Microwave reflectometer system

Abstract

The invention discloses a microwave reflectometer system. An arbitrary waveform generator generates a microwave signal through an X-Ku signal source unit; the coaxial directional coupler divides the generated microwave signal into two paths, one path enters the transmitting unit, and the other path enters the reference unit; a microwave signal entering the transmitting unit is transmitted into the plasma through a fundamental mode rectangular waveguide in the transmitting circuit; the microwave signal entering the reference unit is subjected to flight time compensation through a delay line and then is mixed with a reflected signal received by the receiving unit in a balanced mixer; the calibration unit carries out secondary frequency mixing on the dispersion calibration voltage-time curve signal and the signal obtained after primary frequency mixing of the balanced frequency mixer so as to eliminate dispersion interference; the acquisition card acquires an output signal after secondary frequency mixing of the calibration unit. The system can be integrated with an ion cyclotron resonance antenna, the inherent defects of large attenuation and high dispersion of a long-distance fundamental mode waveguide are overcome, and a high-frequency fundamental mode waveguide through-wall scheme meeting ultrahigh vacuum performance index requirements is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of microwave reflection systems, and in particular to a microwave reflectometer system. Background Art

[0002] By using microwave devices such as voltage-tunable oscillators and frequency multipliers, the measurement of the electron density profile of a tokamak can be achieved. However, the measurement result of the microwave reflectometer for the electron density has locality and cannot fully extrapolate the measurement conclusion to the entire plasma space. Moreover, the currently mainstream waveguide used is a corrugated waveguide, and under the existing technical conditions, sufficient installation space cannot be reserved in the ion cyclotron resonance heating system, and thus the measurement of the electron density profile at the antenna cannot be realized. The measurement of the electron density at the traditional ion cyclotron heating antenna usually adopts the method of placing a probe at the antenna. Its measurement range is usually only limited to a relatively close area near the antenna. Moreover, as a diagnostic means in direct contact with the plasma, the detection result of the probe is also easily affected by the probe itself.

[0003] As the most traditional rectangular waveguide design, the fundamental mode waveguide is widely used in the microwave industry. However, it has the characteristics of large attenuation per unit length and high dispersion compared with other waveguide designs. In a tokamak device limited by space and requiring long-distance waveguide transmission, it is generally only used for wave transmission inside the electronics cabinet. The overmode waveguide is a variant of the rectangular waveguide. It adopts the method of overmode transmission of high-frequency waves in a low-frequency rectangular fundamental mode waveguide, which partially overcomes the problems of large attenuation and high dispersion of the fundamental mode waveguide. However, it requires a long transition waveguide, and for a microwave reflectometer, the turning design should be minimized as much as possible to avoid interference with the signal. The corrugated waveguide is the mainstream wave transmission scheme of the current microwave reflectometer system. It adopts the TEM wave propagation mode and has the characteristics of small attenuation and nearly no dispersion. However, it requires targeted quasi-optical design, and compared with the fundamental mode waveguide and the overmode waveguide, it occupies a large installation space and is not suitable for integrated installation with the ion cyclotron heating system, thus realizing the measurement of the electron density near the ion cyclotron heating antenna.

[0004] Since the tokamak is a vacuum device and the electronics part of the microwave reflectometer usually needs to be arranged outside the vacuum device, the microwave reflectometer system generally needs to be designed and installed with a vacuum feedthrough that can allow microwaves to penetrate the vacuum wall. For a tokamak using normal conductors, a horn antenna is generally installed outside the vacuum chamber, and the microwave is transmitted through a lens made of wave-transparent materials such as quartz and polytetrafluoroethylene to achieve this function; for a tokamak using a superconducting design, due to the existence of the superconducting system, the outermost vacuum wall is relatively far from the plasma, and a relatively long waveguide needs to be supplemented separately, so a special waveguide feedthrough needs to be designed to achieve this function; for a corrugated waveguide, this function is generally achieved by installing a wave-transparent material plane lens with a radius close to that of the corrugated waveguide obliquely; for an overmoded waveguide, this function is generally achieved by directly pressing a wave-transparent thin sheet between rectangular waveguides and sealing it with a rubber ring. However, for a fundamental mode waveguide, the application of the design used for overmoded waveguides has the problem of unqualified vacuum performance. The core reason is that the fundamental mode waveguide in the V / E / W band commonly used in microwave reflectometers has a small size and a short wavelength in this working band, so the selection of the wave-transparent thin sheet material and size is naturally limited and cannot meet the requirements of the ultra-high vacuum of the current tokamak. Summary of the Invention

[0005] The object of the present invention is to provide a microwave reflectometer system that can be integrated with an ion cyclotron resonance antenna, overcome the inherent defects of large attenuation and high dispersion of a long-distance fundamental mode waveguide, and achieve a high-frequency fundamental mode waveguide feedthrough scheme that meets the requirements of ultra-high vacuum performance indicators.

