A megawatt gyrotron output window electromagnetic parameter real-time detection system

Abstract

This invention proposes a real-time detection system for the electromagnetic parameters of the output window of a megawatt-level cyclotron traveling-wave tube, belonging to the field of millimeter-wave and terahertz detection technology. The system includes a quasi-optical cavity testing device, a signal transceiver and processing module, a peak detector, and a transmit signal spread spectrum and transmission channel. This invention implements real-time processing of the quasi-optical cavity test signal through software radio module programming, thereby enabling real-time testing of the output window's electromagnetic parameters under varying temperature conditions. Using an optical displacement stage to adjust the quasi-optical cavity length significantly improves the frequency range of measurable electromagnetic parameters of the output window. An open-slit feeding method for the quasi-optical cavity is invented, improving coupling efficiency and reducing signal power requirements. Using this invention, real-time testing of the output window's electromagnetic parameters under varying temperature conditions can be achieved over a wide frequency range.

Description

Technical Field

[0001] This invention belongs to the field of millimeter wave and terahertz detection technology, and more specifically, relates to a real-time detection system for electromagnetic parameters of the output window of a megawatt-level gyroscopic traveling wave tube, laying the foundation for the development of megawatt-level gyroscopic traveling wave tube output windows in the millimeter wave and terahertz frequency bands. Background Technology

[0002] High-power terahertz windows can maintain the vacuum level inside the tube when transmitting high-power terahertz energy using an output window. However, the introduction of the output window causes electromagnetic wave energy reflection fluctuations due to changes in the dielectric constant, leading to a decrease in the transmission performance of the high-power terahertz window. Therefore, the lifespan and operating performance of a high-power terahertz window are significantly influenced by the dielectric constant of the output window. Thus, it is necessary to select the window material before designing a high-power terahertz window. Because the material itself has dielectric loss, the output window heats up rapidly during electromagnetic wave transmission, and this heat increases with the electromagnetic power. The accumulation of heat leads to excessive thermal stress on the window, potentially causing irreversible damage. Therefore, it is necessary to monitor the electromagnetic parameters of the output window in real time before designing a high-power terahertz vacuum window.

[0003] Current quasi-optical cavity testing methods lack real-time detection capabilities, and the coupling coefficient of existing quasi-optical cavities exhibits poor stability under varying temperature conditions. Summary of the Invention

[0004] To address the aforementioned technical problems in the existing technology, this invention provides a real-time detection system for the electromagnetic parameters of the output window of a megawatt-level gyrotron traveling wave tube, which has significant application value for the selection of output window materials and the analysis of temperature-dependent failure mechanisms in megawatt-level high-power gyrotrons.

[0005] To achieve the above-mentioned objectives, the technical solution of this invention is as follows:

[0006] A real-time electromagnetic parameter detection system for the output window of a megawatt-level cyclotron traveling-wave tube includes: a quasi-optical cavity testing device, a signal transceiver and processing module, a peak detector, and a transmit signal spread spectrum and transmission channel. The signal transceiver and processing module emits a linear frequency modulated (LFM) signal, which is converted into a millimeter-wave signal through the transmit signal spread spectrum and transmission channel and then sent to the quasi-optical cavity testing device to excite the quasi-optical cavity. The millimeter-wave signal is then sent to the peak detector after passing through the quasi-optical cavity testing device to extract the envelope signal, which is then sent to the signal transceiver and processing module. The signal transceiver and processing module performs amplitude matching on the envelope signal, converts it into a digital signal, and then calculates the test result.

