阅读说明：本技术 低纯铌-高纯铌混合制备超导腔及其制备方法 (Superconducting cavity prepared by mixing low-purity niobium and high-purity niobium and preparation method thereof ) 是由 徐孟鑫 黄玉璐 张升学 何源 刘鲁北 蒋天才 王若旭 刘通 李春龙 于 2021-09-09 设计创作，主要内容包括：本发明涉及一种低纯铌-高纯铌混合制备超导腔及其制备方法,该低纯铌-高纯铌混合制备超导腔包括：超导腔的几何结构确定后,通过有限元分析得到所述超导腔内的高频电磁场分布,在运行的过程中,腔体发热最严重的区域在强磁场区,此区域采用高纯铌板材或棒材,而在其他区域采用低纯铌板材或棒材。本发明通过低纯铌和高纯铌来混合制备超导腔,根据超导腔的高频电磁场分布,在不同的位置上采用不同纯度的铌材来制备,从而降低整个工程的造价,还可以提高超导腔的机械强度。(The invention relates to a superconducting cavity prepared by mixing low-purity niobium and high-purity niobium and a preparation method thereof, wherein the superconducting cavity prepared by mixing the low-purity niobium and the high-purity niobium comprises the following steps: after the geometric structure of the superconducting cavity is determined, the high-frequency electromagnetic field distribution in the superconducting cavity is obtained through finite element analysis, in the operation process, the region with the most serious heating of the cavity is in a strong magnetic field region, the region adopts high-purity niobium plates or bars, and other regions adopt low-purity niobium plates or bars. According to the invention, the superconducting cavity is prepared by mixing low-purity niobium and high-purity niobium, and the niobium materials with different purities are adopted at different positions according to the distribution of the high-frequency electromagnetic field of the superconducting cavity, so that the manufacturing cost of the whole project is reduced, and the mechanical strength of the superconducting cavity can be improved.)

1. The superconducting cavity is characterized in that after the geometric structure of the superconducting cavity is determined, the high-frequency electromagnetic field distribution in the superconducting cavity is obtained through finite element analysis, in the operation process, the most serious heating area of the cavity is in a strong magnetic field area, the area adopts high-purity niobium plates or bars, and the other areas adopt low-purity niobium plates or bars.

2. The low purity niobium-high purity niobium hybrid superconducting cavity of claim 1, wherein the superconducting cavity comprises:

the outer conductor (1) is of a hollow structure, the first end of the outer conductor (1) is fixed on the bottom plate (5), two slotted holes which are symmetrically arranged along the axial direction of the outer conductor (1) are formed in the position close to the first end of the outer conductor, nose cones (9) are assembled in the slotted holes, and beam pipelines (10) are assembled on the nose cones (9);

the inner conductor (2) is also of a hollow structure and is arranged in the cavity of the outer conductor (1), a drift tube (8) is assembled at the first end of the inner conductor (2), and the drift tube (8) and the beam pipeline (10) are located on the same central axis.

3. The low purity niobium-high purity niobium hybrid superconducting cavity of claim 2, wherein the superconducting cavity is a quarter wave cavity and the inner conductor (2) is a high purity niobium cavity.

4. The superconducting cavity prepared by mixing low-purity niobium with high-purity niobium as claimed in claim 3, wherein the outer conductor (1) is a low-purity niobium cavity, the nose cone (9) is a low-purity niobium nose cone, the beam line (10) is a low-purity niobium beam line, and the drift tube (8) is a low-purity niobium drift tube.

5. The superconducting cavity prepared by mixing low-purity niobium with high-purity niobium according to claim 4, wherein the second ends of the outer conductor (1) and the inner conductor (2) are provided with an end cap (3) which is connected through the end cap (3), the end cap (3) is provided with a cleaning port (4) for cleaning the outer conductor (1) and the inner conductor (2), the end cap (3) is a high-purity niobium end cap, and the cleaning port (4) is a high-purity niobium cleaning port.

