A high-sensitivity device and method for measuring high-temperature superconducting microwave surface resistance

Abstract

The application discloses a kind of high sensitivity device and method for measuring high-temperature superconducting microwave surface resistance, belongs to electronics technical field, device includes test seat, calibration seat, calibration plate, support plate and sealed cavity, test seat includes test cavity, dielectric column, input coupling structure, output coupling structure and dielectric support device, dielectric column is different diameter coaxial cylindrical, is divided into two parts of support column and resonance column, support column is fixed with test cavity by dielectric support device, the end face of resonance column and the bottom end face of test cavity are in the same plane, the diameter of support column is less than resonance column, so that support column and test cavity jointly constitute a section relative to the cut-off waveguide of required resonance frequency, electromagnetic field is confined around dielectric column, and test sensitivity is improved.The application further proposes a double-sided cross test method for quickly testing the microwave surface resistance of the front and back surfaces of the high-temperature superconductor sample to be tested, which can significantly reduce system error and ensure the accuracy and reliability of the test.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of electronics, and particularly relates to a high-sensitivity device and method for measuring high-temperature superconducting microwave surface resistance. BACKGROUND

[0002] High-temperature superconductors (HTS) have important application value in microwave technology. The superconducting microwave surface resistance (Rs) of HTS is closely related to the energy loss characteristics of superconducting devices, which in turn affects the system efficiency and performance. For high-temperature superconductors, Rs is an important parameter for evaluating the superconducting state characteristics of materials, and can also reflect key information such as grain boundary defects or film uniformity in the microstructure of materials. By accurately measuring the Rs of high-temperature superconducting materials, it not only helps to improve the performance level of superconducting filters, resonators and other devices, but also provides important technical support for research in frontier fields such as quantum communication and terahertz technology.

[0003] Currently, the dielectric resonator method is widely used to measure the Rs of high-temperature superconducting thin films. For example, the national standard adopts a double dielectric resonator method, as shown in Figure 1 The resonator of this method is composed of a metal cavity wall and two dielectric columns of different heights. By placing two high-temperature superconducting thin film samples, the quality factor of the resonator formed is measured, and the microwave surface resistance value of the high-temperature superconducting thin film is obtained through formula derivation. However, the double dielectric resonator method requires at least two high-temperature superconducting thin film samples for general use, and the testing of a single high-temperature superconducting thin film sample requires at least 2 temperature cycles, which affects the testing efficiency. Moreover, the temperature conditions for testing must satisfy both high-temperature superconducting thin film samples, which makes it impossible to test the other high-temperature superconducting thin film sample if one of them loses superconductivity near the superconductivity loss temperature. If one of the two high-temperature superconducting thin film samples is replaced with a metal of known surface resistance, single-sided testing can be achieved, but this change will cause the quality factor of the resonator to decrease, thereby reducing the testing sensitivity. In addition, the double dielectric resonator method uses two dielectric columns of different heights, and assumes that the loss tangent values of the two sapphire dielectric columns are consistent in the calculation. However, in actual devices, the existence of coupling devices and the difference in loss tangent between the two sapphire dielectric columns introduce systematic errors in the measurement.

[0004] The traditional mirror resonator method proposed in Appendix B of the national standard GB / T 22586-2018 realizes the effect of single-sided testing of high-temperature superconducting thin films, but the system error of the device will affect the accuracy of the test. Due to the slight difference in the process, the calibration resonator and the test resonator have a certain degree of asymmetry (such as the conductivity difference caused by inconsistent metal surface oxidation, or the difference in the loss tangent of the used sapphire medium column), which also introduces a certain system error for the test. In addition, the traditional mirror resonator method uses a polytetrafluoroethylene clamping ring to directly contact and fix the sapphire medium column. Since the electromagnetic field of the resonant structure is mainly concentrated near the sapphire medium column, this fixing method will cause the loss of the electromagnetic field of the resonant structure, resulting in a decrease in the quality factor of the resonator, thereby reducing the test sensitivity. SUMMARY

[0005] In view of the problems of low test sensitivity and low test accuracy of the traditional mirror resonator method, the present application provides a high-sensitivity device and method for measuring high-temperature superconducting microwave surface resistance, which uses a coaxial cylindrical medium column with different diameters to reduce the loss introduced by the medium support structure, improve the test sensitivity, and combines a double-sided cross test method to reduce the system error, so as to ensure the accuracy and reliability of the Rs test.

[0006] The technical solutions adopted by the present application are as follows:

[0007] A high-sensitivity device for measuring high-temperature superconducting microwave surface resistance, comprising a test seat, a calibration seat, a calibration plate, a support plate and a sealed cavity.

[0008] The test seat comprises a test cavity with an open bottom end, a medium column, an input coupling structure, an output coupling structure and a medium support device. The medium column is a coaxial cylindrical medium column with different diameters, located in the center of the test cavity, divided into a support column and a resonant column, the support column is fixed with the test cavity through the medium support device, the end face of the resonant column is in the same plane as the bottom end face of the test cavity, and the diameter of the support column is smaller than that of the resonant column, so that the support column and the test cavity together form a section of cutoff waveguide relative to the required resonant frequency.

