagnetic wave can penetrate the edge area of ​​the plasma, and the cutoff position is located in the core of the plasma. After the frequency f2 of the second frequency synthesis source signal is set to the sweep mode by using a microwave device, the reflected signal is mixed with the local oscillator signal, and the intermediate frequency signal in the range of tens of MHz to several GHz can be obtained by using heterodyne detection technology. These intermediate frequency signals carry information of high-frequency waves such as TAE (toroidal Alfvén eigenmode), IBW (ion Bernstein wave), and LHW (low noise wave). By adjusting the frequency f1 of the first frequency synthesis source signal, the cutoff position of the detection microwave can be changed, thereby realizing scanning from the core of the plasma to the boundary, and then studying the propagation and structural characteristics of high-frequency waves inside the plasma.

[0043] For example, assuming that the frequency of the plasma wave to be detected is f=3GHz, the frequency f1 of the first frequency synthesis source signal is set to 15GHz, and the frequency f2 of the second frequency synthesis source signal is set to 15.51GHz. The first frequency synthesis source signal is multiplied 6 times to 90GHz as the target detection signal, and the second frequency synthesis source signal is multiplied 6 times to 93.06GHz as the target local oscillator signal. The multiplied signal 93.06GHz of the target local oscillator signal is mixed with the reflected signal 90GHz±3GHz. After mixing, the signal carrying the plasma wave information is spectrum shifted. The mixed signal passes through a low-pass filter to filter out the high-frequency part. The remaining intermediate frequency signal has a frequency below 100MHz, that is, 93.06GHz-93GHz=0.06GHz (that is, 60MHz). The intermediate frequency signal contains relevant information about the plasma, which can be collected by the data acquisition system.

[0044] The present embodiment provides a microwave reflectometer for measuring plasma waves. The detection signal sending module increases the first frequency synthesis source signal to a higher frequency through frequency doubling conversion, thereby enhancing the signal's penetration and resolution, and being able to more accurately detect high-density or thicker plasmas. Secondly, the local oscillator signal transmitting module adopts a similar frequency doubling conversion technology to increase the frequency of the second frequency synthesis source signal, so that it can be better coupled with the inherent mode of the plasma, thereby improving the signal's response efficiency and detection capability. The reflected signal reflection module provides important information about the plasma state, such as density, temperature, etc., by receiving the reflected signal. Subsequently, the mixing signal modulation module mixes and modulates the target local oscillator signal and the target reflected signal to generate an intermediate frequency signal that is easy to process. This process not only simplifies signal processing and improves the signal-to-noise ratio of the signal, but also effectively improves the accuracy and response speed of data analysis.

[0045] In some embodiments, the detection signal sending module includes a first frequency multiplication unit and a sending unit connected end to end in sequence; The first frequency doubling unit is used for doubling the output first frequency synthesis source signal to the W band to obtain a first W band microwave signal; The sending unit is used to send the target detection signal obtained by attenuation adjustment of the first W-band microwave signal into the plasma.

[0046] Specifically, the first frequency synthesis source signal is frequency-doubled to the W band, and a first W band microwave signal is generated. The W band generally refers to a microwave signal with a frequency range of 75 GHz to 110 GHz, which has strong penetration and high resolution. The frequency doubling process converts the frequency of the first frequency synthesis source signal from a lower frequency to the W band, and the purpose of this conversion is to improve the penetration and resolution of the signal. Plasma has strong absorption and scattering effects, so high-frequency signals can reduce attenuation during the penetration process and increase the effectiveness of the signal. Then, the sending unit further processes the first W band microwave signal, adjusts the attenuation of the signal, and finally transmits it as a target detection signal to the plasma. Through attenuation adjustment, the sending unit can dynamically adjust the signal strength according to the required detection depth or plasma density, thereby improving the flexibility and accuracy of detection. For example, under different experimental conditions, the signal strength can be adjusted to adapt to the response of different plasmas.

[0047] and Figure 2 Compared with the embodiment shown, the detection signal sending module of this embodiment significantly improves the frequency, penetration and detection accuracy of the signal by doubling the first frequency synthesis source signal to the W band. The W band signal has strong energy and can effectively penetrate high-density plasma, reduce signal attenuation, and thus improve the detection efficiency. In addition, the attenuation adjustment function in the sending unit can accurately control the signal strength, avoid excessively strong or weak signals affecting the detection results, and ensure the appropriate intensity of the first frequency synthesis source signal to achieve the best detection effect. It is possible to maintain efficient signal propagation and a stable detection process under different plasma conditions, thereby improving the overall detection accuracy and reliability. Through the coordinated work of the frequency doubling unit and the attenuation adjustment, it not only has stronger adaptability, but also ensures the consistency and stability of the detection results, greatly enhancing the monitoring capability of the plasma state.

