CN111812702A - A low-impedance beam position detector and method of making the same - Google Patents

Abstract

The invention discloses a low-impedance beam position detector and a manufacturing method thereof, wherein the detector comprises contact fingers, a main cavity barrel, corrugated pipes and C-shaped springs, the contact fingers are respectively arranged at two ends of the main cavity barrel, the corrugated pipes are respectively arranged on the peripheries of the joints of the contact fingers and the main cavity barrel, a spring mounting groove is arranged between the outer side of each contact finger and the inner side of each corrugated pipe, and the C-shaped springs are arranged in the spring mounting grooves. The manufacturing method mainly comprises the steps of simulation analysis, part processing, assembly forming and performance detection. The invention is improved and optimized on the basis of the traditional double-finger type shielding structure, can realize smooth and stable transition of an irregular inner cavity and excellent high-frequency conductivity, effectively reduces leakage of a high-order mode, and reduces impedance.

Description

A low-impedance beam position detector and method of making the same

technical field

The invention relates to the technical field of high-energy physics, in particular to a low-impedance beam position detector and a manufacturing method thereof.

Background technique

Beam orbit stability is one of the key performance indicators of modern synchrotron radiation sources, which directly affects the performance of accelerators and the quality and stability of synchrotron beams at experimental line stations. The Beam Position Monitor (BPM) generally has four electrodes. The position of the beam centroid is calculated by collecting the induced signal on each electrode. As an instrument for beam position and orbit measurement, the resolution is required to reach 0.1 μm, the mechanical stability reaches 50nm. The noise and vibration in the environment (~100nm) and the vibration of the surrounding accelerator equipment will affect the stability of the beam trajectory. Therefore, the BPM should adopt a special independent support structure and design bellows at both ends to reduce the vibration transmission of the surrounding environment, and provide installation at the same time. Necessary space and error compensation to absorb thermal expansion and variation during bake-out and operation.

The BPM bellows must have a high-frequency (RF) shielding mechanism, which is generally composed of metal wires or metal strips with low resistance, forming a consistent envelope with the beam vacuum chamber section, and maintaining good electrical contact with the beam vacuum chamber at both ends. The corrugated structure of the bridging bellows forms a direct path for the mirrored wall current to eliminate the cavity-like structure, reduce impedance, reduce higher-order mode (HOM) leakage and beam instability. At the same time, the gaps between the metal strips serve as gas channels inside and outside the envelope, which facilitates the extraction of the gas in the corrugated structure.

The existing bellows shielding spring finger structures mainly include single-finger type, double-finger type, and metal mesh sleeves, and each type of structure has its own characteristics and application scope. The position of the synchrotron radiation light source intensifier has the characteristics of irregular beam cross section, small space, short beam direction length, and large bellows compression. At the same time, the application of the bellows shielding spring finger structure in engineering also needs to meet the radial dislocation and axial deflection, it needs to have good electrical conductivity, uniform and stable contact force, and low impedance. The two-finger shielding structure provides the current path by the contact finger, and the spring finger provides the contact force. Compared with the single-finger type, the contact force is basically lower. change, the resistance remains constant, and at the same time, the high temperature area and the high stress are separated, which reduces the possibility of damage, and has a lower impedance than the mesh sleeve structure, so it is more suitable for this application.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the deficiencies of the prior art, and provide a low-impedance beam position detector, the detector of this structure can realize smooth and smooth transition of irregular inner cavity and excellent high-frequency conductivity, and effectively reduce the high-order mode leakage, reducing impedance.

Another object of the present invention is to provide a manufacturing method of the above-mentioned low-impedance beam position detector.