[0007] The quasi-optical cavity testing device includes: a variable-temperature sample stage, a sample to be tested, a first reflector, a second reflector, a first optical displacement stage, a second optical displacement stage, a displacement stage driver, a bulk absorbing material, a coupling diaphragm, and a conical horn antenna. The first and second reflectors form a quasi-optical cavity, and the variable-temperature sample stage is located at the center of the quasi-optical cavity to fix the sample to be tested. The variable-temperature sample stage is placed on the first optical displacement stage, and the second reflector is placed on the second optical displacement stage. The position of the second reflector is adjusted by adjusting the second optical displacement stage so that the resonant frequency of the quasi-optical cavity is located at the test frequency of the sample to be tested. The first optical displacement stage is adjusted so that the sample to be tested in the variable-temperature sample stage on the displacement stage moves to the center of the quasi-optical cavity. A coupling diaphragm is placed between the second reflector and the sample to be tested. The coupling diaphragm is at a 45° angle to the rotational symmetry axis of the quasi-optical cavity. A conical horn antenna is located above the coupling diaphragm, and a bulk absorbing material is located below the coupling diaphragm.

[0008] The signal transceiver and processing module includes: an embedded microprocessor, a software radio transceiver circuit board, and an AD sampling signal conditioning circuit board; the AD sampling signal conditioning circuit board is connected to the peak detector via an RF cable; the AD sampling signal conditioning circuit board and the software radio transceiver circuit board are connected via an internal data bus, and the software radio transceiver circuit board interacts with the embedded microprocessor via the internal data bus.

[0009] The transmit signal spread spectrum and transmission channel includes a mixer, an up-conversion module, an isolator, a metal waveguide, and a gap coupling structure for waveguide transition; the software radio transceiver circuit board is connected to the mixer in the transmit signal spread spectrum and transmission channel via an RF cable.

[0010] The system is controlled by an embedded microprocessor to generate a linear frequency modulated (LFM) signal from a software-defined radio transceiver circuit board. The LFM signal is coupled to a frequency of f. Lo The local oscillator is up-mixed by a mixer, and then the signal is input to an up-conversion module to be converted into a millimeter-wave signal. The millimeter-wave signal passes through an isolator, through a metal waveguide, and is transmitted to the gap coupling structure of the waveguide transition on the first mirror of the quasi-optical cavity to excite the quasi-optical cavity. The conical horn antenna detects the millimeter-wave signal in the quasi-optical cavity, and the envelope signal of the millimeter wave is extracted by a peak detector. The envelope signal is processed by an AD sampling signal conditioning circuit board to remove high-frequency interference, and automatic gain amplification and conditioning are used to complete the amplitude matching of AD sampling. The amplitude-matched envelope signal is converted into a digital signal by A / D conversion through the receiving path of the software radio transceiver circuit board. The embedded microprocessor calculates the digital signal to obtain the test result.

[0011] The embedded microprocessor sends instructions to the stage driver, which then drives the first and second optical stages according to the control signals.

[0012] The second optical displacement stage is placed on a slide rail parallel to the rotational symmetry axis of the quasi-optical cavity and is used to adjust the cavity length; the first optical displacement stage is also placed on a slide rail parallel to the rotational symmetry axis of the quasi-optical cavity and is used to keep the sample under test at the center of the quasi-optical cavity at all times while the cavity length changes.

[0013] The coupling diaphragm is equipped with a pitch and azimuth angle adjustment device below it. The pitch and azimuth angles of the coupling diaphragm can be changed by rotating the corresponding knob.

[0014] The test data output from the AD sampling signal conditioning circuit board is subjected to Lorentz fitting, and a mathematical model is established using the parameters in the pre-designed function expression. The Lorentz fitting expression is as follows:

[0015]

[0016] In the formula, Indicates the scanning frequency at any point. Indicates the resonant frequency; Indicates the half-power point bandwidth; This represents the ratio of the signal amplitude of the output quasi-optical cavity to that of the input quasi-optical cavity; It is the bias constant; These are first-order coefficients; It is the tilt coefficient; This represents the maximum value of the resonance curve at the resonant frequency. The data processing program is programmed into the embedded microprocessor 1, and the figure-value function is defined. The test data is iterated using the least squares method until the optimal function is obtained from two consecutive iterations. When the difference is less than the set value The optimal value tends to stabilize, thus determining the fitting coefficients;

[0017] Based on the fitting coefficients and fitting parameters of the fitted curve and The exact expression for the quality factor is as follows:

[0018]

[0019] Finally, the resonant frequency obtained from the test... With the calculated quality factor Store;

[0020] Based on the existing electromagnetic parameters and resonant frequency of the sample to be tested and quality factor The formulas and relationships are used to write calculation programs for embedded microprocessors. The embedded microprocessors deduce the real-time dynamic electromagnetic parameters of the sample under test by looking up tables based on the stored test data.

