A fast-sweep microwave reflectometer protection system and method

Abstract

The present invention specifically relates to a fast-sweep microwave reflectometer protection system and method, which belongs to the field of plasma diagnosis. It can autonomously determine whether it is necessary to turn off the Q-band signal each time a magnetic confinement plasma device discharges, thereby preventing the Q-band mixer from being damaged by the electromagnetic radiation generated by the plasma in subsequent discharge experiments, and ensuring the stable operation of the fast-sweep microwave reflectometer. The system includes a longitudinal field current extraction module, a V-band beat frequency processing module, a V-band beat frequency extraction module, a V-band beat frequency identification module, a Q-band switch judgment module, a microwave switch, and a storage module. The invention combines the beat frequency information of the V-band, and the judgment is more accurate and reliable, does not require human intervention, and is more efficient.

Description

Technical Field

[0001] The invention belongs to the field of plasma diagnosis, and in particular relates to a fast-sweep frequency microwave reflectometer protection system and method. Background Art

[0002] The fast-sweep microwave reflectometer is an important diagnostic tool in magnetically confined plasmas. The electron density profile it measures provides important support for device operation and physical analysis. In magnetically confined plasma devices (such as tokamaks), the fast-sweep microwave reflectometer emits a sweeping detection wave to the plasma consisting of three bands: Q (30-50GHz), V (50-75GHz), and W (75-110GHz). The electromagnetic wave emitted by the fast-sweep microwave reflectometer is reflected by the plasma and mixed with the local oscillator signal using a mixer to obtain the collected intermediate frequency signal. However, due to the complex electromagnetic environment of the tokamak device during discharge, the electromagnetic pulses radiated by the plasma can easily damage the Q-band mixer, making the normal operation of the fast-sweep microwave reflectometer face huge challenges.

[0003] In order to protect the fragile mixer, during the experiments of magnetic confinement plasma devices in the past, for high longitudinal field experiments that do not require Q-band signals (high longitudinal field experiments are when the magnetic induction intensity at the center of the device exceeds 2.2 T), the Q-band mixer needs to be manually removed at the experimental site, but this method is very inconvenient. In order to achieve active protection of the mixer, there are usually two measures; one is to add a limiter to the front-end circuit to limit the power of the input signal, but because the electromagnetic pulse intensity of plasma radiation is highly uncertain, the limiter cannot completely protect the mixer and will have a serious adverse effect on the signal-to-noise ratio of the detection signal. Another common practice is to add a filter to the front-end circuit to filter out unnecessary frequencies to prevent the mixer from being damaged by stray waves, but only the Q-band mixer is particularly susceptible to interference from stray waves, indicating that the frequency of the stray wave is mainly in the Q-band and cannot be filtered out from the required Q-band signal according to the frequency. Summary of the invention

[0004] In order to solve the problem that the Q-band mixer is easily damaged, the present invention proposes a fast-sweep microwave reflectometer protection system and method. The core is a programmable on-chip system that can independently determine whether the Q-band signal needs to be turned off during each discharge, thereby preventing the Q-band mixer from being damaged by the electromagnetic radiation generated by the plasma in subsequent discharge experiments, thereby ensuring the stable operation of the fast-sweep microwave reflectometer.

[0005] To achieve the above object, the present invention proposes a fast-sweep microwave reflectometer protection system, which includes a longitudinal field current extraction module, a V-band beat frequency processing module, a V-band beat frequency extraction module, a V-band beat frequency identification module, a Q-band switch judgment module, a microwave switch, and a storage module; wherein,

[0006] The longitudinal field current extraction module is used to obtain current longitudinal field current data;

[0007] The V-band beat frequency processing module is used to convert the V-band original signal into beat frequency information;

[0008] The V-band beat frequency extraction module is used to extract the beat frequency of the V-band as it evolves with the detection frequency;

[0009] The V-band beat frequency identification module is used to identify whether there is a falling edge structure in the V-band beat frequency information;

[0010] The Q-band switch determination module is used to determine whether the microwave switch needs to be turned on or off;

[0011] The microwave switch is used to turn on or off the Q-band signal;

[0012] The storage module is used to store longitudinal field current data.