The technical scheme of the present invention is: a low-impedance beam current position detector, comprising a contact finger, a main cavity cylinder, a bellows and a C-type spring, the two ends of the main cavity cylinder are respectively provided with contact fingers, each contact finger and the main cavity Bellows are respectively arranged on the outer periphery of the connection of the cylinder, spring installation grooves are left between the outer sides of the contact fingers and the inner sides of the bellows, and C-shaped springs are arranged in the spring installation grooves. Among them, the C-type spring is used to press the contact finger to reduce the radial size, and a more uniform and stable contact force is obtained on the irregular beam section, which is better than 100±20g; at the same time, the close contact between the contact finger and the C-type spring is used. Sliding can ensure the electrical conductivity of the device during axial compensation, radial offset and rotation, and shield the cavity-like structure of the bellows to achieve low impedance requirements.

The inner side of the bellows is also provided with a spring fixing ring, one end of the spring fixing ring extends to connect with the main cavity cylinder, and a spring installation groove is formed on the inner side of the spring fixing ring on the outside of the connection between the contact finger and the main cavity cylinder; The C-shaped spring is arranged in the spring installation groove, and the arc-shaped inner side of the C-shaped spring is pressed against the contacting boss of the contact finger and the main cavity cylinder.

The outer circumference of the end of the contact finger is also provided with an outer sleeve, one end of the outer sleeve is welded with the end of the bellows, the other end of the outer sleeve is provided with a knife-edge flange, and the inner cavity of the knife-edge flange is processed with a conical surface, which can be Ensures a smooth transition with the contact fingers to reduce impedance.

An installation support block is also connected to the outer side of the main cavity cylinder, a bellows support block is also connected to the outer periphery of each knife edge flange, and a support screw is arranged between the installation support block and the bellows support block.

The cross section of the inner cavity of the contact finger is oval, and a plurality of fins are distributed on the outer side of the contact finger.

The inner cavity section of the main cavity tube is oval, and the outer circumference of the main cavity tube is distributed with wall penetrations with button electrodes, and each wall penetration is located on the same cross section between the two bellows.

The cross section of the C-shaped spring is C-shaped, and an elliptical annular structure is formed after being rolled and formed.

In addition, when assembling the low-impedance beam position detector of the above structure, in order to ensure welding reliability, transition bridges are welded at both ends of each bellows respectively, and the transition bridges are connected to the main cavity cylinder or the outer sleeve.

The manufacturing method of the above-mentioned low-impedance beam position detector includes the following steps:

(1) Simulation analysis: Use CST software simulation analysis and ANSYS software simulation analysis respectively to build the low-impedance physical structure model of the detector, and optimize the contact finger structure and cavity structure; then use ANSYS software to optimize the axial expansion and contraction of the contact finger amount, radial offset and rotational offset angle; obtain the optimal size parameters of the contact finger and lumen structure;

(2) Parts processing: According to the probe model obtained after the optimization in step (1), the main cavity cylinder, the edge flange, the C-type spring, the contact finger and the bellows are processed respectively;

(3) Assembling and forming: Assemble, debug and weld and fix the parts after processing and forming;

(4) Performance testing: The whole formed probe is subjected to helium mass spectrometry vacuum leak detection, ultimate vacuum extraction, size measurement, impedance measurement and temperature rise measurement.

In the step (1), the optimized contact finger width is 2.39mm, and the finger slit width is 0.31mm; the axial expansion and contraction amount of the bellows obtained after optimization is ±4mm, and the radial offset is ±1mm, The rotation offset angle is ±0.5°.

In the step (2), when each part is processed, the main cavity barrel and the edge flange are processed by the CNC machining center respectively, and after completion, the detection method of the three-coordinate measuring instrument is used to verify the accuracy to ensure that the accuracy requirements are met. After that, polish the inner cavity surfaces of the main cavity cylinder and the knife edge flange respectively;

The C-type spring is formed by die stamping, and then the contact force test is carried out through the motion platform equipped with a digital display precision tension gauge;

The contact finger is processed by wire cutting, and then the cross-section is formed by pressing the mold to obtain an elliptical cross-section. Finally, the surface of the contact finger is gold-plated (the gold-plated contact finger has better conductivity, and it can also prevent the contact finger and C type. Atomic penetration bonding is generated between the springs), and then repeated expansion, deflection and rotation motions are realized on the motion platform through the strain gauges, and stress, deformation and fatigue tests are carried out;

Among them, the corrugated pipe can use the common corrugated pipe of similar equipment in the market.

