The Low Temperature Facility (LTF) of the Tata Institute of Fundamental Research (TIFR) is one of India's largest cryogenic facility under the R & D sector. LTF has been operating and maintaining helium liquefiers for over six decades. For the past twelve years, helium is liquefied using Linde make, L280 Model helium liquefier. Our annual liquid helium consumption is over 1,00,000 liquid litres. Helium is liquefied and stored in 5000-litre liquid helium storage (mother) dewar and dispensed to about 45 research laboratories such as dilution refrigerator, adiabatic de-magnetization, Micro-kelvin refrigerators, NMR spectrometers, SQUID's, PPMS, VSM, STM, Nanoelectronics, Point Contact Spectroscopy, Photo Electron Spectroscopy, Mossbauer Experiments, Nuclear Atomic Physics / Beam hall experiments and many homemade setups. Most of the above systems are kept at 4.2K continuously.
The helium liquefier is expected for an uninterrupted operation. However, interruption of plant operation does occur either for a scheduled or breakdown maintenance. The core objective is to keep the plant downtime less by efficiently approach the problem. Since its installation in June 2008, LTF has carried out many preventive & breakdown maintenances, including critical component like turboexpander, which was successfully tackled in-house at our facility. The helium flow impedance occasionally occurs in the capillary-based experimental cryostats such as SQUID, PPMS, VSM, STM due to choking of impurities in its fine capillary tubes. This clogging prevents it from cooling below 4.2 K, attributed to the trace amounts of hydrogen present in the liquid He. The in-depth details on the detection techniques of hydrogen traces in the helium gas stream and the methodology adopted to rectify the helium-flow impedance issue, which worked without re-occurrence of capillary blockage issues more than three years by now.
About the Speaker:
Dr K V Srinivasan has been working in the Low Temperature Facility, TIFR, Mumbai, for 22 years. He joined TIFR after completing his ME(Cryogenics) in 1999 and later acquired his doctoral degree in Cryogenics. He is currently the In-charge of the Low Temperature (Cryogenic) Facility at TIFR. During his professional career, he served as a course lecturer for the graduate students at TIFR & INO, MSc students of Mumbai University and the Centre for Excellence in Basic Sciences (CBS), Mumbai. He contributes as a technical advisor for the cryogenic facilities of various IISER’s, IIT’s, NIT, Central Universities etc. He is currently the research collaborator on three funded projects with BRNS, ISRO & DRDO in cryogenic development. He is an elected member and treasurer (till 2018) of the Indian Cryogenic Council (West Zone). He has presented more than 60 technical talks at various academic institutes, about 50 technical presentations in the National and international conferences. He has authored more than 18 publication in peer-reviewed journals and his key research areas are Cryocoolers, Heat Transfer, Additive Manufacturing and Automation.