[0009] The calibration seat and the test seat have the same structure and are detachably arranged at the bottom end face of the medium column and the test cavity.

[0010] The microwave surface resistance of the calibration plate is known, and the calibration plate is detachably arranged at the bottom end face of the medium column and the test cavity.

[0011] The high-temperature superconductor sample to be tested is placed at the bottom end face of the medium column and the test cavity, and the high-temperature superconductor sample to be tested is fastened by the detachable support plate.

[0012] The sealed cavity is detachably arranged outside the bottom end face of the test cavity.

[0013] Further, the diameter determination method of the support column is: assuming that the medium column is a regular cylindrical type, adjusting the diameters of the medium column and the inner wall of the test cavity according to the required resonant frequency; taking the diameter of the adjusted medium column as the diameter of the resonant column, placing a support column with an unknown diameter coaxially above the resonant column, and simulating the cutoff frequency of the waveguide formed by the support column and the adjusted test cavity; by adjusting the diameter of the support column, the cutoff frequency of the waveguide is higher than the required resonant frequency, and then the diameter of the support column is determined.

[0014] Further, the input coupling structure and the output coupling structure are symmetrically distributed on both sides of the test cavity, and the test cavity is coaxial with the medium column and the medium support device.

[0015] Further, the input coupling structure and the output coupling structure are both coaxial structures with coupling rings.

[0016] Further, the test cavity is plated with silver by using a hard metal material; the medium column is made of a high-Q value material with low loss and high dielectric constant, including rutile, sapphire, beryllium oxide ceramic, etc.; and the medium support device is made of a material with low loss and high dielectric constant, including nylon, polytetrafluoroethylene, polyethylene foam, etc.

[0017] Further, the thickness of the superconductor film of the to-be-measured high-temperature superconductor sample is greater than 200 nm, and the planar size is greater than the planar size of the bottom end face of the test cavity.

[0018] The present application provides a method for measuring the microwave surface resistance of a high-temperature superconductor, which specifically comprises the following steps:

[0019] Step A1, load the calibration seat to the bottom end face of the test seat, and the two are mirror symmetric about the bottom end face, and seal the calibration seat with a sealed cavity, keep the obtained test device at the working temperature of the to-be-measured high-temperature superconductor sample, and measure the quality factor Q1 at the resonant frequency;

[0020] Step A2, load the calibration plate to the bottom end face of the test seat, and seal the calibration plate with a sealed cavity, keep the obtained test device at the working temperature of the to-be-measured high-temperature superconductor sample, and measure the quality factor Q2 at the resonant frequency;

[0021] Step A3, load the to-be-measured high-temperature superconductor sample to the bottom end face of the test seat, and fix it with the support plate, seal the to-be-measured high-temperature superconductor sample and the support plate with a sealed cavity, keep the obtained test device at the working temperature of the to-be-measured high-temperature superconductor sample, and measure the quality factor Q0 at the resonant frequency;

[0022] Step A4, according to the formula:

[0023]

[0024] The calculated microwave surface resistance R of the high-temperature superconductor sample to be measured at the resonance frequency S , specifically the microwave surface resistance of the high-temperature superconductor sample to be measured towards one side of the test seat; wherein R SN is the microwave surface resistance of the calibration plate at the resonance frequency.

[0025] Further, the working mode of the test device is TE011 mode.

[0026] The present application also proposes another method for measuring the microwave surface resistance of high-temperature superconductors, which can be used to quickly test the microwave surface resistance of the front and back surfaces of the high-temperature superconductor sample to be measured, while greatly reducing system errors.

[0027] A method for measuring the microwave surface resistance of high-temperature superconductors, which is used to test the microwave surface resistance of the front and back surfaces of the high-temperature superconductor sample to be measured, specifically comprising the following steps:

[0028] Step B1, load the calibration seat to the bottom end face of the test seat, and the two are mirror-symmetric about the bottom end face, and use the sealed cavity to seal the calibration seat, keep the obtained test device at the working temperature of the high-temperature superconductor sample to be measured, and measure the quality factor Q1 at the resonance frequency;

[0029] Step B2, load the calibration plate and the calibration seat on the bottom end face of the test seat in turn, and use the sealed cavity to seal the calibration plate and the calibration seat, keep the obtained test device at the working temperature of the high-temperature superconductor sample to be measured, and measure the quality factor Q 1T of the test seat and the quality factor Q 1C of the calibration seat at the resonance frequency;

[0030] Step B3, load the high-temperature superconductor sample to be measured and the calibration seat on the bottom end face of the test seat in turn, wherein the front surface of the high-temperature superconductor sample to be measured faces one side of the test seat, and the back surface faces one side of the calibration seat, and use the sealed cavity to seal the high-temperature superconductor sample to be measured and the calibration seat, keep the obtained test device at the working temperature of the high-temperature superconductor sample to be measured, and measure the quality factor Q 0T_X of the front surface of the test seat and the quality factor Q 0C_Y of the back surface of the calibration seat at the resonance frequency;

[0031] Step B4, turn over the high-temperature superconductor sample to be measured of step B3, specifically the back surface faces one side of the test seat, and the front surface faces one side of the calibration seat, and continue to measure the quality factor Q 0T_Y of the back surface of the test seat and the quality factor Q 0C_X of the front surface of the calibration seat at the resonance frequency;

[0032] Step B5, according to the formula:

[0033]

[0034] The front microwave surface resistance R of the high-temperature superconductor sample to be measured at the resonant frequency is calculated S_X And the back microwave surface resistance R S_Y .

