The Friedrich-Schiller-Universität Jena in Germany has been delivering liquid Helium since 1976 to various users at the University or in the region. In 1992 a new LR20/80 liquefier equipped with 2 turbine expanders was supplied by Linde to replace the original equipment, with a nominal production capacity of 10 l/h of liquid Helium.
In 2007 Linde Kryotechnik AG was awarded a new contract by the “Institute of Solid State Physics” of the Friedrich-Schiller University of Jena who has been producing liquid Helium, for the supply of a new liquefier to increase the production of LHe. However, the project had to respect several constraints, one of the most difficult one being to ensure constant production of liquid Helium during the whole project, including during the installation of the new equipment, the start-up, and the test phase.
The result has been the successful delivery of an L70 liquefier consisting of a new Coldbox, a screw compressor being able to deliver high-pressure gaseous Helium directly to the new Coldbox or to the old one, an additional buffer tank as well as all the equipment requested for the purification of the gas before it enters in the Coldbox. A control system including the visualization rounds off the functionality of the equipment.
The new Coldbox has been installed immediately next to the old one, providing the highest availability for liquid Helium production, the producer being able to switch between old and new production systems. The handover of the new L70 liquefaction unit showed production of 29 l/h without LIN pre-cooling and with 1% impurities resent in the feeding gas. On April 27, 2009, the equipment was officially inaugurated by Prof. Dr. P. Seidel of the Institute of Solid State Physics in presence of Prof. Witte, Vice-Rector of the Friedrich-Schiller-Universität Jena, and more than 70 guests.
The LHe-production is covering the usual cooling needs of all Schools of Natural Science and the School of Medicine. Typical applications are structural analysis methods like NMR. By using LHe in the School of Physics and Astronomy the focus is on preparation and analysis of superconducting films and multilayers used for cryo-electronic devices like Josephson junctions and DC-SQUIDs.
For examples SQUIDS (Superconducting Quantum Interference Devices) are applied in non-invasive medical techniques evaluating bio-magnetism, or to executing gravitational experiments in astronomy.