[0006] The object of the present invention is achieved by the following technical solutions:

[0007] A microwave reflectometer system, the microwave reflectometer system includes an arbitrary waveform generator (1), an X-Ku signal source unit (a), a coaxial directional coupler (6), a transmitting unit (b), a transmitting path (c), a receiving path (d), a receiving unit (e), a reference unit (f), a V / E band balanced mixer (19), a calibration unit (g), and a data acquisition card (23), wherein:

[0008] The arbitrary waveform generator (1) generates a microwave signal after passing through the X-Ku signal source unit (a);

[0009] The coaxial directional coupler (6) divides the generated microwave signal into two paths, one path enters the transmitting unit (b), and the other path enters the reference unit (f);

[0010] The microwave signal entering the transmitting unit (b) is frequency - multiplied by a frequency multiplier, and the frequency is multiplied to the V - band and E - band. The V - band corresponds to the 50 - 75 GHz band, and the E - band corresponds to the 60 - 90 GHz band. After the microwave signal is amplified in the waveguide amplifier, it is injected into the plasma (16) through the fundamental - mode rectangular waveguide in the transmitting path (c); the microwave signal will be reflected by the cut - off layer in the plasma (16), then received by the receiving antenna, and transmitted back to the microwave reflectometer system through the fundamental - mode rectangular waveguide at the end of the receiving path (d) which is nearly as long as the transmitting path (c), and then after being filtered and low - noise amplified by the receiving unit (e), it is supplied to the V / E - band balanced mixer (19) for mixing;

[0011] The microwave signal entering the reference unit (f) is compensated for the flight time by a delay line, and then also frequency - multiplied by a frequency multiplier. The enhanced millimeter - wave signal will directly be mixed with the reflected signal received by the receiving unit (e) in the V / E - band balanced mixer (19), and the frequency is reduced to the MHz magnitude;

[0012] The V / E - band balanced mixer (19) is used to mix the reflected signal received by the receiving unit (e) with the reference signal output by the reference unit (f) once, to down - convert the microwave signal in the V / E - band to a low - frequency signal in the MHz magnitude, and input it into the calibration unit (g);

[0013] The calibration unit (g) is used to mix the dispersion calibration voltage - time curve signal emitted by the arbitrary waveform generator (1) with the signal after the first - stage mixing in the V / E - band balanced mixer (19) for a second - stage mixing to eliminate the dispersion interference;

[0014] The acquisition card (23) is used to acquire the output signal after the second - stage mixing in the calibration unit (g), convert the acquired signal into a complex signal by superimposing a specified - frequency signal, and directly obtain the phase after filtering the complex signal, and perform an inversion on the X - mode dispersion phase matrix to obtain the electron density information near the ion cyclotron antenna.

[0015] It can be seen from the technical solutions provided by the present invention described above that the above - mentioned system can be integrated with the ion cyclotron resonance antenna, overcome the inherent defects of large attenuation and high dispersion of the long - distance fundamental - mode waveguide, and realize the high - frequency fundamental - mode waveguide through - wall scheme that meets the requirements of ultra - high vacuum performance indicators. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0017] Figure 1 Schematic diagram of the structure of the microwave reflectometer system provided by an embodiment of the present invention;

[0018] Figure 2 Schematic diagram of the splicing of the fundamental mode rectangular waveguide in the vacuum chamber according to an embodiment of the present invention;

[0019] Figure 3 Schematic diagram of the attenuation measurement value of the fundamental mode rectangular waveguide according to an embodiment of the present invention. Detailed implementation manners