[0021] The beneficial effects of this invention are as follows:

[0022] Building a quasi-optical cavity-based test system using current mainstream technologies requires a vector network analyzer (or a signal source and spectrum analyzer), a down-conversion module for the receiving signal, and a horn antenna feeder. Because the signal transmitting and receiving devices differ, an automated control platform built on a computer is needed to achieve automatic frequency sweeping of the signal source and spectrum analyzer, as well as spectral line reading, ensuring synchronous transmission and reception. This complicates the measurement system and increases the difficulty of platform construction. Compared to existing technologies, this invention uses a software-defined radio transceiver circuit board for high-speed acquisition and digital-to-analog conversion of analog signals, and interacts with an embedded microcontroller circuit board to form a signal transmission and processing module. This module offers good excitation signal-to-noise ratio and eliminates the need for a computer control platform, achieving integrated signal transmission and processing and simplifying the measurement system.

[0023] For millimeter-wave signals output from quasi-optical cavities, although vector network analyzers can replace spectrum analyzers and signal sources, their receiving intermediate frequency bandwidth is narrow. While this can reduce the noise floor of the received signal, their slow scanning speed prevents them from quickly tracking time-varying signals. Spectrum analyzers, on the other hand, require down-conversion of the millimeter-wave signal before performing data processing algorithms such as FFT transformation after AD sampling to obtain the spectral characteristics. Their real-time response speed is limited by the AD sampling rate and the complexity of the data processing algorithms, making them ineffective at tracking fast time-varying signals. Compared to existing technologies, this invention uses a peak detector to filter out high-frequency signals from the millimeter-wave signals output from the quasi-optical cavity, obtaining an envelope signal containing information about the quasi-optical cavity's resonant characteristics. This envelope signal is then directly acquired by the signal transceiver and processing module. Compared to the signal output by the downconverter module, which still contains high-frequency components, the peak detector directly outputs envelope information, reducing the difficulty of AD acquisition. This envelope signal corresponds to the frequency response information of the quasi-optical cavity, which can be directly stored and displayed without complex data processing. This greatly simplifies the acquisition time, improves the detection rate, and enables real-time detection.

[0024] Meanwhile, this invention introduces an optical displacement platform and a multi-degree-of-freedom rotating optical bench into the quasi-optical cavity testing device, realizing precise position adjustment of the optical mirror and adjustment of the pitch and azimuth angle of the coupling film; the sample to be tested can be loaded onto the variable temperature sample stage to simulate the real-time and variable temperature of the diamond window in the actual working scenario, and then study the characteristics of its electromagnetic parameters affected by temperature. Attached Figure Description

[0025] Figure 1 This is a diagram of a linear frequency modulated signal;

[0026] Figure 2A diagram of the millimeter-wave signal output from the quasi-optical cavity;

[0027] Figure 3 A sampling diagram of the quasi-optical cavity resonance peak;

[0028] Figure 4 This is a block diagram of the overall structural system of the present invention;

[0029] Figure 5 This is a flowchart of the least squares algorithm.