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

The low-impedance beam position detector is improved and optimized on the basis of the traditional two-finger shielding structure, which can realize smooth and smooth transition of irregular cavity and excellent high-frequency conductivity, effectively reduce the leakage of high-order modes, reduce impedance.

In the low-impedance beam position detector and the manufacturing method thereof, by optimizing the finger width and finger slit width of the contact finger, the leakage of the high-order mode can be effectively reduced, and the impedance can be reduced; Thereby reducing the radial size and obtaining a more stable contact force on the irregular beam cross section. At the same time, the contact finger obtains better electrical conductivity and wear resistance through gold plating, avoiding atomic penetration with the C-type spring. cause adhesion.

In the manufacturing method of the low-impedance beam position detector, the structural deformation of the contact finger and the overall impedance of the BPM are analyzed, and the appropriate C-type spring and contact finger structure size are selected optimally, and the axial length compensation and radial offset of the bellows are used. The method of obtaining low impedance during rotation compensation can not only better obtain the shielding spring finger manufacturing method of this irregular beam cross-section, but also apply to the shielding of thin-walled vacuum tubes with more special-shaped or regular cross-sections and special-shaped curved surfaces. Spring refers to the manufacturing method.

Description of drawings

FIG. 1 is a schematic diagram of the overall structure of the low-impedance beam position detector.

FIG. 2 is a top view of the low impedance beam position detector shown in FIG. 1 .

FIG. 3 is a cross-sectional view taken along the line A-A of FIG. 2 .

FIG. 4 is a cross-sectional view taken along the line B-B in FIG. 3 .

FIG. 5 is a cross-sectional view taken along the C-C direction of FIG. 2 .

FIG. 6 is a schematic structural diagram of a single contact finger.

FIG. 7 is a schematic view of a radial cross-section of a contact finger.

FIG. 8 is a schematic structural diagram of a C-type spring.

FIG. 9 is a schematic diagram of a radial cross-section of a C-shaped spring.

FIG. 10 is a partial cross-sectional view along line D-D of FIG. 9 .

In the above figures, the parts shown by the reference numerals are as follows: 1 is the contact finger, 2 is the main cavity cylinder, 3 is the bellows, 4 is the C-shaped spring, 5 is the spring fixing ring, 6 is the outer sleeve, and 7 is the outer sleeve. Knife-edge flange, 8 is an installation support block, 9 is a bellows support block, 10 is a support screw, 11 is a transition bridge), and 12 is a wall penetration with button electrodes.

Detailed ways

The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto.

Example 1

A low-impedance beam position detector in this embodiment has a structure as shown in Figures 1 to 5, including a contact finger 1, a main cavity cylinder 2, a bellows 3 and a C-shaped spring 4. The two ends of the main cavity cylinder are respectively Contact fingers are provided, bellows are respectively arranged on the outer periphery of the junction of each contact finger and the main cavity cylinder, spring installation grooves are left between the outer sides of the contact fingers and the inner side of the bellows, and C-shaped springs are arranged in the spring installation grooves. Among them, the C-shaped spring structure is used to compress the contact fingers, reducing the radial size and obtaining a more uniform and stable contact force on the irregular beam section, which is better than 100±20g; at the same time, through the tight contact between the contact fingers and the C-shaped spring Contact and sliding can ensure the electrical conductivity of the device during axial compensation, radial offset and rotation, shield the cavity-like structure of the bellows, and achieve low impedance requirements.

The inner side of the bellows is also provided with a spring fixing ring 5. One end of the spring fixing ring extends out to connect with the main cavity cylinder. On the outside of the junction between the contact finger and the main cavity cylinder, the inner side of the spring fixing ring forms a spring installation groove ( As shown in Figure 3 or Figure 5); the C-type spring is arranged in the spring installation groove, and the arc-shaped inner side of the C-type spring is pressed against the contacting boss of the contact finger and the main cavity cylinder.