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments, which do not constitute a limitation to the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0021] As Figure 1 shown is a schematic diagram of the structure of the microwave reflectometer system provided by an embodiment of the present invention. The microwave reflectometer system includes an arbitrary waveform generator (1), an X-Ku band signal source unit (a) (X-Ku is the name of the microwave frequency band), a coaxial directional coupler (6), a transmitting unit (b), a transmitting path (c), a receiving path (d), a receiving unit (e), a reference unit (f), a V / E band balanced mixer (19), a calibration unit (g), and an acquisition card (23), where:

[0022] The arbitrary waveform generator (1) generates a microwave signal after passing through the X-Ku signal source unit (a);

[0023] The coaxial directional coupler (6) divides the generated microwave signal into two paths, one path enters the transmitting unit (b), and the other path enters the reference unit (f);

[0024] The microwave signal entering the transmitting unit (b) is frequency-multiplied by a frequency multiplier, and the frequency is multiplied to the V band and the E band. The V band corresponds to the 50-75 GHz band, and the E band corresponds to the 60-90 GHz band. After the microwave signal is amplified by a waveguide amplifier, it is injected into the plasma (16) through the fundamental mode rectangular waveguide in the transmitting path (c); the microwave signal will be reflected by the cut-off layer in the plasma in the plasma (16), and then received by the receiving antenna, and passed back to the microwave reflectometer system through the fundamental mode rectangular waveguide at the end of the receiving path (d) that is nearly the same length as the transmitting path (c), and then filtered and low-noise amplified by the receiving unit (e) for mixing by the V / E band balanced mixer (19);

[0025] After the microwave signal entering the reference unit (f) is compensated for the flight time by the delay line, it is also frequency-multiplied by the six-frequency multiplier, and the enhanced millimeter-wave signal will directly mix with the reflected signal received by the receiving unit (e) in the V / E band balanced mixer (19), and the frequency will be reduced to the MHz level;

[0026] The V / E band balanced mixer (19) is used to mix the reflected signal received by the receiving unit (e) with the reference signal output by the reference unit (f) once, down-convert the microwave signal in the V / E band to a low-frequency signal in the MHz level, and input it into the calibration unit (g);

[0027] The calibration unit (g) is used to mix the dispersion calibration voltage-time curve signal sent by the arbitrary waveform generator (1) with the signal after the first mixing by the V / E band balanced mixer (19) for the second time to eliminate the dispersion interference; this is because the signal after the mixing by the V / E band balanced mixer (19) contains the fundamental mode waveguide dispersion information, which will interfere with the calculation of the flight time of the profile reflectometer, so the second mixing is required.

[0028] The acquisition card (23) is used to acquire the output signal after the second mixing by the calibration unit (g), convert the acquired signal into a complex signal by superimposing a specified frequency signal, and directly obtain the phase after filtering the complex signal, and invert the X-mode dispersion phase matrix to obtain the electron density information near the ion cyclotron antenna.

[0029] In specific implementation, as Figure 1 shown, the X-Ku signal source unit (a) includes a voltage-controlled oscillator (2), a coaxial isolator (3), a coaxial high-power amplifier (4), and a coaxial attenuator (5), where:

[0030] The voltage-controlled oscillator (2) is controlled by the control voltage of the arbitrary waveform generator (1) to generate an X-Ku band signal whose emission frequency linearly changes within a single period over time; in specific implementation, the microwave signal emitted by the voltage-controlled oscillator (2) has an operating frequency band in the X-Ku band (8 - 12.5 GHz, 10 - 15 GHz);

[0031] The coaxial isolator (3) protects the safe operation of the voltage-controlled oscillator (2);

[0032] By controlling the coaxial high-power amplifier (4) and the coaxial attenuator (5), the power of the microwave signal emitted by the X-Ku signal source unit (a) is adjusted.

[0033] As Figure 1As shown, the transmitting unit (b) includes a coaxial attenuator (5), a sextupler (7), a V / E band waveguide amplifier (8), a V / E band waveguide isolator (9), a V / E band bandpass filter (10), a V / E band low-pass filter (11), a V / E band electrically operated waveguide switch (12), and a V / E band waveguide load (13), where:

[0034] The coaxial attenuator (5) adjusts the power of a path of the signal split by the coaxial directional coupler (6) to ensure that it meets the input power requirements of the sextupler (7);

[0035] The sextupler (7) is used to multiply the input microwave signal to the V band and the E band;

[0036] The V / E band waveguide amplifier (8) is used to amplify the V / E band signal multiplied by the sextupler (7) to the watt level to overcome the transmission loss of the microwave signal in the long-distance fundamental mode rectangular waveguide; In specific implementation, the V / E band waveguide amplifier uses an amplifier with saturated output powers of 27 dBm (V band) and 33 dBm (E band) respectively, and by adjusting the output of the multiplier, the saturated output of the amplifier power is achieved, and in this way, the problem of large attenuation in the ultra-long-distance fundamental mode rectangular waveguide is overcome.