6. The superconducting cavity prepared by mixing low-purity niobium with high-purity niobium as claimed in claim 5, wherein a power coupling port (6) is arranged on the bottom plate (5), a signal extraction port (11) is arranged on the outer conductor (1) and is used for collecting signals in the outer conductor (1) and the inner conductor (2), the power coupling port (6) is a low-purity niobium coupling port, and the signal extraction port (11) is a low-purity niobium port.

7. The superconducting cavity made of low-purity niobium and high-purity niobium mixed according to claim 6, wherein the base plate (5) is provided with a reinforcing rib (7) for improving the mechanical strength of the base plate (5), the base plate (5) is a low-purity niobium base plate, and the reinforcing rib (7) is a low-purity niobium reinforcing rib.

8. The method of claim 1, wherein the method comprises:

preparing parts of the most serious cavity heating area by adopting a high-purity niobium material with the RRR value of more than 300 through a stamping die or a machining method;

preparing parts of other regions except the region with the most serious cavity heating by adopting a low-purity niobium material with the RRR value of 30 through a stamping die or a machining method;

ultrasonic cleaning is carried out on the parts processed by the two steps by utilizing an ultrasonic cleaning device;

adopting hydrofluoric acid: nitric acid: phosphoric acid 1: 1: 2, chemically cleaning the parts cleaned by ultrasonic, wherein the temperature of the acid liquor is controlled to be below 20 ℃, and the cleaning time is controlled to be 10-40 minutes;

cleaning the parts after chemical cleaning by using ultrapure water with resistivity not less than 18M omega cm, and airing in an ultra-clean room superior to 1000 grades;

and (5) welding the parts dried in the ultra-clean room by using a vacuum electron beam welding machine, and finishing the manufacturing.

9. A method for preparing a superconducting cavity by mixing low-purity niobium with high-purity niobium according to any one of claims 2 to 7, comprising:

two semi-inner conductors and the end cover (3) are manufactured by adopting a high-purity niobium material with the RRR value larger than 300 through a stamping die;

four cleaning openings (4) are obtained by adopting a high-purity niobium material with the RRR value of more than 300 through a machining method;

two semi-outer conductors, two nose cones (9) and a bottom plate (5) are manufactured by adopting a low-purity niobium material with the RRR value of 30 through a stamping die;

obtaining the beam pipeline (10), the drift tube (8), the power coupling port (6), the signal extraction port (11) and the reinforcing rib (7) by using a low-purity niobium material with an RRR value of 30 through a machining method;

carrying out ultrasonic cleaning on the parts processed in the four steps by using an ultrasonic cleaning device;

adopting hydrofluoric acid: nitric acid: phosphoric acid 1: 1: 2, chemically cleaning the parts cleaned by ultrasonic, wherein the temperature of the acid liquor is controlled to be below 20 ℃, and the cleaning time is controlled to be 10-40 minutes;

cleaning the parts after chemical cleaning by using ultrapure water with resistivity not less than 18M omega cm, and airing in an ultra-clean room superior to 1000 grades;

and (5) welding the parts dried in the ultra-clean room by using a vacuum electron beam welding machine, and finishing the manufacturing.

10. The method for preparing the superconducting cavity by mixing the low-purity niobium and the high-purity niobium according to claim 9, wherein a vacuum electron beam welding machine is used for welding the parts dried in the ultra-clean room, and the method comprises the following specific steps:

welding the two semi-inner conductors into a complete inner conductor (2), and penetrating the drift tube (8) into the inner conductor (2) to be welded into a whole;

welding two semi-outer conductors into a complete outer conductor (1), welding two nose cones (9) with the corresponding beam pipeline (10) and a flange together, and then welding the nose cones and the outer conductor (1) into a whole;

welding the bottom plate (5) on the outer conductor (1), and welding the reinforcing rib (7), the power coupling port (6) and the flange on the bottom plate (5);

splicing the inner conductor (2) and the outer conductor (1) together and the end cover (3), measuring the frequency of a cavity, and determining the trimming amount of the open ends of the inner conductor (2) and the outer conductor (1) according to the welding allowance and the target frequency;

and welding the end cover (3), the inner conductor (2) and the outer conductor (1) into a whole, welding the cleaning opening (4) on the end cover (3), and welding the corresponding flange and the niobium-titanium alloy sheet on the cleaning opening (4).

