Development of a low-dissipation valve for use in a cold-cycle dilution refrigerator

A low-dissipation valve for use at helium temperatures, which uses a polish ed stainless steel valve head and a PCTFE seat for the sealing surfaces, ha s been developed and tested. The leak rate with a closing force of 10 kgf a nd a differential pressure of 8000 Pa across the valve was experimentally d etermined to be approximately 0.2 mu mol/s of gaseous helium at 4.2 K. Esti mates of dissipation obtained using finite element analysis and experimenta l results from bellows tests suggest that this valve has energy dissipation on the order of 2 mu J per cycle. The valve is found to be suitable as a c ompressor valve for a previously proposed cold-cycle dilution refrigerator (CCDR) as well as other refrigeration cycles that require low temperature v alves. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.