[0030] Explanation of reference numerals in the attached figures: 1. Embedded microprocessor; 2. Software radio transceiver circuit board; 3. Mixer; 4. Up-conversion module; 5. Isolator; 6. Metal waveguide; 7. Slot coupling structure for waveguide transition; 8. Variable temperature sample stage; 9. Sample under test; 10. First reflector; 11. Second reflector; 12. First optical displacement stage; 13. Second optical displacement stage; 14. Displacement stage driver; 15. Bulk absorbing material; 16. Coupling diaphragm; 17. Conical horn antenna; 18. Peak detector; 19. AD sampling signal conditioning circuit board. Detailed Implementation

[0031] The following specific examples illustrate the embodiments of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention will now be described in further detail with reference to the accompanying drawings:

[0032] A real-time electromagnetic parameter detection system for the output window of a megawatt-class cyclotron traveling wave tube, such as Figure 4 As shown, it includes:

[0033] The test setup includes a quasi-optical cavity testing device, a signal transceiver and processing module, a peak detector 18, and a transmit signal spread spectrum and transmission channel. The signal transceiver and processing module sends a linear frequency modulated (LFM) signal, which is converted into a millimeter-wave signal through the transmit signal spread spectrum and transmission channel and then sent to the quasi-optical cavity testing device to excite the quasi-optical cavity. The millimeter-wave signal is then sent to the peak detector 18 after passing through the quasi-optical cavity testing device. The envelope signal is extracted and sent to the signal transceiver and processing module. The signal transceiver and processing module performs amplitude matching on the envelope signal, converts it into a digital signal, and then calculates the test result.

[0034] Specifically, the quasi-optical cavity testing device includes: a variable-temperature sample stage 8, a sample to be tested 9, a first reflector 10, a second reflector 11, a first optical displacement stage 12, a second optical displacement stage 13, a displacement stage driver 14, a bulk absorbing material 15, a coupling diaphragm 16, and a conical horn antenna 17; the first reflector 10 and the second reflector 11 form a quasi-optical cavity, and the variable-temperature sample stage 8 is located at the center of the quasi-optical cavity to fix the sample to be tested 9; the variable-temperature sample stage 8 is placed on the first optical displacement stage 12, and the second optical displacement stage 13... Place the second reflector 11; adjust the position of the second reflector 11 by adjusting the second optical displacement stage 13 so that the resonant frequency of the quasi-optical cavity is located at the test frequency of the sample under test; adjust the first optical displacement stage 12 so that the sample under test in the variable temperature sample stage 8 on the displacement stage moves to the center of the quasi-optical cavity; place a coupling diaphragm 16 between the second reflector 11 and the sample under test 9, the coupling diaphragm 16 is at a 45° angle to the rotational symmetry axis of the quasi-optical cavity, the upper part of the coupling diaphragm is a conical horn antenna 17, and the lower part of the coupling diaphragm is a block absorbing material 15.

[0035] The signal transceiver and processing module includes: an embedded microprocessor 1, a software radio transceiver circuit board 2, and an AD sampling signal conditioning circuit board 19; the AD sampling signal conditioning circuit board 19 is connected to the peak detector 18 via an RF cable; the AD sampling signal conditioning circuit board 19 is connected to the software radio transceiver circuit board 2 via an internal data bus, and the software radio transceiver circuit board 2 interacts with the embedded microprocessor 1 via the internal data bus.

[0036] The transmit signal spread spectrum and transmission channel includes a mixer 3, an up-conversion module 4, an isolator 5, a metal waveguide 6, and a gap coupling structure 7 for waveguide transition; the software radio transceiver circuit board 2 is connected to the mixer 3 in the transmit signal spread spectrum and transmission channel via an RF cable.

[0037] The embedded microprocessor 1 issues instructions to control the software radio transceiver circuit board 2 to generate a linear frequency modulation (LFM) signal, the LFM signal being related to the frequency f. Lo The local oscillator is up-mixed by mixer 3 to obtain an intermediate frequency signal. The intermediate frequency signal is input to up-converter module 4 to be converted into a millimeter wave signal. The millimeter wave signal passes through isolator 5, through metal waveguide 6, and is transmitted to the gap coupling structure 7 of waveguide transition on the first mirror of the quasi-optical cavity to excite the quasi-optical cavity.