[0013] The present invention also provides a fast frequency sweep microwave reflectometer protection method, comprising the following steps:

[0014] Step S1, before the discharge starts, using the longitudinal field current data to determine whether the microwave switch needs to be turned on; comprising: a longitudinal field current extraction module obtains the current longitudinal field current data;

[0015] Step S2, V-band beat frequency processing; including: the V-band beat frequency processing module converts the V-band original signal into beat frequency information

[0016] Step S3, V-band beat frequency extraction; comprising: a V-band beat frequency extraction module extracts the beat frequency information of the V-band along with the evolution of the detection frequency;

[0017] Step S4, V-band beat frequency identification; comprising: a V-band beat frequency identification module identifies whether there is a falling edge structure in the V-band beat frequency information;

[0018] Step S5, switch judgment; including: a Q-band switch judgment module is used to judge whether the microwave switch needs to be turned on or off;

[0019] Step S6, if it is necessary to turn off the microwave switch to save the current longitudinal field current data; including: a storage module to save the longitudinal field current data.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The invention proposes a fast-sweep microwave reflectometer protection system and method, which can autonomously determine whether to turn off the Q-band signal during each discharge experiment of a magnetic confinement plasma device, thereby protecting the Q-band mixer. The invention combines the beat frequency information of the V-band, making the judgment more accurate and reliable, without the need for human intervention, and more efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a topological diagram of the fast-sweep microwave reflectometer and protection system;

[0023] Figure 2 It is a schematic diagram of the protection system;

[0024] Figure 3 It is a schematic diagram of the protection system flow;

[0025] Figure 4 It is a schematic diagram of the V-band beat frequency including the falling edge structure and the gradient of the beat frequency relative to the detection frequency;

[0026] Figure 5 It is a schematic diagram of the V-band beat frequency without the falling edge structure and the gradient of the beat frequency relative to the detection frequency. DETAILED DESCRIPTION

[0027] like Figure 1 As shown, the fast-sweep microwave reflectometer includes three detection bands: Q (30-50GHz), V (50-75GHz), and W (75-110GHz). The detection microwave signal generated by the back-end circuit is injected into the plasma through the transmitting antenna. The detection microwave is cut off in the plasma and reflected back and received by the receiving antenna. After being mixed by the Q, V, and W band mixers, they are processed and output respectively. Among them, the Q band signal needs to pass through the protection system proposed by the present invention before entering the Q band mixer to protect the Q band mixer.

[0028] like Figure 2 As shown, the present invention proposes a fast-sweep microwave reflectometer protection system, the core of which is a programmable on-chip system, which includes a longitudinal field current extraction module, a V-band beat frequency processing module, a V-band beat frequency extraction module, a V-band beat frequency identification module, a Q-band switch judgment module, a microwave switch, and a storage module; the longitudinal field current extraction module is used to obtain current longitudinal field current data; the V-band beat frequency processing module is used to convert the V-band original signal into beat frequency information; the V-band beat frequency extraction module is used to extract the V-band beat frequency as the detection frequency evolves, and the V-band beat frequency identification module is used to identify whether there is a falling edge structure in the V-band beat frequency information; the Q-band switch judgment module is used to judge whether the microwave switch needs to be turned on or off; the microwave switch is used to turn on or off the Q-band signal; and the storage module is used to save the longitudinal field current data.

[0029] The specific method of the longitudinal field current extraction module to obtain the current longitudinal field current data is: read the longitudinal field current data stored in the database in real time, read the longitudinal field current data of 0.5 seconds each time, and average the data of this 0.5 second interval.

[0030] The V-band beat frequency processing module includes a signal conditioning circuit. The V-band beat frequency processing module converts the original V-band signal of the fast-sweep microwave reflectometer into a digital signal. After the conversion into a digital signal, a fast Fourier transform is performed on the digital signal by adding a time window to obtain the spectrum distribution corresponding to each window. Each time window corresponds to a detection frequency f d , that is, each detection frequency f d Each corresponds to a spectrum distribution, and the complete beat frequency information is obtained by combining these time windows.

