The subject of cryogenic cooling (cooling to temperatures below -150oC) is unfamiliar to many, as it is rather specialized and limited to special applications. The last few decades saw an increased interest in this technology, which is now forming the basis for a multi-billion dollar industry worldwide. The scope of application is also growing wider: While in the past the main application has been liquefaction of gases (including LNG – Liquefied Natural Gas for transportation in tankers), current applications include many others:
- Cooling of various sensors to abate electronic noise, among them infra-red (IR) sensors for night vision, Gamma ray sensors for monitoring nuclear activity and other sensors for studying atmospheric and space phenomena. In connection with night vision – it is interesting to note that the US Military during the Gulf War has preferred to fight at night, due to a significant advantage over the Iraqi army in this respect.
- Preservation of various biological tissues and cryo-surgery, using cryo-ablation instead of mechanical or thermal incision
- Cooling of large superconductors to generate strong magnetic fields in Magnetic Resonance Imaging (MRI), trains using magnetic levitation (MAGLEV), large ship motors and more.
Many experimental studies requiring low temperatures use cryogens such as liquid nitrogen (77 K) or liquid Helium (4K) which may be obtained from liquefaction plants at the Technion or elsewhere. The activity at the Faculty of Mechanical Engineering concentrates on the development of the cryogenic coolers (cryocoolers) themselves which enables their incorporation in various systems for autonomic operation. This can be compared to the cooling of food, which in the past had required externally-produced ice, while now every home is equipped with an autonomic refrigerator. In the development of cryocoolers efforts concentrate on increasing efficiency and reducing size. Miniature cryocoolers pave the way toward interesting applications such as compact night-vision instruments, medical instruments for diagnostics and cryo-surgery, electronic circuits involving superconducting components (SQUID) and more. For most of the advanced applications of cryogenic cooling there is a need for cryocooler miniaturization, in parallel with improving efficiency. Our main activity at the Rechler Laboratory focuses on the development of micro-cryocoolers along with advanced actuators to replace conventional electric motors.