The outer periphery of the end of the contact finger is also provided with an outer sleeve 6, one end of the outer sleeve is welded with the end of the bellows, the other end of the outer sleeve is provided with a knife-edge flange 7, and the inner cavity of the knife-edge flange is processed with a conical surface (such as 3 or 5), in this embodiment, the inclination ratio of the bevel angle is less than 1:10, which can ensure a smooth transition with the contact finger and thus reduce the impedance.

As shown in FIG. 1 , an installation support block 8 is connected to the outer side of the main cavity, and a bellows support block 9 is also connected to the outer periphery of each blade flange. A support screw 10 is provided between the installation support block and the bellows support block.

As shown in FIG. 6 or FIG. 7 , the cross section of the inner cavity of the contact finger is oval, and a plurality of fins are distributed on the outer surface of the contact finger. In this embodiment, 39 fins are distributed on the outer surface of the contact finger, the finger width (ie the width of the fins) is 2.39mm, the width of the finger slit (ie the distance between two adjacent fins) is 0.31mm, The wall thickness of the contact finger is 0.2mm. The surface of the contact finger is plated with gold to reduce the resistivity, improve the electrical contact performance, avoid the atomic penetration between the C-type spring and lead to adhesion, and at the same time improve the wear resistance and reduce the friction caused by friction. Metal or its oxide dust ions to avoid affecting vacuum performance.

As shown in Fig. 1 or Fig. 2, the section of the inner cavity of the main cavity is oval, and the outer circumference of the main cavity is distributed with wall-penetrating sub-joints 12, and each wall-penetrating sub-joint is located on the same cross-section between the two corrugated pipes . In this embodiment, the outer side of the main cavity cylinder is cylindrical with a diameter of 61.9mm; the inner cavity of the main cavity cylinder is oval, the short axis of the inner diameter is 30mm, the long axis of the inner diameter is 36mm, and the main cavity cylinder is connected with the contact fingers The wall thickness is 0.7mm; the two ends of the main cavity cylinder are symmetrical in structure, the contact position of the main cavity cylinder and the contact finger, the chamfer of the elliptical cavity is 30°, and the transition effect of the chamfer can effectively change the structural mutation , thereby reducing the impedance.

As shown in FIGS. 8 to 10 , the cross-section of the C-shaped spring is C-shaped, and an elliptical annular structure is formed after rolling. In this embodiment, the elastic force of the C-shaped spring is controlled to be 100±20g by the width of the spring installation groove. The width of the C-type spring is 2.6mm, and the thickness of the C-type spring is 0.09mm. Correspondence with deformation.

The bellows can be stretched or compressed in the axial direction, and can also have a certain offset in the radial direction or the rotation direction. In this embodiment, the axial expansion and contraction of the bellows is ±4mm, and the radial offset is ±1mm , the rotation offset angle is ±0.5°. This change is mainly for the contact fingers. It is necessary to ensure that the contact fingers do not fatigue failure, and at the same time ensure the electrical contact performance. Although the bellows also has this requirement, it does not affect the electrical performance. The main consideration is fatigue failure and vacuum damage. .

In addition, when the low-impedance beam position detector of the above structure is installed, in order to further stabilize the structure of the device, transition bridges 11 are also provided where the two ends of each bellows connect with the main cavity cylinder and the outer sleeve respectively.

