Method and device for measuring coaxiality of drift tube linear accelerator

Abstract

The invention provides a drift tube linear accelerator coaxiality measuring method and device, and relates to the field of quality detection and heavy ion accelerators. According to the method, three-coordinate measuring software is utilized to edit a measuring program through a drift tube three-dimensional model, a star-shaped measuring needle is controlled to make contact with measuring elements needed by each measured drift tube, a measuring seat is adjusted to a needed angle by utilizing the characteristic that the star-shaped measuring needle can conduct multi-direction measurement, when the star-shaped measuring needle triggers measuring point information, position information of the touch measuring elements is obtained, and the position information of the touch measuring elements is obtained. And then the information is transmitted to the computer through the control system by the sensor, and the measurement software processes the data, so that the coaxiality of the drift tube can be evaluated and obtained. According to the method, the defect that the coaxiality of each drift tube cannot be measured by a traditional measurement method is overcome, the coaxiality measurement precision of each drift tube is ensured to reach 0.01 through the three-coordinate measurement system and the star-shaped probe, the processing quality of the drift tube is ensured, and the method plays a positive role in promoting the research and development of the whole project of the high-flow-intensity linear injector.

Description

Technical Field

[0001] The present invention relates to the field of quality detection and heavy ion accelerator, and in particular to a method and device for measuring the coaxiality of a drift tube linear accelerator (DTL), which is particularly suitable for a high-current drift tube linear accelerator of a superconducting miniaturized heavy ion cancer treatment device. Background Art

[0002] Heavy ion accelerator is one of the important devices for producing heavy ion beams. It has broad application prospects in frontier disciplines such as materials science, environmental science, particle physics and nuclear physics. Heavy ion synchrotron accelerators require low-energy accelerators as injectors, and high-current drift tube linear accelerators are important components of superconducting miniaturized heavy ion cancer treatment device injectors. When heavy ions pass through the drift tube, when the direction of the electric field is consistent with the direction of the beam, the heavy ions are accelerated through the gap of the drift tube. When the direction of the electric field is opposite to the direction of the beam, the heavy ions just enter the drift tube. Due to the shielding effect of the drift tube, the heavy ion beam is not constrained by the electric field in the opposite direction, that is, it is not decelerated.

[0003] In a linear injector, the DTL drift tube is an important component of the heavy ion beam transmission track. While the electric field is shielded by the DTL drift tube, the beam must pass through the drift tube to enter the vacuum chamber. To ensure that the beam is efficiently transmitted to the vacuum chamber, the axis of each drift tube must coincide with the theoretical center of the heavy ion beam transmission path as much as possible. Therefore, the coaxiality of the DTL drift tube has become a key indicator of the injector. Currently, the industry requires the coaxiality to be less than 0.05. Whether the coaxiality of the DTL drift tube can be measured with high precision is the key to ensuring the processing quality of the injector.

[0004] The existing drift tube coaxiality measurement methods mainly have the following problems:

[0005] 1) Use conventional measuring instruments such as height gauge, depth gauge, vernier caliper, etc., in conjunction with equal height blocks or measuring fixtures for testing. This method cannot accurately measure the coaxiality with a tolerance of 0.05 due to the systematic errors, processing errors, and instrument accuracy of the measuring fixtures and equal height blocks themselves;

[0006] 2) Use various specifications of mandrels with an outer diameter smaller than the inner diameter of the drift tube by 0~0.2mm and a generatrix straightness less than 0.02 to try to pass through each drift tube. The mandrel diameter is indirectly reflected. On the one hand, the specific result of coaxiality cannot be accurately measured. On the other hand, the error in mandrel processing leads to inaccurate measurement;

[0007] 3) Use the three-coordinate ordinary straight probe measurement method. Due to the limited length of the ordinary straight probe, it is difficult to measure the coaxiality of each drift tube when the distance between the beam inlet and outlet is large, the gap is large, and the number of drift tubes is large.