[0031] The V-band beat frequency extraction module extracts the V-band beat frequency f b With the detection frequency f d The specific extraction of the evolution includes: traversing each detection frequency f d The corresponding spectrum distribution, and find the frequency corresponding to the spectrum peak, that is, the beat frequency f b , that is, each detection frequency f d Each corresponds to a beat frequency f b , combine these data and smooth them to get the beat frequency f in the V band b With the detection frequency f d evolution data.

[0032] The V-band beat frequency identification module identifies whether there is a falling edge structure in the V-band beat frequency information, including: finding the beat frequency f b Relative detection frequency f d The gradient d(f b ) / d(f d ), if the minimum gradient value is greater than the set threshold, it indicates that the beat frequency f b There is no falling edge structure in the information, otherwise it is necessary to further judge the falling amplitude of the beat frequency; the falling amplitude of the beat frequency is the difference between the average values ​​of the beat frequency before and after the minimum gradient; if the falling amplitude of the beat frequency exceeds the set threshold, it indicates that there is a falling edge structure in the beat frequency information, otherwise it indicates that there is no falling edge structure.

[0033] The Q-band switch judgment module judges whether the microwave switch needs to be turned on or off, including: if the beat frequency f in the V-band b If a falling edge structure is identified in the process, the microwave switch is turned off; in a new round of discharge, if the current longitudinal field current is less than the longitudinal field current recorded in the storage module, the microwave switch is turned on.

[0034] The insertion loss of the microwave switch is less than 1.5dB and the switching speed is less than 200ns.

[0035] The storage cycle of the storage module is less than 200ns and the storage capacity is greater than 1MB.

[0036] The present invention proposes a fast frequency sweep microwave reflectometer protection method, which includes the following method steps: Figure 3 As shown:

[0037] Step S1, before the discharge starts, using the longitudinal field current data to determine whether the microwave switch needs to be turned on;

[0038] Including: the longitudinal field current extraction module obtains the current longitudinal field current data; to ensure the integrity of the Q-band signal, the current longitudinal field current data is compared with the longitudinal field current data recorded in the storage module before the start of a new round of discharge. If the current longitudinal field current data is less than the recorded longitudinal field current data, the microwave switch needs to be turned on to ensure that the Q-band signal can be collected normally after the discharge starts, and the subsequent steps are executed. Otherwise, the original state is maintained; when the system is first run, the current data in the storage module needs to be initialized to 99999.

[0039] Step S2, V-band beat frequency processing;

[0040] The V-band beat frequency processing module converts the V-band original signal into beat frequency information; the V-band original signal is subjected to fast Fourier transform by adding a time window to obtain the spectrum distribution corresponding to each window, and each time window corresponds to a detection frequency f d , that is, each detection frequency f d Each corresponds to a spectrum distribution. By combining these time windows, the complete V-band beat frequency information is obtained, such as Figure 4 (a) and Figure 5 As shown in (a).

[0041] Step S3, V-band beat frequency extraction;

[0042] It includes: a V-band beat frequency extraction module extracts the beat frequency information of the V-band as the detection frequency evolves; according to the result of step S2, traverses each detection frequency f d The corresponding spectrum distribution, and find the frequency corresponding to the spectrum peak (beat frequency f b ), that is, each measured frequency f d Each corresponds to a beat frequency f b , combine these data and smooth them to get the beat frequency f in the V band b With the detection frequency f d Evolution data, such as Figure 4 (b) and Figure 5(b) shows the cross-shaped data points and lines, where the lines are the smoothed data.

