Research on Beam Dynamics of a 2 GeV 6 MW Isochronous FFA

CIAE has proposed an innovative design for a 2 GeV/6 MW isochronous FFA in 2019. This study aims to present the results of beam dynamics research, demonstrating the feasibility to accelerate the intense proton beam with the energy beyond 1 GeV limitation of isochronous cyclotrons. By introducing 1st - 3rd radial gradient of peak magnetic field to simulate the quadrupole to octupole component of the isochronous machine, three different lattice designs are obtained. Adjusting the radial gradient of the peak field allows an option to avoid or cross integer resonances. Various inherent and coupled resonances are investigated subsequently, with a focus on the destructive effects of the Vr=3 on the transverse phase space. Based on PIC method, we simulate the vortex motion caused by space charge in a large-scale alternating gradient field. Results indicated that the radial size of beam is ~ 10 mm, which is expected to be improved after considering the effects of neighboring bunches. Additionally, high-Q RF cavities and precession extraction further enlarge the turn separation to 30 mm, ensuring efficient beam extraction in the extraction region.