Plasma radial electric field diagnosis system and method based on microwave frequency sweep reflectometer

Abstract

The invention discloses a plasma radial electric field diagnosis system and method based on a microwave frequency sweep reflectometer, and the system comprises a Q-band microwave frequency sweep reflectometer which receives a control instruction of a collection and control unit and then outputs a frequency-adjustable Q-band radio frequency signal; the receiving unit receives radio frequency signals reflected by a front-end microwave quasi-optical reflector and an antenna, and outputs in-phase signals and orthogonal signals to the acquisition and control unit after down-conversion and demodulation; the front-end microwave quasi-optical reflector and antenna transmits and emits the Q-band radio-frequency signal into the plasma to be measured, receives a microwave radio-frequency signal reflected by the plasma at the same time, and transmits the microwave radio-frequency signal to a radio-frequency input port of the Q-band microwave frequency sweeping reflectometer; and the acquisition and control unit is used for sending a control instruction to the Q-band microwave frequency sweeping reflectometer and carrying out subsequent acquisition processing. A numerical control frequency source is adopted to flexibly adjust the output frequency waveform.

Description

Technical Field

[0001] The invention relates to the field of magnetic confinement fusion diagnostic equipment, and in particular to a plasma radial electric field diagnostic system and method based on a microwave sweep reflectometer. Background Art

[0002] In magnetic confinement fusion research, the radial electric field of plasma is crucial to understanding the turbulent behavior of plasma. Although traditional electric field diagnostic techniques, such as the probe method, can provide certain electric field information, in a high-temperature, strong magnetic field plasma environment, the insertion of the probe will cause plasma disturbances and it is impossible to obtain comprehensive electric field distribution information in real time. In addition, the spatial resolution of the probe technology is usually limited by the size and layout of the probe, which makes it difficult to meet the high-resolution requirements of modern fusion experiments.

[0003] In recent years, microwave diagnostic technology has gradually become an important means of measuring plasma electric fields. Microwave Doppler reflectometers can obtain electric field information of plasma without directly contacting it by analyzing the Doppler frequency shift changes of reflected signals.

[0004] However, most existing microwave Doppler reflectometer systems use fixed-frequency multi-frequency points or single-frequency point step sweep schemes, which are difficult to flexibly adjust for different plasma parameters.

[0005] In view of this, this application is hereby filed. Summary of the invention

[0006] The technical problem to be solved by the present invention is that the existing microwave sweep frequency Doppler reflectometer for plasma radial electric field diagnosis has the problem that the sweep frequency interval and pulse width cannot be flexibly adjusted to meet the diagnostic needs under different plasma conditions. The purpose of the present invention is to provide a plasma radial electric field diagnosis system and method based on a microwave sweep frequency reflectometer, which adopts a digitally controlled frequency source to flexibly adjust the output frequency waveform.

[0007] The present invention is achieved through the following technical solutions:

[0008] In a first aspect, the present invention provides a plasma radial electric field diagnostic system based on a microwave sweep reflectometer, the system comprising:

[0009] The Q-band microwave sweep reflectometer is used to adjust the internal digital control frequency source according to the preset waveform after receiving the control instructions of the acquisition and control unit, and accurately output the frequency-adjustable Q-band RF signal; and receive the RF signal reflected by the front-end microwave quasi-optical reflector and antenna, and output the in-phase signal and orthogonal signal to the acquisition and control unit after down-conversion and demodulation;

[0010] The front-end microwave quasi-optical reflector and antenna are used to transmit and launch the Q-band radio frequency signal output by the Q-band microwave sweep reflectometer into the plasma to be measured, and at the same time receive the microwave radio frequency signal reflected by the plasma, and transmit the microwave radio frequency signal to the radio frequency input port of the Q-band microwave sweep reflectometer;

[0011] The acquisition and control unit is used to send control instructions to the Q-band microwave sweep frequency reflectometer; receive the in-phase signal and the orthogonal signal output by the signal output port of the Q-band microwave sweep frequency reflectometer, and acquire them as digital signals to calculate the radial electric field distribution of the plasma; at the same time, calculate the received power of the radio frequency signal, and feedback control the output attenuation decibel setting signal to the Q-band microwave sweep frequency reflectometer to adjust the internal digitally controlled adjustable attenuator.

[0012] The present invention designs a plasma radial electric field diagnostic system based on a microwave sweep reflectometer. A digitally controlled frequency source is used in the Q-band microwave sweep reflectometer to flexibly adjust the output frequency waveform. The system has the characteristics of arbitrary switching between fixed frequency and sweep frequency modes. In the sweep frequency mode, the frequency interval and pulse width of any step can be flexibly adjusted according to measurement requirements.

