Radio frequency superconducting cavity coaxiality adjustment device and method

Abstract

A coaxiality adjustment device for a radio frequency superconducting cavity includes an adjustment and measuring mechanism, a clamping and fixing mechanism, a U-shaped support seat for supporting the two ends of the radio frequency superconducting cavity, and a test flange installed at the two ends of the radio frequency superconducting cavity; the clamping and fixing mechanism includes a downward pressure component and a top support component arranged on both sides of the downward pressure component; the top support component supports the radio frequency superconducting cavity upward, and the downward pressure component presses the radio frequency superconducting cavity downward to achieve the fixation of the radio frequency superconducting cavity; the adjustment and measuring mechanism includes a fixed support component and a dial indicator arranged on the fixed support component for measuring the height and level of the downward pressure component. A coaxiality adjustment method for a radio frequency superconducting cavity is also provided, in which the coaxial adjustment of the cavity cell is achieved by measuring the concentric deviation between the middle cylinder of each cavity cell of the radio frequency superconducting cavity and the reference axis through the adjustment and measuring mechanism. The device of the present invention has a simple structure, the superconducting cavity is easy to install, the adjustment direction range is wide, and superconducting cavities with the same diameter but different lengths can be adjusted coaxially.

Description

Technical Field

[0001] The present invention relates to the technical field of superconducting high-frequency cavities, and in particular to a coaxiality adjustment device and method for a radio frequency superconducting cavity. Background Art

[0002] The radio frequency superconducting cavity is the core component of the superconducting accelerator. The superconducting cavity used in the accelerator can be called a radio frequency superconducting accelerating cavity, or superconducting cavity for short. It is a radio frequency resonant cavity that is widely used to accelerate electrons and other particles. As the core component of the linear accelerator, the 9cell radio frequency superconducting cavity works at 2.0K to accelerate electrons to the required energy. It mainly includes 9 accelerating cavities and two end cavity components, as well as a pure titanium helium tank welded to the end cavity components. The superconducting cavity is formed by deep stamping and electron beam welding of high-purity niobium materials, and is processed through a series of processes such as chemical polishing. Special tools are used for frequency tuning and field flatness adjustment. Due to the stamping rebound of niobium materials, assembly deviations, and electron beam welding deformation, the coaxiality deviation of the manufactured 9cell radio frequency superconducting cavity is about 1-3mm, which cannot meet the accelerator's 0.4mm technical requirement.

[0003] The invention patent with application number 202310872065.4 discloses a semi-automatic pre-tuning device suitable for a multi-cavity ellipsoidal superconducting cavity. The superconducting cavity is installed on a tension and compression mechanism, and the lifting mechanism is fixed on the main frame and connected to the tension and compression mechanism to move the tension and compression mechanism. The winding mechanism is fixed on the main frame and makes the thin wire passing through the superconducting cavity move evenly along the cavity axis of the superconducting cavity to measure the frequency and field distribution. The control system is fixed on the main frame to control the direction and speed of the thin wire movement through the program, so as to mechanically fine-tune each accelerating cavity cell of the superconducting cavity so that its overall frequency and the flatness of the electric field along the cavity axis meet the working requirements. However, when this technical solution is actually used, the thin wire will swing during the horizontal movement, thereby affecting the accuracy of the coaxial adjustment; secondly, its structure is complex, and the installation process of the superconducting cavity and the device is more cumbersome. Summary of the invention

[0004] In order to solve the technical problems existing in the above-mentioned technology, it is necessary to provide a radio frequency superconducting cavity coaxiality adjustment device.

[0005] A radio frequency superconducting cavity coaxiality adjustment device comprises an adjustment and measurement mechanism, a clamping and fixing mechanism, a U-shaped support seat for supporting two ends of the radio frequency superconducting cavity, and a test flange installed at the two ends of the radio frequency superconducting cavity;

[0006] The clamping and fixing mechanism includes a pressing component and supporting components arranged on both sides of the pressing component; the supporting component supports the RF superconducting cavity upward, and the pressing component presses the RF superconducting cavity downward, so as to fix the RF superconducting cavity by using the mutual cooperation between the pressing component and the supporting component;

[0007] The adjustment and measurement mechanism includes a fixed support component and a dial indicator arranged on the fixed support component for measuring the height and level of the pressing component.