[0037] The V / E band waveguide isolator (9) is used to protect the safe operation of the V / E band waveguide amplifier (8);

[0038] The V / E band bandpass filter (10) is used to filter the amplified V / E band signal to ensure that only the multiplied signal is emitted;

[0039] The V / E band low-pass filter (11) is used to filter out potential 140 GHz electron cyclotron signal interference;

[0040] The V / E band electrically operated waveguide switch (12) and the V / E band waveguide load (13) are used to turn on or off the transmitting unit (b).

[0041] As Figure 1 As shown, the reference unit (f) includes a coaxial delay line (18), a sextupler (7), and a V / E band waveguide isolator (9), where:

[0042] The coaxial delay line (18) is used to compensate for the flight time of the long-distance rectangular waveguide to ensure that the frequency range mixed by the V / E band balanced mixer (19) is within the specified range; In specific implementation, the delay line length of the coaxial delay line (18) is selected to be approximately the same as the transmission time of the fundamental mode waveguide without considering different frequency dispersions, about 10 meters for the V band and about 9 meters for the E band, and according to the actual calibration results, it is adjusted by flexibly adding short delay lines on both paths;

[0043] The sextupler (7) is used to multiply the X-Ku band signal to the V / E band;

[0044] The V / E band waveguide isolator (9) is used to protect the sextupler (7).

[0045] As Figure 1 shown, the receiving unit (e) includes a V / E band motorized waveguide switch (12), a V / E band waveguide load (13), a V / E band low-pass filter (11), a V / E band band-pass filter (10), and a V / E band low-noise waveguide amplifier (17), where:

[0046] The V / E band motorized waveguide switch (12) and the V / E band waveguide load (13) are used to open or close the receiving unit (e);

[0047] The V / E band low-pass filter (11) is used to filter out potential 140 GHz electron cyclotron signal interference;

[0048] The V / E band band-pass filter (10) is used to filter the received reflected signal to ensure that only signals within the V / E band range enter the V / E band low-noise waveguide amplifier (17);

[0049] The V / E band low-noise waveguide amplifier (17) is used to amplify the filtered reflected signal to improve the mixing effect of the balanced mixer.

[0050] As Figure 1 shown, the transmitting path (c) includes a waveguide-coaxial vacuum feedthrough (14), a horn antenna (15), and a fundamental mode rectangular waveguide, and is used to inject the millimeter wave signal transmitted by the transmitting unit (b) into the plasma (16) through the fundamental mode rectangular waveguide;

[0051] The receiving path (d) also includes a waveguide-coaxial vacuum feedthrough (14), a horn antenna (15), and a fundamental mode rectangular waveguide, and is used to receive the microwave signal reflected by the plasma (16) and transmit the received reflected signal to the receiving unit (e) through the fundamental mode rectangular waveguide.

[0052] Here, since both the transmitting path (c) and the receiving path (d) use ultra-long distance fundamental mode rectangular waveguides, the transmitting unit (b) and the receiving unit (e) are uniquely designed, and a watt-level waveguide amplifier is used for the first time; in addition, for the reflectometer installed in the ion cyclotron antenna and needing to cope with the interference of 140 GHz electron cyclotron signals, both the transmitting unit (b) and the receiving unit (e) adopt a low-pass filtering plus band-pass filtering scheme.