[0008] In summary, the above three measurement methods are difficult to achieve high-precision and full-coverage measurement of the coaxiality of the linear injector DTL drift tube. Summary of the invention

[0009] Aiming at the defects of inaccurate and incomplete measurement in the traditional measurement method of the coaxiality of a linear injector DTL drift tube, the present invention provides a method and device for measuring the coaxiality of a drift tube linear accelerator.

[0010] In order to solve the above problems, the present invention provides a method for measuring the coaxiality of a drift tube linear accelerator, which uses a three-coordinate measurement system and a star-shaped probe to measure the coaxiality of multiple drift tubes to be measured, wherein the star-shaped probe includes probes No. 2 and No. 4 pointing to the positive and negative directions of the X-axis, probes No. 3 and No. 5 pointing to the positive and negative directions of the Y-axis, and probe No. 1 pointing to the negative direction of the Z-axis; the method comprises: step S1, installing the star-shaped probe on a measuring seat, adjusting the probes No. 3 and No. 5 to be parallel to the Y-axis direction of the three-coordinate measurement system, and calibrating the star-shaped probe; step S2, placing multiple drift tubes to be measured at the same height on the three-coordinate measurement system, and controlling the axes of the multiple drift tubes to be measured to be parallel to the Y-axis direction of the three-coordinate measurement system; step S3, The No. 3 probe is inserted into the front end face of the first drift tube to be tested with a predetermined length to measure a first cross-sectional circle, and the No. 5 probe is inserted into the rear end face of the last drift tube to be tested with the predetermined length to measure another first cross-sectional circle, and the centers of the two first cross-sectional circles are used to construct the reference axes of the multiple drift tubes to be tested; step S4, for each drift tube to be tested, the No. 3 and No. 5 probes are respectively inserted into the front and rear end faces of the current drift tube to be tested with the predetermined length to measure two second cross-sectional circles, and the centers of the two second cross-sectional circles are used to construct the central axis of the current drift tube to be tested; step S5, for each drift tube to be tested, the constructed intermediate axis and the reference axis are subjected to data processing to obtain the coaxiality of the current drift tube to be tested.

[0011] Furthermore, a stylus ball is provided at the end of each stylus in the star-shaped stylus; in the step S1, calibrating the star-shaped stylus includes: calibrating the corresponding stylus using a standard ball.

[0012] Furthermore, each of the star-shaped measuring needles is made of stainless steel, and each of the measuring balls is made of ruby.

[0013] Furthermore, the step S2 specifically includes: using equal height blocks to raise multiple drift tubes to be measured and place them on the three-coordinate measurement system; adjusting the installation reference surface parallel to the axial direction of each drift tube to be measured so that the axis of each drift tube to be measured is parallel to the Y-axis direction of the three-coordinate measurement system.

[0014] Further, the adjusting of the installation reference plane parallel to the axial direction of each drift tube under test includes: collecting a measuring point at the same height of the front and rear ends of the installation reference plane, so that the deviation of the two measuring points in the X-axis direction of the three-coordinate measurement system is within a predetermined range.

[0015] Furthermore, the predetermined lengths are smaller than the lengths of the No. 3 and No. 5 measuring needles.

[0016] Furthermore, the three-coordinate measurement system is built with measurement software; the step S5 comprises: using the measurement software to process the constructed intermediate axis and the reference axis to obtain the coaxiality of the drift tube being measured.

