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The heat capacity of superfluid ^4He in the presence of a constant heat flux near Tλ

Citation

Harter, Alexa Welsh (2001) The heat capacity of superfluid ^4He in the presence of a constant heat flux near Tλ. Dissertation (Ph.D.), California Institute of Technology. https://resolver.caltech.edu/CaltechTHESIS:07252014-090646708

Abstract

We present the first experimental evidence that the heat capacity of superfluid 4He, at temperatures very close to the lambda transition temperature, Tλ,is enhanced by a constant heat flux, Q. The heat capacity at constant Q, CQ,is predicted to diverge at a temperature Tc(Q) < Tλ at which superflow becomes unstable. In agreement with previous measurements, we find that dissipation enters our cell at a temperature, TDAS(Q),below the theoretical value, Tc(Q). Our measurements of CQ were taken using the discrete pulse method at fourteen different heat flux values in the range 1µW/cm2 ≤ Q≤ 4µW /cm2. The excess heat capacity ∆CQ we measure has the predicted scaling behavior as a function of T and Q:∆CQ • tα ∝ (Q/Qc)2, where QcT) ~ t is the critical heat current that results from the inversion of the equation for Tc(Q). We find that if the theoretical value of Tc( Q) is correct, then ∆CQ is considerably larger than anticipated. On the other hand,if Tc(Q)≈ TDAS(Q),then ∆CQ is the same magnitude as the theoretically predicted enhancement.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Physics,superfluid ^4He ,constant heat Tλ
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Restricted to Caltech community only
Research Advisor(s):
  • Goodstein, David L.
Thesis Committee:
  • Unknown, Unknown
Defense Date:20 July 2000
Record Number:CaltechTHESIS:07252014-090646708
Persistent URL:https://resolver.caltech.edu/CaltechTHESIS:07252014-090646708
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8606
Collection:CaltechTHESIS
Deposited By: Dan Anguka
Deposited On:25 Jul 2014 17:34
Last Modified:04 Oct 2019 00:06

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