A superconducting magnet testing and calibration method and device based on angular symmetric rotation

Abstract

The present invention discloses a method and device for testing and calibrating a superconducting magnet of a gyrotron traveling wave tube based on angular symmetric rotation, belonging to the fields of vacuum electronics and high-power millimeter wave source devices. The present invention first solves the test error of a gaussmeter based on the angular symmetric rotation method, and then solves the axis tilt error and axial offset error generated during the production and processing of the wire coils inside the magnet. By using the axial magnetic field and angular magnetic field data obtained from the gaussmeter test, the test error is effectively deducted, and the magnetic field distribution and concentricity are measured with high precision. The present invention can effectively overcome the defects of large test and calibration errors in the concentricity and coaxiality of the superconducting magnet and the gyrotron traveling wave tube body in the existing measurement technology, and cannot achieve the required precision, and can effectively improve the output power and efficiency of the gyrotron traveling wave tube, providing guarantee for the stable operation of the gyrotron traveling wave tube.

Description

Technical Field

[0001] The present invention belongs to the fields of vacuum electronics and high-power millimeter-wave source devices, and particularly relates to a high-precision testing and calibration method and device for a superconducting magnet of a gyrotron traveling wave tube based on angular symmetry rotation. Background Art

[0002] As a fast-wave device, the gyrotron traveling wave tube has characteristics such as high power, high efficiency, and high frequency, and has important application prospects in many fields such as next-generation high-resolution imaging radar, millimeter-wave electronic countermeasure, and high-speed long-distance communication, and has received great attention both internationally and domestically.

[0003] The superconducting magnet is the core device of the gyrotron traveling wave tube system, and its schematic diagram is as Figure 1 shown, which is mainly composed of an external Dewar structure and an internal wire coil. Among them, the main function of the external Dewar structure is to encapsulate the wire coil; the main function of the internal wire coil is to generate a magnetic field and guide the electron beam to perform cyclotron motion along the magnetic field lines. The magnetic field generated by it can be divided into three parts along the axial direction: the rising region, the uniform region, and the falling region. Errors will occur during the production and processing of the internal wire coil of the superconducting magnet. Whether its position is on the same central axis as the gyrotron tube body has a crucial impact on the high power, high efficiency, and high-frequency band operation of the gyrotron traveling wave tube. The motion state of the electron beam is greatly affected by the axial magnetic field distribution. The error of the axial magnetic field in the electron gun region will increase the velocity dispersion of the electron beam in the high-frequency structure region, change the transverse and longitudinal velocity ratios and the guiding center radius, resulting in a decrease in the interaction efficiency between microwaves and the electron beam or even no interaction, and the microwaves cannot be stably amplified. When the gyrotron traveling wave tube operates in the high-frequency band, the waveguide size of the high-frequency structure is small. Affected by the magnetic field error, the electron beam will even be intercepted by hitting the wall surface in severe cases. Taking the W-band gyrotron traveling wave tube as an example, the radius of the dielectric-loaded high-frequency structure is 2 mm and the interaction length is 200 mm. When the internal wire coil of the superconducting magnet is tilted by 0.5°, the magnetic field at the electron gun changes, resulting in most electrons being intercepted at the high-frequency structure, making the gyrotron traveling wave tube unable to operate stably. Therefore, it is necessary to test and calibrate the concentricity and coaxiality of the superconducting magnet of the gyrotron traveling wave tube efficiently and accurately.

[0004] The axial magnetic field of the superconducting magnet obtained by testing is different from the ideal magnetic field distribution. These differences are mainly caused by the testing error and the error generated during the production and processing of the internal wire coil of the magnet. At present, the Gaussian meter and the sample tube experiment are mainly used at home and abroad to test and calibrate the superconducting magnet of the gyrotron traveling wave tube.

[0005] 1) As can be seen from Equation (1), the traditional Gaussian meter testing method is to characterize the difference between the actual magnetic field and the ideal magnetic field by measuring the radial magnetic field at different axial positions. In Equation (1), z represents the axial position of the Hall probe, r represents the distance between the Hall probe and the central axis of the superconducting magnet warm hole, Bz and B r respectively represent the axial magnetic field and the radial magnetic field at this position. However, due to the test accuracy of the instrument itself having an error of about 1°, and at the same time, the radius of the temperature hole is comparable to the radius at the position of the high-frequency structure of the gyrotron traveling wave tube, which is much larger than the size of the Hall element, this causes an angle to exist between the Hall element probe and the temperature hole during the test, resulting in test errors and the inability to meet the requirements of the gyrotron traveling wave tube in the high-frequency band. At the same time, the error superposition of the three-dimensional axis tilt and axial offset of the magnet leads to low accuracy and great difficulty in magnetic field measurement. When calibrating the magnet according to this method, since there are already errors in the measurement results of the magnetic field, it may cause a greater gap between the finally calibrated magnetic field and the ideal magnetic field, and it cannot be guaranteed that the calibrated superconducting magnet meets the working requirements of the gyrotron traveling wave tube.

