Cooling Stability Test of MgB₂ Wire Immersed in Liquid Hydrogen under External Magnetic Field

11th European Conference on Applied Superconductivity (EUCAS2013)Liquid hydrogen (LH₂), which has large latent heat, low viscosity coefficient, is expected to be a candidate for a cryogen for superconducting wires, not only MgB₂ but also other HTC superconductors. LH₂ cooled superconducting wires are expected to have excellent electro-magnetic characteristics, which is necessary to be clear for cooling stability design of LH₂ cooled superconducting device, however, due to handling difficulties of LH₂, there are only few papers on the properties of LH₂ cooled superconductors, especially under external magnetic field. We designed and made an experimental setup which can energize superconducting wires immersed in LH₂ with the current of up to 500A under the condition of external magnetic field up to 7 T and pressure up to 1.5 MPa. In order to confirm experimental method and safety operation of the setup, over current tests were carried out using MgB₂ superconducting wires under various external magnetic field conditions. Critical current of the test wire at the temperature 21, 24, 27, 29 K under external magnetic fields up to 1.2 T was successfully measured. The resistance of the wire also was measured, while the transport current exceeded the critical current of the wire

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

Over Current Properties of HTC Superconducting Wire Cooled by Liquid Hydrogen

An experimental setup which can energize superconducting wires immersed in LH2 was designed and made. Over current tests were carried out using MgB2 wire. Critical current and resistivity of a test MgB2 wire submerged in liquid hydrogen were measured for exponentially increasing heat input, while the transport current exceeded the critical current. The resistivity of the conductor was obtained as a function of current and the temperature of the conductor by using the transient heating method. The distribution ratio of the current through the superconductor and the sheath, and the resistivity of the MgB2 conductor itself were estimated

Cooling Stability Test of MgB 2

11th European Conference on Applied Superconductivity (EUCAS2013)Liquid hydrogen (LH₂), which has large latent heat, low viscosity coefficient, is expected to be a candidate for a cryogen for superconducting wires, not only MgB₂ but also other HTC superconductors. LH₂ cooled superconducting wires are expected to have excellent electro-magnetic characteristics, which is necessary to be clear for cooling stability design of LH₂ cooled superconducting device, however, due to handling difficulties of LH₂, there are only few papers on the properties of LH₂ cooled superconductors, especially under external magnetic field. We designed and made an experimental setup which can energize superconducting wires immersed in LH₂ with the current of up to 500A under the condition of external magnetic field up to 7 T and pressure up to 1.5 MPa. In order to confirm experimental method and safety operation of the setup, over current tests were carried out using MgB₂ superconducting wires under various external magnetic field conditions. Critical current of the test wire at the temperature 21, 24, 27, 29 K under external magnetic fields up to 1.2 T was successfully measured. The resistance of the wire also was measured, while the transport current exceeded the critical current of the wire