[0038] The conical horn antenna 17 detects the millimeter-wave signal in the quasi-optical cavity. The envelope signal of the millimeter wave is extracted by the peak detector 18. The envelope signal is processed by the AD sampling signal conditioning circuit board 19 to remove high-frequency interference. Automatic gain amplification and conditioning complete the amplitude matching of AD sampling. The amplitude-matched envelope signal is converted into a digital signal by A / D conversion through the receiving path of the software radio transceiver circuit board 2. The embedded microprocessor 1 calculates the digital signal to obtain the test result.

[0039] The pulse repetition period of the linear frequency modulated signal emitted by the software radio transceiver circuit board 2 is Tn, and the starting frequency is - The termination frequency is + The pulse width is dt, such as Figure 1 As shown.

[0040] The intermediate frequency signal output by mixer 3 has a lower limit frequency of [missing information]. The upper limit frequency is: , This represents the resonant frequency. Wherein, The center frequency of the linear frequency modulation signal emitted by the software radio transceiver circuit board. It is half the bandwidth.

[0041] The lower limit frequency of the millimeter-wave signal output by the upconversion module 4 is: N. The upper limit frequency is: N The bandwidth is 2N. N is the multiplication factor of the upconverter module.

[0042] The embedded microprocessor 1 sends instructions to the stage driver 14, which drives the first optical stage 12 and the second optical stage 13 according to the control signal.

[0043] The second optical displacement stage 13 is placed on a slide rail parallel to the rotational symmetry axis of the quasi-optical cavity and is used to adjust the cavity length; the first optical displacement stage 12 is also placed on a slide rail parallel to the rotational symmetry axis of the quasi-optical cavity and is used to keep the sample under test at the center of the quasi-optical cavity at all times while the cavity length changes.

[0044] The coupling diaphragm 16 is equipped with a pitch and azimuth angle adjustment device below it, which can change the pitch and azimuth angle of the coupling diaphragm by rotating the corresponding knob.

[0045] The millimeter-wave signal output by the quasi-optical cavity is as follows: Figure 2 As shown, the resonance peak can be obtained by extracting the envelope of the signal by inputting the signal into the peak detector 18.

[0046] The resonant peak signal extracted by the peak detector 18 is conditioned by the AD sampling signal conditioning circuit board 19 and then sampled by the software radio transceiver circuit board 2. The obtained sampled data can be obtained by... Figure 3 To express.

[0047] To effectively reduce the interference of random noise on the test data, the test data output by the AD sampling signal conditioning circuit board 19 can be Lorentz fitted. A mathematical model is established using the parameters in the pre-designed function expression, and the unknown coefficients are solved while ensuring the model's fitting accuracy is as high as possible. Let the Lorentz fitting expression be as follows:

[0048]

[0049] In the formula, Indicates the scanning frequency at any point. Indicates the resonant frequency; Indicates the half-power point bandwidth; This represents the ratio of the signal amplitude of the output quasi-optical cavity to that of the input quasi-optical cavity; It is the bias constant; These are first-order coefficients; It is the tilt coefficient; This represents the maximum value of the resonance curve at the resonant frequency. The data processing program is programmed into the embedded microprocessor 1, and the least squares method is used to obtain the parameters to be determined. , , , , , The specific algorithm flow is as follows: Figure 5 As shown, the details are as follows: First, set two initial sets of parameter values ​​and define the optimization function. Based on the Lorentz function of the two initial sets of parameter values ​​and the test data, two initial sets of parameters are derived. Value, if the two groups before and after If the absolute value of the difference is greater than the set value ε (default is 10 to the power of negative 5), the parameter is updated and recalculated. With the two groups before and after The absolute value of the difference; repeat the above process until the absolute value of the difference between the two merit functions is less than the set value ε (preset to be 10 to the power of negative 5), The optimal value that tends to stabilize is determined as the fitting coefficient.

[0050] Based on the fitting coefficients and fitting parameters of the fitted curve and The exact expression for the quality factor is as follows:

[0051]

[0052] Finally, the resonant frequency obtained from the test... With the calculated quality factor Store it.

