The development of compact electron storage rings have already started in West Germany (BESSY) and France (Neyrpic Corp.) and recently in Japan and the USA. On February 28, 1986 the ETL (Electrotechnical Lab.) first completed, jointly with the Sumitomo Electric Industries Ltd., a small test ring “NIJI-I” and succeeded in storing a 160-MeV beam of more than 340mA in March 1987. A superconducting type compact ring will be completed by them in 1989. The NTT Corp. and the Sumitomo Heavy Industries Ltd. are also developing superconducting type compact rings. The wide applicability of SR depends on its several important properties such as high intensity of more than four orders compared with the conventional sources, broad spectral range from infrared to X-ray region, narrow divergence of the order of milli-radian. Although the present applications of SR concentrate in the analysis and evaluation of the properties of materials, recently much attention has come to be paid to the applications of SR and wiggler X-rays to ULSI lithography, CVD technology and medical diagnosis. The conventional storage ring can't achieve uniform and wide-area exposure of SR for ULSI lithography because of the vertically narrow divergence of SR. However, the electron undulating ring has made possible uniform large-area exposure of SR by a factor of more than five. The development of a compact X-ray ring measuring about 10m in mean diameter is also expected to realize the medical diagnosis by angiography in the hospital scale.
During cool-down operation of a helium liquefier, turbo-expanders are most susceptible to mechanical damage resulting from the extreme operating conditions. Growth and distribution of internal turbine losses were therefore calculated based on inlet temperature transitions. These were predicted by assuming a steady state in the liquefier. Predicted turbine performance was compared with actual measured data. A simplified prediction method is proposed for customers to correlate measured turbine performance on the manufacturer's test stand with their liquefiers that have different cool-down characteristics.
It is important for superconducting rotors to maintain a stable flow pattern of liquid helium to prevent an accidental transition of superconducting field windings into the normal state. Liquid helium within the rotating helium pool of superconducting rotors has two major flow patterns. One is a gravity dominant flow pattern and the other is a centrifugal force dominant flow pattern. The former has a flat horizontal surface of a liquid, and on the other hand the latter has a cylindrical one. This paper describes the transition phenomena between these two flow patterns. The results of a visual experiment using water, fron 113 and silicon oil are presented in the first report of this paper.
We have investigated AC losses in a seven-strand superconducting sub-cable, in which a few normal-metal strands with high conductivity are located for stabilization. In a transverse magnetic field with a trapezoidal wave form, approximate expressions for coupling losses among superconducting strands through normal-metal strands were obtained in addition to intra-strand AC losses by using equivalent electrical-circuit models. The total losses measured in several types of the stabilized sub-cables were well explained by the theoretical results. An optimized arrangement of the normal-metal strands in the sub-cable was also discussed in relation to minimizing the AC loss.
This paper describes the feasibility study of the regenerative cryocooler operating directly by the hydride absorption compressor. The gas compression parts of the split Stirling or Vuilleumier cycle could be replaced with the gas absorption compressor, if the pressure response of the absorption compressor is high enough to drive the regenerative cryocooler directly. Our simplified theory indicate that the pressure response of the order of seconds could be obtained by increasing the heat transfer area keeping heat capacity of the hydride and the wall material constant. We found a number of flattened capillary tubes as the hydride receptacle was suitable to the high response hydride compressor system. As the experimental results of this compressor system connected with pneumatic controlled expander, the minimum temperature of 95K was obtained when the heating and cooling temperature of the hydride receptacle was 90 and 20°C, and the cycle frequency of 0.5Hz.
The application of a laser Doppler velocimeter (LDV) is successfully attempted to He II jet, which is produced by pushing bellows, by employing neutral buoyant H2-D2 solid particles as scattering tracers. The LDV measurement gives detail information of the normal fluid velocity in He II with high temporal and spatial resolution. It was found that the normal fluid velocity in circular He II jet could be measured at least up to 15cm/s by the LDV without any appreciable degradation. The fluiddynamic behaivor of He II jet was found as the result of the present measurement to be similar to those of the turbulent jets of usual viscous fluids.