[0048] Figure 3 A block diagram of a first frequency multiplication unit provided in an embodiment of the present application, the unit comprising a first frequency source synthesizer, a first coaxial isolator and a first frequency multiplier connected end to end in sequence; The first frequency source synthesizer is used to output a first frequency synthesizer source signal.

[0049] Specifically, the main task of the first frequency source synthesizer is to output the first frequency synthesis source signal. By combining a fixed reference frequency (from a high-stability crystal oscillator) and a programmable frequency divider, the frequency source synthesizer can generate one or more precise output frequencies to generate the required first frequency synthesis source signal.

[0050] The first coaxial isolator is used for unidirectionally transmitting the first frequency synthesis source signal to the first frequency multiplier.

[0051] Specifically, the first coaxial isolator is used to unidirectionally transmit the first frequency synthesis source signal from the first frequency source synthesizer to the first frequency multiplier, and effectively avoid signal reflection or echo interference. The function of the first coaxial isolator is to prevent the first frequency synthesis source signal from returning to the first frequency source synthesizer due to any reflection, causing the performance of the microwave reflectometer to deteriorate. For example, if the signal is reflected back to the first frequency source synthesizer, it will cause phase noise, frequency instability, and even damage the first frequency source synthesizer.

[0052] The first frequency multiplier is used for multiplying the frequency of the first frequency synthesis source signal to the W band to obtain a first W band microwave signal.

[0053] Specifically, the main task of the first frequency multiplier is to perform frequency multiplication conversion on the first frequency synthesis source signal, and to increase the lower frequency first frequency synthesis source signal to the W band (75 GHz to 110 GHz) range, thereby obtaining the required high-frequency detection signal. The first frequency multiplier increases the input low-frequency signal to a higher frequency band through nonlinear elements such as diodes, transistors or special frequency multiplication materials. In this process, the frequency of the signal is doubled to generate a new high-frequency signal (for example, a 10 GHz signal is converted to 20 GHz, or a lower frequency signal is multiplied to the W band). This embodiment multiplies the frequency to the W band six times.

[0054] and Figure 2 Compared with the embodiment shown in the figure, the first frequency source synthesizer in this embodiment generates a stable and accurate low-frequency signal, providing a reliable signal source for the subsequent frequency doubling process. Then, the first coaxial isolator realizes the unidirectional transmission of the signal and effectively isolates the reverse signal, avoids echo interference, and ensures the purity and transmission stability of the signal. Finally, the first frequency multiplier multiplies the low-frequency signal to the W band, significantly enhancing the signal's penetration and detection accuracy. Therefore, high-precision detection can be performed in complex environments, ensuring that the signal is stable and reliable, and effectively improving the overall performance of the microwave reflectometer.

[0055] Figure 4 A block diagram of a transmitting unit provided in an embodiment of the present application, the unit comprising a first waveguide isolator, an adjustable attenuator and a first horn antenna connected end to end in sequence; The first waveguide isolator is used for unidirectionally transmitting the first W-band microwave signal to the adjustable attenuator.

[0056] Specifically, the main function of the first waveguide isolator is to achieve unidirectional transmission of signals. It guides the first W-band microwave signal to the adjustable attenuator and effectively isolates the reverse signal. By blocking the transmission of the reverse signal, the first waveguide isolator prevents signal reflection and interference. Because the reverse signal may cause an echo effect, affecting stability and signal quality. In addition, the unidirectional characteristics of the first waveguide isolator can ensure the unidirectional flow of signals, reduce any potential signal loss or interference, and thus improve overall performance.

[0057] The adjustable attenuator is used to adjust the intensity of the first W-band microwave signal to obtain a target detection signal.

[0058] Specifically, the function of the adjustable attenuator is to adjust the intensity of the first W-band microwave signal to obtain the required target detection signal. By reducing the amplitude of the signal, the signal can meet different detection requirements and avoid excessive or weak signals affecting the detection accuracy. For example, when facing strong interference or high-density plasma, it may be necessary to reduce the signal strength to avoid overload or excessive reflection; when detecting distant targets, it is necessary to increase the signal strength to ensure the signal penetration and detection range. The application of the adjustable attenuator makes it possible to maintain the best detection effect and signal strength under different conditions.

