Preliminary Study of the High Temperature Superconducting Solution for 2 GeV CW FFAG Magnet

Proton beam with an average power of 5 MW-10 MW have important applications in particle physics towards the intensity frontier, as well as in the advanced energy, and material science. The fixed field alternating gradient (FFAG) accelerator combines the advantages of existing accelerators, which has a higher limitation of beam energy than high power cyclotron and has a higher beam-to-grid efficiency than existing high power linac and synchrotron, thus is considered as a good candidate for high power proton machine. By utilizing the strong focusing and large acceptance features of FFAG in the theoretical framework of the fixed field and fixed frequency of isochronous cyclotron, a continue wave FFAG capable of producing 2 GeV/3 mA protons (with an beam power of 6 MW) has been proposed in China Institute of Atomic Energy (CIAE). Due to the beam loss of high power proton beams, the resulting high radiation will deposit a large amount of radiation dose and heat load on the superconducting (SC) magnet. As the high temperature superconductors (HTS) have a much larger thermal margin due to high critical temperature (> 90 K) and high upper critical field (>100 T) than the traditional low temperature superconductors, and have been also considered have the lower overall construction costs and power consumption than the conventional magnet, currently the HTS magnet is the favorable solution for the 2 GeV FFAG magnet design. In this paper, the lattice design along with the requirements on the F-D-F magnet of the 2 GeV FFAG design is briefly introduced first. Then, the design of the F-D-F magnet is outlined. The details of the HTS coil design utilizing ReBCO conductor and operating at ~30 K is also included.