[0035] Further, the working mode of the test device is TE011 mode.

[0036] Compared with the prior art, the present application has the following beneficial effects:

[0037] 1. The present application provides a high-sensitivity device for measuring high-temperature superconducting microwave surface resistance, which uses TE011 mode as the working mode of the dielectric resonator, introduces a section of cutoff waveguide between the dielectric support device and the resonant structure (composed of the resonant column and the corresponding part of the test cavity) using a coaxial cylindrical dielectric column, effectively reduces the loss introduced by the dielectric support structure to the resonant cavity, confines the electromagnetic field around the dielectric column, reduces the cavity wall loss, and thus improves the test sensitivity.

[0038] 2. Based on the above high-sensitivity device, the present application provides two methods for measuring high-temperature superconducting microwave surface resistance. Specifically, based on the first traditional test method, the second double-sided cross test method for quickly testing the microwave surface resistance of the front and back surfaces of the high-temperature superconductor sample to be measured is innovatively proposed. The calibration seat is not only used for calibrating the test seat, but also participates in the same test process as the test seat, thereby significantly reducing the system error of the device, ensuring the accuracy and reliability of the Rs test. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0040] Figure 1 The cross-sectional structure diagram of the device for measuring microwave surface resistance by using double dielectric resonator method;

[0041] Figure 2 The cross-sectional structure diagram of the test seat in the high-sensitivity device for measuring high-temperature superconducting microwave surface resistance according to Embodiment 1 of the present application;

[0042] Figure 3 The cross-sectional structure diagram of the test device after loading the calibration seat on the test seat in Embodiment 1 of the present application;

[0043] Figure 4 The cross-sectional structure diagram of the test device after loading the calibration plate on the test seat in Embodiment 1 of the present application;

[0044] Figure 5 The test device cross-sectional structure diagram after the test seat in the embodiment 1 of the application sequentially loads the high-temperature superconductor sample to be tested and the support plate;

[0045] Figure 6 The partial S parameter test image of the high-sensitivity device for measuring the microwave surface resistance of the high-temperature superconductor proposed in the embodiment 1 of the application calibrates the A value and the B value; wherein (a) is the calibration A value; (b) is the calibration B value;

[0046] Figure 7 The partial S parameter test image of the high-sensitivity device for measuring the microwave surface resistance of the high-temperature superconductor proposed in the embodiment 1 of the application loads different high-temperature superconductor samples to be tested; wherein (a) is the first high-temperature superconductor sample to be tested; (b) is the second high-temperature superconductor sample to be tested; (c) is the third high-temperature superconductor sample to be tested;

[0047] Figure 8 The test device cross-sectional structure diagram after the test seat in the embodiment 2 of the application sequentially loads the calibration plate and the calibration seat;

[0048] Figure 9 The test device cross-sectional structure diagram after the test seat in the embodiment 2 of the application sequentially loads the high-temperature superconductor sample to be tested and the calibration seat;

[0049] Figure 10 The partial S parameter test image of the high-sensitivity device for measuring the microwave surface resistance of the high-temperature superconductor proposed in the embodiment 2 of the application calibrates the A value and the B value; wherein (a) is the calibration A value; (b) is the calibration B T value; (c) is the calibration B C value;

[0050] Figure 11 The partial S parameter test image of the test seat in the embodiment 2 of the application loads the high-temperature superconductor sample to be tested; wherein (a) is the front of the high-temperature superconductor sample to be tested; (b) is the back of the high-temperature superconductor sample to be tested;

[0051] Figure 12 The partial S parameter test image of the calibration seat in the embodiment 2 of the application loads the high-temperature superconductor sample to be tested; wherein (a) is the front of the high-temperature superconductor sample to be tested; (b) is the back of the high-temperature superconductor sample to be tested;

[0052] Figure 13 The intrinsic simulation modeling and partial electric field simulation results of the different-diameter coaxial cylindrical dielectric column in the embodiment 3 of the application;

[0053] Figure 14 The intrinsic simulation modeling and partial electric field simulation results of the traditional regular cylindrical dielectric column in the comparative example 1;

[0054] The various marks in the drawings represent the following items:

[0055] 1 - test seat; 2 - calibration seat; 3 - sealed cavity; 4 - support plate; 5 - test cavity; 6 - resonant cavity; 7 - input coupling structure; 8 - output coupling structure; 9 - medium support device; 10 - medium column; 11 - calibration plate; 12 - high-temperature superconductor sample to be measured. DETAILED DESCRIPTION

[0056] In order to further understand the present application, the preferred embodiments of the present application are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present application, and are not limitations to the claims of the present application.

[0057] All raw materials of the present application are not particularly limited in source, and can be purchased on the market or prepared according to conventional methods well known to those skilled in the art.

[0058] All raw materials of the present application are not particularly limited in purity, and the present application preferably uses analytical purity or the purity required in the field of atomic layer deposition.

