Helium gas is an important factor for the cryogenic engineering and cryogenic industries. The history of the large-scale helium production, an estimated resource of helium and current helium uses have been reviewed. The helium conservation program in USA and its recent termination have been discribed. Furture aspects of the helium problems for cryogenic engineering have been discussed.
A.C. losses of superconducting Nb-Ti alloy wires were measured by electrical method with alternating electrical current through wires. The losses were measured on various diameter of wires which were chemically or mechanically thined, and it was found that there were no size effects. The losses were measured under the external parallel D.C. magnetic field, and those of commercial fine wires were also investigated. We computed the loss of multi cores wire, form the results obtained from single core wires and compared it with the experimental resuls of fine multi cores wires. The effects of chemical etching and mechanical drawing on the losses are considered in the metallurgical points of view. The losses of Nb-Ti wires in the region of low magnetic field seem to fit Yasukochi's model.
A method and its test results of pneumatic controlled refrigerators are reported. Simple analysis is given to have a Modified Kirk cycle and a Modified Solvay cycle with this method. In our experiment a minimum temperature of 27°K and 32 watts at 78°K with a single stage Modified solvay cycle were attained, and it is concluded that the refrigerator using this method has a good performance with small vibration.
It is very important to separate air and the undesirable impurities from helium gas which is used for low temperature refrigerators or liquefires. But very few data are available for such requirements. We have made adsorption measurements of charcoal and natural zeolite at high pressures up to 110kg/cm3 G and at liquid nitrogen temperatures. The results show that there are two steps of adsorption mechanisms and these data are found to be very useful for actual helium purifier design.