Technical Field

The invention relates to a superconducting cavity prepared by mixing low-purity niobium and high-purity niobium and a preparation method thereof, belonging to the field of processing and manufacturing of particle accelerators.

Background

The radio frequency resonant cavity is a key component of the high-energy particle accelerator, and charged particles can be accelerated or deflected by utilizing a high-intensity electromagnetic field established in the resonant cavity by high-power microwaves (radio frequency). Compared with a normal-temperature resonant cavity made of oxygen-free copper, the radio-frequency superconducting cavity made of superconducting materials and working at 2K or 4.2K has higher quality factor, and can enable particles to obtain larger energy increase within the same distance. The radio frequency superconducting resonant cavity is generally prepared from high-purity niobium (with the residual resistivity RRR being more than 300 and the RRR being the ratio of the resistance at 300K to the resistance at 4.2K) through a series of stamping forming, machining, surface treatment, frequency control, welding and weld grinding. The high-purity niobium is expensive, about 4500 yuan/kg, and has low mechanical strength, and the yield strength at normal temperature is only about 50 MPa. The low-purity niobium (RRR-30) has low price of about 2000 yuan/kg and good mechanical strength which can reach 125MPa at the maximum at normal temperature. In the current processing of the superconducting cavity, all parts in contact with the high-frequency surface are processed and welded by high-purity niobium, and only the reinforcing ribs which are not in contact with the high-frequency surface are processed by low-purity niobium, so that the processing scheme has high cost and poor mechanical property of the cavity. In actual engineering operation, the limit of single-cavity performance is not pursued, and the mechanical stability of the whole system is emphasized. How to improve the mechanical strength of the existing radio frequency superconducting resonant cavity and reduce the engineering cost is a problem which needs to be solved urgently.

Disclosure of Invention

In order to solve the technical problems, the invention provides a superconducting cavity prepared by mixing low-purity niobium and high-purity niobium and a preparation method thereof.

In order to achieve the purpose, the invention adopts the following technical scheme:

a superconducting cavity prepared by mixing low-purity niobium and high-purity niobium comprises:

the superconducting cavity is prepared by mixing low-purity niobium and high-purity niobium, preferably, after the geometric structure of the superconducting cavity is determined, the high-frequency electromagnetic field distribution in the superconducting cavity is obtained through finite element analysis, in the operation process, the region with the most serious heating of the cavity is in a strong magnetic field region, the region adopts high-purity niobium plates or bars, and the other regions adopt low-purity niobium plates or bars.

The low-purity niobium-high-purity niobium mixed superconducting cavity comprises:

the outer conductor is of a hollow structure, the first end of the outer conductor is fixed on the bottom plate, two slotted holes which are symmetrically arranged along the axial direction of the outer conductor are formed in the position close to the first end of the outer conductor, nose cones are assembled in the slotted holes, and beam current pipelines are assembled on the nose cones;

the inner conductor is also of a hollow structure and is arranged in the cavity of the outer conductor, a drift tube is assembled at the first end of the inner conductor, and the drift tube and the beam pipeline are located on the same central axis.

The superconducting cavity is prepared by mixing low-purity niobium and high-purity niobium, preferably, the superconducting cavity is a quarter-wavelength cavity, and the inner conductor is a high-purity niobium cavity.

The superconducting cavity is prepared by mixing low-purity niobium and high-purity niobium, preferably, the outer conductor is a low-purity niobium cavity, the nose cone is a low-purity niobium nose cone, the beam pipeline is a low-purity niobium beam pipeline, and the drift tube is a low-purity niobium drift tube.

