Oscillation of Two Cylinders in Liquid Helium

Abstract

A torsion pendulum was used to oscillate two solid cylinders in liquid helium II at subcritical velocities. The cylinders were sections of Plexiglas rod, constrained to move with their axes parallel to and equidistant from the axis of rotation by means of two parallel disks (end plates). Theoretical expressions based on the two-fluid model are derived for the added moment of inertia Ia and the logarithmic decrement 2πδ. The experimental results between 2.17 and 1.25°K are in close agreement with theory except for a small (1 to 2%) end effect on Ia. Penetration depths ranged between 0.03 and 0.59 of the cylinder radius. No dependence of Ia and δ on amplitude was observed for amplitudes up to 0.5 radius.