Helium Liquefier

Helium Liquefier

Liquefying of the helium gas at the J. Stefan Institute (JSI) began in 1975, following the installation of one of the first commercially available NMR superconducting magnets (BRUKER 6.3 T) at the Solid State Physics Department (the NMR laboratory of prof. Robert Blinc). In 1975-1986, this NMR magnet was the only liquid helium consumer at the JSI. The helium liquefier was Collins brand with a liquefying capacity 3-4 litres per hour.

In 1986, the second NMR magnet (OXFORD 2.35 T horizontal bore imaging magnet) was installed in the NMR laboratory. During the same year a new liquefier machine Linde (Munich, Germany) with the capacity 10-12 litres per hour has replaced the old liquefier. Since that year numerous new helium consumers appeared at the JSI and the Institute of Mathematics, Physics and Mechanics (IMFM) in Ljubljana. Currently (as of April 2004) these are: five NMR superconducting magnets (2.35 T field sweep, 2.35 T horizontal bore, 4.7 T, 6.3 T, 9.0 T), SQUID susceptometer with 5 T magnet and numerous continuous-flow and bath cryostats for spectroscopic measurements (NMR, EPR, light scattering, STM microscope, dielectric spectroscopy, specific heat).

In the last years, the helium liquefier team (Milan Rožmarin, B. Sc., Bojan Ložar, B. Sc., Iztok Ograjenšek and Dražen Ivanov) produces yearly 17000 - 20000 litres of liquid helium. All the helium consumed by the users is collected in a helium gas recovery system and is recycled to liquid state in the next cycle. In each cycle, 15% of helium is lost into the atmosphere, which is replaced by gas supply.

The operation of the helium liquefying infrastructure centre at JSI is made possible by the financial funds offered by the Slovenian Ministry of Education, Science and Sports. At present the largest helium consumer is the Solid State Physics Dept. at JSI (75% of total production), followed by IMFM (19%).

M. Rozmarin, April 2004