[0017] On the other hand, the present invention provides a device for measuring the coaxiality of a drift tube linear accelerator, which uses a three-coordinate measuring system and a star-shaped probe to measure the coaxiality of multiple drift tubes to be measured, wherein the star-shaped probe includes probes No. 2 and No. 4 pointing to the positive and negative directions of the X-axis, probes No. 3 and No. 5 pointing to the positive and negative directions of the Y-axis, and probe No. 1 pointing to the negative direction of the Z-axis; the device includes: a probe installation module, which is used to install the star-shaped probe on a measuring seat, adjust the probes No. 3 and No. 5 to be parallel to the Y-axis direction of the three-coordinate measuring system, and calibrate the star-shaped probe; a drift tube setting module, which is used to place multiple drift tubes to be measured at the same height on the three-coordinate measuring system, and control the axes of the multiple drift tubes to be measured to be parallel to the Y-axis direction of the three-coordinate measuring system; a reference axis determination module, which is used to place the The No. 3 probe is inserted into the front end face of the first drift tube to be tested with a predetermined length to measure a first cross-sectional circle, and the No. 5 probe is inserted into the rear end face of the last drift tube to be tested with the predetermined length to measure another first cross-sectional circle, and the centers of the two first cross-sectional circles are used to construct the reference axes of the multiple drift tubes to be tested; a central axis determination module is used to, for each drift tube to be tested, insert the No. 3 and No. 5 probes into the front and rear end faces of the current drift tube to be tested with the predetermined length respectively to measure two second cross-sectional circles, and the centers of the two second cross-sectional circles are used to construct the central axis of the current drift tube to be tested; a coaxiality determination module is used to, for each drift tube to be tested, perform data processing on the constructed intermediate axis and the reference axis to obtain the coaxiality of the current drift tube to be tested.

[0018] Furthermore, a stylus ball is provided at the end of each stylus in the star-shaped stylus; and the stylus mounting module is further used to calibrate the corresponding stylus using a standard ball.

[0019] Furthermore, each of the star-shaped measuring needles is made of stainless steel, and each of the measuring balls is made of ruby.

[0020] Compared with the prior art, the drift tube linear accelerator coaxiality measurement method and device provided by the present invention have at least the following beneficial effects:

[0021] (1) It not only makes up for the defect that the traditional measurement method cannot measure the coaxiality of each drift tube, but also ensures that the coaxiality measurement accuracy of each drift tube reaches 0.01 through the three-coordinate measurement system and star-shaped probe;

[0022] (2) The processing quality of the drift tube was ensured, which played a positive role in promoting the research and development of the entire high-current linear injector project. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0024] Figure 1 A schematic diagram of the structure of a star-shaped probe according to an embodiment of the present invention is shown;

[0025] Figure 2 Schematically shows the Figure 1 A dimensional drawing of a star stylus;

[0026] Figure 3 A flow chart schematically shows a method for measuring the coaxiality of a drift tube linear accelerator according to an embodiment of the present invention;

[0027] Figure 4 Schematically shows the Figure 3 A layout diagram of the installation reference surface parallel to the axial direction of each drift tube to be measured;

[0028] Figure 5 Schematically shows the Figure 3 Arrangement diagram of multiple drift tubes and star probes to be measured;

[0029] Figure 6 Schematically shows the Figure 5 The layout diagram of the cross-section circle is measured using the No. 3 and No. 5 probes of the star probe;

[0030] Figure 7 The structure block diagram of the device for measuring the coaxiality of a drift tube linear accelerator according to an embodiment of the present invention is schematically shown. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings. Obviously, the described embodiments are 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] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0033] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0034] The embodiment of the present invention provides a method for measuring the coaxiality of a drift tube linear accelerator, using a three-coordinate measurement system and a star-shaped probe to measure each drift tube to evaluate the coaxiality. For ease of understanding, the star-shaped probe used in the method is first introduced.

[0035] Figure 1 The structure of a star probe according to an embodiment of the present invention is schematically shown.

[0036] In this embodiment, the star-shaped probes include probes No. 1, No. 2 and No. 4 pointing to the positive and negative directions of the X-axis respectively, probes No. 3 and No. 5 pointing to the positive and negative directions of the Y-axis respectively, and probe No. 1 pointing to the negative direction of the Z-axis.

[0037] Thus, a star stylus comprises multiple styli, ensuring maximum flexibility. In addition, a star stylus can inspect a wide range of different geometries with its multi-directional styli.

[0038] In this embodiment, a stylus ball is disposed at the end of each stylus in the star-shaped stylus. Optionally, each stylus in the star-shaped stylus is made of stainless steel, and each stylus ball is made of ruby.

