Experimental Set-Up for Evaluation of Electro-Magnetic Characteristics of High-Tc Superconductors Cooled by Liquid Hydrogen

Liquid hydrogen (LH₂) has excellent properties as a coolant, such as large latent heat, low viscosity coefficient, etc. Not only MgB₂ but also other high-Tc superconductors are expected to have excellent properties when cooled by LH₂. It is necessary for a stability design of a high-Tc superconductor cooled by LH₂ to make an electro-magnetic characteristic clear. However, due to the handling difficulties of LH₂, there are only few papers on the properties of LH₂-cooled superconductors, especially under the external magnetic field. In this paper, an experimental set-up is described, which was designed and fabricated for the evaluation of the electro-magnetic characteristics of high-Tc superconductors cooled by LH₂. The LH₂ cryostat of 309 mm inner diameter was set co-axially with vacuum layer in the LHe cryostat in which the LHe-cooled superconducting magnet for external magnetic field (up to 7 T) was set. The LH₂ cryostat has three power leads for feeding up to 500 A to the test high-Tc superconductors.