Fusan Chen

20-T Dipole Magnet With Common-Coil Configuration: Main Characteristics and Challenges

The Institute of High Energy Physics (Beijing, China) is pursuing R&D of high-field accelerator magnet technology for the recently proposed CEPC-SPPC project, which will need thousands of 20-T level accelerator magnets in 20 years. A long-term plan has been made aiming to realize the 20-T magnets in 15 years. The conceptual design study has been ongoing from 2014 based on the current Jc level of superconductors. As both Nb3Sn and high-temperature superconductor superconducting materials are strain sensitive, the common-coil configuration has been chosen as the first option for the design study of the 20-T dipoles, to simplify the coil structure, raise the bending radius, and lower the strain level in superconducting coils. The magnetic analysis, mechanical analysis, and preliminary design study of the straight section and the coil ends have been completed for a 20-T common-coil dipole magnet. The main characteristics and challenges of this design concept will be presented in this paper.

Research and Development of the AC Magnets for CSNS/RCS

Chinese Spallation Neutron Source (CSNS) is a facility planned to be built in China in the coming years. It is composed of 80 MeV Linac, 1.6 GeV Rapid Cycling Synchrotron (RCS) and target station. To accelerate the proton beam from 80 MeV to 1.6 GeV, the RCS requires the field of dipole and quadrupole magnets to change with sine waveform of 25 Hz plus a biased DC. For large amplitude AC magnets with large aperture, there are critical issues to be addressed, such as eddy current induced in the magnet yoke, coils and endplates, vibration of the yoke and coil, field tracking between dipoles and quadrupoles, and so on. To study these issues, one prototype dipole magnet and one prototype quadrupole magnet have been developed and tested. In this paper, the design, fabrication and tests of the two magnets will be described.

Application of Transient Electromagnetic Simulation to the DC-Biased AC Dipole Magnet for CSNS/RCS

In this paper, we investigate the magnetic field properties and temperature rise in the China Spallation Neutron Source (CSNS)/Rapid Cycling Synchrotron (RCS) dipole magnets powered by dc-biased alternating currents. To understand the properties of these magnets, we perform transient electromagnetic simulation and thermal analysis. Eddy current losses from the transient electromagnetic results are applied in the thermal analysis. The eddy current losses from the transient electromagnetic simulations are discussed. The results of the thermal analysis are in good agreement with the test results of the prototype dipole magnet. Finally, the method has been applied to the optimization of the slit arrangements for the standard dipole magnets in CSNS/RCS.