[0053] Based on the existing electromagnetic parameters and resonant frequency of the sample to be tested and quality factor The embedded microprocessor is programmed with formulas to calculate the electromagnetic parameters of the sample under test. Based on the small changes in the resonant frequency over time in the stored test data, the embedded microprocessor calculates the real-time dynamic electromagnetic parameters of the sample under test by looking up a table, and finally displays the electromagnetic parameter test results on the screen.

[0054] This testing system integrates quasi-optical cavity testing, high-speed data acquisition and calculation, and display, and features real-time detection of electromagnetic parameters, enabling automated testing and data sharing in mass production.

[0055] This invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this invention.

[0056] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A megawatt gyrotron output window electromagnetic parameter real-time detection system, characterized in that, include: Quasi-optical cavity testing device, signal transceiver and processing module, peak detector (18), and transmit signal spread spectrum and transmission channel; The signal transceiver and processing module sends out a linear frequency modulated (LFM) signal. The LFM signal is converted into a millimeter-wave signal through the transmit signal spread spectrum and transmission channel and then sent to the quasi-optical cavity test device to excite the quasi-optical cavity. After passing through the quasi-optical cavity test device, the millimeter-wave signal is sent to the peak detector (18) to extract the envelope signal and send it to the signal transceiver and processing module. The signal transceiver and processing module performs amplitude matching on the envelope signal, then converts it into a digital signal and calculates the test result. The quasi-optical cavity testing device includes: a variable-temperature sample stage (8), a sample to be tested (9), a first reflector (10), a second reflector (11), a first optical displacement stage (12), a second optical displacement stage (13), a displacement stage driver (14), a block absorbing material (15), a coupling diaphragm (16), and a conical horn antenna (17); the first reflector (10) and the second reflector (11) form a quasi-optical cavity, and the variable-temperature sample stage (8) is located at the center of the quasi-optical cavity to fix the sample to be tested (9); the variable-temperature sample stage (8) is placed on the first optical displacement stage (12), and the second optical displacement stage (13) is placed on the second optical displacement stage (14). 13) Place the second reflector (11) on the first optical stage; adjust the position of the second reflector (11) by adjusting the second optical displacement stage (13) so that the resonant frequency of the quasi-optical cavity is located at the test frequency of the sample; adjust the first optical displacement stage (12) so that the sample to be tested in the variable temperature sample stage (8) on the displacement stage moves to the center of the quasi-optical cavity, and place a coupling diaphragm (16) between the second reflector (11) and the sample to be tested (9). The coupling diaphragm (16) forms a 45° angle with the rotational symmetry axis of the quasi-optical cavity. Above the coupling diaphragm is a conical horn antenna (17), and below the coupling diaphragm is a blocky absorbing material (15). The signal transceiver and processing module includes: an embedded microprocessor (1), a software radio transceiver circuit board (2), and an AD sampling signal conditioning circuit board (19); the AD sampling signal conditioning circuit board (19) is connected to the peak detector (18) via an RF cable; the AD sampling signal conditioning circuit board (19) is connected to the software radio transceiver circuit board (2) via an internal data bus, and the software radio transceiver circuit board (2) interacts with the embedded microprocessor (1) via the internal data bus; The transmit signal spread spectrum and transmission channel includes a mixer (3), an up-conversion module (4), an isolator (5), a metal waveguide (6), and a gap coupling structure (7) for waveguide transition; the software radio transceiver circuit board (2) is connected to the mixer (3) in the transmit signal spread spectrum and transmission channel via an RF cable.