[0039] Figure 2 Schematically shows the Figure 1 A dimension diagram of a star-shaped probe. Specifically, the following is selected in the measurement Figure 2 The star-shaped probe shown has specifications as shown in Table 1. EWL1 / EWL2 refers to the effective measuring length.

[0040] Table 1

[0041]

[0042] In the actual measurement process, the appropriate star-shaped probe can be selected according to the mechanical properties of the DTL drift tube.

[0043] Based on this, an embodiment of the present invention provides a method for measuring the coaxiality of a drift tube linear accelerator, and electrically connects a star-shaped probe to a three-dimensional coordinate measurement system. The measurement principle is to use the three-dimensional coordinate measurement software to edit the measurement program through the drift tube three-dimensional model, control the star-shaped probe to contact the measurement elements required for each drift tube to be measured, and use the characteristics of the star-shaped probe that can perform multi-directional measurements to adjust the measuring seat to the required angle. When the star-shaped probe triggers the measuring point information, the position information of the touched element is obtained, and then the information is transmitted to the computer through the control system through the sensor. The measurement software processes the data to evaluate the coaxiality of the drift tube.

[0044] Figure 3 The flowchart of the method for measuring the coaxiality of a drift tube linear accelerator according to an embodiment of the present invention is schematically shown.

[0045] Please combine Figure 1 and Figure 3 According to the method for measuring the coaxiality of a drift tube linear accelerator of this embodiment, a three-coordinate measuring system and a star-shaped probe are used to measure the coaxiality of multiple drift tubes to be measured, and the star-shaped probe includes a first, second and fourth probes pointing to the positive and negative directions of the X-axis, respectively, a third and fifth probes pointing to the positive and negative directions of the Y-axis, respectively, and a first probe pointing to the negative direction of the Z-axis; the method includes steps S1 to S5.

[0046] Step S1, install the star probe on the measuring base, adjust the No. 3 and No. 5 probes parallel to the Y-axis direction of the three-dimensional coordinate measurement system, and calibrate the star probe.

[0047] Adjust the No. 3 and No. 5 probes parallel to the Y-axis direction of the three-dimensional coordinate measurement system, and calibrate the star probe so that the star probe can be calibrated successfully. Since a probe ball is provided at the end of each probe in the star probe, the corresponding probe can be calibrated using a standard ball. The calibration method of the probe can refer to the prior art, and the specific description of the present invention will not be repeated.

[0048] Optionally, each stylus in the star-shaped stylus is made of stainless steel, and each stylus ball is made of ruby.

[0049] Step S2, placing a plurality of drift tubes to be measured at the same height on a three-coordinate measurement system, and controlling the axes of the plurality of drift tubes to be measured to be parallel to the Y-axis direction of the three-coordinate measurement system.

[0050] For example, multiple drift tubes to be measured are elevated and placed on a three-coordinate measuring system using equal height blocks; the mounting reference surface parallel to the axis direction of each drift tube to be measured is adjusted so that the axis of each drift tube to be measured is parallel to the Y-axis direction of the three-coordinate measuring system.

[0051] Figure 4 Schematically shows the Figure 3 A layout diagram of the installation reference surface parallel to the axial direction of each drift tube to be measured. Figure 4 As shown, by adjusting the installation reference surface, the drift tube axis can be made parallel to the Y-axis direction of the three-coordinate measurement system.

[0052] For further information, please refer to Figure 3 , the above-mentioned adjustment of the installation reference plane parallel to the axial direction of each drift tube to be measured includes: collecting a measuring point at the same height of the front and rear ends of the installation reference plane, so that the deviation of the two measuring points in the X-axis direction of the three-coordinate measurement system is within a predetermined range. The predetermined range can be independently predetermined according to actual conditions, and the present invention does not impose any specific restrictions. Controlling the deviation in the X-axis direction within the predetermined range is to ensure that the star-shaped probe can measure the expected measured element and avoid interference between the probe and the measuring ball and the drift tube to be measured.