[0013] Further, the Q-band microwave swept frequency reflectometer comprises:

[0014] The radio frequency transmitting circuit is used to adjust the internal digital control frequency source according to the preset waveform after receiving the control instruction of the acquisition and control unit to generate a Q-band radio frequency signal of the preset waveform;

[0015] The radio frequency receiving circuit is used to receive the radio frequency signal reflected by the front-end microwave quasi-optical reflector and the antenna and perform down-conversion processing;

[0016] The signal demodulation circuit is used to demodulate the plasma information carried in the intermediate frequency signal after down-conversion processing, and output an in-phase signal and an orthogonal signal.

[0017] Further, the radio frequency transmitting circuit includes a reference clock, a first power divider, a first low-frequency amplifier, a digitally controlled frequency source, a low-frequency 4-multiplier, a second power divider, a first mixer, a first Q-band 4-multiplier, an X-band power amplifier, an X-band bandpass filter and a second Q-band 4-multiplier; the first mixer is an X-band IQ mixer;

[0018] Reference clock, used to generate a 100MHz clock signal;

[0019] The first power divider is used to divide the 100MHz clock signal into multiple paths, the first path inputs the digital control frequency source as a reference signal; the second path inputs the first low-frequency amplifier, and after amplification, inputs the IQ port of the first mixer; the third path inputs the low-frequency 4-multiplier, and after frequency multiplication, outputs the signal to the third mixer of the signal demodulation circuit as a local oscillator signal;

[0020] A digitally controlled frequency source is used to receive control instructions from an acquisition and control unit, output an X-band radio frequency signal in a frequency range of fs=8.25-12.5 GHz, and is divided into two paths by a second power divider: the first path is input into the first mixer as a local oscillator signal, and the second path is input into the first Q-band 4-frequency multiplier and then input into the second mixer of the radio frequency receiving circuit as a local oscillator signal after frequency multiplication;

[0021] The first mixer is used to convert the 100MHz signal amplified by the first low-frequency amplifier into a radio frequency signal with a frequency of fs output by the digital control frequency source, and the output frequency is f=fs+100MHz; after the power is increased by the X-band power amplifier and filtered by the X-band bandpass filter, it is input into the second Q-band quadruple frequency multiplier;

[0022] The second Q-band quadruple frequency multiplier is used to quadruple the X-band radio frequency signal to the Q-band, and then output it to the outside of the Q-band microwave sweep reflectometer through the radio frequency signal output port.

[0023] Further, the radio frequency receiving circuit includes a Q-band digitally controlled adjustable attenuator, a Q-band low noise amplifier and a second mixer, and the second mixer is a Q-band mixer;

[0024] The Q-band digitally controlled adjustable attenuator is used to receive the radio frequency signal input into the Q-band microwave sweep reflectometer via the radio frequency signal input port, and attenuate the signal by a set decibel according to the control instruction to obtain an attenuated radio frequency signal;

[0025] A Q-band low noise amplifier is used to amplify the attenuated RF signal to improve the signal-to-noise ratio of the system. The amplified RF signal enters the second mixer;

[0026] The second mixer is used to down-convert the amplified radio frequency signal to a low frequency band signal with a center frequency of 400 MHz, and input the low frequency band signal into a signal demodulation circuit.

[0027] Further, the signal demodulation circuit includes a low-frequency bandpass filter, a low-frequency digitally controlled adjustable attenuator, a third mixer, a second low-frequency amplifier and a low-pass filter; the third mixer is a low-frequency IQ mixer;

[0028] The frequency range of the low-frequency bandpass filter is 300-500MHz, and it is used to filter out the signals below 300MHz and above 500MHz in the low-frequency band signal, and input them into the low-frequency digitally controlled adjustable attenuator;

[0029] A low-frequency digitally controlled adjustable attenuator, used to attenuate the signal by a set decibel according to a control instruction and input it into the third mixer;

[0030] The third mixer is used for orthogonally demodulating the low-frequency band signal into an in-phase signal and an orthogonal signal. The in-phase signal and the orthogonal signal are amplified by the second low-frequency amplifier and filtered by the low-pass filter, and then output to the outside of the Q-band microwave sweep reflectometer through the first signal output port and the second signal output port.

[0031] Furthermore, the control instruction includes a frequency range, an interval and a pulse width.

[0032] Furthermore, the frequency range is 34-50 GHz, the interval is 2 GHz, and the pulse width is 20 ms.