2. The real-time detection system of electromagnetic parameters of an output window of a megawatt gyrotron according to claim 1, characterized in that, The system is controlled by an embedded microprocessor (1) to generate a linear frequency modulated (LFM) signal from a software radio transceiver circuit board (2). The LFM signal is related to the frequency f. Lo The local oscillator is up-mixed by the mixer (3), and then the signal is input to the up-conversion module (4) to be converted into a millimeter wave signal. The millimeter wave signal passes through the isolator (5), through the metal waveguide (6), and is transmitted to the gap coupling structure (7) of the waveguide transition on the first mirror of the quasi-optical cavity to excite the quasi-optical cavity. The conical horn antenna (17) detects the millimeter wave signal in the quasi-optical cavity, and the envelope signal of the millimeter wave is extracted by the peak detector (18). The envelope signal is removed by the AD sampling signal conditioning circuit board (19) to remove high frequency interference, and the automatic gain amplification and conditioning completes the amplitude matching of AD sampling. The amplitude-matched envelope signal is converted into a digital signal by A / D through the receiving path of the software radio transceiver circuit board (2). The embedded microprocessor (1) calculates the digital signal to obtain the test result.

3. The real-time detection system of electromagnetic parameters of an output window of a megawatt gyrotron according to claim 2, characterized in that, The embedded microprocessor (1) sends instructions to the stage driver (14), and the stage driver (14) drives the first optical stage (12) and the second optical stage (13) according to the control signal. The second optical displacement stage (13) is placed on a slide rail parallel to the rotational symmetry axis of the quasi-optical cavity and is used to adjust the cavity length; the first optical displacement stage (12) is also placed on a slide rail parallel to the rotational symmetry axis of the quasi-optical cavity and is used to keep the sample under test at the center of the quasi-optical cavity at all times while the cavity length changes.

4. The real-time detection system of electromagnetic parameters of an output window of a megawatt gyrotron according to claim 3, characterized in that, The pitch and azimuth angle adjustment device is installed below the coupling diaphragm (16), and the pitch and azimuth angles of the coupling diaphragm can be changed by rotating the corresponding knob.

5. The real-time detection system of electromagnetic parameters of an output window of a megawatt gyrotron according to claim 4, characterized in that, The mixer outputs an intermediate frequency signal, the lower limit frequency being and the upper limit frequency being wherein denotes the resonance frequency; is the center frequency of the frequency modulated signal emitted by the software defined radio transceiver circuit board, f is half the bandwidth.

6. The real-time detection system of electromagnetic parameters of an output window of a megawatt gyrotron according to claim 5, characterized in that, The test data output by the AD sampling signal conditioning circuit board (19) is subjected to Lorentz fitting, and a mathematical model is established using the parameters in the pre-designed function expression. The Lorentz fitting expression is as follows: In the formula, Indicates the scanning frequency at any point. Indicates the resonant frequency; Indicates the half-power point bandwidth; This represents the ratio of the signal amplitude of the output quasi-optical cavity to that of the input quasi-optical cavity; It is the bias constant; These are first-order coefficients; It is the tilt coefficient; The value of the resonance curve at the resonant frequency is represented; the data processing program is programmed into the embedded microprocessor (1), and the parameters to be determined are obtained using the least squares method: , , , , , ; Based on the fitting coefficients and fitting parameters of the fitted curve and The exact expression for the quality factor is as follows: Finally, the resonance frequency and the calculated quality factor are stored; According to the existing formula relationship between the electromagnetic parameters of the sample to be tested and the resonance frequency and the quality factor , a calculation program is written for an embedded microprocessor, and the embedded microprocessor calculates the real-time dynamic electromagnetic parameters of the sample to be tested according to the stored test data through a table lookup method.

7. The real-time detection system of electromagnetic parameters of an output window of a megawatt gyrotron according to claim 6, characterized in that, The specific calculation process for obtaining the undetermined parameters using the least squares method is as follows: First, set two initial sets of parameter values ​​and define the merit function. Based on the Lorentz function of the two initial sets of parameter values ​​and the test data, two initial sets of parameters are derived. Value, if the two groups before and after If the absolute value of the difference is greater than the set value, the parameter is updated and recalculated. With the two groups before and after The absolute value of the difference; repeat the above process until the absolute value of the difference between the two merit functions is less than the set value, The optimal value that tends to stabilize is determined as the fitting coefficient.

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