Current leads for superconducting magnets have been studied since 1960's. The technology of current leads may seem to have been established both in theory and experiment before the middle of 1970's. Nevertheless, a wide variety of superconducting magnets have been introduced in the last 15 years, and the demands for special current leads have increased in accordance to the variety. A steady advance has been made in the design theory and fabrication of current leads. This paper describes the recent current lead technology regarding the design theory, safety in accidents, and high current capability.
In recent studies of high temperature plasmas, an improvement of plasma confinement properties during auxiliary heating is the most important item. A solid hydrogen-isotope pellet injector is a useful tool for this purpose. This report reviewed a production method of a solid hydrogen-isotope and an acceleration technique of the pellet by pneumatic, electromagnetic and centrifugal forces.
The purpose of this paper is to give an experimental proof of the dynamic stability of face-cooled superconducting tapes presented by one of the authors (T. O). The specimens are made by stacking disk-shape Nb3Sn and stabilizing copper disk alternatively. Stability is estimated by observing flux jumps for specimens of different cooling conditions or different thicknesses of stabilizing copper. The experimental results agree well with the analysis. This work will offer a useful criterion for application of superconducting tapes.
With the stringent requirement from the user community for high-resolution multichannel detectors which cause much heat generation, a future space-borne infrared radiometer on an Earth observation satellite must incorporate a small closed cycle refrigerator instead of the passive radiator which has been used for rejecting heat from small size detectors of satellite radiometers in the past. The Vuilleumier cooler, one such refrigerator, is a heat engine which uses heat energy rather than mechanical energy to cyclically pressurize the working gas. This machine has the potential advantages of long lifetime and low mechanical vibration. This paper first describes the specifications required for the machine, and next the details of design and the test results. As typical specification values, the machine has cooling capacity of 1.5 watts at 80K under input heater power of 150W, charged working gas pressure of 2.5MPa and cycl