Abstract
A ferrite loaded radio-frequency (rf) cavity with resonant frequency of several MHz is commonly used for proton synchrotrons. It became clear from our study that Ni-Zn-Co ferrites were preferable to Ni-Zn ferrites for the rf cavity because they had low rf loss due to their induced magnetic anisotropy by Co ions. Therefore, we tried to improve existing Ni-Zn-Co ferrite by controlling CoO content.
This paper presents test results of rf characteristics for the improved ferrite with large diameter of 500mm, using a ferrite test bench. Compared with the ferrite "4M2" supplied by Philips, our improved ferrite has superior rf characteristics both for dc bias field and ac bias field. Especially, the high loss effect, which is troublesome in dc bias operation, is considerably suppressed. If we can increase its mechanical strength without deterioration of rf characteristics, this ferrite will be applied to actual rf cavities.
