Permanent magnet assembly for particle spectrometer

A permanent magnet assembly is presented according to the primary requirement for the magnetic field in the particle spectrometer. The permanent magnet assembly adopts the C-type magnetic circuit along with assistant magnets. Magnet circuits are validated and optimized by simulation technology. The results of both simulation and experiments show that the uniform working region is enlarged， and the magnetic field homogeneity is improved with the optimized magnetic circuit. The Magnetic field strength of the optimized permanent magnet assembly is up to 0.75 T in the uniform working region of 200 mm120 mm， and the magnetic field inhomogeneity is 0.67%.In addition， the magnetic properties of the permanent magnet assembly at different temperatures are simulated, the change rate of the magnetic field strength in the uniform region is about 4% from -55~70 ℃.