Research On Key Technologies Of Precision Manufacturing Of High-frequency Cavity Of Accelerator

As an important part of high-power proton beam accelerator,waveguide-type high frequency cavity has the characteristics of high energy and high density of proton beam,mainly including moment type,omega type,boat type and other types.Among them,the boat-shaped high-frequency cavity has the highest no-load Q value and shunt impedance R value,which is the best choice for the～GeV proton beam accelerator.In order to master the key manufacturing process of the ship-type high-frequency cavity and carry out high-power experimental research,this paper has carried out the design optimization and key technology research of the special boat-type high-frequency cavity with a 1:4 scale model and a working frequency of 177.6 MHz.Firstly,this paper studies and analyzes the structural characteristics and performance of the boat-shaped high-frequency cavity.Based on the technical requirements of the boat-shaped high-frequency cavity with complex cavity,the overall design of the boat-shaped high-frequency cavity and the cavity and tuning control scheme are completed.In order to study whether the semi-Y-state oxygen free copper(Y/2 OFC)meets the design requirements of mechanical properties and frequency of boat shaped RF cavity.In this paper,the self-consistent multi-physical coupling simulation(RFthermal-structure-RF analysis)of boat-shaped RF cavity is carried out by using HFSS and Workbench simulation software.Through simulation analysis,it is verified that the mechanical properties of Y/2 OFC meet the frequency design requirements of boat-shaped high-frequency cavity,which provides a theoretical basis for the frequency test of boat-shaped high-frequency cavity.Secondly,the deformation theory and calculation method of high frequency cavity and the basic simulation flow of PAM-STAMP2G numerical simulation are introduced.Using PAM-STAMP2G numerical simulation software,the numerical simulation of high frequency cavity elliptical arc molding is carried out,which provides a theoretical basis for the actual molding.The structure design of the forming die for the high frequency cavity elliptical shell is carried out,and the actual molding process of the elliptical arc is introduced.The laser tracker measures that the forming accuracy of the cavity is less than ± 2 mm,and the high-precision molding development is completed.The biggest difficulty of boat-shaped high frequency cavity is the electron beam welding of the cavity.This paper introduces the welding difficulties of boat-shaped high frequency cavity in detail.The boat-shaped high-frequency cavity is designed with reasonable slicing scheme,and the reasonable welding process is developed.At the same time,different welding tooling is designed to reduce the deformation of the high-frequency cavity by electron beam welding.The laser tracker is used to ensure the positioning accuracy of welding assembly and the forming accuracy of the cavity,thus ensuring the high-precision welding of the boat-shaped high-frequency cavity,and completing the precise size control of the high-frequency cavity.Finally,through the cold measurement of the high frequency cavity of the accelerator,the frequency of the cavity can be adjusted at any time to meet the frequency requirements of the high frequency cavity,providing a reliable process guidance route and method for manufacturing the high frequency cavity.Complete the tuning test of the high frequency cavity,change the frequency of the cavity by controlling the electric cylinder to pull and press the cavity,meet the tuning requirements of the high frequency cavity ±170 kHz,and provide data support for the online test and high power coupling test of the accelerator high frequency cavity.The distance of the electric cylinder is adjusted by the control system of the high-frequency cavity,and the measured value of the displacement sensor is recorded in real time.Through the test,it is found that the measured value of the displacement sensor and the adjustment distance of the electric cylinder are basically linear.In this paper,the structural design,simulation analysis,shell forming,electron beam welding and frequency and tuning test of the high frequency cavity of the accelerator have been thoroughly studied,which provides a theoretical basis for the manufacture of the boat-shaped high frequency cavity,it provides valuable engineering experience for the ship cavity of high frequency cavity of accelerator and fills the blank of new cavity shape of high frequency cavity.