This thesis describes the findings of two experiments carried ~ut in 3He-B at ultra low temperatures. The princip,le tool used for thermometry in both experiments is vibrating wire resonators. Vibrating wire resonators are used at Lancaster as thermometers and heaters and they can be used to produce turbulence in superfluid 3He-B. Turbulence in 3He-B is created using a vibrating wire resonator and a black body radiator is used to create a beam of quasi-particles which are retro-reflected off the turbulence. The properties of a black body radiator are used to create a model to investigate the vortex line density. The vortex line density is shown to be dependent on the temperature of the bulk superfluid. The properties of two different substrates immersed in 3He-B are studied. It has been found that when a proprietary material, Kapton, is subjected to a changing magnetic field, a large amount of heating and cooling is observed. When a different substrate, aerogel, is used the same effects are observed. We show that when aerogel that is immersed in 3He-B is subjected to a changing magnetic field the surrounding helium cools from rv 200 JLK to rv 115 JLK. It is thought that the effects are caused by the solid helium that coats the strands. Several models have been developed to calculate the heat capacity and some interesting features have been observed. We identify the fact that aerogel in 3He-B would make an excellent second cooling stage for many ultra low temperature experiments.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:485253 |
| Date | January 2006 |
| Creators | Whitehead, Rebecca |
| Publisher | Lancaster University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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