[0059] The first horn antenna is used to send a target detection signal into the plasma.

[0060] Specifically, the main function of the first horn antenna is to effectively send the target detection signal adjusted by the adjustable attenuator into the plasma for detection. The horn antenna is a high-frequency signal radiation device that can convert microwave signals into electromagnetic waves and radiate them outward. Since the W band has strong penetration ability, the precise radiation of the horn antenna can ensure that the signal propagates in the plasma without too much attenuation and can achieve the expected detection effect.

[0061] and Figure 2 Compared with the embodiment shown in the figure, this embodiment effectively isolates the reverse signal through the first waveguide isolator to avoid signal interference and ensure stable signal transmission. Then, the adjustable attenuator adjusts the signal strength as needed to ensure that the signal always maintains the optimal strength under different detection conditions, avoiding the influence of too strong or too weak signal on the detection accuracy. Finally, the first horn antenna can efficiently transmit the target detection signal into the plasma, ensure that the signal propagates at a low attenuation rate, and has a strong penetration ability, ensuring that the detection signal can accurately reach the target area.

[0062] In some embodiments, the local oscillator signal transmission module includes a second frequency multiplication unit and a power amplifier connected end to end in sequence; The second frequency doubling unit is used for doubling the frequency of the second frequency synthesis source signal to the W band to obtain a second W band microwave signal; The power amplifier is used to amplify the power of the second W-band microwave signal to obtain a target local oscillator signal.

[0063] Specifically, the second frequency synthesizer source signal is frequency-doubled to the W band, and a second W band microwave signal is generated. The W band generally refers to microwave signals with a frequency range of 75 GHz to 110 GHz, which have strong penetration and high resolution. The frequency doubling process converts the frequency of the second frequency synthesizer source signal from a lower frequency to the W band. The purpose of this conversion is to improve the penetration and resolution of the signal. The main function of the power amplifier is to amplify the second W band microwave signal. The power of the signal is increased to the required level to ensure that the signal can be effectively propagated and meet the needs of detection or communication. The power amplifier usually adopts high power amplification technology, such as solid-state amplifiers, traveling wave tube amplifiers (TWTA) or tube amplifiers.

[0064] and Figure 2 Compared with the embodiment shown in the figure, the combination of the second frequency multiplication unit and the power amplifier in this embodiment can effectively improve the performance in high-frequency applications. The frequency multiplication unit converts the low-frequency signal to the W band, and by increasing the signal frequency, it has stronger penetration and higher resolution. At the same time, the power amplifier amplifies the power of the converted signal to ensure that the signal maintains sufficient strength during the propagation process, thereby overcoming path loss and external interference, and ensuring that the signal can cover a larger range and remain stable.

[0065] Figure 5 A block diagram of a second frequency multiplication unit provided in an embodiment of the present application, the unit comprising a second frequency source synthesizer, a second coaxial isolator and a second frequency multiplier connected end to end in sequence; The second frequency source synthesizer is used to output a second frequency synthesizer source signal.

[0066] Specifically, the main task of the second frequency source synthesizer is to output the second frequency synthesis source signal. By combining a fixed reference frequency (from a high-stability crystal oscillator) and a programmable frequency divider, the frequency source synthesizer can generate one or more precise output frequencies to generate the required second frequency synthesis source signal.

[0067] The second coaxial isolator is used for unidirectionally transmitting the second frequency synthesis source signal to the second frequency multiplier.

[0068] Specifically, the second coaxial isolator is used to unidirectionally transmit the second frequency synthesis source signal from the second frequency source synthesizer to the second frequency multiplier, and effectively avoid signal reflection or echo interference. The function of the first coaxial isolator is to prevent the second frequency synthesis source signal from returning to the second frequency source synthesizer due to any reflection, causing the performance of the microwave reflectometer to deteriorate. For example, if the signal is reflected back to the second frequency source synthesizer, it will cause phase noise, frequency instability, and even damage the second frequency source synthesizer.

[0069] The second frequency multiplier is used for multiplying the frequency of the second frequency synthesis source signal to the W band to obtain a second W band microwave signal.