[0006]

[0007] 2) When using a sample tube for on-line testing and calibration experiments, it is mainly to judge the concentricity and coaxiality of the superconducting magnet and the gyrotron traveling wave tube body according to the position where the electron beam emitted from the electron gun hits the output window. This method can directly measure the axial magnetic field value and observe the motion state of the electron beam in the magnetic field. However, when testing and calibrating the magnetic field, it is necessary to produce a sample tube of the gyrotron traveling wave tube, which is costly and inconvenient. At the same time, the output window may be punctured by the electron beam, and the safety is relatively low. Summary of the Invention

[0008] The present invention proposes a method and device for testing and calibrating a superconducting magnet of a gyrotron traveling wave tube based on angular symmetric rotation. The method of the present invention first solves the test error of the gaussmeter based on the angular symmetric rotation method, and then solves the axis tilt error and axial offset error generated during the production and processing of the wire coils inside the magnet. Through the axial magnetic field and angular magnetic field data obtained by the gaussmeter test, the test error is effectively deducted, and the magnetic field distribution and concentricity are measured with high precision. The present invention can effectively overcome the problems in the existing measurement technology that the test and calibration errors of the concentricity and coaxiality of the superconducting magnet and the gyrotron traveling wave tube body are relatively large, and the required accuracy cannot be achieved, resulting in low output power and low efficiency of the gyrotron traveling wave tube, etc., and provides a guarantee for the stable operation of the gyrotron traveling wave tube.

[0009] Assume that there is only an axial offset error in the wire coil inside the magnet in the uniform region. At this time, the axial magnetic field value remains unchanged, that is, B zis a constant. From Equation (1), it can be seen that the radial magnetic field value in the uniform region is zero, which contradicts the assumption. Therefore, the axial offset of the magnet will not affect the magnetic field value in the uniform region. Only when the axis of the magnet is tilted will it affect the magnetic field value in the uniform region. In the magnetic field rising region, the axial magnetic fields at different positions are different, resulting in a non-zero radial magnetic field in the magnetic field rising region. There are two error factors, axial offset and axis tilt, in the rising region. Therefore, when testing and calibrating the superconducting magnet of the gyrotron traveling wave tube in the present invention, the error caused by the axis tilt of the magnet is first tested and calibrated in the uniform region. After calibrating the axis tilt error of the magnet, the axial offset error of the magnet is then tested and calibrated in the rising region, and finally the superconducting magnet is adjusted to the optimal position.

[0010] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0011] A method for testing and calibrating a superconducting magnet of a gyrotron traveling wave tube based on angular symmetric rotation, characterized by comprising the following steps:

[0012] S1. Solve the test error of the gaussmeter based on the angular symmetric rotation method.

[0013] S1.1. Determine the rising region, uniform region, and falling region of the superconducting magnet through the gaussmeter.

[0014] S1.2. Solve the test error of the gaussmeter.

[0015] The test error of the gaussmeter is the superposition of the processing error of the Hall probe of the gaussmeter and the position deviation between the Hall probe and the superconducting magnet during the test.

[0016] Taking the end face of the superconducting magnet as the XY plane and the direction perpendicular to the end face of the magnet as the Z axis; placing the Hall probe in the magnetic field uniform region, at this time there are only the test error of the gaussmeter and the axis tilt error of the internal wire coil; keeping the radial relative distance between the Hall probe and the thermal hole of the magnet unchanged, and then rotating the Hall probe angularly. Record the readings in the X direction on the gaussmeter every π / 4. The readings of the gaussmeter are expressed by Equations (2) and (3):

[0017]

[0018]

[0019] where B0 and G x respectively represent the magnetic field at this axial position in the magnetic field uniform region where the Hall probe is located and the magnitude of the component of the magnetic field in the X-axis direction. G x:π is the magnitude of the component of the magnetic field in the X-axis direction when the rotation angle is π. θ is the magnetic field tilt angle caused by the axis tilt of the internal wire coil. α is the angle between the Hall probe and the X axis. β is the angle between the Hall probe and the Y axis. is the angular rotation angle of the Hall probe.

[0020] When testing the magnetic field in the uniform region, it is assumed that the Hall probe and the superconducting magnet are parallel to the Z-axis. Therefore:

[0021] B z ≈B0 cos(θ) (4)

[0022] where the value of B z is the reading on the Gaussmeter at G z . To minimize the number of unknowns in equations (2) and (3), the G x values at two radial positions with a difference of π are summed to derive equation (5):

[0023] G x +G x:π =2B0cos(θ)cos(α)≈2B z cos(α) (5)

[0024] Therefore, the angle α between the Hall probe and the X-axis is calculated by equation (6); similarly, the angle β between the Gaussmeter Hall probe and the Y-axis is calculated by equation (7).