[0033] Furthermore, the acquisition and control unit is also used to calculate the microwave frequency range corresponding to the position of the area of ​​interest based on preset magnetic field and plasma current and density parameters before conducting a plasma discharge experiment of a magnetic confinement fusion device; and send control instructions to the Q-band microwave sweep reflectometer based on the required time and space resolution.

[0034] In a second aspect, the present invention further provides a plasma radial electric field diagnostic method based on a microwave sweep reflectometer, the method comprising:

[0035] The acquisition and control unit sends a control signal of a set frequency to the Q-band microwave sweep reflectometer;

[0036] After receiving the control command, the Q-band microwave sweep reflectometer adjusts the internal digital control frequency source according to the preset waveform and accurately outputs the Q-band RF signal with adjustable frequency;

[0037] The front-end microwave quasi-optical reflector and antenna transmit and emit the Q-band radio frequency signal output by the Q-band microwave sweep frequency reflectometer into the plasma to be measured, and simultaneously receive the microwave radio frequency signal reflected by the plasma, and transmit the microwave radio frequency signal to the radio frequency input port of the Q-band microwave sweep frequency reflectometer;

[0038] The Q-band microwave swept frequency reflectometer receives the RF signal reflected by the front-end microwave quasi-optical reflector and antenna, and outputs the in-phase signal and the orthogonal signal to the acquisition and control unit after down-conversion and demodulation;

[0039] At the same time, the acquisition and control unit receives the in-phase signal and the orthogonal signal outputted from the signal output port of the Q-band microwave sweep reflectometer, acquires them as digital signals, and calculates the radial electric field distribution of the plasma; at the same time, the received power of the RF signal is calculated, and the output attenuation decibel setting signal is fed back and controlled to be output to the Q-band microwave sweep reflectometer to adjust its internal numerically controlled adjustable attenuator.

[0040] Furthermore, the control instruction includes a frequency range, an interval and a pulse width, the frequency range is 34-50 GHz, the interval is 2 GHz, and the pulse width is 20 ms.

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

[0042] The plasma radial electric field diagnosis system and method based on the microwave sweep reflectometer of the present invention adopts a digitally controlled frequency source to flexibly adjust the output frequency waveform, and has the characteristics of arbitrary switching between fixed frequency and sweep frequency modes. In the sweep frequency mode, the frequency interval and pulse width of any step can be flexibly adjusted according to measurement requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0044] Figure 1 This is a schematic diagram of the Q-band microwave sweep reflectometer of the present invention;

[0045] Figure 2 This is a structural diagram of the plasma radial electric field diagnostic system based on microwave sweep reflectometer of the present invention.

[0046] Reference numerals and corresponding component names:

[0047] 1-reference clock, 2-first power divider, 3-first low-frequency amplifier, 4-low-frequency 4-multiplier, 5-second power divider, 6-first mixer, 7-first Q-band 4-multiplier, 8-X-band power amplifier, 9-X-band bandpass filter, 10-second Q-band 4-multiplier, 11-Q-band digitally controlled adjustable attenuator, 12-Q-band low noise amplifier, 13-second mixer, 14-low-frequency bandpass filter, 15-low-frequency digitally controlled adjustable attenuator, 16-third mixer, 1 7-second low-frequency amplifier, 18-low-pass filter, 19-first signal output port, 20-second signal output port, 21-reference clock input port, 22-RF signal output port, 23-RF signal input port, 24-Q-band microwave swept frequency reflectometer, 25-front-end microwave quasi-optical reflector and antenna, 26-acquisition and control unit, 27-microwave RF transmission line, 28-Q waveguide horn antenna, 29-plasma, 30-control cable, 31-coaxial transmission line. DETAILED DESCRIPTION

[0048] Hereinafter, the term "include" or "may include" used in various embodiments of the present invention indicates the presence of the invented function, operation or element, and does not limit the addition of one or more functions, operations or elements. In addition, as used in various embodiments of the present invention, the terms "include", "have" and their cognates are intended only to indicate specific features, numbers, steps, operations, elements, components or combinations of the foregoing items, and should not be understood as first excluding the presence of one or more other features, numbers, steps, operations, elements, components or combinations of the foregoing items or the possibility of adding one or more features, numbers, steps, operations, elements, components or combinations of the foregoing items.

[0049] In various embodiments of the present invention, the expression "or" or "at least one of A or / and B" includes any combination or all combinations of the words listed at the same time. For example, the expression "A or B" or "at least one of A or / and B" may include A, may include B, or may include both A and B.