[0059] All raw materials and processes of the present application are of conventional grade or abbreviation, which are clear and explicit in the field of their related use. Those skilled in the art can purchase or prepare them by conventional methods according to the grade, abbreviation and corresponding use, or use the corresponding equipment to realize them.

[0060] The present application is further described in detail below in conjunction with examples:

[0061] Example 1

[0062] This embodiment proposes a high-sensitivity device for measuring high-temperature superconducting microwave surface resistance, which comprises a test seat 1, a calibration seat 2, a calibration plate 11, a support plate 4 and a sealed cavity 3. The structure of the test seat 1 is shown in Figure 2 and comprises a test cavity 5 with an open bottom end surface, a medium column 10, an input coupling structure 7, an output coupling structure 8 and a medium support device 9.

[0063] The input coupling structure 7 and the output coupling structure 8 are symmetrically distributed on both sides of the test cavity 5, and are both coaxial structures with coupling holes, which can effectively avoid direct coupling and have high testing accuracy.

[0064] The medium column 10 is a coaxial cylinder with different diameters, located in the center of the test cavity 5, and is divided into two parts of a support column and a resonance column connected with each other. The support column is fixed with the test cavity 5 through the medium support device 9, and the end face of the resonance column is in the same plane with the bottom end face of the test cavity 5. The diameter of the support column is smaller than that of the resonance column, so that the support column and the test cavity together form a section of a cutoff waveguide relative to the required resonance frequency.

[0065] The test cavity 5 is coaxial with the medium column 10 and the medium support device 9.

[0066] The calibration seat 2 has the same structure as the test seat 1, and is detachably arranged at the bottom end face of the medium column 10 and the test cavity 5, so that the calibration seat 2 and the test seat 1 are symmetrical about the bottom end face.

[0067] The microwave surface resistance of the calibration plate 11 is known, and the calibration plate 11 is detachably arranged at the bottom end face of the medium column 10 and the test cavity 5.

[0068] The sample of the high-temperature superconductor film plated on one side of the 1mm-thick lanthanum aluminate cylindrical wafer is taken as the high-temperature superconductor sample 12 to be measured, and the nominal thickness of the film is 500nm. The high-temperature superconductor sample 12 to be measured is placed at the bottom end face of the medium column 10 and the test cavity 5, and is fastened through the detachable support plate 4.

[0069] The sealed cavity 3 is detachably arranged outside the bottom end face of the test cavity 5.

[0070] In the embodiment, the test cavity 5 is plated with silver on brass, and has a diameter of about 40mm and a height of 20mm. The medium column 10 is made of a high-Q value material with low loss and high dielectric constant, specifically sapphire. The resonance column has a diameter of about 11mm and a height of about 5mm, and the support column has a diameter of about 2mm and a height of about 14mm. The medium support device 9 is made of a material with low loss and high dielectric constant, specifically polytetrafluoroethylene.

[0071] In the embodiment, the high-temperature superconductor sample 12 to be measured and the test seat 1 form a dielectric resonator with a working mode of TE011 mode. The hollow area inside the dielectric resonator forms a resonance cavity 6. The relationship between the quality factor Q0 of the dielectric resonator at the resonance frequency 12GHz and the microwave surface resistance R s of the high-temperature superconductor sample 12 to be measured is as follows.

[0072] Q0 -1 =A+BR s Equation (1)

[0073] Wherein, A and B are both constants, which are determined by the measurement method.

[0074] Based on the high-sensitivity device, the embodiment proposes a method for measuring the microwave surface resistance of a high-temperature superconductor, which comprises the following steps:

[0075] Step A1, load the calibration seat 2 to the bottom end face of the test seat 1, which is mirror-symmetric about the bottom end face, and seal the calibration seat 2 with the sealed cavity 3, and the obtained test device is as shown in Figure 3 The test device is kept at the working temperature 77K of the high-temperature superconductor sample 12 to be measured, and the quality factor Q1 at the resonance frequency is measured.

[0076] Step A2, load the calibration plate 11 to the bottom end face of the test seat 1, and seal the calibration plate 11 with the sealed cavity 3, and the obtained test device is as shown in Figure 4 The test device is kept at the working temperature 77K of the high-temperature superconductor sample 12 to be measured, and the quality factor Q2 at the resonance frequency is measured.

[0077] Step A3, load the high-temperature superconductor sample 12 to be measured to the bottom end face of the test seat 1, and the high-temperature superconductor film of the high-temperature superconductor sample 12 to be measured faces the test seat 1, and is fixed by the support plate 4, and the high-temperature superconductor sample 12 to be measured and the support plate 4 are sealed with the sealed cavity 3, and the obtained test device is as shown in Figure 5 The test device is kept at the working temperature 77K of the high-temperature superconductor sample 12 to be measured, and the quality factor Q0 at the resonance frequency is measured.

[0078] Step A4, the quality factors Q1 and Q2 are brought into formula (1), and A=1 / Q1 and B=(1 / Q2-A) / R SN are calculated.

