S. H. Castles and M. J. DiPirro
Goddard Space Flight Center
Greenbelt, MD 20771
A growing number of NASA scientific payloads are using stored liquid helium. Four have flown to date and more are scheduled for flight in 1989 and throughout the next decade. In all cases these payloads have flown or are planning to fly superfluid helium to take advantage of its greater cooling capacity per unit volume. The fountain effect, unique to superfluid helium, provides another important advantage since it can be used for fluid management in 0-g. To date the fountain effect, also called the thermomechanical effect, has been used to perform liquid-vapor phase separation, as in IRAS, IRT and COBE. Future users of superfluid in space will use the fountain effect for liquid-vapor phase separation; for pumping superfluid helium from a storage vessel to a payload, as in the Superfluid Helium On Orbit Transfer Flight Demonstration and the Superfluid Helium Tanker; for actuating a low temperature refrigerator called a vortex cooler; and for circulating liquid helium within a cryostat, as in the Astromag dewar. An introduction to the thermomechanical effect will be given and each particular application in aerospace cryogenics will be discussed.
Advances in Cryogenic Engineering 35, 211 (1990).