[0008] Preferably, the pressing assembly includes a pressing base, a pressing block, and a pressing rod; the pressing rod is longitudinally arranged on the pressing base, the pressing block is slidably arranged on the pressing rod and is located directly above the pressing base, and a pressing nut is threadedly sleeved on the pressing rod for pressing the pressing block downward.

[0009] Preferably, the top support assembly includes a support base, a support block, and a support rod; the support rod is longitudinally arranged on the support base, the support block is slidably arranged on the support rod and is located directly above the support base, and a support nut is threadedly mounted on the support rod for squeezing the support block upward.

[0010] Preferably, the fixed support assembly includes a fixed seat, a longitudinal rod, and a transverse rod for mounting a dial indicator; the longitudinal rod is longitudinally arranged on the fixed seat, the transverse rod is horizontally arranged on the longitudinal rod, and the transverse rod can adjust the height up and down along the longitudinal rod.

[0011] Preferably, it also includes a platform for installing the calibration and measuring mechanism, the clamping and fixing mechanism, and the U-shaped support seat.

[0012] A method for adjusting the coaxiality of a radio frequency superconducting cavity is provided, wherein the coaxiality adjustment device for the radio frequency superconducting cavity is used for adjustment, and the method comprises the following steps:

[0013] S1: Establish a measurement reference coordinate system with the vertical line of the RF superconducting cavity passing through the center of the coupling flange as the X-axis, the line connecting the centers of the two reference rings of the RF superconducting cavity as the Z-axis, and the normal of the intersection of the Z-axis and the X-axis as the Y-axis;

[0014] S2: First, fix the U-shaped support seat on the platform, then put the beam tube flanges on both sides of the RF superconducting cavity into the U-shaped support seat, and fix them with a plastic gun to ensure that the coupling flanges of the RF superconducting cavity are rotated to the vertical direction;

[0015] S3: After the RF superconducting cavity is fixed, first measure the XYZ axis of the reference coordinate system, then measure the middle cylinder of each cavity cell, and obtain the center point of each cavity cell, the deviation distance between the center point of the cavity cell and the Z axis, that is, the coaxial deviation, and the position of the center point of the cavity cell in the quadrant, that is, the coaxial deviation direction;

[0016] S4: According to the measurement results, determine the offset value and direction of the cavity cell, and rotate the cavity cell or several cavity cells with the largest offset to the top;

[0017] S5: Adjust the upper end surface of the clamping block to be level with the platform, place dial indicators at both ends and adjust them to zero, and magnetically absorb the fixing base onto the platform; install the test flange and antenna on the two end cavity flanges of the RF superconducting cavity, connect one end to the channel 1 of the vector network instrument, and the other end to the channel 2 of the vector network instrument, and monitor the cavity cell frequency during the whole process of coaxial adjustment;

[0018] S6: Use a wrench to tighten the two clamping nuts at the same time, observe the size of the dial indicator descent, and the pressure drop is 0.05mm each time to ensure that the two dial indicators drop to the same height. Observe the change in cavity cell frequency during the coaxial adjustment process; measure the cavity cell frequency every 0.2mm drop and record the change value; maintain the pressure for 5 minutes after adjusting to the position, and then loosen the clamping nuts one by one, and the dial indicator rises 0.05mm each time until the clamping nuts are completely loosened. Record the value of the dial indicator descent, that is, the actual change in cavity cell adjustment, and record the cavity cell frequency.

[0019] Preferably, in step S3, the rotation angle of the cavity cell can be determined based on the angle between the coupling flange and the platform; the clamping block is fixed to the cavity cell with the maximum deviation, and the clamping block is adjusted to a horizontal deviation of less than 0.1 mm; the support base is fixed on both sides of the cavity cell with the maximum deviation, and the support nut is adjusted to make the support block fit tightly against the cavity cell; the U-shaped support seat, the support base, the clamping base and the platform are fixed with a pressure plate.

