Superfluid frictional force in adiabatic flow of HEII

Abstract

The superfluid frictional force and/or the pressure drop across the flow path produced by the superfluid component flow were obtained up to about 70 cm/s of its velocity, v s , in the CuNi capi11ary of 0.2 m i.d. and 480 mm length. The results show that the pressure drop is simply proportional to v s in the region of v s >15 cm/s, although the vortex line density, L 0 , shows rather complex v s dependence. Discussions are given in the light of the new-type mutual friction force.