[0050] The expressions (such as "first", "second", etc.) used in various embodiments of the present invention may modify the various constituent elements in various embodiments, but may not limit the corresponding constituent elements. For example, the above expressions do not limit the order and / or importance of the elements. The above expressions are only used for the purpose of distinguishing an element from other elements. For example, the first user device and the second user device indicate different user devices, although both are user devices. For example, without departing from the scope of various embodiments of the present invention, the first element may be referred to as the second element, and similarly, the second element may also be referred to as the first element.

[0051] It should be noted that if it is described that one component element is “connected” to another component element, the first component element may be directly connected to the second component element, and a third component element may be “connected” between the first component element and the second component element. Conversely, when one component element is “directly connected” to another component element, it can be understood that there is no third component element between the first component element and the second component element.

[0052] The terms used in various embodiments of the present invention are only used for the purpose of describing specific embodiments and are not intended to limit various embodiments of the present invention. As used herein, the singular form is intended to also include the plural form, unless the context clearly indicates otherwise. Unless otherwise limited, all terms used here (including technical terms and scientific terms) have the same meaning as the meaning generally understood by those of ordinary skill in the art to which the various embodiments of the present invention belong. The terms (such as the terms defined in the dictionary generally used) will be interpreted as having the same meaning as the contextual meaning in the relevant technical field and will not be interpreted as having an idealized meaning or an overly formal meaning, unless clearly defined in various embodiments of the present invention.

[0053] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0054] The present invention adopts a single frequency point solution and has the characteristics of flexible adjustment of frequency waveform. Compared with the existing measurement technology, the system can switch between fixed frequency and sweep frequency mode. In the sweep frequency mode, the frequency interval and pulse width of any step can be flexibly adjusted according to the measurement requirements.

[0055] The system of the present invention can provide plasma radial electric field information in magnetic confinement controlled nuclear fusion experiments, has the advantages of high robustness, non-invasiveness, real-time and high spatial resolution, and can provide important data support for controlled nuclear fusion research and plasma physics research.

[0056] Example 1

[0057] like Figure 1 and Figure 2 As shown, the plasma radial electric field diagnostic system based on microwave sweep reflectometer of the present invention comprises:

[0058] The Q-band microwave sweep reflectometer 24 is used to adjust the internal digital control frequency source 3 according to the preset waveform after receiving the control instruction of the acquisition and control unit 26, and accurately output the frequency-adjustable Q-band radio frequency signal; and receive the radio frequency signal reflected by the front-end microwave quasi-optical reflector and antenna 25, and output the in-phase signal and the orthogonal signal to the acquisition and control unit 26 after down-conversion and demodulation;

[0059] The front-end microwave quasi-optical reflector and antenna 25 are used to transmit and emit the Q-band radio frequency signal output by the Q-band microwave sweep frequency reflectometer 24 into the plasma to be measured, and at the same time receive the microwave radio frequency signal reflected by the plasma, and transmit the microwave radio frequency signal to the radio frequency input port of the Q-band microwave sweep frequency reflectometer 24;

[0060] The acquisition and control unit 26 is used to send control instructions to the Q-band microwave sweep frequency reflectometer 24; and receive the in-phase signal and the orthogonal signal output by the signal output port of the Q-band microwave sweep frequency reflectometer 24, and collect them as digital signals to calculate the radial electric field distribution of the plasma; at the same time, calculate the received power of the RF signal, and feedback control the output attenuation decibel setting signal to the Q-band microwave sweep frequency reflectometer 24 to adjust the internal digitally controlled adjustable attenuator.

[0061] The present invention designs a plasma radial electric field diagnostic system based on a microwave sweep reflectometer. A digitally controlled frequency source is used in the Q-band microwave sweep reflectometer to flexibly adjust the output frequency waveform. The system has the characteristics of arbitrary switching between fixed frequency and sweep frequency modes. In the sweep frequency mode, the frequency interval and pulse width of any step can be flexibly adjusted according to measurement requirements.

[0062] In this embodiment, the Q-band microwave sweep reflectometer 24 includes a radio frequency transmitting circuit (single sideband modulation SSMB), a radio frequency receiving circuit (first stage: down conversion) and a signal demodulation circuit (second stage: mixing), which are specifically as follows:

[0063] The radio frequency transmitting circuit is used to adjust the internal digital control frequency source 3 according to the preset waveform after receiving the control instruction of the acquisition and control unit 26, so as to generate a Q-band radio frequency signal with a preset waveform;

[0064] The radio frequency receiving circuit is used to receive the radio frequency signal reflected by the front-end microwave quasi-optical reflector and the antenna 25 and perform down-conversion processing;

[0065] The signal demodulation circuit is used to demodulate the plasma information carried in the intermediate frequency signal after down-conversion processing, and output an in-phase signal and an orthogonal signal.

