Hydrogen cooled superferric magnets for accelerators and beam lines

The possibility of superferric accelerator and beam line magnets is described. A cooling system that is not helium and nitrogen based, but one based on hydrogen, is proposed to make full use of the recent MgB₂ superconductor around 20 K. A hydrogen cooling system is more effective than the nitrogen cooling for usual high T_c superconductors around 70 K. Liquid hydrogen is also excellent as refrigerant for high T_c superconducting apparatus to increase the critical current and to provide a self-sustained cooling system by means of a combination of evaporated hydrogen and a fuel cell. This paper also discusses hydrogen safety issues, as compared to that of helium and nitrogen. It is expected that dipole magnets for a synchrotron would be good candidates for a superferric design based on these principles.