[0053] In specific implementation, as Figure 1As shown, the calibration unit (g) includes a 3 kHz - 3 MHz coaxial low-noise amplifier (20), a 5 MHz high-pass filter (21), and a coaxial mixer (22), where:

[0054] The 3 kHz - 3 MHz coaxial low-noise amplifier (20) is used to amplify the mixing result of the V / E band balanced mixer (19);

[0055] The 5 MHz high-pass filter (21) is used to filter the amplified signal to remove low-frequency interference signals;

[0056] The coaxial mixer (22) is used to perform secondary mixing on the dispersion calibration voltage-time curve signal and the filtered signal to eliminate dispersion interference;

[0057] Among them, the method for obtaining the dispersion calibration voltage-time curve signal is as follows:

[0058] Remove the transmitting antenna, directly connect the transmitting path (c) and the receiving path (d), so that the microwave signal is completely transmitted within the closed waveguide, and obtain it after removing the interference of the plasma;

[0059] This dispersion calibration voltage-time curve signal is sent out by an arbitrary waveform generator (1).

[0060] In specific implementation, the temperature regulation of the voltage-controlled oscillator (2) is controlled by a PID temperature controller; the refrigeration scheme is realized by installing thermoelectric coolers and cooling fans on the upper and lower surfaces of the voltage-controlled oscillator (2). The total power of the thermoelectric coolers is 120 watts, and there are two 6 cm cooling fans on each of the upper and lower sides.

[0061] In specific implementation, the installation method of the fundamental mode rectangular waveguide is to split the entire waveguide design into several ultra-long straight waveguides and short bent waveguides with a length exceeding 50 cm, and splice them by docking the waveguide flanges at both ends of the waveguide and fixing them with waveguide screws, as Figure 2 shown in the schematic diagram of the splicing of the fundamental mode rectangular waveguide in the vacuum chamber in the embodiment of the present invention. Its overall single-pass attenuation is 10 - 16 dB (2 dB / m) in the V band and 13 - 21 dB (3 dB / m) in the E band. As Figure 3 shown in the schematic diagram of the attenuation measurement value of the fundamental mode rectangular waveguide in the embodiment of the present invention. It can be seen from Figure 3 that the output power at the antenna port can still be maintained within the range of 10 dBm. Considering the waveguide attenuation of the transmitted reflected signal, it can be considered that it can meet the power requirements of the balanced mixer for RF signals after using the low-noise amplifier.

[0062] In addition, the waveguide-coaxial vacuum feedthrough (14) adopts the method of converting the waveguide to a 1.0 mm inner diameter SMA (SubMiniature version A) radio frequency coaxial cable and then converting it back to the waveguide. A 1.0 mm SMA vacuum feedthrough with an operating frequency of DC - 110 GHz is used for vacuum isolation. The vacuum leakage rate is approximately 5.4 - 7.8×10-10 Pa·m -3 / s, meeting the requirements of the tokamak device for the vacuum leakage rate of vacuum components; at the same time, in order to minimize the possible damage to the SMA inner core caused by vibration, an SMA coaxial cable with an extremely short distance is used to connect the waveguide-to-coaxial component and the coaxial feedthrough.

[0063] It should be noted that the content not described in detail in the embodiments of the present invention belongs to the prior art well-known to those skilled in the art.

[0064] In summary, the microwave reflectometer system described in the embodiments of the present invention has the following advantages:

[0065] 1. Through integrated design with the ion cyclotron resonance system, it can directly diagnose the electron density distribution information near the ion cyclotron resonance antenna, further provide important plasma physics information for understanding the interaction between the ion cyclotron antenna and the plasma, and thus help the magnetic confinement fusion industry better understand the physical mechanism of ion cyclotron resonance heating and the physical process of the interaction between the ion cyclotron resonance heating antenna and the plasma scrape-off layer;

[0066] 2. An electron density measurement device for the ion cyclotron resonance antenna is added. Through cross-verification of multiple devices, a higher-precision measurement result of electron density information can be achieved;

[0067] 3. The transmission power of the microwave reflectometer is increased, and the feasibility and reliability of the operation of the watt-level microwave reflectometer system are solved and verified. It provides experience for the research and development of the electronics equipment layout for future fusion reactors using corrugated waveguides at a longer distance, and provides a new design scheme for the new waveguide vacuum window structure;

[0068] 4. By developing a scheme of directly mixing the dispersion calibration voltage-time curve calculated from the closed waveguide test results with the original signal, the elimination of the fundamental mode waveguide dispersion is achieved at the hardware level, and thus the measurement accuracy of the electron density distribution can be improved.

[0069] As described above, it is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims. The information disclosed in the background art part of this article is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or any form of implication that this information constitutes the prior art already known to those skilled in the art.