The superconducting cavity is prepared by mixing low-purity niobium and high-purity niobium, preferably, an end cover is assembled at the second end of the outer conductor and the second end of the inner conductor, the outer conductor and the inner conductor are connected through the end cover, a cleaning port is formed in the end cover and used for cleaning the outer conductor and the inner conductor, the end cover is a high-purity niobium end cover, and the cleaning port is a high-purity niobium cleaning port.

Preferably, the bottom plate is provided with a power coupling port, the outer conductor is provided with a signal extraction port for collecting signals in the outer conductor and the inner conductor, the power coupling port is a low-purity niobium coupling port, and the signal extraction port is a low-purity niobium port.

The superconducting cavity is prepared by mixing low-purity niobium and high-purity niobium, preferably, the bottom plate is provided with a reinforcing rib for improving the mechanical strength of the bottom plate, the bottom plate is a low-purity niobium bottom plate, and the reinforcing rib is a low-purity niobium reinforcing rib.

The invention also provides a preparation method of the superconducting cavity based on the low-purity niobium-high-purity niobium mixed preparation, which comprises the following steps:

preparing parts of the most serious cavity heating area by adopting a high-purity niobium material with the RRR value of more than 300 through a stamping die or a machining method;

preparing parts of other regions except the region with the most serious cavity heating by adopting a low-purity niobium material with the RRR value of 30 through a stamping die or a machining method;

ultrasonic cleaning is carried out on the parts processed by the two steps by utilizing an ultrasonic cleaning device;

adopting hydrofluoric acid: nitric acid: phosphoric acid 1: 1: 2, chemically cleaning the parts cleaned by ultrasonic, wherein the temperature of the acid liquor is controlled to be below 20 ℃, and the cleaning time is controlled to be 10-40 minutes;

cleaning the parts after chemical cleaning by using ultrapure water with resistivity not less than 18M omega cm, and airing in an ultra-clean room superior to 1000 grades;

and (5) welding the parts dried in the ultra-clean room by using a vacuum electron beam welding machine, and finishing the manufacturing.

Based on the low-purity niobium-high-purity niobium mixed superconducting cavity, the invention also provides a preparation method of the quarter wave field superconducting cavity, which comprises the following steps:

manufacturing two semi-inner conductors and the end cover by adopting a high-purity niobium material with the RRR value larger than 300 through a stamping die;

adopting a high-purity niobium material with RRR value more than 300, and obtaining four cleaning ports by a machining method;

two semi-outer conductors, two nose cones and a bottom plate are manufactured by adopting a low-purity niobium material with the RRR value of 30 through a stamping die;

obtaining the beam pipeline, the drift tube, the power coupling port, the signal extraction port and the reinforcing rib by using a low-purity niobium material with an RRR value of 30 through a machining method;

carrying out ultrasonic cleaning on the parts processed in the four steps by using an ultrasonic cleaning device;

adopting hydrofluoric acid: nitric acid: phosphoric acid 1: 1: 2, chemically cleaning the parts cleaned by ultrasonic, wherein the temperature of the acid liquor is controlled to be below 20 ℃, and the cleaning time is controlled to be 10-40 minutes;

cleaning the parts after chemical cleaning by using ultrapure water with resistivity not less than 18M omega cm, and airing in an ultra-clean room superior to 1000 grades;

and (5) welding the parts dried in the ultra-clean room by using a vacuum electron beam welding machine, and finishing the manufacturing.

Preferably, the method for preparing the superconducting cavity by mixing low-purity niobium and high-purity niobium comprises the following steps of welding parts dried in an ultra-clean room by using a vacuum electron beam welding machine:

welding the two semi-inner conductors into a complete inner conductor, penetrating the drift tube into the inner conductor, and welding the drift tube into a whole;

welding the two semi-outer conductors into a complete outer conductor, and welding the two nose cones, the corresponding beam pipeline and the corresponding flange together to be welded with the outer conductor into a whole;

welding the bottom plate on the outer conductor, and welding the reinforcing rib, the power coupling port and the flange on the bottom plate;

splicing the inner conductor and the outer conductor together with the end cap, measuring the frequency of a cavity, and determining the trimming amount of the open ends of the inner conductor and the outer conductor according to the welding allowance and the target frequency;

and welding the end cover, the inner conductor and the outer conductor into a whole, welding the cleaning port on the end cover, and welding the corresponding flange and the niobium-titanium alloy sheet on the cleaning port.