[0066] Specifically, the radio frequency transmitting circuit includes a reference clock 1, a first power divider, a first low-frequency amplifier 2, a digitally controlled frequency source 3, a low-frequency 4-multiplier 4, a second power divider 5, a first mixer 6, a first Q-band 4-multiplier 7, an X-band power amplifier 8, an X-band bandpass filter 9, and a second Q-band 4-multiplier 10; the first mixer 6 is an X-band IQ mixer; the second power divider 5 is an X-band directional coupler 5;

[0067] Reference clock 1 is a 100MHz constant temperature crystal oscillator, used to generate a 100MHz clock signal;

[0068] The first power divider is used to divide the 100MHz clock signal into multiple paths, the first path is input to the digital control frequency source 3 as a reference signal; the second path is input to the first low-frequency amplifier 2, and after amplification, it is input to the IQ port of the first mixer 6; the third path is input to the low-frequency 4-multiplier 4, and after frequency multiplication, the signal is output to the third mixer 16 of the signal demodulation circuit as a local oscillator signal;

[0069] The digitally controlled frequency source 3 is used to receive the control instruction of the acquisition and control unit 26, and output an X-band radio frequency signal with a frequency range of fs=8.25-12.5GHz, which is divided into two paths by the second power divider 5: the first path is input into the first mixer 6 as a local oscillator signal, and the second path is input into the first Q-band 4-frequency multiplier 7 and then input into the second mixer 13 of the radio frequency receiving circuit as a local oscillator signal after frequency multiplication; wherein, the digitally controlled frequency source 3 adopts a digitally controlled PLL source with an adjustment range of 8.25-12.5GHz, a minimum step of 50MHz, and a locking time of 10 microseconds.

[0070] The first mixer 6 is used to convert the 100MHz signal amplified by the first low-frequency amplifier 2 into a radio frequency signal with a frequency of fs output by the digital control frequency source 3, and the output frequency is f=fs+100MHz; after the power is increased by the X-band power amplifier 8 and filtered by the X-band bandpass filter 9 (filtering range is 8.35-12.6GHz), it is input into the second Q-band quadruple frequency multiplier 10;

[0071] The second Q-band quadrupler 10 is used to quadruple the X-band radio frequency signal to the Q-band, and then output it to the outside of the Q-band microwave sweep reflectometer via the radio frequency signal output port 22 .

[0072] Specifically, the radio frequency receiving circuit includes a Q-band digitally controlled adjustable attenuator 11, a Q-band low noise amplifier 12 and a second mixer 13, wherein the second mixer 13 is a Q-band mixer;

[0073] The Q-band digitally controlled adjustable attenuator 11 is used to receive the radio frequency signal input into the Q-band microwave sweep reflectometer via the radio frequency signal input port 23, and attenuate the signal by a set decibel according to the control instruction to obtain an attenuated radio frequency signal;

[0074] A Q-band low noise amplifier 12 is used to amplify the attenuated radio frequency signal to improve the signal-to-noise ratio of the system, and the amplified radio frequency signal enters the second mixer 13;

[0075] The second mixer 13 is used to down-convert the amplified RF signal into a low-frequency signal with a center frequency of 400 MHz, and input the low-frequency signal into a signal demodulation circuit.

[0076] Specifically, the signal demodulation circuit includes a low-frequency bandpass filter 14, a low-frequency digitally controlled adjustable attenuator 15, a third mixer 16, a second low-frequency amplifier 17 and a low-pass filter 18; the third mixer 16 is a low-frequency IQ mixer;

[0077] The frequency range of the low-frequency bandpass filter 14 is 300-500 MHz, and it is used to filter out the signals below 300 MHz and above 500 MHz in the low-frequency band signal, and input them into the low-frequency digitally controlled adjustable attenuator 15;

[0078] A low-frequency digitally controlled adjustable attenuator 15 is used to attenuate the signal by a set decibel according to a control instruction and input it to a third mixer 16;

[0079] The third mixer 16 is used to orthogonally demodulate the low-frequency band signal into an in-phase (I) signal and a quadrature (Q) signal. Both the in-phase (I) signal and the quadrature (Q) signal are amplified by the second low-frequency amplifier 17 and filtered by the low-pass filter 18 (filtering range is DC-100MHz), and then output to the outside of the Q-band microwave sweep reflectometer through the first signal output port 19 and the second signal output port 20.

