Design and verification of a novel high gradient quadrupole magnet

Abstract

BackgroundHigh gradient quadrupole magnet has become a key element with the development of diffraction-limited storage ring for the fourth generation light source. The gradient of magnetic field of a quadrupole magnet depends on the inscribed radius, ampere-turns per pole and magnetic efficiency. However, the radius and ampere-turns per pole cannot be reduced or increased indefinitely. Improving magnetic efficiency has become an effective method to improve the gradient of magnetic field.PurposeThis study aims to design a novel magnetic circuit to improve magnetic efficiency and verify the effectiveness by simulation.MethodsPermanent magnets were installed on both sides of the poles face to improve the efficiency of saturated magnets, so as to improve the magnetic field gradient of the quadrupole magnet. A novel high gradient quadrupole magnet, targeted 100 T·m-1, was designed to verify the theory by simulation calculation using Poisson for 2D analysis and OPERA for 3D analysis. The effect to the magnetic field quality of the novel magnetic circuit was optimized to achieve good field region.ResultsSimulation results show the magnetic field gradient of designed novel high gradient quadrupole magnet reaches to 100 T·m-1 when the ampere-turns per pole is about 5400AT. The magnetic efficiency is about 91%. All of the multipole components of magnetic field meet the requirements.ConclusionsThe design of the new quadrupole magnet provides a feasible and effective solution for the design of high gradient quadrupole magnet in the future.

Keywords

• quadrupole magnet
• high gradient of magnetic field
• permanent magnet
• magnetic field quality