[0020] Preferably, in step S5, during the coaxial adjustment process, the cavity cell frequency is allowed to vary by ±0.2 MHz.

[0021] Preferably, in step S6, the total amount of each coaxial adjustment is 30% of the maximum value of the cavity cell offset, that is, the total height of the dial indicator descending is 30% of the cavity cell offset.

[0022] Preferably, in step S6, no matter whether the coaxial adjustment is performed each time or multiple times, the frequency change is always calculated with reference to the initial frequency of the cavity cell; during the adjustment process, if the frequency change exceeds the allowable change, the adjustment step is immediately stopped, the initial state of the adjustment is restored, the tooling condition and the measurement circuit are checked, and then the adjustment is started from the initial state; after multiple coaxial measurements and multiple coaxial adjustments of the RF superconducting cavity, the coaxiality of the cavity cell of the RF superconducting cavity can be adjusted to ≤0.4mm.

[0023] Compared with the prior art, the coaxiality adjustment device and method of the radio frequency superconducting cavity provided by the present invention adopts the mutual cooperation between the lower pressure component and the top support component to realize the fixation of the radio frequency superconducting cavity, measures the concentricity deviation between the middle cylinder of each cavity cell of the radio frequency superconducting cavity and the reference axis through the adjustment and measurement mechanism, and completes the coaxial adjustment of the cavity cell through the coaxiality adjustment device of the radio frequency superconducting cavity with a bridge structure, and can freely adjust the length and adjustment direction of the coaxiality adjustment device of the radio frequency superconducting cavity according to the concentricity offset and direction of the cavity cell, and can be applied to the coaxial adjustment of superconducting cavities of the same diameter and different lengths. The device of the present invention has a simple structure, the superconducting cavity is easy to install, the adjustment direction range is wide, and the superconducting cavities of the same diameter but different lengths can be adjusted coaxially. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0025] Figure 1 It is a structural schematic diagram of the reference coordinate system of the present invention.

[0026] Figure 2 It is a schematic structural diagram of the coaxiality adjustment device of the radio frequency superconducting cavity of the present invention.

[0027] Figure 3 For the present invention Figure 2 Schematic diagram of the structure from another angle.

[0028] Figure 4 It is a schematic diagram of the structure of the radio frequency superconducting cavity coaxiality adjustment device of the present invention when in use.

[0029] Figure 5 For the present invention Figure 4 Schematic diagram of the structure from another angle.

[0030] In the figure: adjustment and measurement mechanism 01, fixed support assembly 11, fixed seat 111, longitudinal rod 112, transverse rod 113, dial indicator 12, clamping and fixing mechanism 02, pressing assembly 21, clamping base 211, clamping block 212, clamping rod 213, clamping nut 214, top support assembly 22, support base 221, support block 222, support rod 223, support nut 224, U-shaped support seat 03, test flange 04, platform 05, radio frequency superconducting cavity 06. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] In the description of the present invention, it should be understood that the terms "upper", "middle", "outer", "inner", "lower" and the like indicating directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the components or elements referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0033] Please see Figure 2 , Figure 5 In one embodiment, the present invention provides a coaxiality adjustment device for a radio frequency superconducting cavity, comprising an adjustment and measurement mechanism 01, a clamping and fixing mechanism 02, a U-shaped support seat 03 for supporting the two ends of the radio frequency superconducting cavity 06, and a test flange 04 installed at the two ends of the radio frequency superconducting cavity 06; the clamping and fixing mechanism 02 comprises a down-pressing component 21, and a top support component 22 arranged on both sides of the down-pressing component 21; the top support component 22 supports the radio frequency superconducting cavity 06 upward, and the down-pressing component 21 presses the radio frequency superconducting cavity 06 downward, so as to achieve the fixation of the radio frequency superconducting cavity 06 by the mutual cooperation between the down-pressing component 21 and the top support component 22. The adjustment and measurement mechanism 01 comprises a fixed support component 11, and a dial gauge 12 arranged on the fixed support component 11 for measuring the height and level of the down-pressing component 21.