[0070] Specifically, the main task of the second frequency multiplier is to perform frequency multiplication conversion on the second frequency synthesis source signal, and to increase the lower frequency second frequency synthesis source signal to the W band (75 GHz to 110 GHz) range, thereby obtaining the required high-frequency local oscillator signal. The second frequency multiplier increases the input low-frequency signal to a higher frequency band through nonlinear elements such as diodes, transistors or special frequency multiplication materials. In this process, the frequency of the signal is doubled to generate a new high-frequency signal (for example, converting a 10 GHz signal to 20 GHz, or multiplying a lower frequency signal to the W band). This embodiment multiplies the frequency to the W band six times.

[0071] and Figure 2 Compared with the embodiment shown in FIG. 1 , the second frequency source synthesizer in this embodiment generates a stable and accurate low-frequency signal, providing a reliable signal source for the subsequent frequency doubling process. Then, the second coaxial isolator realizes the unidirectional transmission of the signal and effectively isolates the reverse signal, avoids echo interference, and ensures the purity of the signal and the transmission stability. Finally, the second frequency multiplier multiplies the low-frequency local oscillator signal to the W band to meet the requirements of mixing with the reflected signal, ensuring the signal is stable and reliable, and effectively improving the overall performance of the microwave reflectometer.

[0072] Figure 6 A block diagram of a reflected signal reflection module provided in an embodiment of the present application, the module comprising a second horn antenna, a second waveguide isolator and a low noise amplifier connected end to end in sequence; The second horn antenna is used to send the reflected signal reflected by the plasma after receiving the target detection signal to the second waveguide isolator.

[0073] Specifically, the second horn antenna is capable of receiving reflected signals within a certain angle range while maximizing the receiving efficiency through its beam characteristics (such as beam width, directivity, etc.). The antenna interacts with the reflected signal reflected back from the detection target plasma, so that the target detection signal is reflected back after colliding with the target plasma. The received reflected signal is transmitted from the second horn antenna outlet to the second waveguide isolator.

[0074] The second waveguide isolator is used to transmit the reflected signal unidirectionally to the low noise amplifier.

[0075] Specifically, the main function of the second waveguide isolator is to ensure unidirectional transmission of signals, thereby preventing the reflected signal from being reflected back to the source unnecessarily or interfering with other components. The second waveguide isolator can achieve unidirectional flow of signals, ensuring that the reflected signal is transmitted from the second horn antenna to the low-noise amplifier without signal reflux or reverse propagation. Its working principle is based on the characteristics of nonlinear materials or magnetic materials, which can effectively prevent the reverse propagation of signals, thereby protecting downstream equipment and improving stability.

[0076] The low noise amplifier is used to amplify the reflected signal to obtain the target reflected signal.

[0077] Specifically, since the reflected signal is often accompanied by a certain amount of noise, it is necessary to amplify the reflected signal through a low noise amplifier while avoiding the introduction of excessive noise as much as possible. The main feature of the low noise amplifier LNA is low noise, which can minimize the introduction of additional noise while amplifying the signal.

[0078] and Figure 2 Compared with the embodiment shown in the figure, this embodiment can significantly improve the quality and stability of the signal through the synergy of the second horn antenna, the second waveguide isolator and the low-noise amplifier. The second horn antenna effectively receives the reflected signal and transmits it to the second waveguide isolator; the second waveguide isolator ensures unidirectional transmission of the signal to avoid reverse signal interference, thereby improving the anti-interference ability; while amplifying the signal, the low-noise amplifier minimizes the introduction of additional noise and ensures a high signal-to-noise ratio of the signal. Overall, the coordination of the three modules not only optimizes the signal reception and processing process, but also improves the detection accuracy, ensures the quality of the reflected signal, and provides an accurate basis for subsequent analysis and target detection.

[0079] Figure 7 A block diagram of a mixed signal modulation module provided in an embodiment of the present application, the module comprising a mixer, a first low-pass filter, a gain amplifier, a second low-pass filter and a third low-pass filter connected end to end in sequence; The mixer is used to mix the target local oscillator signal and the target reflected signal to obtain a mixed signal.

[0080] Specifically, a mixer receives two input signals, a desired local oscillator signal and a desired reflected signal, and combines them through nonlinear processes such as multiplication to produce a spectrum that contains the sum (high frequency signal) and difference (low frequency signal) of the two original frequencies.