Example 2

This embodiment provides a method for manufacturing the low-impedance beam position detector described in Embodiment 1, including the following steps:

(1) Simulation analysis: Use CST software simulation analysis and ANSYS software simulation analysis respectively to build a low-impedance physical structure model of the detector, and optimize the structure of the contact finger (according to actual needs, the optimized parameters include the finger width of the contact finger, Finger slit width) and inner cavity structure (main cavity cylinder steps and angles of rounded or chamfered corners, etc.), so as to obtain data corresponding to low impedance results as much as possible; and then optimize the length, width and thickness of the contact fingers through ANSYS software to achieve Axial expansion, radial offset and rotation angle; obtain the optimal size parameters of the contact finger and inner cavity structure;

Among them, in the optimization process of the contact finger structure, the CST simulation results show that the wider the contact finger width and the smaller the finger gap, the smaller the impedance is; while the ANSYS simulation results show that the longer the contact finger, the narrower the finger width, the smaller the thickness The thinner it is, the smaller the maximum principal stress is, but it may also cause large deformation, resulting in irregular ellipse of the lumen or non-uniform change in size to increase the impedance, and too small finger slit also affects the vacuum pumping rate; therefore, it is necessary to combine the two analysis results, The preferred contact finger dimensions;

In this embodiment, the optimized contact finger width is 2.39 mm, and the finger slit width is 0.31 mm. The optimized corrugated tube and its shielding structure can ensure that the axial expansion and contraction amount are ±4 mm, and the radial offset is ±1 mm. Rotation angle ±0.5°;

(2) Parts processing: According to the detector model obtained after the optimization in step (1), the main cavity cylinder, the edge flange, the C-type spring, the contact finger and the bellows are processed respectively;

When processing each part, the main cavity barrel and the knife edge flange are processed by the CNC machining center respectively. After completion, the detection method of the three-coordinate measuring instrument is used to verify the accuracy. After ensuring that the accuracy requirements are met, the main cavity barrel and the knife edge The inner cavity surface of the flange is polished separately;

The C-type spring is formed by die stamping, and then the contact force test is carried out through the motion platform equipped with a digital display precision tension meter; during the test, the relationship between the contact force and the spring deformation is established, and the depth of the spring installation groove is adjusted according to the test results corresponding to the structural design to ensure spring contact force;

The contact finger is processed by wire cutting, and then the surface of the contact finger is plated with gold. After completion, the pressed section is formed with a mold to obtain an elliptical section. Finally, the strain gauge is used to realize repeated expansion and contraction, offset and rotation on the moving platform to carry out stress. , deformation and fatigue test, according to the test results to determine the best temperature, time and other parameters of the processing technology to ensure the service life of the contact finger. .

Among them, the corrugated pipe can use the common corrugated pipe of similar equipment in the market.

(3) Assembling and forming: Assemble and weld the parts after processing and forming;

Among them, the knife-edge flange and the contact finger are first fixed by argon arc welding, and the welding seam is polished after welding to ensure a smooth transition, the ellipse section is detected by the mold calibration, and the C-type spring is preliminarily assembled after completion; The axial length of the unilateral knife-edge flange relative to the main cavity is ±4mm, the radial offset is 1mm, and the rotation angle is ±0.5°, and its deformation, stress and fatigue life are detected (can be cut and tested) to meet the requirements After that, use argon arc welding; then weld the main cavity cylinder and the wall penetration with button electrodes, flanges and bellows in sequence; finally weld the main cavity cylinder and the installation support block to complete the assembly of the detector;

(4) Performance testing: Perform helium mass spectrometry vacuum leak detection, ultimate vacuum extraction, size measurement, impedance measurement and temperature rise measurement on the assembled detector as a whole. Impedance measurements were made, and temperature rise measurements were made by means of a thermal test device.

As described above, the present invention can be well realized, and the above-mentioned embodiments are only preferred embodiments of the present invention, and are not intended to limit the scope of implementation of the present invention; It is covered by the scope of protection of the claims of the present invention.

Claims (10)

1. The low-impedance beam position detector is characterized by comprising contact fingers, a main cavity barrel, a corrugated pipe and a C-shaped spring, wherein the contact fingers are arranged at two ends of the main cavity barrel respectively, the corrugated pipe is arranged on the periphery of the joint of each contact finger and the main cavity barrel respectively, a spring mounting groove is reserved between the outer side of each contact finger and the inner side of the corrugated pipe, and the C-shaped spring is arranged in the spring mounting groove.

