Motion of Charged Quantized Vortex Lines in Superfluid 4He in the Low Temperature Limit

UoM administered thesis: Phd

  • Authors:
  • Peter Tompsett

Abstract

This thesis will examine the interactions of a cloud of charged vortex rings (CVRs) in the low temperature limit in helium-II (0.2 < T < 0.8 K) in a cubic cell containing a quasi-uniform electric field. A model of geometric collisions between vortex rings is proposed to explain the observed critical density of CVRs given by nR^3 ~ 3 cm^{-1} R where n is the CVR number density and R is the average CVR radius. This model was simulated in a simplified situation where two perfectly circular parent CVRs collide geometrically to create two perfectly circular daughter CVRs, conserving momentum and charge and dissipating a random amount of energy. The simulations are in qualitative and quantitative agreement with experiment.For an intense injection of CVRs into a strong electric field the CVRs quickly reconnect with one another to form a tangle of charged vortex loops. These loops move as one quasi-connected unit, it was found that the charged tangle's response to forcing was given by a law of the form t3 ~ (QE)^{-1/3} where t3 is the charged tangle time of flight, Q is the charge of the tangle and E is the applied electric field. Simulations of the displacement current induced in two electrodes in the cell were run in order to glean some information as to the transverse distribution of charge in the tangle, which was found to be approximately constant with time of flight and injected charge.

Details

Original languageEnglish
Awarding Institution
Supervisors/Advisors
Award date1 Aug 2013