A three-terminal superconducting devise composed of a semiconductor coupled Josephson junction and an oxide-insulated gate was described. It was possible to control the superconducting coherence length ξn in the semiconductor by applying a gate voltage; consequently, the junction's superconducting critical current, which depends on ξn, was changeable. Power dissipation and switching time constant would be expected to be approximately 1μW and 10ps, respectively.
Mechanical properties of carbon-glass hybrid composite materials have been studied in order to check the applicability of hybrid composite materials at low temperature. Four types of interlaminate hybrid composites, which were reinforced by high-modulus carbon and glass or high-tensile carbon and glass cloth, were prepared. Their volume fraction of reinforcement were identical but the geometrical arrangement of the reinforcements was different. Tensile and dynamic flexural elastic modulus were measured and the law of mixture was found to be valid. Tensile tests were also performed and the breaking stress of hybrid materials was confirmed to follow the law of mixture at both room and low temperature. Not only the elastic modulus but the breaking stress of hybrid materials could be improved compared with those of glass fiber reinforced plastics even at low temperature.
The forced-convective heat transfer to supercritical helium has been investigated. The test section is a 1.25mm I.D., 200mm long vertical straight tube through which helium flows upward or downward and heated uniformly. The conditions covered are inlet fluid temperature between 4.7 and 10.8K, system pressures of 0.3, 0.5 and 0.8MPa, mass velocities of 20, 40 and 80kg/(m2·s) and heat fluxes of 500, 1000, 2000 and 4000W/m2. Experimental results on the distribution of wall temperature and heat transfer coefficient are presented. A comparison of the experimental results between upward and downward flow directions and discussion about the differences between them, in the light of the buoyancy effect, are done.