[0079] Further, the calculation formula of the microwave surface resistance R S of the high-temperature superconductor sample 12 to be measured at the resonance frequency is obtained:

[0080]

[0081] The obtained microwave surface resistance R S is the microwave surface resistance of the high-temperature superconductor film; wherein R SN is the microwave surface resistance of the calibration plate 11 at the resonance frequency.

[0082] In order to verify the test precision of the high-sensitivity device proposed in the embodiment, three different high-temperature superconductor samples 12 to be measured (first high-temperature superconductor sample to be measured, second high-temperature superconductor sample to be measured and third high-temperature superconductor sample to be measured) are loaded into the high-sensitivity device for testing, and the quality factors Q1, Q2 and Q0 are tested at the resonance frequency of about 12GHz and the working temperature of 77K, and the microwave surface resistance R SNThe nominal value is 18.23 mΩ, and the microwave surface resistance R of the three to-be-tested high-temperature superconductor samples 12 is calculated S .

[0083] Figure 6 The partial S parameter test images of the calculated calibration A value and B value are as follows, wherein Figure 6 (a) is the calibration A value image, Figure 6 (b) is the calibration B value image; Figure 7 The partial S parameter test images of the high-sensitivity device loaded with different to-be-tested high-temperature superconductor samples are as follows, wherein Figure 7 (a) is the first to-be-tested high-temperature superconductor sample, Figure 7 (b) is the second to-be-tested high-temperature superconductor sample, Figure 7 (c) is the third to-be-tested high-temperature superconductor sample.

[0084] According to the partial S parameter test images of Figure 6 and Figure 7 , the test results shown in Table 1 are obtained.

[0085]

[0086] In the actual test of the present embodiment, 3 repeated tests were performed on each of the three different to-be-tested high-temperature superconductor samples 12, and the test sample was removed and reloaded each time. The test results of each to-be-tested high-temperature superconductor sample 12 are relatively stable, and the R S The relative standard deviation of the calculated value is within 0.005 mΩ, indicating that the high-sensitivity device for measuring the high-temperature superconducting microwave surface resistance proposed in the present embodiment has high test precision.

[0087] Taking the repeated test of the first to-be-tested high-temperature superconductor sample as an example, the results of the repeated test are shown in Table 2.

[0088] Table 2

[0089]

[0090] The high-sensitivity device and method for measuring the microwave surface resistance of high-temperature superconductors proposed in this embodiment were compared with the improved mirror dielectric resonator method (Appendix B) recommended in the national standard GB / T 22586-2018. Specifically, the device recorded in the improved mirror dielectric resonator method was used, and the device worked in the TE011 mode. The test method was the same as the method in this embodiment. Two different high-temperature superconductor samples (the fourth high-temperature superconductor sample and the fifth high-temperature superconductor sample, with nominal values of 0.259 mΩ and 0.300 mΩ, respectively) were loaded for testing. Specifically, the quality factors Q1, Q2 and Q0 were tested at a resonant frequency of about 12 GHz and an operating temperature of 77 K. Then, the microwave surface resistance R S of the two high-temperature superconductor samples was calculated. The results are shown in Table 3.

[0091] Table 3

[0092] Load case Quality factor Calibration seat Q1 = 2.60 x 10 5 ]]> Calibration plate Q2 = 40300 Fourth high temperature superconductor sample to be tested Q0 = 2.35 x 10 5 ]]> Fifth high temperature superconductor sample to be tested Q0 = 2.31 x 10 5 ]]

[0093] As can be seen from the comparison between Table 1 and Table 2, the quality factor Q1 of the test device obtained by loading the calibration seat 2 can be increased by 3 times, and the quality factor Q0 of the test device obtained by loading the high-temperature superconductor sample 12 can be increased by 2 times, compared with the device recorded in the improved mirror dielectric resonator method.

[0094] If the test sensitivity of the device is defined as:

[0095]

[0096] It can be found that the test sensitivity is related to the test reference value. In general, R S The smaller the reference value of the test, the higher the sensitivity of the test. When R S tends to 0, the value of S is defined as the theoretical maximum sensitivity S0 of the device, and then

[0097]

[0098] At this time, the value of S0 is 5.5734e+5 (mΩ) -1 . Compared with S0 = 78323 (mΩ) -1 of the device recorded in the improved mirror dielectric resonator method, the sensitivity of the high-sensitivity device described in this embodiment is increased by more than 7 times.

[0099] Embodiment 2

[0100] In this embodiment, the high-sensitivity device for measuring the microwave surface resistance of high-temperature superconductors proposed in Embodiment 1 was used to test the microwave surface resistance of the high-temperature superconductor sample 12 with high-temperature superconductor films plated on both the front and back surfaces.

[0101] The high-temperature superconductor sample 12 used in this embodiment is specifically a sample with high-temperature superconductor films deposited on both sides of a 1mm thick lanthanum aluminate cylindrical wafer, with a nominal film thickness of 500nm.