Claims

1. A microwave reflectometer system, characterized in that: The microwave reflectometer system comprises an arbitrary waveform generator (1), an X-Ku signal source unit (a), a coaxial directional coupler (6), a transmitting unit (b), a transmitting path (c), a receiving path (d), a receiving unit (e), a reference unit (f), a V / E band balanced mixer (19), a calibration unit (g) and an acquisition card (23), wherein: The arbitrary waveform generator (1) generates a microwave signal after passing through the X-Ku signal source unit (a); The coaxial directional coupler (6) divides the generated microwave signal into two paths, one path enters the transmitting unit (b), and the other path enters the reference unit (f); The microwave signal entering the transmitting unit (b) is frequency-multiplied by a sextuple frequency multiplier to the V band and the E band, wherein the V band corresponds to the 50-75 GHz band and the E band corresponds to the 60-90 GHz band. After the microwave signal is amplified by the waveguide amplifier, it is injected into the plasma (16) via the fundamental mode rectangular waveguide in the transmitting path (c); the microwave signal is reflected by the cutoff layer in the plasma (16), then received by the receiving antenna, and transmitted back to the microwave reflectometer system via the fundamental mode rectangular waveguide at the end of the receiving path (d) which is almost the same length as the transmitting path (c), and then filtered and low-noise amplified by the receiving unit (e) before being mixed by the V / E band balanced mixer (19); The microwave signal entering the reference unit (f) is compensated for the flight time by the delay line and then frequency-multiplied by the sextuple frequency multiplier. The boosted millimeter wave signal is directly mixed with the reflected signal received by the receiving unit (e) in the V / E band balanced mixer (19) and the frequency is reduced to the MHz level. The V / E band balanced mixer (19) is used to perform a mixing operation on the reflected signal received by the receiving unit (e) and the reference signal output by the reference unit (f), so as to reduce the frequency of the microwave signal in the V / E band to a low frequency signal of the MHz level, and input the low frequency signal into the calibration unit (g); The calibration unit (g) is used to perform secondary mixing on the dispersion calibration voltage time curve signal emitted by the arbitrary waveform generator (1) and the signal after primary mixing by the V / E band balanced mixer (19) to eliminate dispersion interference; The acquisition card (23) is used to acquire the output signal of the calibration unit (g) after secondary mixing, convert the acquired signal into a complex signal by superimposing a designated frequency signal, directly obtain the phase after filtering the complex signal, invert the X-mode dispersion phase matrix, and obtain the electron density information near the ion cyclotron antenna.

2. The microwave reflectometer system according to claim 1, characterized in that: The X-Ku signal source unit (a) comprises a voltage controllable oscillator (2), a coaxial isolator (3), a coaxial high power amplifier (4) and a coaxial attenuator (5), wherein: The voltage controllable oscillator (2) is controlled by the control voltage of the arbitrary waveform generator (1) to generate an X-Ku band signal whose transmission frequency changes linearly with time within a single cycle; The coaxial isolator (3) protects the safe operation of the voltage-controlled oscillator (2); The power of the microwave signal emitted by the X-Ku signal source unit (a) is adjusted by controlling a coaxial high power amplifier (4) and a coaxial attenuator (5).

3. The microwave reflectometer system according to claim 1, characterized in that: The transmitting unit (b) comprises a coaxial attenuator (5), a sextuple frequency multiplier (7), a V / E band waveguide amplifier (8), a V / E band waveguide isolator (9), a V / E band bandpass filter (10), a V / E band low-pass filter (11), a V / E band electric waveguide switch (12), and a V / E band waveguide load (13), wherein: The coaxial attenuator (5) performs power adjustment on a signal separated by the coaxial directional coupler (6) to ensure that the power meets the input power requirement of the sextuple frequency multiplier (7); The sextuple frequency multiplier (7) is used for multiplying the frequency of the input microwave signal to the V band and the E band; The V / E band waveguide amplifier (8) is used to gain the V / E band signal after frequency multiplication by the sextuple frequency multiplier (7) to reach the watt level, so as to overcome the microwave signal transmission loss of the long-distance fundamental mode rectangular waveguide; The V / E band waveguide isolator (9) is used to protect the safe operation of the V / E band waveguide amplifier (8); The V / E band bandpass filter (10) is used to filter the V / E band signal after gain, ensuring that only the sextuple frequency signal is emitted; The V / E band low-pass filter (11) is used to filter out potential 140 GHz electron cyclotron signal interference; The V / E band electric waveguide switch (12) and the V / E band waveguide load (13) are used to turn on or off the transmitting unit (b).