[0080] Specifically, the front-end microwave quasi-optical reflector and antenna include a microwave RF transmission line 27, a Q-waveguide horn antenna 28 and a metal reflector, which are used to transmit and emit the Q-band RF signal output from the RF signal output port 22 of the Q-band microwave swept frequency reflectometer into the plasma to be measured 29, and at the same time receive the microwave RF signal reflected by the plasma and transmit it to the RF input port 23 of the Q-band microwave swept frequency reflectometer.

[0081] Specifically, the control instruction includes a frequency range, an interval and a pulse width. The frequency range is 34-50 GHz, the interval is 2 GHz, and the pulse width is 20 ms.

[0082] Specifically, the acquisition and control unit 26 is also used to calculate the microwave frequency range corresponding to the position of the area of ​​interest based on preset magnetic field and plasma current and density parameters before conducting a plasma discharge experiment of the magnetic confinement fusion device; and send control instructions to the Q-band microwave sweep reflectometer based on the required time and space resolution.

[0083] It should be noted that the five ports in the Q-band microwave sweep reflectometer 24 are Figure 1 The first signal output port 19 is Figure 2 IF-I in Figure 1 The second signal output port 20 is Figure 2 IF-Q in the, and the first signal output port 19 and the second signal output port 20 are ports for post-processing; Figure 1 The RF signal output port 22 is Figure 2 RF_OUT in the frequency range is 33.4-50.4GHz and the power is 15dBm; Figure 1 The RF signal input port 23 is Figure 2 RF_IN in the RF_IN, and the RF signal output port 22 is facing the measurement object, i.e., the plasma; Figure 1 The reference clock input port 21 is Figure 2 The REF in the example has a frequency of 100MHz and a power of 5±3dBm.

[0084] In addition, the control port Control of the acquisition and control unit 26 is connected to the control port Control of the Q-band microwave swept frequency reflectometer 24 through a control cable 30, and the IF-Q of the Q-band microwave swept frequency reflectometer 24 and the ADC_CH1 of the acquisition and control unit 26, the IF-I of the Q-band microwave swept frequency reflectometer 24 and the ADC_CH2 of the acquisition and control unit 26, and the REF of the Q-band microwave swept frequency reflectometer 24 and the REF_OUT of the acquisition and control unit 26 are all connected through a coaxial transmission line 31.

[0085] Example 2

[0086] The difference between this embodiment and embodiment 1 is that this embodiment provides a plasma radial electric field diagnostic method based on microwave sweep frequency reflectometry, which is based on the plasma radial electric field diagnostic system based on microwave sweep frequency reflectometry in embodiment 1; the method comprises:

[0087] Before conducting a plasma discharge experiment of a magnetic confinement fusion device, the acquisition and control unit 26 calculates the microwave frequency range corresponding to the position of the region of interest according to the preset magnetic field and plasma current and density parameters; and sends a control signal of a set frequency to the Q-band microwave sweep reflectometer 24 according to the required time and space resolution, for example, a step sweep waveform with a set frequency of 34-50 GHz, an interval of 0.4 GHz, and a pulse width of 5 ms;

[0088] After receiving the control command, the Q-band microwave sweep reflectometer 24 adjusts the internal digital control frequency source 3 according to the preset waveform and accurately outputs a Q-band radio frequency signal with adjustable frequency;

[0089] The front-end microwave quasi-optical reflector and antenna 25 transmits and launches the Q-band radio frequency signal output by the Q-band microwave sweep frequency reflectometer 24 into the plasma to be measured, and simultaneously receives the microwave radio frequency signal reflected by the plasma, and transmits the microwave radio frequency signal to the radio frequency input port 23 of the Q-band microwave sweep frequency reflectometer 24;

[0090] The Q-band microwave swept frequency reflectometer 24 receives the radio frequency signal reflected by the front-end microwave quasi-optical reflector and antenna 25, and outputs the in-phase (I) signal and the orthogonal (Q) signal to the acquisition and control unit 26 after down-conversion and demodulation;

[0091] At the same time, the acquisition and control unit 26 receives the in-phase (I) signal and the orthogonal (Q) signal output by the signal output port of the Q-band microwave sweep reflectometer 24, and collects them as digital signals to calculate the radial electric field distribution of the plasma; at the same time, the RF signal receiving power is calculated, and the feedback control output attenuation decibel setting signal is sent to the Q-band microwave sweep reflectometer 24 to adjust the internal digitally controlled adjustable attenuator.

[0092] As a further implementation, the acquisition and control unit calculates the radial electric field distribution of the plasma in real time based on the digital signal, and adjusts the set frequency range to ensure the optimal measurement setting, such as changing the frequency range from 34-50 GHz to 40-50 GHz in the next sweep cycle to reduce the invalid measurement range.