[0034] Specifically, the pressing assembly 21 includes a pressing base 211, a pressing block 212, and a pressing rod 213; the pressing rod 213 is longitudinally arranged on the pressing base 211, the pressing block 212 is slidably arranged on the pressing rod 213, and the pressing block 212 is located directly above the pressing base 211, and a pressing nut 214 is threadedly sleeved on the pressing rod 213. Rotating the pressing nut 214 can press the pressing block 212 downward, causing the pressing block 212 to be close to the cavity cell, thereby exerting downward pressure on the cavity cell. There are two pressing rods 213, and the two pressing rods 213 are symmetrically arranged along the pressing base 211, so that the pressing rods 213 can be symmetrically arranged on both sides of the RF superconducting cavity 06.

[0035] Specifically, the top support assembly 22 includes a support base 221, a support block 222, and a support rod 223; the support rod 223 is longitudinally arranged on the support base 221, the support block 222 is slidably arranged on the support rod 223, and the support block 222 is located directly above the support base 221, and a support nut 224 is threadedly mounted on the support rod 223, and the support block 222 can be squeezed upward by rotating the support nut 224, so that the support block 222 can be closely attached to the cavity cell to form a support. There are two support rods 223, and the two support rods 223 are symmetrically arranged along the support base 221, so that the support rods 223 can be symmetrically arranged on both sides of the RF superconducting cavity 06.

[0036] The surfaces of the pressing block 212 and the supporting block 222 that are in contact with the cavity cells are both in an arc-shaped structure, thereby ensuring that the pressing block 212 and the supporting block 222 can form a better fit with the cavity cells.

[0037] Specifically, the fixed support assembly 11 includes a fixed seat 111, a longitudinal rod 112, and a transverse rod 113 for mounting the dial gauge 12; the longitudinal rod 112 is longitudinally arranged on the fixed seat 111, and the transverse rod 113 is horizontally arranged on the longitudinal rod 112, and the transverse rod 113 can be adjusted up and down along the longitudinal rod 112. Secondly, the transverse rod 113 can also rotate with the longitudinal rod 112 as an axis, so that the dial gauge 12 can be adjusted to a suitable position for measurement.

[0038] Specifically, in order to ensure the accuracy of measurement and adjustment, a platform 05 is further provided below the adjustment and measurement mechanism 01 , the clamping and fixing mechanism 02 , and the U-shaped support seat 03 .

[0039] In one embodiment, the present invention provides a method for adjusting the coaxiality of a radio frequency superconducting cavity, using a radio frequency superconducting cavity coaxiality adjustment device for adjustment, and the specific steps are as follows:

[0040] S1: Please refer to Figure 1 , establish a measurement reference coordinate system with the vertical line of the RF superconducting cavity 06 passing through the center of the coupling flange as the X-axis, the line connecting the centers of the two reference rings of the RF superconducting cavity 06 as the Z-axis, and the normal of the intersection of the Z-axis and the X-axis as the Y-axis;

[0041] S2: First, fix the U-shaped support seat 03 on the platform 05, then put the beam tube flanges on both sides of the RF superconducting cavity 06 into the U-shaped support seat 03, and fix them with a plastic gun to ensure that the coupling flanges of the RF superconducting cavity 06 are rotated to the vertical direction;

[0042] S3: After the RF superconducting cavity 06 is fixed, first measure the XYZ axis of the reference coordinate system, then measure the middle cylinder of each cavity cell, and obtain the center point of each cavity cell, the deviation distance between the center point of the cavity cell and the Z axis, that is, the coaxial deviation, and the position of the center point of the cavity cell in the quadrant, that is, the coaxial deviation direction;

[0043] S4: According to the measurement results, determine the offset value and direction of the cavity cell, and rotate the cavity cell or several cavity cells with the largest offset to the top;

