Permanent magnet system design of the 8mm third harmonic peniotron

Based on the reliability of current magnetic and process condition, the permanent magnet system for the 8mm third harmonic peniotron is designed. The NdFeB32 is used for the permanent magnet material. The size of the total magnet is small and compact enough that the total weight is about 100kg. The amplitude of the main field is 0.396T, and the length of the uniform region is as long as 50mm. After optimization, an axis-encircling electron beam with axial velocity spread 4.48%, guiding centre deviation ratio 6.97% and high velocity ratio 2.03 is obtained, which satisfies the third harmonic peniotron. Driven by the electron gun, an output power of 35.4kW is obtained and the device efficiency is up to 56.0%, this is an attractive result in laboratory platform.