According to the preparation method for preparing the superconducting cavity by mixing the low-purity niobium and the high-purity niobium, the welding seams of the welding parts in each step are preferably ground, and the grinding of the welding seams comprises mechanical grinding.

Due to the adoption of the technical scheme, the invention has the following advantages:

1. according to the invention, the superconducting cavity is prepared by mixing low-purity niobium and high-purity niobium, and the niobium materials with different purities are adopted at different positions according to the distribution of the high-frequency electromagnetic field of the superconducting cavity, so that the manufacturing cost of the whole project is reduced, and the mechanical strength of the superconducting cavity can be improved.

2. The invention obtains the high-frequency electromagnetic field distribution in the superconducting cavity through finite element analysis. In the operation process, the area with the most serious heat generation of the cavity is usually in a strong magnetic field area, so that high-purity niobium is adopted in the area, and low-purity niobium is adopted in other areas, so that the manufacturing cost of the whole cavity is reduced, and the mechanical strength of the cavity is improved.

Drawings

FIG. 1 is a schematic perspective view of a superconducting cavity made of a low purity niobium-high purity niobium mixture according to an embodiment of the present invention;

fig. 2 is a multi-side view of a superconducting cavity made of a low purity niobium-high purity niobium mixture according to this embodiment of the present invention, wherein a is a side view and b is an internal view;

FIG. 3 is a schematic diagram showing the distribution of the high-frequency electromagnetic field in the superconducting cavity prepared by mixing low-purity niobium with high-purity niobium provided by the embodiment of the invention and the distribution diagrams of high-purity niobium and low-purity niobium in the superconducting cavity of the invention, wherein a is the distribution diagram of the electric field contour, b is the distribution diagram of the magnetic field contour, and c is the distribution diagrams of high-purity niobium and low-purity niobium in the superconducting cavity of the invention;

FIG. 4 is an exploded view of a superconducting cavity made of a low purity niobium-high purity niobium mixture according to this embodiment of the present invention;

the respective symbols in the figure are as follows:

1-an outer conductor; 2-an inner conductor; 3-end cover; 4-cleaning the mouth; 5-a bottom plate; 6-power coupling port; 7-reinforcing ribs; 8-a drift tube; 9-nose cone; 10-beam flow pipeline; 11-signal extraction port.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention are described clearly and completely below, and it is obvious that the described embodiments are some, not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. The use of "first," "second," "third," "fourth," "upper," "lower," "left," and similar terms in the context of the present invention do not denote any order, quantity, or importance, but rather the terms "first," "second," "third," "fourth," "upper," "lower," "left," and similar terms are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

The finite element analysis is to establish a thin shell model (or an air body model in a cavity) of the radio frequency resonant cavity in finite element analysis software, set the material property of the model as niobium (or vacuum), define the contact surface of the air body and the niobium shell as an electrical boundary, divide the model into a plurality of limited small units, and solve by using an eigenmode solver of the high frequency analysis in the finite element analysis software to obtain the electromagnetic field distribution of the cavity.