[0044] S5: Adjust the upper end surface of the clamping block 212 to be level with the platform 05, place the dial gauge 12 at both ends and adjust it to zero, and magnetically absorb the fixing seat 111 on the platform 05; install the test flange 04 and the antenna on the two end cavity flanges of the radio frequency superconducting cavity 06, connect one end to the vector network instrument channel 1, and the other end to the vector network instrument channel 2, and adjust the coaxial whole process to monitor the cavity cell frequency;

[0045] S6: Use a wrench to tighten the two clamping nuts 214 at the same time, observe the descending size of the dial indicator 12, and the pressure drop is 0.05mm each time to ensure that the two dial indicators 12 descend to the same height. Observe the change in cavity cell frequency during the coaxial adjustment process; measure the cavity cell frequency every 0.2mm drop and record the change value; maintain the pressure for 5 minutes after adjusting to the position, and then loosen the clamping nuts 214 in turn, and the dial indicator 12 rises 0.05mm each time until the clamping nuts 214 are completely loosened, record the descending value of the dial indicator 12, that is, the actual change in cavity cell adjustment, and record the cavity cell frequency.

[0046] Among them, in step S3, the rotation angle of the cavity cell can be determined based on the angle between the coupling flange and the platform 05; the clamping block 212 is fixed to the cavity cell with the largest deviation, and the clamping block 212 is adjusted to a horizontal deviation of less than 0.1 mm; the support base 221 is fixed on both sides of the cavity cell with the largest deviation, and the support nut 224 is adjusted to make the support block 222 close to the cavity cell; the U-shaped support seat 03, the support base 221, the clamping base 211 and the platform 05 are fixed with a pressure plate.

[0047] Wherein, in step S5, during the coaxial adjustment process, the cavity cell frequency is allowed to vary by ±0.2 MHz.

[0048] Among them, in step S6, the total amount of each coaxial adjustment is 30% of the maximum value of the cavity cell offset, that is, the total height of the dial indicator 12 descending is 30% of the cavity cell offset.

[0049] Among them, in step S6, no matter whether the coaxial adjustment is performed each time or multiple times, the initial frequency of the cavity cell is always used as a reference to calculate the frequency change; during the adjustment process, if the frequency change exceeds the allowable change, the adjustment step is immediately stopped, the initial state of the adjustment is restored, the tooling condition and the measurement circuit are checked, and then the adjustment is started from the initial state; after multiple coaxial measurements and multiple coaxial adjustments of the RF superconducting cavity 06, the coaxiality of the cavity cell of the RF superconducting cavity 06 can be adjusted to ≤0.4mm.