[0053] Next, the workpiece coordinate system can be established using the above-mentioned installation reference plane and drawing reference plane to clarify each direction.

[0054] Step S3, inserting probe No. 3 into the front end face of the first drift tube to be measured with a predetermined length to measure a first cross-sectional circle, and inserting probe No. 5 into the rear end face of the last drift tube to be measured with a predetermined length to measure another first cross-sectional circle, and using the centers of the two first cross-sectional circles to construct the reference axes of multiple drift tubes to be measured.

[0055] In this embodiment, the predetermined length is smaller than the lengths of the No. 3 and No. 5 measuring needles. Figure 5 Schematically shows the Figure 3 Arrangement diagram of multiple drift tubes and star probes under test. Figure 6 Schematically shows the Figure 5 Use the No. 3 and No. 5 probes of the star probe to measure the layout of the cross-section circle. Figure 5 and Figure 6 As shown, the No. 3 and No. 5 probes are selected to extend into the front and rear end faces of each drift tube to be measured by a predetermined length less than the first probe to ensure that the extending length is effective. Since each of the front and rear end faces can measure a first cross-sectional circle, two first cross-sectional circles are obtained.

[0056] It is understandable that the multiple drift tubes to be tested are generally arranged on the heavy ion beam transmission track and arranged in sequence along the same direction. The two outermost end faces of the multiple drift tubes to be tested, that is, the front end face and the rear end face, are located on different drift tubes. This step uses the centers of the two measured first cross-section circles to construct a unified reference axis of the multiple drift tubes to be tested.

[0057] Step S4, for each drift tube under test, insert No. 3 and No. 5 probes into the front and rear end surfaces of the drift tube under test with a predetermined length, measure two second cross-sectional circles, and use the centers of the two second cross-sectional circles to construct the central axis of the drift tube under test.

[0058] According to the same principle as the previous step, each drift tube under test has two end faces, front and back, and two second cross-sectional circles can be measured using probes No. 3 and No. 5. Then, the center of the two second cross-sectional circles is used to construct the central axis of each drift tube under test. Thus, each drift tube under test can construct a corresponding intermediate axis.

[0059] Step S5: for each drift tube under test, data processing is performed on the constructed intermediate axis and the reference axis to obtain the coaxiality of the drift tube under test.

[0060] Since each drift tube under test can construct a corresponding intermediate axis, and multiple drift tubes under test also have a unified reference axis, in this step, the intermediate axis of each drift tube is processed (eg, compared, fitted) with the unified reference axis to obtain the coaxiality of each drift tube.

[0061] Optionally, the three-coordinate measuring system is equipped with built-in measuring software, which can be used to process the constructed intermediate axis and the reference axis to obtain the coaxiality of the drift tube being measured.

[0062] It can be seen from the above description that the method for measuring the coaxiality of the drift tube linear accelerator provided in the above-mentioned embodiment of the present invention not only makes up for the defect that the traditional measurement method cannot measure the coaxiality of each drift tube, but also, through the three-coordinate measurement system and the star-shaped probe, ensures that the coaxiality measurement accuracy of each drift tube reaches 0.01, thereby ensuring the processing quality of the drift tube and playing a positive role in promoting the research and development of the entire project of high-current linear injector.

[0063] Based on the method disclosed in the above embodiment, the present invention also provides a device for measuring the coaxiality of a drift tube linear accelerator. Figure 7 The device is described in detail.

[0064] Figure 7 The structure block diagram of the device for measuring the coaxiality of a drift tube linear accelerator according to an embodiment of the present invention is schematically shown.