[0025]

[0026]

[0027] where G y represents the magnitude of the component of the magnetic field in the Y-axis direction at the axial position of the Gaussmeter Hall probe; G y:π represents the magnitude of the component of the magnetic field in the Y-axis direction when the rotation angle is π.

[0028] Therefore, in the X-axis direction, the Gaussmeter test error is 90° - α, and in the Y-axis direction, the Gaussmeter test error is 90° - β.

[0029] By angularly rotating the Hall probe by different angles it is ensured that the influence of the Gaussmeter test error on the magnetic field is eliminated during magnetic field testing and calibration.

[0030] S2. Solve the production and processing errors of the inner winding of the superconducting magnet.

[0031] The production and processing errors of the inner winding of the superconducting magnet include axis tilt error and axial offset error.

[0032] S2.1. Solve the axis tilt error.

[0033] By angularly rotating by different angles After eliminating the influence of the Gauss meter test error on the magnetic field, there are two error factors, namely axis tilt and axial offset, in the magnetic field rising region, while only the axis tilt of the magnet will affect the magnetic field value in the magnetic field uniform region. Keep the position of the Hall probe in the magnetic field uniform region unchanged and solve the axis tilt error.

[0034] The relationship between the magnitude of the magnetic field component in the X-axis direction at the position of the Hall probe and the magnetic field tilt angle caused by the tilt of the internal wire coil axis is expressed by Equation (8):

[0035]

[0036] Similarly, the relationship between the magnitude of the magnetic field component in the Y-axis direction at the position of the Hall probe and the magnetic field tilt angle caused by the tilt of the internal wire coil axis is expressed by Equation (9):

[0037]

[0038] Regarding the angles between the Hall probe and the X and Y axes as 90°, so:

[0039] sin(α)≈sin(β)≈1 (10)

[0040] Substitute Equation (10) into Equation (8) and Equation (9) to obtain:

[0041]

[0042]

[0043] Solve Equation (4), Equation (11) and Equation (12) simultaneously to obtain Equation (13):

[0044]

[0045] Substitute the magnetic field readings in the X, Y, and Z directions on the Gauss meter and the α and β angles into Equation (13) to solve for the magnetic field tilt angle θ.

[0046] S2.2. Axial projection error elimination method to solve the axial offset error.

[0047] Place the Hall probe in the magnetic field rising region and the uniform region to solve the axial offset error of the magnet. The Gauss meter readings in the uniform region and the rising region are respectively expressed as:

[0048]

[0049]

[0050] Where B c and G xcrespectively represent the magnetic field at this axial position when the Hall element probe is in the rising region of the magnetic field and the component of the magnetic field in the X-axis direction, B x-修正 represents the component of the radial offset magnetic field in the rising region in the X-axis direction. By combining Equation (14) and Equation (15), B x-修正 is obtained from Equation (16); similarly, the component of the radial offset magnetic field in the rising region in the Y-axis direction is obtained from Equation (17).

[0051]

[0052]

[0053] where B y-修正 represents the component of the radial offset magnetic field in the rising region in the Y-axis direction, G yc represents the component of the magnetic field in the rising region in the Y-axis direction.

[0054] By combining Equation (16) and Equation (17) through geometric relationships, the radial offset magnetic field in the rising region is obtained as shown in Equation (18); finally, the axial offset error of the magnetic field is calculated according to Equation (19):

[0055]

[0056]

[0057] where B r-修正 represents the radial offset magnetic field in the rising region, represents the average value of the radial offset magnetic field in the rising region, ΔR represents the axial offset error of the magnetic field, and R represents the rotation radius of the Hall element probe.

[0058] S3. Magnetic field calibration.

[0059] According to the calculated value of the magnetic field axis tilt error, use a gaussmeter to calibrate the axis tilt error in the magnetic field uniform region; after the axis tilt error in the uniform region is calibrated, fix the Hall element probe to the rising region of the magnetic field to calibrate the axial offset error; after the axial offset error in the rising region of the magnetic field is calibrated, a magnetic field axis tilt may occur, and then return to the uniform region again for magnetic field axis tilt testing and calibration; repeatedly test and calibrate until the error is within the range allowed for the normal operation of the gyrotron.