[0043] Step S4, V-band beat frequency recognition;

[0044] The invention comprises: a V-band beat frequency identification module identifies whether there is a falling edge structure in the V-band beat frequency information; in a high longitudinal field discharge experiment of a magnetic confinement plasma device, there will be a falling edge structure in the V-band beat frequency, such as Figure 4 This structure does not exist in the low longitudinal field experiment, as shown in (a). Figure 5 According to the result of step S3, the beat frequency f is obtained. b Relative detection frequency f d The gradient d(f b ) / d(f d ),like Figure 4 (c) and Figure 5 As shown in (c), if the minimum gradient value is greater than the set threshold, it indicates that the beat frequency f b There is no falling edge structure in the beat frequency information, otherwise it is necessary to further determine the falling amplitude of the beat frequency; the falling amplitude of the beat frequency is the difference between the average values ​​of the beat frequency before and after the minimum gradient; if the falling amplitude of the beat frequency exceeds the set threshold, it indicates that there is a falling edge structure in the beat frequency information, otherwise it indicates that there is no falling edge structure.

[0045] Step S5, switch determination;

[0046] It includes: a Q-band switch judgment module for judging whether the microwave switch needs to be turned on or off; if a falling edge structure is identified in the beat frequency of the V band in step S4, indicating that the relevant experiment is a high longitudinal field experiment that does not require a Q-band signal, the microwave switch is turned off, otherwise the original state is maintained.

[0047] Step S6: If it is necessary to turn off the microwave switch to save the current longitudinal field current data;

[0048] It includes: a storage module saves longitudinal field current data; according to the result in step S5, if the microwave switch needs to be turned off, the current longitudinal field current data is saved in the storage module, and the storage module compares the size of the data to be saved and the data in storage, and only saves the minimum value each time.

Claims

1. A fast-sweep microwave reflectometer protection system, It is characterized in that The system includes a longitudinal field current extraction module, a V-band beat frequency processing module, a V-band beat frequency extraction module, a V-band beat frequency identification module, a Q-band switch judgment module, a microwave switch, and a storage module; wherein, The longitudinal field current extraction module is used to obtain current longitudinal field current data; The V-band beat frequency processing module is used to convert the V-band original signal into beat frequency information; The V-band beat frequency extraction module is used to extract the beat frequency information of the V-band along with the evolution of the detection frequency; The V-band beat frequency identification module is used to identify whether there is a falling edge structure in the V-band beat frequency information; The Q-band switch determination module is used to determine whether the microwave switch needs to be turned on or off; The microwave switch is used to turn on or off the Q-band signal; The storage module is used to store longitudinal field current data; The V-band beat frequency identification module identifies whether there is a falling edge structure in the V-band beat frequency information, including: finding the beat frequency f b Relative detection frequency f d The gradient d(f b ) / d(f d ), if the minimum gradient value is greater than the set threshold, it indicates that the beat frequency f b If there is no falling edge structure in the information, otherwise, it is necessary to further determine the falling amplitude of the beat frequency; the falling amplitude of the beat frequency is the difference between the average values ​​of the beat frequency before and after the minimum gradient; if the falling amplitude of the beat frequency exceeds the set threshold, it indicates that there is a falling edge structure in the beat frequency information, otherwise it indicates that there is no falling edge structure; The Q-band switch judgment module judges whether the microwave switch needs to be turned on or off, including: if the beat frequency f in the V-band b If a falling edge structure is identified in the process, the microwave switch is turned off; in a new round of discharge, if the current longitudinal field current is less than the longitudinal field current recorded in the storage module, the microwave switch is turned on.

2. A fast-sweep microwave reflectometer protection system according to claim 1, It is characterized in that The specific method of the longitudinal field current extraction module to obtain the current longitudinal field current data is: read the longitudinal field current data stored in the database in real time, read the longitudinal field current data of 0.5 seconds each time, and average the data of this 0.5 second interval.

3. A fast-sweep microwave reflectometer protection system according to claim 1, It is characterized in that The V-band beat frequency processing module includes a signal conditioning circuit. The V-band beat frequency processing module converts the original V-band signal of the fast-sweep microwave reflectometer into a digital signal. After the conversion into a digital signal, a fast Fourier transform is performed on the digital signal by adding a time window to obtain the spectrum distribution corresponding to each window. Each time window corresponds to a detection frequency f d , that is, each detection frequency f d Each corresponds to a spectrum distribution, and the complete beat frequency information is obtained by combining these time windows.