[0102] In this embodiment, the high-temperature superconductor sample 12 under test, the test stand 1, and the calibration stand 2 all constitute a dielectric resonator operating in TE011 mode. The quality factor Q of the high-temperature superconductor sample 12 under test is loaded onto the bottom surface of the test stand 1. 0T The quality factor Q of the high-temperature superconductor sample 12 to be tested is loaded onto the bottom surface of the calibration holder 2. 0C Microwave surface resistance R of the high-temperature superconductor sample 12 to be tested S The relation is:

[0103] Q 0T -1 +Q 0C -1 =2A+(B T +B C )R s Equation (2)

[0104] In the formula, A and B T and B C Both are constants; A is determined by the test method in Example 1, and B... T The B value obtained after loading calibration plate 11 onto the bottom surface of test seat 1. C The B value obtained after loading the calibration plate 11 onto the bottom surface of the calibration base 2.

[0105] Based on the high-sensitivity device described in Example 1, the method for measuring the surface resistance of high-temperature superconducting microwaves proposed in this embodiment specifically includes the following steps:

[0106] Step B1: Load calibration seat 2 onto the bottom surface of test seat 1, ensuring they are mirror-symmetrical about the bottom surface. Seal calibration seat 2 with sealing cavity 3, and then... Figure 3 The test setup shown was maintained at the operating temperature of the high-temperature superconductor sample 12 under test, and the quality factor Q1 at the resonant frequency was measured.

[0107] Step B2: Load calibration plate 11 and calibration base 2 sequentially onto the bottom surface of test base 1, and seal calibration plate 11 and calibration base 2 using sealing cavity 3. The resulting... Figure 8 The test setup shown was maintained at the operating temperature of the high-temperature superconductor sample 12 under test, and the quality factor Q of the test stand at the resonant frequency was measured. 1T and calibration fixture quality factor Q 1C ;

[0108] Step B3: Load the high-temperature superconductor sample 12 and calibration base 2 sequentially onto the bottom surface of the test base 1, with the front of the high-temperature superconductor sample 12 facing the test base 1 and the back facing the calibration base 2. Seal the high-temperature superconductor sample 12 and calibration base 2 using the sealing cavity 3. The resulting... Figure 9 The test setup shown was maintained at the operating temperature of the high-temperature superconductor sample 12 under test, and the quality factor Q of the test stand at the resonant frequency was measured. 0T_X Quality factor Q of the reverse side of the calibration base 0C_Y ;

[0109] Step B4: Flip the high-temperature superconductor sample 12 from step B3, specifically with the reverse side facing the test stand 1 and the front side facing the calibration stand 2, and continue to measure the quality factor Q of the reverse side of the test stand at the resonant frequency. 0T_Y and the quality factor Q of the front of the calibration base 0C_X ;

[0110] Step B5: Adjust the quality factors Q1 and Q... 1T and Q 1C Substituting into equation (2), we calculate A = 1 / Q1, B T =(1 / Q) 1T -A) / R SN B C =(1 / Q) 1C -A) / R SN ;

[0111] This allows us to obtain the front microwave surface resistance R of the high-temperature superconductor sample 12 at the resonant frequency. S_X With the reverse microwave surface resistance R S_Y The calculation formula is as follows:

[0112]

[0113] Microwave surface resistance R of calibration plate 11 SN The nominal value is 18.23mΩ. The quality factors Q1 and Q2 were tested at a resonant frequency of approximately 12GHz and an operating temperature of 77K. 1T and Q 1C and obtain as Figure 10 The image shows partial S-parameter test images of the calibration A and B values, where... Figure 10 (a) is the calibration A value. Figure 10 (b) is for calibration B T value, Figure 10 (c) is for calibration B C The values ​​were used to obtain the data results shown in Table 4.

[0114] Table 4

[0115]

[0116] Based on the method for measuring high-temperature superconducting microwave surface resistance proposed in Embodiment 1, the microwave surface resistance R of the high-temperature superconductor sample 12 is tested at a resonant frequency of about 12 GHz and an operating temperature of 77 K S , specifically, the front and back surfaces of the high-temperature superconductor sample 12 are respectively directed towards the test seat 1, and step A3 is performed once to obtain the front surface quality factor of the test seat and the back surface quality factor of the test seat; the calibration seat 2 is used to replace the test seat 1, and the front and back surfaces of the high-temperature superconductor sample 12 are respectively directed towards the calibration seat 2, and the front surface quality factor of the calibration seat and the back surface quality factor of the calibration seat are also obtained; then, the microwave surface resistance R corresponding to the front surface quality factor of the test seat, the back surface quality factor of the test seat, the front surface quality factor of the calibration seat and the back surface quality factor of the calibration seat is calculated by using the formula of step A4 S , and the obtained R S is normalized to the microwave surface resistance at 10 GHz, which is recorded as Rs@10GHz(mΩ), and the data results are shown in Table 5.

[0117] Table 5

[0118]

[0119] Based on the method for measuring high-temperature superconducting microwave surface resistance proposed in this embodiment, the quality factors Q 0T_X , Q 0C_Y , Q 0T_Y and Q 0C_X are obtained at a resonant frequency of about 12 GHz and an operating temperature of 77 K, and then the microwave surface resistance R of the front and back surfaces of the high-temperature superconductor sample 12 after symmetry correction is calculated according to the formula of step B5 S , and the obtained R S is normalized to the microwave surface resistance at 10 GHz, which is recorded as Rs@10GHz(mΩ). Figure 11 is a partial S parameter test image of the test seat loaded with the high-temperature superconductor sample in this embodiment, wherein, Figure 11 (a) of is the front surface of the high-temperature superconductor sample loaded, Figure 11 (b) of is the back surface of the high-temperature superconductor sample loaded; Figure 12 is a partial S parameter test image of the calibration seat loaded with the high-temperature superconductor sample in this embodiment, wherein, Figure 12 (a) of is the front surface of the high-temperature superconductor sample loaded, Figure 12 (b) of is the back surface of the high-temperature superconductor sample loaded. According to the partial S parameter test images of Figure 11 and Figure 12 , the test results shown in Table 6 are obtained.