[0081] The first low-pass filter is used to perform a first filtering on the mixed signal to obtain a first mixed signal.

[0082] Specifically, the signal output by the mixer contains the sum and difference of the frequencies of the target reflected signal and the local oscillator signal. The first low-pass filter sets a cutoff frequency to filter out high-frequency components and only allows the low-frequency signal, which is the frequency difference between the target reflected signal and the local oscillator signal, to pass through to obtain the first mixed signal. This step is to reduce high-frequency clutter in the signal and reduce the complexity of subsequent processing.

[0083] The gain amplifier is used to amplify the first mixing signal to obtain an amplified first mixing signal.

[0084] Specifically, although the high-frequency components have been removed from the first mixed signal after the first low-pass filter, its amplitude is usually weak. The gain amplifier amplifies this signal to make its amplitude reach a suitable level, thereby improving the signal-to-noise ratio. The amplified signal can better pass the subsequent filtering process and enhance the detection capability of the target reflection signal.

[0085] The second low-pass filter is used to perform a second filtering on the amplified first mixed signal to obtain a second mixed signal.

[0086] Specifically, the signal output by the gain amplifier, although amplified, may still contain some high-frequency noise or unwanted frequency bands. The task of the second low-pass filter is to further suppress these high-frequency parts and retain only the low-frequency components. The second filtering can adjust the signal more finely, ensuring that only the part with frequency within the predetermined range is retained, further clearly defining the spectrum of the target intermediate frequency signal.

[0087] The third low-pass filter is used to perform a third filtering on the second mixed signal to obtain a target intermediate frequency signal.

[0088] Specifically, after the processing of the first two filters, the signal has greatly removed unnecessary high-frequency components. However, in order to ensure that the intermediate frequency signal obtained is clear and does not contain interference noise, the third low-pass filter further optimizes the signal quality, filters out the last part of high-frequency clutter, and obtains the final target intermediate frequency signal.

[0089] It should be noted that the first low-pass filter, the second low-pass filter and the third low-pass filter are all 100MHz low-pass filters, which ensure that the target intermediate frequency signal below 100MHz can be output. The target intermediate frequency signal can be used to study the propagation and structural characteristics of high-frequency waves inside the plasma, such as the position and amplitude of the high-frequency waves and the relationship between them and the distribution of fast ions.

[0090] and Figure 2 Compared with the embodiment shown in the figure, this embodiment mixes the target local oscillator signal with the target reflected signal through a mixer, and converts the high-frequency signal into an intermediate frequency signal suitable for processing. Then, the first low-pass filter removes the high-frequency clutter in the mixed signal, retains the frequency difference part of the target reflected signal, and reduces noise interference. The gain amplifier further amplifies the amplitude of the signal, enhances the signal-to-noise ratio of the signal, and improves the processability of the signal. The second and third low-pass filters gradually clean up the high-frequency noise in the signal to ensure that the output target intermediate frequency signal is purer. Through these multi-stage processing, the signal quality is significantly improved, the noise and interference of the signal are effectively suppressed, and a basis is provided for subsequent target recognition and signal analysis.

[0091] Accordingly, according to an embodiment of the present application, an embodiment of a measurement method of a microwave reflectometer is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0092] Please refer to Figure 8 A flow chart of a microwave reflectometer measurement method provided in an embodiment of the present application, such as Figure 8 As shown, the process includes the following steps: Step S1, the detection signal sending module outputs a first frequency synthesis source signal, and sends a target detection signal obtained by frequency doubling the first frequency synthesis source signal to the plasma; Step S3, the local oscillator signal transmitting module outputs a second frequency synthesis source signal, and performs frequency doubling conversion on the second frequency synthesis source signal to obtain a target local oscillator signal; Step S5, the reflection signal reflection module obtains the target reflection signal reflected by the plasma after receiving the target detection signal; Step S7: The mixing signal modulation module mixes and modulates the target local oscillator signal and the target reflected signal to obtain a target intermediate frequency signal.

[0093] In some optional implementations, the detection signal sending module includes a first frequency multiplication unit and a sending unit connected end to end in sequence; The first frequency doubling unit is used for doubling the output first frequency synthesis source signal to the W band to obtain a first W band microwave signal; The sending unit is used to send a target detection signal obtained by attenuation adjustment of the first W-band microwave signal into the plasma.

