An evaporation source of simple and compact construction was devised. This source is 20 mm in diameter and 30 mm long; is composed of a ring filament, control aperture, and disk-shaped sample (source) and shield cover; and enables the evaporation of source material to be easily controlled at a constant rate without the use of a feedback system. This evaporation source ensures depositions at constant rates for several hours. Refractory metal films of several thousand angstroms thickness can be deposited onto substrates held 10 cm from the source. Typical performance characteristics in the application to Ti films are presented.

The absorption and desorption velocities of oxygen in a Y1Ba2Cu3O7-δ sintered sample were measured by a thermogravimetric analysis when the atmospheric gas of nitrogen was exchanged for oxygen and oxygen for nitrogen. The weight change of the sample could be expressed by an exponential function of time in each process. In the absorption process of oxygen, the time constant was a complex function of the temperature, while in the desorption process, it was the monotonous temperature dependence. The diffusion constant and the activation energy were estimated at the temperature range of the tetragonal phase.

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We investigated the critical current density and the flux creep in melt-processed Bi-Pb-Sr-Ca-Cu-O for the purpose of studying the existence of strong flux pinning forces due to normal conducting precipitates. We fabricated samples with a similar microstructure to melt-processed Y-Ba-Cu-O and Tl-Sr-Ca-Cu-O having a strong pinning force. When the matrix was (Bi, Pb)2Sr2Ca1Cu2O y (2212) phase, the irreversibility field B irr was expressed as B irr\propt(1-T/T c)3/2, which suggested that the expected flux pinning was due to normal conducting precipitates. A part of the matrix was transformed to (2223) phase by the postannealing of the sample; however, the superconducting properties were inferior to those observed in (2223) polycrystals.

Next generation high-energy accelerators, (VLHC for example), require magnets in the range of 10 to 12T. It is necessary to use Nb 3 Sn conductor with current density over 2000 A/mm 2 @12T for these magnets. Increase of current density can be still done by the reduction of unnecessary bronze portion of the conductor and uniform synthesis of NbsSn. Through the optimization consideration using finite element analysis, we have introduced new configurations of niobium and tin. FIT (filament in Tube) and DT (Distributed Tin) method were tried and the DT method gave a very good result. The current density of DT conductor reached 2120 A/mm 2 @ 12T. The critical field of DT conductor appeared to be high even it is cured at low temperature to suppress the grain size growth.