DYNAMICAL BEHAVIOR OF HE-I HE-II INTERFACE LAYER CAUSED BY FORCED HEAT-FLOW

The appearance and dynamical behavior of a He I-He II phase interface is investigated experimentally. The experimental mode in which nearly saturated He I initially at a little bit higher temperature than the l ambda temperature is cooled by sudden evaporative cooling is primarily employed in the present experiment among several possibilities. In th is mode where an interface appears and propagates downward, some dynam ical aspects of an interface layer can be preferably investigated. The phenomenon is investigated by the application of the schlieren visual ization method, and by measuring the temperature variation by supercon ductive temperature sensors and the pressure variation as well as the evaporating vapor flow rate which can be converted into the cooling ra te. (C) 1998 American Institute of Physics.