Research On The Magnetic Field Measurement Methods For Curved Superconducting Magnets

Curved superconducting magnets,one of the key components of the next generation heavy ion therapy system,are of utmost importance.They have a compact structure and produce a superior magnetic field.This thesis focuses on the research of magnetic field measurement methods for curved superconducting magnets.Magnetic field measurement is an essential part of accelerator magnets.Data from magnetic field measurement can not only verify the feasibility of magnet design and process routes but also provide an important basis for beam tuning.The curved superconducting magnets have a small bending radius and a large bending angle.The methods for measuring the magnetic field of curved magnets are still in their infancy.Therefore,this thesis conducts the following research on the magnetic field measurement methods for curved superconducting magnets:(1)A cryogenic-temperature vertical testing fixture for curved superconducting dipole magnets was developed.The magnetic field measurement method of the Hall probe array was used to measure the magnetic field of a curved CCT superconducting dipole magnet at cryogenic temperature,and the measurement results were analyzed.(2)Combining the requirements for magnetic field measurement,such as integral field homogeneity and harmonic components,a magnetic field measuring system for curved superconducting magnets was developed based on Hall probe and rotating coil.The ultrasonic motor was introduced into the magnetic field measuring system,and the measuring element was driven to move along the set path inside the curved magnet so as to realize three functions: 360° arc scanning,Hall probe transverse measurement,and rotating coil measurement.(3)The magnetic field measurement of a curved CCT superconducting dipole magnet with little current at room temperature was completed by using the curved magnetic field measuring system,and the systematic error was evaluated.The validity of the magnets design and fabrication was confirmed by comparing the measured magnetic field value to the design value.In summary,this thesis closely focuses on the magnetic field measurement requirements of curved superconducting dipole magnets,conducts research on the magnetic field measurement for this type of magnet,and summarizes appropriate magnetic field measurement methods,which lays the foundation for further magnetic field measurement of curved superconducting magnets.