Visualizing quantum turbulence in He-II

Abstract

This thesis will outline an experimental setup which has been designed to image vortices in superfluid 4He using metastable He*2 excimers, which can be made to fluoresce. Understanding the dynamics of vortices is essential to the study of superfluid turbulence. These excimers have the potential to be useful tracers of the vortices as they have a 13 s radiative lifetime and have been shown to trap on vortices at low temperatures. A dilution refrigerator was used to cool the sample of He-II to temperatures as low at 170 mK, and optical fibres provided optical access to the sample. A single photon sensitive camera was used to detect the fluorescent photons from the excimers. The optical properties of excimers have been investigated across a range of temperatures. We have also shown no evidence of excimers trapping on vortices at T = 0.2 K with vortex line densities greater than 10^4 cm^-2. Finally the velocity of a jet of fluid was found to have a weak temperature dependence in the range of 1.3 K to 1.9 K.

Date of Award	1 Aug 2022
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Andrei Golov (Supervisor) & Paul Walmsley (Supervisor)