[0060] Based on the above-mentioned testing and calibration methods, the present invention also proposes a high-precision testing and calibration device for the superconducting magnet of a gyrotron traveling-wave tube based on angular symmetric rotation, which is characterized by comprising a magnet tooling sleeve, a gaussmeter sleeve, a centering ring, two fixed chucks, a rotating device, and a testing rod; a circular through-hole is provided at the center of the fixed chuck, and the two fixed chucks are respectively detachably arranged at the upper end and the lower end of the superconducting magnet temperature hole, and the relative positions of the two fixed chucks and the temperature hole are adjusted to achieve error calibration of the superconducting magnet; the rotating device is coaxially arranged with the two fixed chucks, and the rotating device comprises a fixed part on the periphery and a rotating part inside, and the rotating part can freely rotate circumferentially relative to the fixed part; the fixed part is coaxially and fixedly installed with the upper fixed chuck, and the rotating part is provided with an eccentric circular hole and a concentric circular hole; the magnet tooling sleeve is coaxially sleeved in the circular through-holes of the two fixed chucks, and the magnet tooling sleeve is fixedly installed with the rotating part and can rotate circumferentially along with the rotating part; the centering ring is a disc structure provided with an eccentric circular hole and a concentric circular hole, and is fixed at the bottom of the magnet tooling sleeve, and the eccentric circular hole and the concentric circular hole of the centering ring are respectively axially aligned with the eccentric circular hole and the concentric circular hole of the rotating part for keeping the inserted gaussmeter sleeve from shifting; the gaussmeter sleeve is a hollow cylindrical structure, and according to different testing contents, the gaussmeter sleeve is fixed in the eccentric circular hole or the concentric circular hole, and its hollow interior is used for placing the testing rod and ensuring that the testing rod only moves axially; the testing rod is a hollow cylindrical structure with scales, and its hollow interior is used for placing the Hall probe and keeping the position of the Hall probe fixed at the bottom of the testing rod.

[0061] Further, the fixed part and the rotating part achieve relative circumferential rotation through a bearing.

[0062] When testing and calibrating the magnet error, the gaussmeter sleeve is fixed in the eccentric circular hole of the rotating device. First, the testing rod is placed in the gaussmeter sleeve to make the Hall probe located in the magnetic field uniform region, and the gaussmeter testing error is solved and eliminated based on the angular symmetric rotation method; then, keeping the position of the Hall probe unchanged in the magnetic field uniform region, the axis inclination error of the inner winding of the superconducting magnet is solved; then, by axially stretching the testing rod, the axial position of the Hall probe is changed to make the Hall probe placed in the magnetic field rising region and the uniform region, and the magnetic field axial offset error is solved; finally, when the magnetic field error calibration is completed, the gaussmeter sleeve is fixed in the concentric circular hole of the rotating device, and the axial distribution of the magnetic field is tested by axially stretching the testing rod inside the gaussmeter sleeve.

[0063] Due to the adoption of the above technical solutions, the present invention has the following advantages:

[0064] 1. By introducing three rectangular coordinate systems, the relationship between the Gauss meter test error, the superconducting magnet processing error, and the ideal magnetic field can be clearly characterized in space. Using this test method to numerically solve the Gauss meter test data, the magnitudes of the two error values can be accurately calculated, making the test and calibration of the magnet more convenient and rapid.

[0065] 2. The test and calibration process is carried out in two steps. The error caused by the tilt of the magnet axis is tested and calibrated in the uniform region, and the error caused by the axial offset of the magnet is tested and calibrated in the rising region. By testing and calibrating using the two-step method, the accuracy of the magnetic field position can be guaranteed to a large extent.

[0066] 3. A high-precision test and calibration method and device for a superconducting magnet of a gyrotron traveling wave tube based on angular symmetric rotation can accurately calculate and eliminate the Gauss meter test error by angular symmetrically rotating the Hall plate, reducing the magnetic field error to within 0.2%, ensuring the working requirements of the gyrotron traveling wave tube in the high-frequency band. Description of the Drawings

[0067] Figure 1 Schematic diagram of the superconducting magnet of the gyrotron traveling wave tube and the axial magnetic field distribution;

[0068] Figure 2 Schematic diagram of the test and calibration device for the superconducting magnet of the gyrotron traveling wave tube and its assembly;

[0069] Figure 3 Schematic diagram of the structures of the components of the test and calibration device for the superconducting magnet of the gyrotron traveling wave tube;

[0070] Figure 4 Schematic diagram of the principle of the tilt of the magnetic field test axis;

[0071] Figure 5 Schematic diagram of the principle of the axial offset of the magnetic field test;

[0072] Figure 6 Physical diagram of the superconducting magnet of the W-band dielectric-loaded gyrotron traveling wave tube;

[0073] Figure 7 Schematic diagram of the data processing for the test and calibration of the superconducting magnet;

[0074] Figure 8 Schematic diagram of the comparison of the magnetic field error before and after calibration.

[0075] Description of the reference numerals: 1. Dewar structure; 2. Coil; 3. Copper test rod; 4. Magnet tooling sleeve; 5. Gauss meter sleeve; 6. Rotating device; 7. Hall plate probe; 8. Centering ring; 9. Fixed chuck. Detailed Embodiment

[0076] To better understand the above objects, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0077] The present invention provides an example of testing and calibration of a superconducting magnet for a W-band dielectric-loaded gyrotron traveling-wave tube.

