AC Loss and Ramp Up Related Heating Effects in Superconducting MgB2 Coils

Superconducting coils modeled by using single core MgB
₂
wires having copper or iron or both in the cross section as sheath materials have been examined numerically by using the magnetic field formulation and heat transfer modules of COMSOL Multiphysics software. Heating effects due to the core ac losses and skin effects in MgB
₂
coils are revealed for alternating currents in a liquid helium environment. Temperature changes, magnetic flux density profiles, core ac losses for each coil are obtained in one full cycle of applied alternating current. The effect of copper layer thickness on core ac loss behavior of MgB
₂
/Cu coil and transport losses in MgB
₂
/Cu and MgB
₂
/Fe coils as a function of current ramp rate are investigated for an applied direct current up to 300 A.