Takeo Nemoto

Thermal conductivity of alumina and silicon carbide ceramics at low temperatures

Abstract Thermal conductivity is measured on AI2O3 ceramic, structural SiC and high thermal conductivity SiC (2 wt% BeO addition) ceramics at a temperature range of 4–300 K. These ceramics possess conductivity maxima, the values of which are 0.9 W cm−1 K−1at ≈ 80 K for AI2O3; 4 W cm−1 K−1at ≈ 100 K for high thermal conductivity SiC; and 0.65 W cm−1 K−1at ≈150 K for structural SiC.

Cryostat and nuclear magnetic resonance imaging apparatus including a cryostat

A magnetically shielded cryostat, e.g. in a MRI imaging apparatus, has a heat-insulating tank having an outer wall. A magnetic shield is spaced from the tank, covers at least partly the outer wall of the tank and is not supported by the tank. A refrigerator having a cooled member extends into the tank. In order to avoid direct transmission of vibration of the refrigerator to a center region of the shield, the refrigerator is supported on the magnetic shield by at least one elongate support member connected to the shield only at or close to the ends of the shield.