Phenomena Resulting from the Heating of Small Wires in He II

In a previous experiment the scintillation of He II was found to be enhanced at certain critical values of heat flux introduced into the fluid by a small heated wire. Results are presented here which demonstrate that this phenomenon is related to the formation of some form of visible turbulence or, alternatively, of a vapor bubble around the wire, depending on the depth of the wire in the He II bath. Results are presented also on the dependence of the critical heat current on wire depth and on temperature.