[0078] A testing and calibration device for a superconducting magnet of a gyrotron traveling-wave tube based on angular symmetric rotation includes a magnet tooling sleeve, a gaussmeter sleeve, a centering ring, two fixed chucks, a rotating device, and a test rod; a circular through-hole is provided at the center of the fixed chuck; the two fixed chucks are respectively detachably arranged at the upper and lower ends of the superconducting magnet temperature hole, and by adjusting the relative positions of the two fixed chucks and the temperature hole, the error calibration of the superconducting magnet is achieved; the rotating device is coaxially arranged with the two fixed chucks, and the rotating device includes a fixed part on the periphery and a rotating part inside, and the fixed part and the rotating part achieve relative circumferential rotation through a bearing; the fixed part is coaxially fixedly installed with the upper fixed chuck through a screw, and the rotating part is provided with an eccentric circular hole and a concentric circular hole; the magnet tooling sleeve is coaxially sleeved in the circular through-holes of the two fixed chucks, and the magnet tooling sleeve is fixedly installed with the rotating part and can rotate circumferentially following the rotating part; the centering ring is a disc structure provided with an eccentric circular hole and a concentric circular hole and is fixed at the bottom of the magnet tooling sleeve, and the eccentric circular hole and the concentric circular hole of the centering ring are axially aligned with the eccentric circular hole and the concentric circular hole of the rotating part respectively, for keeping the inserted gaussmeter sleeve from shifting; the gaussmeter sleeve is a hollow cylindrical structure, and according to different test contents, the gaussmeter sleeve is fixed into the eccentric circular hole or the concentric circular hole, and its hollow interior is used to place the test rod and ensure that it only moves axially; the test rod is a hollow cylindrical structure with scales, and its hollow interior is used to place the Hall probe and keep the position of the Hall probe fixed at the bottom of the test rod.

[0079] A high-precision testing and calibration method for a superconducting magnet of a gyrotron traveling-wave tube based on angular symmetric rotation, characterized by comprising the following steps:

[0080] S1. Solve the gaussmeter test error based on the angular symmetric rotation method.

[0081] S1.1. Determine the rising region, uniform region, and falling region of the superconducting magnet through the gaussmeter.

[0082] Fix the gaussmeter sleeve in the concentric circular hole of the rotating device, change the axial position of the Hall probe by axially stretching the copper test rod inside it, and then record the axial magnetic field values at different axial positions, so as to determine the position ranges of the rising region, uniform region, and falling region of the magnetic field, which is convenient for subsequent magnet error testing and calibration.

[0083] S1.2. Solve the gaussmeter test error.

[0084] The measurement error of the gaussmeter is the superposition of the machining error of the Hall probe of the gaussmeter and the positional deviation between the Hall probe and the superconducting magnet during measurement.

[0085] Taking the end face of the superconducting magnet as the XY plane and the direction perpendicular to the end face of the magnet as the Z axis; first, fix the gaussmeter sleeve in the eccentric circular hole, then insert the test rod into the gaussmeter sleeve so that the Hall probe is placed in the uniform magnetic field region. At this time, there are only the measurement error of the gaussmeter and the tilt error of the internal wire coil axis; keep the radial relative distance between the Hall probe and the magnetic temperature hole unchanged, rotate the test rod angularly, and record the X-direction readings on the gaussmeter every π / 4. The gaussmeter readings are expressed by Equations (2) and (3):

[0086]

[0087]

[0088] where B0 and G x respectively represent the magnetic field at the axial position of the Hall probe and the magnitude of the component of the magnetic field in the X-axis direction. G x:π is the magnitude of the component of the magnetic field in the X-axis direction when the rotation angle is π. θ is the magnetic field tilt angle caused by the tilt of the internal wire coil axis, α is the angle between the Hall probe and the X axis, β is the angle between the Hall probe and the Y axis, is the angular rotation angle.

[0089] When measuring the magnetic field in the uniform region, it is assumed that the Hall probe and the superconducting magnet are parallel in the Z axis. Therefore:

[0090] B z ≈B0 cos(θ) (22)

[0091] where B z value is the reading of G z on the gaussmeter. To minimize the number of unknowns in Equations (2) and (3) as much as possible, sum the G x values with a radial position difference of π, and derive Equation (5):

[0092] G x +G x:π =2B0 cos(θ)cos(α)≈2B z cos(α) (23)

[0093] Therefore, the angle α between the Hall probe and the X axis is calculated by Equation (6); similarly, the angle β between the Hall probe of the gaussmeter and the Y axis is calculated by Equation (7).

[0094]

[0095]

[0096] where G y represents the magnitude of the component of the magnetic field in the Y-axis direction at the axial position of the Hall probe of the gaussmeter; G y:π represents the magnitude of the component of the magnetic field in the Y-axis direction when the rotation angle is π.

[0097] Therefore, in the X-axis direction, the test error of the gaussmeter is 90° - α, and in the Y-axis direction, the test error of the gaussmeter is 90° - β.

[0098] By rotating at different angular positions ensure that the influence of the test error of the gaussmeter on the magnetic field is eliminated during magnetic field testing and calibration.

[0099] S2. Solve the production and processing errors of the in-line coils inside the superconducting magnet.