4. The microwave reflectometer system according to claim 1, characterized in that: The reference unit (f) comprises a coaxial delay line (18), a sextuple frequency multiplier (7), and a V / E band waveguide isolator (9), wherein: The coaxial delay line (18) is used to compensate the flight time of the long-distance rectangular waveguide to ensure that the frequency range mixed by the V / E band balanced mixer (19) is within a specified range; The sextuple frequency multiplier (7) is used for multiplying the X-Ku band signal to the V / E band; The V / E band waveguide isolator (9) is used to protect the sextuple frequency multiplier (7).

5. The microwave reflectometer system according to claim 1, characterized in that: The receiving unit (e) comprises a V / E band electric waveguide switch (12), a V / E band waveguide load (13), a V / E band low-pass filter (11), a V / E band band-pass filter (10), and a V / E band low-noise waveguide amplifier (17), wherein: The V / E band electric waveguide switch (12) and the V / E band waveguide load (13) are used to turn on or off the receiving unit (e); The V / E band low-pass filter (11) is used to filter out potential 140 GHz electron cyclotron signal interference; The V / E band bandpass filter (10) is used to filter the received reflected signal to ensure that only signals within the V / E band range enter the V / E band low noise waveguide amplifier (17); The V / E band low noise waveguide amplifier (17) is used to amplify the reflected signal after filtering and improve the mixing effect of the balanced mixer.

6. The microwave reflectometer system according to claim 1, characterized in that: The transmitting path (c) comprises a waveguide-coaxial vacuum wall penetration component (14), a horn antenna (15) and a fundamental mode rectangular waveguide, and is used to inject the millimeter wave signal emitted by the transmitting unit (b) into the plasma (16) via the fundamental mode rectangular waveguide; The receiving path (d) also includes a waveguide-coaxial vacuum wall penetration component (14), a horn antenna (15) and a fundamental mode rectangular waveguide, and is used to receive the microwave signal reflected by the plasma (16), and transmit the received reflected signal to the receiving unit (e) via the fundamental mode rectangular waveguide.

7. The microwave reflectometer system according to claim 1, characterized in that: The calibration unit (g) comprises a 3kHz-3MHz coaxial low-noise amplifier (20), a 5MHz high-pass filter (21), and a coaxial mixer (22), wherein: The 3kHz-3MHz coaxial low noise amplifier (20) is used to amplify the mixing result of the V / E band balanced mixer (19); The 5MHz high-pass filter (21) is used to filter the amplified signal and remove low-frequency interference signals; The coaxial mixer (22) is used to perform secondary mixing on the dispersion calibration voltage time curve signal and the signal after filtering to eliminate dispersion interference; The dispersion calibration voltage-time curve signal is obtained as follows: Remove the transmitting antenna and directly connect the transmitting path (c) and the receiving path (d) so that the microwave signal is completely transmitted in the closed waveguide and the interference of the plasma is removed; The dispersion calibration voltage time curve signal is sent out through an arbitrary waveform generator (1).

8. The microwave reflectometer system according to claim 2, characterized in that: The temperature regulation of the voltage controllable oscillator is controlled by a PID temperature controller; the cooling scheme is implemented by installing semiconductor cooling sheets and cooling fans on the upper and lower surfaces of the voltage controllable oscillator.

9. The microwave reflectometer system according to claim 6, characterized in that: The installation method of the fundamental mode rectangular waveguide is to split the entire waveguide design into several ultra-long straight waveguides and short curved waveguides with a length of more than 50 cm, and splice them by docking the waveguide flanges at both ends of the waveguide and fixing them with waveguide screws.

10. The microwave reflectometer system according to claim 6, characterized in that: The waveguide-coaxial vacuum wall penetration component (14) adopts the method of converting a waveguide to a 1.0 mm inner diameter SMA radio frequency coaxial line and then converting it back to a waveguide, and uses a 1.0 mm SMA vacuum wall penetration component with an operating frequency of DC-110 GHz for vacuum isolation.

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