For a radio frequency resonant cavity of a certain shape, the spatial distribution of the electromagnetic field in the cavity is also determined. The high frequency electromagnetic field in the cavity generates high frequency heat which is dissipated to the cavity wall, causing the temperature of the cavity wall to rise. For the superconducting cavity, when the superconducting cavity works, the whole superconducting cavity is soaked in liquid helium, and high-frequency heat on the cavity wall is taken away by the liquid helium, so that the temperature of the whole cavity is kept below the superconducting transition temperature of niobium, and the cavity can be kept in a superconducting state all the time. If the high-frequency heat on the cavity wall cannot be taken away by the liquid helium in time, the temperature on the cavity wall can rise along with the high-frequency heat, and if the temperature of the cavity wall is higher than the superconducting transition temperature of the niobium material, the cavity is quenched. The heat transfer efficiency of niobium is closely related to the residual resistivity, so that high-purity niobium (RRR >300) is generally used in the processing of superconducting cavities. However, high purity niobium is expensive and has low mechanical strength. Low purity niobium (RRR 30) is inexpensive and mechanically strong and is commonly used for ribs outside the cavity. In order to reduce the overall cost of the superconducting cavity and improve the mechanical strength of the cavity, the application provides a method for preparing the superconducting cavity by mixing high-purity niobium and low-purity niobium, namely, the high-purity niobium is adopted in the region with serious heating of the cavity, and the low-purity niobium is adopted in other regions.

The invention provides a technical scheme for preparing a superconducting cavity by mixing low-purity niobium and high-purity niobium, and the technical scheme is explained in detail by taking a quarter-wavelength accelerating cavity as an example.

In a preferred embodiment of the present invention, as shown in fig. 1 and 2, the quarter-wave cavity comprises: the outer conductor 1 is of a hollow structure, the first end of the outer conductor 1 is fixed on the bottom plate 5, two slotted holes are symmetrically arranged along the axial direction of the outer conductor 1 at the position close to the first end of the outer conductor 1, nose cones 9 are arranged in the slotted holes, and beam pipelines 10 are arranged on the nose cones 9; inner conductor 2, it also is hollow structure, sets up in outer conductor 1's cavity, and inner conductor 2's first end is equipped with drift tube 8, and drift tube 8 lies in same central axis with line 10, and outer conductor 1's second end passes through end cover 3 with inner conductor 2's second end to be connected, has seted up washing mouth 4 on the end cover 3, has seted up power coupling mouth 6 on the bottom plate 5, and signal extraction port 11 has been seted up in the place that outer conductor 1's first end is close to bottom plate 5.

In a preferred embodiment of the present invention, as shown in fig. 3, taking a quarter-wavelength superconducting cavity as an example, after the geometric structure of the cavity is determined, the high-frequency electromagnetic field distribution in the cavity is obtained through finite element analysis (as shown in fig. 3a and 3b, through finite element analysis, the maximum surface magnetic field value on the cavity wall can be obtained, we use 1/3 of the maximum magnetic field value (Bmax) as a boundary, the region with the surface field larger than 1/3Bmax uses high-purity niobium, the region with the surface magnetic field smaller than 1/3Bmax uses low-purity niobium, and other types of cavities can also be divided by 1/3 of the maximum magnetic field value (Bmax), and high-purity niobium and low-purity niobium are selected). In the operation process, the area with the most serious heat generation of the cavity is usually in a strong magnetic field area, so that high-purity niobium is adopted in the area, and low-purity niobium is adopted in other areas, so that the manufacturing cost of the whole cavity is reduced, and the mechanical strength of the cavity is improved.

In a preferred embodiment of the invention, the inner conductor 2 is a high purity niobium cavity, as shown in fig. 3c, taking a quarter wave superconducting cavity as an example.

In a preferred embodiment of the present invention, as shown in fig. 3c, taking a quarter-wave superconducting cavity as an example, the outer conductor 1 is a low-purity niobium cavity, the nose cone 9 is a low-purity niobium nose cone, the beam conduit 10 is a low-purity niobium beam conduit, and the drift tube 8 is a low-purity niobium drift tube.

In a preferred embodiment of the present invention, as shown in fig. 1, 2 and 4, the second ends of the outer conductor 1 and the inner conductor 2 are equipped with an end cap 3, the end cap 3 is provided with a cleaning port 4 for cleaning the outer conductor 1 and the inner conductor 2, and the end cap 3 and the cleaning port 4 are made of high purity niobium.

In a preferred embodiment of the present invention, as shown in fig. 1, 2 and 4, a power coupling port 6 is provided on the bottom plate 5, and a signal extraction port 11 is provided on the outer conductor 1 for extracting a signal in the cavity. The bottom plate 5, the power coupling port 6 and the signal extraction port 11 are made of low purity niobium.