[0120] Table 6

[0121]

[0122] Comparing Table 4 and Table 5, it can be seen that for the material physical property electric parameter asymmetry of the test seat 1 and the calibration seat 2, the embodiment can significantly improve the microwave surface resistance test accuracy of the high-temperature superconductor sample 12 by improving the test method and the calculation formula.

[0123] Example 3

[0124] In the simulation software, the embodiment establishes the step-diameter coaxial cylindrical dielectric column model adopted in Example 1, and specifically adopts a one-piece support column and a resonant column made of sapphire material. Since the support column is fixed with the test cavity 5 through the polytetrafluoroethylene material dielectric support device 9, a polytetrafluoroethylene clamping structure is arranged above the step-diameter coaxial cylindrical dielectric column model.

[0125] Comparative Example 1

[0126] In the simulation software, the comparative example establishes a traditional regular cylindrical dielectric column model. In order to ensure structural consistency, the comparative example replaces the sapphire material of the support column with polytetrafluoroethylene material on the basis of Example 3, and then only the resonant column adopts sapphire material. Since the resonant column and the support column are made of different materials, a clamping ring made of polytetrafluoroethylene material is inevitably introduced and arranged integrally with the support column. The bottom end surface boundary condition of the traditional regular cylindrical dielectric column model is an ideal electric conductor boundary (PEC).

[0127] In order to verify the effect of the cutoff waveguide formed by the support column and the test cavity, the step-diameter coaxial cylindrical dielectric column model established in Example 3 and the traditional regular cylindrical dielectric column model established in Comparative Example 1 are simulated and tested, and the intrinsic simulation modeling and partial electric field simulation results are shown in Figure 13 and Figure 14 The color represents the electric field intensity, and the arrow direction represents the electric field direction. The intrinsic simulation data results are shown in Table 7.

[0128] Table 7

[0129] Resonance frequency (GHz) Quality factor Example 3 11.997 639478 Comparative example 1 11.621 391309

[0130] By comparing the simulation results of Example 3 and Comparative Example 1, it can be seen that compared with the traditional regular cylindrical dielectric column model, the unloaded quality factor of the resonant cavity of the step-diameter coaxial cylindrical dielectric column model is improved by 60%, and the intrinsic simulation modeling and partial electric field simulation results are shown in Figure 13 and Figure 14The electric field shown can also be found in the traditional regular cylindrical dielectric column model, a part of the working mode electric field acts on the polytetrafluoroethylene clamping ring, and in the different-diameter coaxial cylindrical dielectric column model, the working mode electric field is bound in the sapphire resonant column due to the action of the cutoff waveguide, and the working mode electric field acts on the sapphire and air. Since polytetrafluoroethylene is an organic polymer material, it has a larger loss tangent (nearly 2 orders of magnitude) than sapphire, and the loss characteristics of air can be ignored, so compared with the different-diameter coaxial cylindrical dielectric column model, the traditional regular cylindrical dielectric model will cause greater energy loss. It can be further known that the energy consumption of the traditional regular cylindrical dielectric column model to the resonator is obviously higher than that of the different-diameter coaxial cylindrical dielectric column model, indicating that introducing a section of cutoff waveguide between the dielectric support device and the resonant structure (composed of the resonant column and the corresponding part of the test cavity) can effectively reduce the loss introduced by the dielectric support structure to the resonant cavity and improve the quality factor.