[0065] like Figure 7 As shown, according to the drift tube linear accelerator coaxiality measuring device 700 of this embodiment, the coaxiality of multiple drift tubes to be measured is measured by using a three-coordinate measuring system and a star-shaped probe, and the star-shaped probe includes probes No. 2 and No. 4 pointing to the positive and negative directions of the X-axis, probes No. 3 and No. 5 pointing to the positive and negative directions of the Y-axis, and probe No. 1 pointing to the negative direction of the Z-axis. The measuring device 700 includes a probe installation module 710, a drift tube setting module 720, an intermediate axis determination module 730, a reference axis determination module 740, and a coaxiality determination module 750.

[0066] The stylus installation module 710 is used to install the star stylus on the measuring base, adjust the No. 3 and No. 5 stylus parallel to the Y-axis direction of the three-dimensional coordinate measurement system, and calibrate the star stylus.

[0067] The drift tube setting module 720 is used to place multiple drift tubes to be measured at the same height on the three-coordinate measurement system, and control the axes of the multiple drift tubes to be measured to be parallel to the Y-axis direction of the three-coordinate measurement system.

[0068] The reference axis determination module 730 is used to extend the No. 3 probe into the front end face of the first drift tube to be measured with a predetermined length to measure a first cross-sectional circle, and to extend the No. 5 probe into the rear end face of the last drift tube to be measured with a predetermined length to measure another first cross-sectional circle, and to use the centers of the two first cross-sectional circles to construct the reference axes of multiple drift tubes to be measured.

[0069] The intermediate axis determination module 740 is used to extend the No. 3 and No. 5 probes into the front and rear end surfaces of the drift tube under test with a predetermined length for each drift tube under test, measure two second cross-sectional circles, and use the centers of the two second cross-sectional circles to construct the central axis of the drift tube under test.

[0070] The coaxiality determination module 750 is used to perform data processing on the constructed intermediate axis and the reference axis for each drift tube under test, so as to obtain the coaxiality of the drift tube under test.

[0071] In this embodiment, a stylus ball is provided at the end of each stylus in the star-shaped stylus; the stylus installation module 710 is further used to calibrate the corresponding stylus using a standard ball.

[0072] In this embodiment, each measuring needle in the star-shaped measuring needle is made of stainless steel, and each measuring ball is made of ruby.

[0073] It should be noted that the implementation method of the device part is similar to the implementation method of the method part, and the technical effects achieved are also similar. For specific details, please refer to the above-mentioned method implementation method part, which will not be repeated here.

[0074] The flow chart and block diagram in the accompanying drawings illustrate the possible architecture, function and operation of the system, method and computer program product according to various embodiments of the present invention. In this regard, each box in the flow chart or block diagram can represent a module, a program segment, or a part of a code, and the above-mentioned module, program segment, or a part of a code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flow chart, and the combination of the boxes in the block diagram or flow chart can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0075] In addition, the terms "first" and "second" are used only for descriptive purposes and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the feature. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In addition, the word "one" or "an" preceding an element does not exclude the presence of multiple such elements.

[0076] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for measuring the coaxiality of a drift tube linear accelerator, using a three-coordinate measuring system and a star-shaped probe to measure the coaxiality of multiple drift tubes to be measured, wherein the star-shaped probe comprises probes No. 2 and No. 4 pointing to the positive and negative directions of the X-axis, probes No. 3 and No. 5 pointing to the positive and negative directions of the Y-axis, and probe No. 1 pointing to the negative direction of the Z-axis; characterized in that: The method comprises: Step S1, installing the star-shaped stylus on the measuring base, adjusting the No. 3 and No. 5 stylus to be parallel to the Y-axis direction of the three-dimensional coordinate measurement system, and calibrating the star-shaped stylus; Step S2, placing a plurality of drift tubes to be measured at the same height on the three-coordinate measurement system, and controlling the axes of the plurality of drift tubes to be measured to be parallel to the Y-axis direction of the three-coordinate measurement system; Step S3, inserting the No. 3 probe into the front end face of the first drift tube to be measured with a predetermined length to measure a first cross-sectional circle, and inserting the No. 5 probe into the rear end face of the last drift tube to be measured with the predetermined length to measure another first cross-sectional circle, and using the centers of the two first cross-sectional circles to construct reference axes of the multiple drift tubes to be measured; Step S4, for each drift tube under test, extending the No. 3 and No. 5 probes into the front and rear end surfaces of the drift tube under test with the predetermined lengths, respectively, to measure two second cross-sectional circles, and using the centers of the two second cross-sectional circles to construct the central axis of the drift tube under test; Step S5: for each drift tube under test, data processing is performed on the constructed intermediate axis and the reference axis to obtain the coaxiality of the drift tube under test.