[0093] The acquisition and control unit dynamically adjusts the time and space resolution according to the discharge parameters, such as 0-800ms, set frequency to 34-50GHz, interval 2GHz, pulse width 20ms step sweep waveform, 800-1000ms, set frequency to 34-40GHz, interval 0.4GHz, pulse width 5ms step sweep waveform, to meet the time and space resolution requirements under different conditions.

[0094] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A plasma radial electric field diagnostic system based on microwave sweep reflectometry, characterized in that: The system includes: A Q-band microwave sweep reflectometer (24) is used to adjust the internal digital control frequency source (3) according to a preset waveform after receiving a control instruction from the acquisition and control unit (26) to output a Q-band radio frequency signal with adjustable frequency; and to receive the radio frequency signal reflected by the front-end microwave quasi-optical reflector and antenna (25), and output an in-phase signal and an orthogonal signal to the acquisition and control unit (26) after down-conversion and demodulation; A front-end microwave quasi-optical reflector and antenna (25) is used to transmit and emit the Q-band radio frequency signal output by the Q-band microwave sweep frequency reflectometer (24) into the plasma to be measured, and simultaneously receive the microwave radio frequency signal reflected by the plasma, and transmit the microwave radio frequency signal to the radio frequency input port of the Q-band microwave sweep frequency reflectometer (24); The acquisition and control unit (26) is used to send a control instruction to the Q-band microwave sweep frequency reflectometer (24); receive an in-phase signal and an orthogonal signal outputted from a signal output port of the Q-band microwave sweep frequency reflectometer (24), acquire them as digital signals, and calculate the radial electric field distribution of the plasma; and simultaneously calculate the received power of the radio frequency signal, and feedback control the output attenuation decibel setting signal to the Q-band microwave sweep frequency reflectometer (24) to adjust the digitally controlled adjustable attenuator inside the Q-band microwave sweep frequency reflectometer (24).

2. The plasma radial electric field diagnostic system based on microwave sweep reflectometry according to claim 1, characterized in that: The Q-band microwave sweep reflectometer (24) comprises: A radio frequency transmitting circuit is used to, after receiving a control instruction from an acquisition and control unit (26), adjust an internal digital control frequency source (3) according to a preset waveform to generate a Q-band radio frequency signal of a preset waveform; A radio frequency receiving circuit, used for receiving the radio frequency signal reflected by the front-end microwave quasi-optical reflector and the antenna (25) and performing down-conversion processing; The signal demodulation circuit is used to demodulate the plasma information carried in the intermediate frequency signal after down-conversion processing, and output an in-phase signal and an orthogonal signal.

3. The plasma radial electric field diagnostic system based on microwave sweep reflectometry according to claim 2, characterized in that: The radio frequency transmission circuit comprises a reference clock (1), a first power divider, a first low-frequency amplifier (2), a digitally controlled frequency source (3), a low-frequency quadruple frequency multiplier (4), a second power divider (5), a first mixer (6), a first Q-band quadruple frequency multiplier (7), an X-band power amplifier (8), an X-band bandpass filter (9) and a second Q-band quadruple frequency multiplier (10); the first mixer (6) is an X-band IQ mixer; The reference clock (1) is used to generate a 100 MHz clock signal; The first power divider is used to divide the 100 MHz clock signal into multiple paths, the first path inputting the digital control frequency source (3) as a reference signal; The second path is input into the first low-frequency amplifier (2), and after amplification, is input into the IQ port of the first mixer (6); the third path is input into the low-frequency quadruple frequency multiplier (4), and after frequency multiplication, outputs a signal to the third mixer (16) of the signal demodulation circuit as a local oscillator signal; The digital control frequency source (3) is used to receive control instructions from the acquisition and control unit (26), output an X-band radio frequency signal with a frequency range of fs=8.25-12.5 GHz, and is divided into two paths through a second power divider (5): the first path is input into the first mixer (6) as a local oscillator signal, and the second path is input into the first Q-band quadruple frequency multiplier (7) and then input into the second mixer (13) of the radio frequency receiving circuit as a local oscillator signal after frequency multiplication; The first mixer (6) is used to convert the 100 MHz signal amplified by the first low-frequency amplifier (2) into a radio frequency signal with a frequency of fs output by the digital control frequency source (3), wherein the output frequency is f=fs+100 MHz; after the power is increased by the X-band power amplifier (8) and filtered by the X-band bandpass filter (9), the signal is input into the second Q-band quadruple frequency multiplier (10); The second Q-band quadruple frequency multiplier (10) is used to quadruple the X-band radio frequency signal to the Q-band, and then output it to the outside of the Q-band microwave sweep reflectometer via the radio frequency signal output port (22).

