Heat flow in liquid helium with clamped normal fluid

• Main Author: Pollack, Gerald Leslie
• Format: Others
• Published: 1962
• Online Access: https://thesis.library.caltech.edu/6567/1/Pollack_gl_1962.pdf; Pollack, Gerald Leslie (1962) Heat flow in liquid helium with clamped normal fluid. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/29ZJ-PQ17. https://resolver.caltech.edu/CaltechTHESIS:08032011-103945376 <https://resolver.caltech.edu/CaltechTHESIS:08032011-103945376>

With very few additional assumptions the wave equations for First Sound and Second Sound in liquid helium admit of simultaneous solution for the motion of both superfluid and normal fluid in the presence of a large viscous force on the normal fluid. If these fluids are set in motion by the presence of heat energy their consequent motion, through a viscous medium, is a mixture of two modes - a diffusive heat flow and a wave heat flow. These experiments aim at seeking each of these modes and examining them. It was found that the only observable heat was transmitted diffusively although a very high degree of experimental sensitivity to waves was reached. The investigation includes heat transmission by both pulses and monochromatic waves and the viscous medium varies from coarse emery powder to very tightly packed rouge. The measurements were carried out at temperatures from 1.3°K to the lambda point. The consequences of the absence of waves are analyzed.