4. A fast-sweep microwave reflectometer protection system according to claim 3, It is characterized in that The V-band beat frequency extraction module extracts the V-band beat frequency f b With the detection frequency f d The evolution of is extracted by traversing each detection frequency f d The corresponding spectrum distribution, and find the frequency corresponding to the spectrum peak, that is, the beat frequency f b , that is, each detection frequency f d Each corresponds to a beat frequency f b , combine these data and smooth them to get the beat frequency f in the V band b With the detection frequency f d evolution data.

5. The fast-sweep microwave reflectometer protection system according to claim 1, It is characterized in that The insertion loss of the microwave switch is less than 1.5dB and the switching speed is less than 200ns.

6. A fast-sweep microwave reflectometer protection system according to claim 1, It is characterized in that The storage cycle of the storage module is less than 200ns and the storage capacity is greater than 1MB.

7. A microwave reflectometer protection method for a fast frequency sweep microwave reflectometer protection system according to any one of claims 1 to 6, It is characterized in that The method comprises the following steps: Step S1: before the discharge starts, the longitudinal field current extraction module obtains the current longitudinal field current data, and uses the longitudinal field current data to determine whether the microwave switch needs to be turned on; Step S2, the V-band beat frequency processing module converts the V-band original signal into beat frequency information; Step S3, the V-band beat frequency extraction module extracts the evolution of the V-band beat frequency information along with the detection frequency; Step S4, the V-band beat frequency identification module identifies whether there is a falling edge structure in the beat frequency information of the V-band; Step S5: The Q-band switch determination module determines whether the microwave switch needs to be turned on or off; Step S6: If the microwave switch needs to be turned off, the storage module saves the current longitudinal field current data.

8. The microwave reflectometer protection method of the fast frequency sweep microwave reflectometer protection system according to claim 7, It is characterized in that In the step S1, during a new round of discharge, if the current longitudinal field current is less than the recorded longitudinal field current, the microwave switch is turned on and subsequent steps are performed, otherwise the original state is maintained.

9. The microwave reflectometer protection method of the fast frequency sweep microwave reflectometer protection system according to claim 7, It is characterized in that In step S2, a fast Fourier transform is performed on the V-band original signal by adding a time window to obtain the spectrum distribution corresponding to each time window, and each time window corresponds to a detection frequency f d , that is, each detection frequency f d They all correspond to a spectrum distribution, and the complete V-band beat frequency information is obtained by combining the time windows.

10. The microwave reflectometer protection method of the fast frequency sweep microwave reflectometer protection system according to claim 9, It is characterized in that In step S3, according to the result of step S2, each detection frequency f is traversed. d The corresponding spectrum distribution, and find the frequency corresponding to the spectrum peak, that is, the beat frequency f b , that is, each measured frequency f d Each corresponds to a beat frequency f b , combine these data and smooth them to get the beat frequency f in the V band b With the detection frequency f d evolution data.

11. The microwave reflectometer protection method of the fast frequency sweep microwave reflectometer protection system according to claim 10, It is characterized in that In step S4, the beat frequency f is obtained based on the result of step S3. b Relative detection frequency f d The gradient d(f b ) / d(f d ), if the minimum gradient value is greater than the set threshold, it indicates that the beat frequency f b If there is no falling edge structure in the information, otherwise, the falling amplitude of the beat frequency is further determined; the falling amplitude of the beat frequency is the difference between the average values ​​of the beat frequency before and after the minimum gradient; if the falling amplitude of the beat frequency exceeds the set threshold, it indicates that there is a falling edge structure in the beat frequency information, otherwise, it indicates that there is no falling edge structure.

12. The microwave reflectometer protection method of the fast frequency sweep microwave reflectometer protection system according to claim 11, It is characterized in that In step S5, if the beat frequency f in the V band in step S4 is b If a falling edge structure is identified, the microwave switch is turned off, otherwise the original state is maintained.

13. The microwave reflectometer protection method of the fast frequency sweep microwave reflectometer protection system according to claim 12, It is characterized in that In step S6, according to the result in step S5, if the microwave switch is turned off, the current longitudinal field current data is saved in the storage module, and the storage module compares the size of the data to be saved and the data in storage, and only saves the minimum value each time.

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