2. The low impedance beam position detector of claim 1, wherein a spring fixing ring is further disposed inside the bellows, one end of the spring fixing ring extends to be connected to the main chamber cylinder, and a spring mounting groove is formed inside the spring fixing ring outside a connection point of the contact finger and the main chamber cylinder; the C-shaped spring is arranged in the spring mounting groove, and the arc inner side of the C-shaped spring is tightly propped against the connecting boss of the contact finger and the main cavity barrel.

3. The low impedance beam position detector of claim 1, wherein an outer sleeve is further provided around the end of the contact finger, the end of the corrugated tube at one end of the outer sleeve is welded, a knife-edge flange is provided at the other end of the outer sleeve, and the inner cavity of the knife-edge flange is machined with a conical surface.

4. The low impedance beam position detector of claim 3, wherein the outside of the main chamber cylinder is further connected with a mounting support block, the periphery of each knife-edge flange is further connected with a bellows support block, and a support screw is arranged between the mounting support block and the bellows support block.

5. The low impedance beam position detector of claim 1, wherein the contact finger has an elliptical cross-section and a plurality of fins are distributed on the outer side of the contact finger.

6. The low impedance beam position detector of claim 1, wherein the cross section of the inner cavity of the main cavity cylinder is elliptical, wall penetrating devices with button electrodes are distributed on the periphery of the main cavity cylinder, and each wall penetrating device is located on the same cross section between the two corrugated pipes.

7. The low impedance beam position detector of claim 1, wherein the cross section of the C-shaped spring is C-shaped, and an elliptical ring-shaped structure is formed after rolling.

8. The method for manufacturing the low impedance beam position detector of any one of claims 1 to 7, characterized by comprising the following steps:

(1) simulation analysis: respectively adopting CST software simulation analysis and ANSYS software simulation analysis to construct a low-impedance physical structure model of the detector and optimize the structures of the contact fingers and the inner cavity; then optimizing a contact finger structure by ANSYS software to realize axial expansion amount, radial offset and rotary offset angle; obtaining optimal size parameters of the contact fingers and the inner cavity structure;

(2) processing parts: respectively processing a main cavity cylinder, a knife edge flange, a C-shaped spring, a contact finger and a corrugated pipe according to the probe model obtained after optimization in the step (1);

(3) assembling and forming: assembling, debugging and welding and fixing the machined and molded parts;

(4) and (3) performance detection: and performing helium mass spectrum vacuum leak detection, ultimate vacuum pumping, size measurement, impedance measurement and temperature rise measurement on the whole formed probe.

9. The method for manufacturing a low impedance beam current position detector according to claim 8, wherein in the step (1), the contact finger width after optimization is 2.39mm, and the finger slit width is 0.31 mm; the axial expansion amount of the corrugated pipe and the shielding structure of the corrugated pipe obtained after optimization is +/-4 mm, the radial offset is +/-1 mm, and the axial rotation offset angle is +/-0.5 degrees.

10. The manufacturing method of the low impedance beam position detector according to claim 8, wherein in the step (2), when each part is processed, the main cavity cylinder and the knife-edge flange are respectively processed through a numerical control processing center, after the processing, a detection mode of a three-coordinate measuring instrument sampling point is adopted for precision verification, and after the precision requirement is met, the inner cavity surfaces of the main cavity cylinder and the knife-edge flange are respectively polished;

the C-shaped spring is punched and formed by a die, and then a digital display precision tension meter is carried on a motion platform to carry out contact force test;

the contact finger is processed by linear cutting, then gold plating treatment is carried out on the surface of the contact finger, a mould is utilized to shape the pressed section to obtain an oval section, and finally repeated stretching, deviation and rotation motion is realized on a motion platform through a strain gauge to carry out stress, deformation and fatigue test.

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