[0100] The production and processing errors of the in-line coils inside the superconducting magnet include axis tilt error and axial offset error.

[0101] S2.1. Solve the axis tilt error.

[0102] By rotating at different angular positions after eliminating the influence of the test error of the gaussmeter on the magnetic field, there are two error factors, namely axis tilt and axial offset, in the magnetic field rising region, while only the axis tilt of the magnet will affect the magnetic field value in the magnetic field uniform region. Keep the position of the test rod unchanged and solve the axis tilt error.

[0103] The relationship between the magnitude of the component of the magnetic field in the X-axis direction at the Hall probe position and the magnetic field tilt angle caused by the axis tilt of the in-line coil is expressed by Equation (8):

[0104]

[0105] Similarly, the relationship between the magnitude of the component of the magnetic field in the Y-axis direction at the Hall probe position and the magnetic field tilt angle caused by the axis tilt of the in-line coil is expressed by Equation (9):

[0106]

[0107] Regarding the angles between the Hall probe and the X and Y axes as 90°, so:

[0108] sin(α)≈sin(β)≈1 (28)

[0109] Substitute Equation (10) into Equations (8) and (9) to obtain:

[0110]

[0111]

[0112] Solving equation (13) by combining equation (4), equation (11) and equation (12) gives:

[0113]

[0114] Substitute the magnetic field readings in the X, Y, and Z directions and the angles α and β on the Gaussmeter into equation (13) to obtain the magnetic field inclination angle θ.

[0115] S2.2. Axial projection error elimination method is used to solve the axial offset error.

[0116] The Gaussmeter sleeve is fixed in the eccentric circular hole, and the axial stretching test rod changes the position of the Hall plate probe, so that the Hall plate probe is placed in the magnetic field rising area and uniform area respectively, and the axial offset error of the magnet is solved. The Gaussmeter readings in the uniform area and the Gaussmeter readings in the rising area are expressed as:

[0117]

[0118]

[0119] Among them B c and G xc They represent the magnetic field at the axial position and the component of the magnetic field in the X-axis direction when the Hall probe is in the magnetic field rising zone, respectively. x-修正 represents the component of the radial offset magnetic field in the X-axis direction of the rising zone. Combining equations (14) and (15), B x-修正 It is obtained by formula (16); similarly, the component of the radial offset magnetic field in the Y-axis direction of the rising zone is obtained by formula (17).

[0120]

[0121]

[0122] Among them B y-修正 It represents the component of radial offset magnetic field in the Y-axis direction of the rising zone, G yc It represents the component of the magnetic field in the ascending area in the Y-axis direction.

[0123] The radial offset magnetic field in the ascending zone is obtained by combining equations (16) and (17) through geometric relationships as shown in equation (18); finally, the axial offset error of the magnetic field is calculated according to equation (19):

[0124]

[0125]

[0126] Among them B r-修正 Indicates the radial offset magnetic field in the rising zone, represents the average value of the radial offset magnetic field in the rising region, ΔR represents the axial offset error of the magnetic field, and R represents the rotation radius of the Hall probe.

[0127] To more intuitively show the error value of the magnetic field, the ratio of the difference between the maximum and minimum values of the radial offset magnetic field in the rising region and the longitudinal magnetic field is used to represent:

[0128]

[0129] where represents the average value of the longitudinal magnetic field at the same axial position in the rising region.

[0130] S3. Magnetic field calibration.

[0131] According to the calculated axis tilt error value of the magnetic field, use a gaussmeter to calibrate the axis tilt error in the uniform region; after calibrating the axis tilt error in the uniform region, fix the Hall probe to the rising region to calibrate the axial offset error; after calibrating the axial offset error in the magnetic field rising region, there may be an axis tilt of the magnetic field, and then return to the uniform region again to test and calibrate the axis tilt of the magnetic field; repeatedly test and calibrate until the error is within the range allowed for the normal operation of the gyrotron traveling wave tube.

[0132] Figure 2 is a schematic diagram of the test and calibration device for the superconducting magnet of the gyrotron traveling wave tube and its assembly.

[0133] Figure 3 is a schematic diagram of the test for the axial translation error in the uniform region of the superconducting magnet of the gyrotron traveling wave tube.

[0134] Figure 4 is a schematic diagram of the principle of axis tilt in magnetic field testing. Taking the end face of the superconducting magnet as the XY plane and the direction perpendicular to the end face of the magnet as the Z axis; where the solid line represents the coordinate of the superconducting magnet and the dashed line represents the coordinate of the Hall probe of the gaussmeter. Due to the axis angle deviation between the Hall probe and the superconducting magnet, the two coordinate systems are inconsistent.

[0135] Figure 5 is a schematic diagram of the principle of axial offset in magnet testing. In the rising region, the longitudinal magnetic field is different, and the magnet offset will cause the longitudinal magnetic field to change, and B r also changes accordingly. Therefore, move the Hall probe down to the magnetic field rising region to solve the axial offset error of the magnet.