[0131] The principles and implementations of the present application are described herein by applying specific examples, and the above description of the examples is only used to help understand the method of the present application and its core idea, including the best mode, and also enables any person skilled in the art to practice the present application, including manufacturing and using any device or system, and implementing any combined method. It should be noted that for those skilled in the art, without departing from the principles of the present application, some improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application. The scope of protection of the present application is defined by the claims, and can include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements that are not different from the literal expression of the claims, or if they include equivalent structural elements that are not substantially different from the literal expression of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A method of measuring high temperature superconducting microwave surface resistance, characterized by, The high-sensitivity device is based on a high-temperature superconducting microwave surface resistance measuring device, and comprises a test seat, a calibration seat, a calibration plate, a support plate and a sealed cavity. The test seat comprises a test cavity with an open bottom end face, a dielectric column, an input coupling structure, an output coupling structure and a dielectric support device; the dielectric column is a coaxial cylindrical column with different diameters, is located at the center inside the test cavity, is divided into a support column and a resonant column, the support column is fixed with the test cavity through the dielectric support device, the end face of the resonant column is in the same plane as the bottom end face of the test cavity, and the diameter of the support column is smaller than that of the resonant column, so that the support column and the test cavity together form a section of cutoff waveguide relative to the required resonant frequency. The calibration seat is completely the same in structure as the test seat, and is detachably arranged at the bottom end face of the dielectric column and the test cavity. The microwave surface resistance of the calibration plate is known, and the calibration plate is detachably arranged at the bottom end face of the dielectric column and the test cavity. The high-temperature superconductor sample to be measured is placed at the bottom end face of the dielectric column and the test cavity, and is fastened by the detachable support plate. The sealed cavity is detachably arranged outside the bottom end face of the test cavity. The method specifically comprises the following steps: Step B1, load the calibration mount to the bottom end face of the test mount, both are mirror symmetric about the bottom end face, and seal the calibration mount with a sealed cavity, keep the resulting test device at the working temperature of the HTS sample to be measured, measure the quality factor at the resonance frequency ; Step B2, load the calibration plate and the calibration holder on the bottom end face of the test holder in sequence, and seal the calibration plate and the calibration holder with the sealed cavity, keep the obtained test device at the working temperature of the high-temperature superconductor sample to be tested, and measure the quality factor of the test holder at the resonant frequency and the quality factor of the calibration holder ; Step B3, sequentially loading the high-temperature superconductor sample to be tested and the calibration seat on the bottom end face of the test seat, wherein the front face of the high-temperature superconductor sample to be tested faces the side of the test seat, and the back face faces the side of the calibration seat, and sealing the high-temperature superconductor sample to be tested and the calibration seat with a sealed cavity, keeping the obtained test device at the working temperature of the high-temperature superconductor sample to be tested, and measuring the front face quality factor of the test seat at the resonant frequency and the back face quality factor of the calibration seat ; Step B4, flip the high temperature superconductor sample under test of step B3, specifically the reverse side faces the test seat side, the front side faces the calibration seat side, continue to measure the test seat reverse side quality factor under the resonant frequency and the calibration seat front side quality factor ; Step B5, according to the formula: ； The front and back microwave surface resistances of the high temperature superconductor sample under test at the resonant frequency are calculated and the resonant frequency is calculated ; The microwave surface resistance of the calibration plate at the resonant frequency is calculated; The working mode of the test device in the method is TE011 mode.

2. The method of measuring high temperature superconducting microwave surface resistance according to claim 1, wherein, The method is also used for measuring the microwave surface resistance of the high-temperature superconductor sample to be measured at the resonant frequency, and specifically comprises the following steps: Step Al, loading the calibration mount to the bottom end face of the test mount, both being mirror symmetric about the bottom end face, and sealing the calibration mount with a sealed cavity, keeping the resulting test device at the working temperature of the HTS sample under test, measuring the quality factor at the resonance frequency ; Step A2, load the calibration plate to the bottom end face of the test seat, and seal the calibration plate with a sealed cavity, keep the resulting test device at the working temperature of the high temperature superconductor sample to be measured, and measure the quality factor at the resonance frequency ; Step A3, loading the sample of high temperature superconductor to be tested to the bottom end face of the test seat and fixing with the support plate, sealing the sample of high temperature superconductor to be tested and the support plate with the sealed cavity, keeping the obtained test device at the working temperature of the sample of high temperature superconductor to be tested, and measuring the quality factor at the resonant frequency ; Step A4, according to the formula: ； The microwave surface resistance of the high-temperature superconductor sample to be measured at the resonance frequency is calculated , specifically the microwave surface resistance of the high-temperature superconductor sample to be measured on the side facing the test seat; The working mode of the test device in the method is TE011 mode.

3. The method of measuring high temperature superconducting microwave surface resistance according to claim 1 or 2, wherein, The diameter of the support column is determined as follows: assuming that the dielectric column is a regular cylindrical column, the diameter of the dielectric column and the inner wall of the test cavity is adjusted according to the required resonant frequency; a support column with an unknown diameter is coaxially placed above the resonant column with the diameter of the adjusted dielectric column as the diameter of the resonant column, and the cutoff frequency of the waveguide formed by the support column and the adjusted test cavity is simulated; the diameter of the support column is adjusted so that the cutoff frequency of the waveguide is higher than the required resonant frequency, and then the diameter of the support column is determined.

4. The method of measuring high temperature superconducting microwave surface resistance according to claim 1 or 2, wherein, The input coupling structure and the output coupling structure are symmetrically distributed on both sides of the test cavity, and the test cavity is coaxial with the dielectric column and the dielectric support device.

5. The method of measuring high temperature superconducting microwave surface resistance according to claim 1 or 2, wherein, The input coupling structure and the output coupling structure are both coupling ring coaxial structures.

6. The method of measuring high temperature superconducting microwave surface resistance according to claim 1 or 2, wherein, The test cavity is plated with silver by using a hard metal material; the material of the dielectric column is rutile, sapphire or beryllium oxide ceramic; and the material of the dielectric support device is nylon, polytetrafluoroethylene or polyethylene foam.

7. The method of measuring high temperature superconducting microwave surface resistance according to claim 1 or 2, wherein, The thickness of the superconductor film of the high-temperature superconductor sample to be measured is greater than 200 nm, and the planar size is greater than the planar size of the bottom end face of the test cavity.

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