[0094] In some optional embodiments, the first frequency multiplication unit includes a first frequency source synthesizer, a first coaxial isolator, and a first frequency multiplier connected end to end in sequence; The first frequency source synthesizer is used to output a first frequency synthesis source signal; The first coaxial isolator is used for unidirectionally transmitting the first frequency synthesis source signal to the first frequency multiplier; The first frequency multiplier is used for multiplying the frequency of the first frequency synthesis source signal to the W band to obtain a first W band microwave signal.

[0095] In some optional embodiments, the transmitting unit includes a first waveguide isolator, an adjustable attenuator, and a first horn antenna connected end to end in sequence; The first waveguide isolator is used for unidirectionally transmitting the first W-band microwave signal to the adjustable attenuator; The adjustable attenuator is used to adjust the intensity of the first W-band microwave signal to obtain a target detection signal; The first horn antenna is used to send the target detection signal into the plasma.

[0096] In some optional implementations, the local oscillator signal transmission module includes a second frequency multiplication unit and a power amplifier connected end to end in sequence; The second frequency doubling unit is used for doubling the frequency of the second frequency synthesis source signal to the W band to obtain a second W band microwave signal; The power amplifier is used to amplify the power of the second W-band microwave signal to obtain a target local oscillator signal.

[0097] In some optional embodiments, the second frequency multiplication unit includes a second frequency source synthesizer, a second coaxial isolator, and a second frequency multiplier connected end to end in sequence; The second frequency source synthesizer is used to output a second frequency synthesizer signal; The second coaxial isolator is used for unidirectionally transmitting the second frequency synthesis source signal to the second frequency multiplier; The second frequency multiplier is used for multiplying the frequency of the second frequency synthesis source signal to the W band to obtain a second W band microwave signal.

[0098] In some optional embodiments, the reflected signal reflection module includes a second horn antenna, a second waveguide isolator, and a low noise amplifier connected end to end in sequence; The second horn antenna is used to send a reflected signal reflected by the plasma after receiving the target detection signal to the second waveguide isolator; The second waveguide isolator is used to transmit the reflected signal unidirectionally to the low noise amplifier; The low noise amplifier is used to amplify the reflected signal to obtain the target reflected signal.

[0099] In some optional implementations, the mixed signal modulation module includes a mixer, a first low-pass filter, a gain amplifier, a second low-pass filter, and a third low-pass filter connected in sequence; The mixer is used to mix the target local oscillator signal and the target reflected signal to obtain a mixed signal; The first low-pass filter is used to perform a first filtering on the mixed signal to obtain a first mixed signal; The gain amplifier is used to amplify the first mixing signal to obtain an amplified first mixing signal; The second low-pass filter is used to perform a second filtering on the amplified first mixed signal to obtain a second mixed signal; The third low-pass filter is used to perform a third filtering on the second mixed signal to obtain a target intermediate frequency signal.

[0100] In some optional embodiments, the frequencies of the first frequency synthesis source signal and the second frequency synthesis source signal are 12.5 GHz-18.33 GHz; the frequencies of the target detection signal and the target local oscillator signal are 75 GHz-110 GHz; the frequencies of the target detection signal, the target local oscillator signal and the plasma wave need to meet the following conditions: |F1+f-F2|≤100 MHz, wherein F1 is the frequency of the target detection signal, f is the frequency of the plasma wave, and F2 is the frequency of the target local oscillator signal.

[0101] The further functional description of each of the above modules and units is the same as that of the above corresponding embodiments and will not be repeated here.

[0102] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

[0103] Although the embodiments of the present application have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present application, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A microwave reflectometer for measuring plasma waves, characterized in that: include: A detection signal sending module, used for outputting a first frequency synthesis source signal, and sending a target detection signal obtained by frequency doubling the first frequency synthesis source signal into the plasma; A local oscillator signal transmitting module, used for outputting a second frequency synthesis source signal, and performing frequency doubling conversion on the second frequency synthesis source signal to obtain a target local oscillator signal; A reflection signal reflection module, used for obtaining a target reflection signal reflected by the plasma after receiving the target detection signal; The mixing signal modulation module is used to mix and modulate the target local oscillator signal and the target reflected signal to obtain a target intermediate frequency signal.

2. The microwave reflectometer according to claim 1, characterized in that: The detection signal sending module comprises a first frequency multiplication unit and a sending unit connected end to end in sequence; The first frequency doubling unit is used to frequency-multiply the output first frequency synthesis source signal to the W band to obtain a first W band microwave signal; The sending unit is used to send a target detection signal obtained by attenuation adjustment of the first W-band microwave signal into the plasma.