[0136] Figure 6 is a physical diagram of the superconducting magnet of the W-band dielectric-loaded gyrotron traveling wave tube. The gyrotron traveling wave tube is vertically placed in the warm hole of the superconducting magnet.

[0137] Figure 7It is a processing diagram of superconducting magnet test calibration data. The test and calibration device based on angular symmetric rotation designed by the present invention is used to test and calibrate the W-band superconducting magnet. First, fix the gaussmeter sleeve in the eccentric circular hole, then fix the test rod in the magnetic field uniform area, record 9 groups of test data by angular symmetric rotation of the test rod, and calculate the test error of the gaussmeter and the tilt error of the inner wire package axis of the superconducting magnet; then move the test rod to the magnetic field rising area, and also record 9 groups of test data by angular symmetric rotation of the test rod to calculate the axial offset error of the inner wire package of the superconducting magnet. The included angles α and β between the gaussmeter Hall plate and the X-axis and Y-axis of the superconducting magnet are 88.574° and 92.4606° respectively, the axis tilt error θ of the magnet is -0.0204°, and the axial offset error of the magnet is 0.2322 mm.

[0138] Table 1 Comparison of test data before and after calibration

[0139]

[0140] Table 1 shows the comparison of magnetic field test data of the superconducting magnet before and after calibration. It can be seen from the above measurement data that the axis tilt error of the magnet before calibration is small and meets the working requirements of the gyrotron traveling wave tube; however, the axial offset error of the magnet is large and needs to be calibrated. Calibrate the magnet according to the above calibration method, and the axial offset error is significantly reduced. Among them, the axis tilt error of the magnetic field remains basically unchanged, the axial offset error drops by 76.7%, and the error value drops by 90.6%.

[0141] Figure 8 It is a comparison diagram of magnetic field errors obtained by different calibration methods. It can be seen from the figure that after calibrating the superconducting magnet using the present invention, the error in the magnetic field rising area is greatly reduced; at the same time, the error value after calibration of the magnetic field in the rising area is less than 0.002, which can ensure the stable operation of the gyrotron traveling wave tube.

[0142] The above embodiments are only the preferred embodiments of the present invention. Through the above design examples, a new type of angular symmetric rotation test and calibration system for the superconducting magnet of the gyrotron traveling wave tube is provided, which overcomes the problems of large errors in traditional test and calibration methods, resulting in poor concentricity of the superconducting magnet and ineffective calibration, and realizes the rapid and accurate measurement and calibration of the concentricity and coaxiality between the superconducting magnet and the gyrotron traveling wave tube body.

Claims

1. A method for testing and calibrating a superconducting magnet of a gyrotron traveling wave tube based on angular symmetric rotation, characterized in that, It includes the following steps: S1. Solve the Gaussmeter test error based on the angular symmetric rotation method; S1.

1. Determine the rising region, uniform region, and falling region of the superconducting magnet through the Gaussmeter; S1.

2. Solve the Gaussmeter test error; The Gaussmeter test error is the superposition of the processing error of the Gaussmeter Hall probe and the position deviation between the Hall probe and the superconducting magnet during testing; Taking the end face of the superconducting magnet as the XY plane and the direction perpendicular to the magnet end face as the Z axis; place the Hall probe in the magnetic field uniform region. At this time, there are only the Gaussmeter test error and the internal winding axis tilt error; keep the radial relative distance between the Hall probe and the magnetic body temperature hole unchanged, and then rotate the Hall probe angularly. Record the X-direction readings on the Gaussmeter every π / 4. The Gaussmeter readings are expressed by Equations (1) and (2): where B0 and G x respectively represent the magnetic field at this axial position and the magnitude of the X - component of the magnetic field when the Hall - plate probe is in the uniform magnetic field region. G x:π is the magnitude of the X - component of the magnetic field when the rotation angle is π, θ is the magnetic - field tilt angle caused by the tilt of the internal coil axis, α is the angle between the Hall - plate probe and the X - axis, β is the angle between the Hall - plate probe and the Y - axis, is the angular rotation angle of the Hall - plate probe; When testing the magnetic field in the uniform region, assume that the Hall probe and the superconducting magnet are parallel in the Z axis. Therefore: B z ≈ B0 cos(θ) (3) where B z is the value of G z read on the gaussmeter; To reduce the number of unknowns in Equations (1) and (2), the G values at two radial positions with a difference of π are summed to derive Equation (4): x ​ G x +G x:π = 2B0 cos(θ)cos(α) ≈ 2B z cos(α) (4) Therefore, the angle α between the Hall probe and the X axis is calculated by Equation (5); similarly, the angle β between the Gaussmeter Hall probe and the Y axis is calculated by Equation (6); Among which G y represents the magnitude of the Y-axis component of the magnetic field at the axial position of the Hall probe of the gaussmeter; G y:π represents the magnitude of the Y-axis component of the magnetic field when the rotation angle is π; Therefore, in the X-axis direction, the Gaussmeter test error is 90° - α, and in the Y-axis direction, the Gaussmeter test error is 90° - β; S2. Solve the production and processing error of the internal winding of the superconducting magnet; The production and processing error of the internal winding of the superconducting magnet includes the axis tilt error and the axial offset error; S2.