4. The plasma radial electric field diagnostic system based on microwave sweep reflectometry according to claim 2, characterized in that: The radio frequency receiving circuit comprises a Q-band digitally controlled adjustable attenuator (11), a Q-band low noise amplifier (12) and a second mixer (13), wherein the second mixer (13) is a Q-band mixer; The Q-band digitally controlled adjustable attenuator (11) is used to receive a radio frequency signal input into the Q-band microwave sweep reflectometer via a radio frequency signal input port (23), and attenuate the signal by a set decibel according to a control instruction to obtain an attenuated radio frequency signal; The Q-band low noise amplifier (12) is used to amplify the attenuated radio frequency signal, and the amplified radio frequency signal enters the second mixer (13); The second mixer (13) is used to down-convert the amplified radio frequency signal into a low frequency band signal with a center frequency of 400 MHz, and input the low frequency band signal into a signal demodulation circuit.

5. The plasma radial electric field diagnostic system based on microwave sweep reflectometry according to claim 2, characterized in that: The signal demodulation circuit comprises a low-frequency bandpass filter (14), a low-frequency digitally controlled adjustable attenuator (15), a third mixer (16), a second low-frequency amplifier (17) and a low-pass filter (18); the third mixer (16) is a low-frequency IQ mixer; The low-frequency bandpass filter (14) is used to filter out signals below 300 MHz and above 500 MHz in the low-frequency band signal, and input the signals into the low-frequency digitally controlled adjustable attenuator (15); The low-frequency digitally controlled adjustable attenuator (15) is used to attenuate the signal by a set decibel according to the control instruction and input it into the third mixer (16); The third mixer (16) is used for orthogonally demodulating the low-frequency band signal into an in-phase signal and an orthogonal signal. The in-phase signal and the orthogonal signal are amplified by the second low-frequency amplifier (17) and filtered by the low-pass filter (18), and then output to the outside of the Q-band microwave sweep reflectometer through the first signal output port (19) and the second signal output port (20).

6. The plasma radial electric field diagnostic system based on microwave sweep reflectometry according to claim 1, characterized in that: The control instructions include frequency range, interval and pulse width.

7. The plasma radial electric field diagnostic system based on microwave sweep reflectometry according to claim 6, characterized in that: The frequency range is 34-50 GHz, the interval is 2 GHz, and the pulse width is 20 ms.

8. The plasma radial electric field diagnostic system based on microwave sweep reflectometry according to claim 1, characterized in that: The acquisition and control unit (26) is also used to calculate the microwave frequency range corresponding to the position of the region of interest according to preset magnetic field and plasma current and density parameters before conducting a plasma discharge experiment of the magnetic confinement fusion device; and send control instructions to the Q-band microwave sweep reflectometer according to the required time and space resolution.

9. A plasma radial electric field diagnostic method based on microwave sweep reflectometry, characterized in that: The method includes: The acquisition and control unit (26) sends a control signal of a set frequency to the Q-band microwave sweep reflectometer (24); After receiving the control instruction, the Q-band microwave sweep reflectometer (24) adjusts the internal digital control frequency source (3) according to the preset waveform and outputs a Q-band radio frequency signal with adjustable frequency; The front-end microwave quasi-optical reflector and antenna (25) transmits and emits the Q-band radio frequency signal output by the Q-band microwave sweep frequency reflectometer (24) into the plasma to be measured, and simultaneously receives the microwave radio frequency signal reflected by the plasma, and transmits the microwave radio frequency signal to the radio frequency input port (23) of the Q-band microwave sweep frequency reflectometer (24); The Q-band microwave sweep reflectometer (24) receives the radio frequency signal reflected by the front-end microwave quasi-optical reflector and antenna (25), and outputs the in-phase signal and the orthogonal signal to the collection and control unit (26) after down-conversion and demodulation; At the same time, the acquisition and control unit (26) receives the in-phase signal and the orthogonal signal output from the signal output port of the Q-band microwave sweep frequency reflectometer (24), acquires them as digital signals, and calculates the radial electric field distribution of the plasma; at the same time, the radio frequency signal receiving power is calculated, and the attenuation decibel setting signal is output through feedback control to the Q-band microwave sweep frequency reflectometer (24) to adjust the digitally controlled adjustable attenuator inside it.

10. The plasma radial electric field diagnosis method based on microwave sweep reflectometry according to claim 9, characterized in that: The control instructions include frequency range, interval and pulse width.

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