LIQUID HELIUM

Press, Volume C, Issue 29610, 5 September 1961, Page 18

LIQUID HELIUM

The helium liquifying machine shown in the picture above was built in Sydney by the Commonwealth Scientific and Industrial Research Organisation, A similar machine will be installed in the physics dejpartment of the University of Canterbury in November. A lecturer from the department, Mr T. J. Seed, who read a paper to the spectroscopy conference held in Sydney, recently spent about a week studying the machine. Helium had the lowest boiling point of any known substance —453 degrees Fahrenheit, Mr Seed said yesterday. For this reason it could be used to freeze the molecular movements of solids which would normally tend to obscure their behaviour when they were studied with a spectroscope. In the machine the helium gas had impurities frozen out of it and was then put through a three-stage compressor and heat exchanging

units before it was liquified. Mr Seed said. “One of the great difficulties in the last stage is that no lubrication may be used because of the exceedingly low temperatures at which even air becomes as hard as glass.” Mr Seed said. One of the most important reasons for his visit to the machine in Sydney was to study how the gas which comes off from the boiling liquid helium could be conserved and used again, he said. Besides its low temperature liquid helium also had the advantage of being safe to handle, Mr Seed said. It was light, about half the density of cork. The department would be getting 12 cylinders of the gas. Helium is obtained from the United S-ates. It is one of the elements of which there was only a limited supply and special arrangements between the New Zealand and United States Governments are necessary for it to be imported.