1. Solve the axis tilt error; Keep the position of the Hall probe unchanged in the magnetic field uniform region. The relationship between the magnitude of the magnetic field component in the X-axis direction at the position of the Hall probe and the magnetic field tilt angle caused by the axis tilt of the internal winding is expressed by Equation (7): Similarly, the relationship between the magnitude of the magnetic field component in the Y-axis direction at the position of the Hall probe and the magnetic field tilt angle caused by the axis tilt of the internal winding is expressed by Equation (8): Regarding the angles between the Hall probe and the X and Y axes as 90°, so: sin(α)≈sin(β)≈1(9) Substitute Equation (9) into Equations (7) and (8) to obtain: Simultaneously solve Equations (3), (10), and (11) to obtain Equation (12): Substitute the magnetic field readings in the X, Y, and Z directions on the Gaussmeter and the α and β angles into Equation (12) to solve for the magnetic field tilt angle θ; S2.

2. Solve the axial offset error by the axial projection error elimination method; Place the Hall probe in the magnetic field rising region and the uniform region to solve the magnetic body axial offset error; the Gaussmeter readings in the uniform region and the rising region are respectively expressed as: Among which B c and G xc respectively represent the magnetic field and the component of the magnetic field in the X-axis direction at this axial position when the Hall probe is in the rising region of the magnetic field. B x-修正 represents the component of the radially offset magnetic field in the X-axis direction in the rising region; by combining Equation (13) and Equation (14), B x-修正 is obtained from Equation (15); similarly, the component of the radially offset magnetic field in the Y-axis direction in the rising region is obtained from Equation (16); Among which B y-修正 represents the component of the radial offset magnetic field in the rising region in the Y-axis direction, and G yc represents the component of the magnetic field in the rising region in the Y-axis direction; Obtain the radial offset magnetic field in the rising region as shown in Equation (17) by simultaneously solving Equations (15) and (16) through geometric relations; finally, calculate the magnetic field axial offset error according to Equation (18): Among which B r-修正 represents the radial offset magnetic field in the rising region, represents the average value of the radial offset magnetic field in the rising region, ΔR represents the axial offset error of the magnetic field, and R represents the rotation radius of the Hall chip probe; S3. Magnetic field calibration; According to the calculated magnetic field axis tilt error value, use a gaussmeter to calibrate the axis tilt error in the magnetic field uniform region; after the axis tilt error in the uniform region is calibrated, fix the Hall probe to calibrate the axial offset error in the magnetic field rising region; after the axial offset error in the magnetic field rising region is calibrated, return to the uniform region again to test and calibrate the magnetic field axis tilt; repeatedly test and calibrate until the error is within the allowable range for the normal operation of the gyrotron traveling wave tube.

2. An apparatus for implementing the method of claim 1, characterized in that, It includes a magnet tooling sleeve, a gaussmeter sleeve, a centering ring, two fixed chucks, a rotating device, and a test rod; a circular through hole is provided at the center of the fixed chuck, and the two fixed chucks are respectively detachably arranged at the upper and lower ends of the superconducting magnet temperature hole. By adjusting the relative positions of the two fixed chucks and the temperature hole, the error calibration of the superconducting magnet is realized; the rotating device is coaxially arranged with the two fixed chucks. The rotating device includes a fixed part on the periphery and a rotating part inside, and the rotating part can freely rotate circumferentially relative to the fixed part; the fixed part is coaxially and fixedly installed with the upper fixed chuck, and the rotating part is provided with an eccentric circular hole and a concentric circular hole; the magnet tooling sleeve is coaxially sleeved in the circular through holes of the two fixed chucks, and the magnet tooling sleeve is fixedly installed with the rotating part and can rotate circumferentially following the rotating part; the centering ring is a disc structure provided with an eccentric circular hole and a concentric circular hole and is fixed at the bottom of the magnet tooling sleeve. The eccentric circular hole and the concentric circular hole of the centering ring are axially aligned with the eccentric circular hole and the concentric circular hole of the rotating part respectively, and are used to keep the inserted gaussmeter sleeve from shifting; the gaussmeter sleeve is a hollow cylindrical structure. According to different test contents, the gaussmeter sleeve is fixed in the eccentric circular hole or the concentric circular hole, and its hollow interior is used to place the test rod and ensure that it only moves axially; the test rod is a hollow cylindrical structure with scales, and its hollow interior is used to place the Hall probe and keep the position of the Hall probe fixed at the bottom of the test rod.

3. The device according to claim 2, characterized in that, The relative circumferential rotation between the fixed part and the rotating part is realized through a bearing.

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