The development and the operation records of a Liquid Helium Recirculation System for a Magnetoencephalograph Measurement system

Abstract

We have developed a helium collection and re-liquefaction system for a MEG measurement system, and used the system applying to a 195 channel SQUID system. The helium purchase quantity became half the amount in our former report. However, this SQUID system has the large amount of consumption of helium compared with other MEG systems. So, we applied the re-liquefaction system to 122-channel SQUID system (Neuromag 122^TM) which used the general amount of the helium (about 100 liters/week). The helium purchase quantity became less than 1/4, and the whole expenses of cooling also became an about 43% decrease.