Vacuum-Adiabatic Characteristic of High Temperature Super-Conducting Cable

The hot temperature super conducting cables (HTS cable) are cooled by the liquid nitrogen and the super conducting condition of the cable is achieved. The HTS cable has many merits, for example, large power capacity, compact size, low loss and no leakage of magnetic field. So it is thought that the cable is applied to the ducts in a narrow underground space. As the liquid nitrogen of which temperature is 77(K) is used as the coolant, the thermal heat load transfered between environment and the cable must be interrupted. The thermal insulating space, that is, cryostat is installed at outer part of the cable. The space is kept in high vacuum condition. We experimented at various vacuum condition and studied heat transfer characteristic of the cryostat