SIMPLE APPARATUS FOR THE LIQUEFACTION OF NEON DIRECTLY INTO A RESEARCH DEWAR

A simple apparatus for liquefying neon is described for use in experim ents that require a stable thermal environment at 27 K. This apparatus makes use of a closed-cycle refrigerator attached to an insulated col d finger inserted into a conventional stainless steel Dewar to liquefy a quantity of neon gas stored previously in a tank. The system is ine xpensive and easy to use. Furthermore, the neon is recovered for subse quent reuse upon completion of the experiment. Starting with a Dewar h olding a small coil that had not been precooled, and using a refrigera tor with rated cooling capacity of 15 W at 26 K, approximately 0.5 l o f liquid neon was condensed into the Dewar in approximately 4 h. The a pparatus has been used to measure the critical currents of high T(c) o xide tape coils both with and without the application of an external m agnetic field.