2. The method according to claim 1, characterized in that A stylus ball is disposed at the end of each stylus in the star-shaped stylus; in step S1, calibrating the star-shaped stylus comprises: Use the reference ball to calibrate the corresponding stylus.

3. The method according to claim 2, characterized in that Each of the star-shaped measuring needles is made of stainless steel, and each of the measuring balls is made of ruby.

4. The method according to claim 1, characterized in that The step S2 specifically includes: Using equal height blocks, multiple drift tubes to be measured are raised and placed on the three-coordinate measuring system; The mounting reference surface parallel to the axis direction of each drift tube to be measured is adjusted so that the axis of each drift tube to be measured is parallel to the Y-axis direction of the three-coordinate measurement system.

5. The method according to claim 4, characterized in that The step of adjusting the installation reference surface parallel to the axial direction of each drift tube to be measured comprises: A measuring point is collected at the same height of the front and rear ends of the installation reference surface, respectively, so that the deviation of the two measuring points in the X-axis direction of the three-coordinate measurement system is within a predetermined range.

6. The method according to claim 1, characterized in that The predetermined lengths are smaller than the lengths of the No. 3 and No. 5 measuring needles.

7. The method according to claim 1, characterized in that The three-coordinate measurement system has built-in measurement software; the step S5 includes: The constructed intermediate axis and the reference axis are processed by using the measurement software to obtain the coaxiality of the drift tube being measured.

8. A device for measuring the coaxiality of a drift tube linear accelerator, which uses a three-coordinate measuring system and a star-shaped probe to measure the coaxiality of multiple drift tubes to be measured, wherein the star-shaped probe includes probes No. 2 and No. 4 pointing to the positive and negative directions of the X-axis, probes No. 3 and No. 5 pointing to the positive and negative directions of the Y-axis, and probe No. 1 pointing to the negative direction of the Z-axis; characterized in that: The device comprises: A stylus installation module, used for installing the star-shaped stylus on the measuring base, adjusting the No. 3 and No. 5 stylus to be parallel to the Y-axis direction of the three-dimensional coordinate measurement system, and calibrating the star-shaped stylus; A drift tube setting module, used to place a plurality of drift tubes to be measured at the same height on the three-coordinate measurement system, and control the axes of the plurality of drift tubes to be measured to be parallel to the Y-axis direction of the three-coordinate measurement system; A reference axis determination module, for inserting the No. 3 probe into the front end face of the first drift tube to be measured with a predetermined length to measure a first cross-sectional circle, and inserting the No. 5 probe into the rear end face of the last drift tube to be measured with the predetermined length to measure another first cross-sectional circle, and using the centers of the two first cross-sectional circles to construct the reference axes of the multiple drift tubes to be measured; A central axis determination module is used to extend the No. 3 and No. 5 probes into the front and rear end surfaces of the current drift tube under test with the predetermined lengths for each drift tube under test, measure two second cross-sectional circles, and use the centers of the two second cross-sectional circles to construct the central axis of the current drift tube under test; The coaxiality determination module is used to perform data processing on the constructed intermediate axis and the reference axis for each drift tube under test, so as to obtain the coaxiality of the drift tube under test.

9. The device according to claim 8, characterized in that Each stylus in the star-shaped stylus is provided with a stylus ball at the end thereof; the stylus mounting module is further used for: Use the reference ball to calibrate the corresponding stylus.

10. The device according to claim 9, characterized in that Each of the star-shaped measuring needles is made of stainless steel, and each of the measuring balls is made of ruby.

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