[0050] What is disclosed above is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. A person skilled in the art can understand that all or part of the processes of the above embodiments and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A method for adjusting the coaxiality of a radio frequency superconducting cavity, using a radio frequency superconducting cavity coaxiality adjustment device for adjustment, the radio frequency superconducting cavity coaxiality adjustment device comprising an adjustment and measurement mechanism, a clamping and fixing mechanism, a U-shaped support seat for supporting two ends of the radio frequency superconducting cavity, and a test flange installed at two ends of the radio frequency superconducting cavity, and a platform for installing the adjustment and measurement mechanism, the clamping and fixing mechanism, and the U-shaped support seat; The clamping and fixing mechanism includes a pressing component and supporting components arranged on both sides of the pressing component; the supporting component supports the RF superconducting cavity upward, and the pressing component presses the RF superconducting cavity downward, so as to fix the RF superconducting cavity by using the mutual cooperation between the pressing component and the supporting component; The top support assembly includes a support base, a support block, and a support rod; the support rod is longitudinally arranged on the support base, the support block is slidably arranged on the support rod and is located directly above the support base, and a support nut for squeezing the support block upward is threadedly sleeved on the support rod; The adjustment and measurement mechanism includes a fixed support assembly and a dial indicator disposed on the fixed support assembly for measuring the height and level of the pressing assembly; The fixed support assembly includes a fixed seat, a longitudinal rod, and a transverse rod for mounting a dial indicator; the longitudinal rod is longitudinally arranged on the fixed seat, the transverse rod is horizontally arranged on the longitudinal rod, and the transverse rod can be adjusted up and down along the longitudinal rod; The pressing assembly comprises a pressing base, a pressing block and a pressing rod; the pressing rod is longitudinally arranged on the pressing base, the pressing block is slidably arranged on the pressing rod and is located directly above the pressing base, and a pressing nut for pressing the pressing block downward is threadedly sleeved on the pressing rod; Features: The following steps are included: S1: Establish a measurement reference coordinate system with the vertical line of the RF superconducting cavity passing through the center of the coupling flange as the X-axis, the line connecting the centers of the two reference rings of the RF superconducting cavity as the Z-axis, and the normal of the intersection of the Z-axis and the X-axis as the Y-axis; S2: First, fix the U-shaped support seat on the platform, then put the beam tube flanges on both sides of the RF superconducting cavity into the U-shaped support seat, and fix them with a plastic gun to ensure that the coupling flanges of the RF superconducting cavity are rotated to the vertical direction; S3: After the RF superconducting cavity is fixed, first measure the XYZ axis of the reference coordinate system, then measure the middle cylinder of each cavity cell, and obtain the center point of each cavity cell, the deviation distance between the center point of the cavity cell and the Z axis, that is, the coaxial deviation, and the position of the center point of the cavity cell in the quadrant, that is, the coaxial deviation direction; S4: According to the measurement results, determine the offset value and direction of the cavity cell, and rotate the cavity cell or several cavity cells with the largest offset to the top; S5: Adjust the upper end surface of the clamping block to be level with the platform, place dial indicators at both ends and adjust them to zero, and magnetically absorb the fixing base onto the platform; install the test flange and antenna on the two end cavity flanges of the RF superconducting cavity, connect one end to the channel 1 of the vector network instrument, and the other end to the channel 2 of the vector network instrument, and monitor the cavity cell frequency during the whole process of coaxial adjustment; S6: Use a wrench to tighten the two clamping nuts at the same time, observe the size of the dial indicator descent, and the pressure drop is 0.05mm each time to ensure that the two dial indicators drop to the same height. Observe the change in cavity cell frequency during the coaxial adjustment process; measure the cavity cell frequency every 0.2mm drop and record the change value; maintain the pressure for 5 minutes after adjusting to the position, and then loosen the clamping nuts one by one, and the dial indicator rises 0.05mm each time until the clamping nuts are completely loosened. Record the value of the dial indicator descent, that is, the actual change in cavity cell adjustment, and record the cavity cell frequency.

2. The method for adjusting the coaxiality of a radio frequency superconducting cavity according to claim 1, characterized in that: In step S3, the rotation angle of the cavity cell can be determined based on the angle between the coupling flange and the platform; the clamping block is fixed to the cavity cell with the largest deviation, and the clamping block is adjusted to a horizontal deviation of less than 0.1 mm; the support base is fixed to both sides of the cavity cell with the largest deviation, and the support nut is adjusted to make the support block fit tightly against the cavity cell; the U-shaped support seat, the support base, the clamping base and the platform are fixed with a pressure plate.

3. The method for adjusting the coaxiality of a radio frequency superconducting cavity according to claim 1, characterized in that: In step S5, during the coaxial adjustment process, the cavity cell frequency is allowed to vary by ±0.2 MHz.

4. The method for adjusting the coaxiality of a radio frequency superconducting cavity according to claim 1, characterized in that: In step S6, the total amount of each coaxial adjustment is 30% of the maximum value of the cavity cell offset, that is, the total height of the dial indicator descending is 30% of the cavity cell offset.

5. The method for adjusting the coaxiality of a radio frequency superconducting cavity according to claim 1, characterized in that: In step S6, no matter the coaxial adjustment is performed each time or multiple times, the frequency change is always calculated with reference to the initial frequency of the cavity cell; During the adjustment process, if the frequency change exceeds the allowable change, stop the adjustment steps immediately, restore the initial state of the adjustment, check the tooling condition and measurement circuit, and then start the adjustment from the initial state; After multiple coaxial measurements and adjustments of the RF superconducting cavity, the coaxiality of the cavity cell of the RF superconducting cavity can be adjusted to ≤0.4mm.

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