In a preferred embodiment of the present invention, as shown in fig. 1, 2 and 4, the base plate 5 is provided with reinforcing ribs 7 for improving the mechanical strength of the base plate 5, and the reinforcing ribs 7 are made of low-purity niobium.

The invention also provides a preparation method of the superconducting cavity based on the low-purity niobium-high-purity niobium mixed preparation, which comprises the following steps:

the method comprises the following steps of manufacturing two semi-inner conductors and an end cover 3 by adopting a high-purity niobium material with the RRR value larger than 300 through a stamping die, wherein the two semi-inner conductors have trimming margins at the joint with the end cover 3, and the die forming method comprises but is not limited to stamping, spinning, hydraulic pressure and the like;

adopting a high-purity niobium material with the RRR value larger than 300, and obtaining four cleaning ports 4 by a machining method, wherein the machining method comprises but is not limited to a numerical control lathe, linear cutting, water cutting, machining center and the like; the niobium-titanium alloy flange and the niobium-titanium alloy disk are assembled on the cleaning port 4;

two semi-outer conductors, two nose cones 9 and a bottom plate 5 are manufactured by adopting a low-purity niobium material with the RRR value of about 30 through a stamping die, wherein the joint of the two semi-outer conductors and the end cover 3 is provided with trimming allowance, and the forming method comprises but is not limited to stamping, spinning, hydraulic pressure and the like;

adopting a low-purity niobium material with RRR value of about 30, and obtaining a beam pipeline 10, a drift tube 8, a power coupling port 6, a signal extraction port 11 and a reinforcing rib 7 by a machining method, wherein the machining method comprises but is not limited to a numerical control lathe, linear cutting, water cutting, a machining center and the like; the beam pipeline 10, the power coupling port 6 and the signal extraction port 11 are provided with a niobium-titanium alloy flange and a niobium-titanium alloy disk;

ultrasonic cleaning is carried out on the parts processed in the four steps by an ultrasonic cleaning device, and the cleaning time is not less than 40 minutes;

hydrofluoric acid (40 wt%) is used: nitric acid (68 wt%): phosphoric acid (85 wt%) ═ 1: 1: 2, chemically cleaning the parts subjected to ultrasonic cleaning by using mixed acid with the volume ratio, wherein the temperature of the acid liquid is controlled to be below 20 ℃, and the cleaning time is controlled to be 10-40 minutes;

cleaning the parts after chemical cleaning by using ultrapure water with resistivity not less than 18M omega cm, and airing in an ultra-clean room superior to 1000 grades;

and welding the parts dried in the ultra-clean room by using a vacuum electron beam welding machine, wherein the welding method comprises but is not limited to electron beam welding, laser welding and the like.

The specific welding comprises the following steps:

welding the two semi-inner conductors into a complete inner conductor 2, penetrating the central drift tube 8 into the inner conductor 2, and welding the two semi-inner conductors into a whole;

welding the two semi-outer conductors into a complete outer conductor 1, welding the two nose cones 9 with the corresponding beam pipelines 10 and the flange together, and then welding the two nose cones and the outer conductor 1 into a whole;

welding a bottom plate 5 on the outer conductor 1, and welding a reinforcing rib 7, a power coupling port 6 and a flange on the bottom plate 5;

splicing the complete inner conductor 2, the complete outer conductor 1 and the end cover 5 together through a tool, measuring the frequency of a cavity, and determining the trimming amount of the opening end of the inner conductor and the opening end of the outer conductor according to the welding allowance and the target frequency;

welding the end cover 3, the inner conductor 2 and the outer conductor 1 into a whole, welding the cleaning port 4 on the end cover 3, and welding the corresponding flange and the niobium-titanium alloy sheet on the cleaning port 4;

and (3) performing weld grinding on the welded part at each step in the welding process, wherein the weld grinding comprises but is not limited to mechanical grinding and the like.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.