3. The microwave reflectometer according to claim 2, characterized in that: The first frequency multiplication unit comprises a first frequency source synthesizer, a first coaxial isolator and a first frequency multiplier which are connected end to end in sequence; The first frequency source synthesizer is used to output the first frequency synthesizer source signal; The first coaxial isolator is used to unidirectionally transmit the first frequency synthesis source signal to the first frequency multiplier; The first frequency multiplier is used for multiplying the frequency of the first frequency synthesis source signal to the W band to obtain the first W band microwave signal.

4. The microwave reflectometer according to claim 2, characterized in that: The transmitting unit comprises a first waveguide isolator, an adjustable attenuator and a first horn antenna connected end to end in sequence; The first waveguide isolator is used to unidirectionally transmit the first W-band microwave signal to the adjustable attenuator; The adjustable attenuator is used to adjust the intensity of the first W-band microwave signal to obtain a target detection signal; The first horn antenna is used to send the target detection signal into the plasma.

5. The microwave reflectometer according to claim 1, characterized in that: The local oscillator signal transmitting module comprises a second frequency multiplication unit and a power amplifier connected end to end in sequence; The second frequency multiplication unit is used for multiplying the second frequency synthesis source signal to the W band to obtain a second W band microwave signal; The power amplifier is used to amplify the power of the second W-band microwave signal to obtain the target local oscillator signal.

6. The microwave reflectometer according to claim 5, characterized in that: The second frequency multiplication unit comprises a second frequency source synthesizer, a second coaxial isolator and a second frequency multiplier which are connected end to end in sequence; The second frequency source synthesizer is used to output the second frequency synthesizer signal; The second coaxial isolator is used to unidirectionally transmit the second frequency synthesis source signal to the second frequency multiplier; The second frequency multiplier is used for multiplying the frequency of the second frequency synthesis source signal to the W band to obtain the second W band microwave signal.

7. The microwave reflectometer according to claim 1, characterized in that: The reflected signal reflection module comprises a second horn antenna, a second waveguide isolator and a low noise amplifier connected end to end in sequence; The second horn antenna is used to send a reflection signal reflected by the plasma after receiving the target detection signal to the second waveguide isolator; The second waveguide isolator is used to unidirectionally transmit the reflected signal to the low noise amplifier; The low noise amplifier is used to amplify the reflection signal to obtain the target reflection signal.

8. The microwave reflectometer according to claim 1, characterized in that: The mixed signal modulation module includes a mixer, a first low-pass filter, a gain amplifier, a second low-pass filter and a third low-pass filter connected in sequence; The mixer is used to mix the target local oscillator signal and the target reflected signal to obtain a mixed signal; The first low-pass filter is used to perform a first filtering on the mixed signal to obtain a first mixed signal; The gain amplifier is used to amplify the first mixing signal to obtain an amplified first mixing signal; The second low-pass filter is used to perform a second filtering on the amplified first mixed signal to obtain a second mixed signal; The third low-pass filter is used to perform a third filtering on the second mixing signal to obtain the target intermediate frequency signal.

9. The microwave reflectometer according to claim 1, characterized in that: The frequencies of the first frequency synthesis source signal and the second frequency synthesis source signal are 12.5GHz-18.33GHz; the frequencies of the target detection signal and the target local oscillator signal are 75GHz-110GHz; the frequencies of the target detection signal, the target local oscillator signal and the plasma wave need to meet the following conditions: |F1+f-F2|≤100MHz, wherein F1 is the frequency of the target detection signal, f is the frequency of the plasma wave, and F2 is the frequency of the target local oscillator signal.

10. A microwave reflectometer measurement method according to any one of claims 1 to 9, characterized in that: The method comprises: The detection signal sending module outputs a first frequency synthesis source signal, and sends a target detection signal obtained by frequency doubling the first frequency synthesis source signal to the plasma; The local oscillator signal transmitting module outputs a second frequency synthesis source signal, and performs frequency doubling conversion on the second frequency synthesis source signal to obtain a target local oscillator signal; The reflection signal reflection module obtains the target reflection signal reflected by the plasma after receiving the target detection signal; The mixing signal modulation module mixes and modulates the target local oscillator signal and the target reflected signal to obtain a target intermediate frequency signal.

Images