Development of dual-harmonic RF system for CSNS-II

The upgrade of the China Spallation Neutron Source (CSNS-II) encompasses the development of a dual harmonic RF system for the Rapid Cycling Synchrotron (RCS). The objective of this system is to achieve a maximum second harmonic voltage of 100 kV. To meet this requirement, a high gradient cavity is being used in place of the traditional ferrite loaded cavity. Magnetic alloy (MA) loaded cavities, which can attain very high field gradients, have demonstrated their suitability for high -intensity proton synchrotrons. As a result, designing an RF system with MA -loaded cavities has emerged as a primary focus. Over the past decade, substantial advancements have been made in the development of MA -loaded cavities at CSNS. This paper provides an overview of the RF system that incorporates the MA -loaded cavity and presents the high -power test and beam test results of the system.