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The Heat Capacity of Superfluid ⁺He in the Presence of a Constant Heat Flux Near Tλ


Harter, Alexa Welsh (2001) The Heat Capacity of Superfluid ⁺He in the Presence of a Constant Heat Flux Near Tλ. Dissertation (Ph.D.), California Institute of Technology.


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 ⁺He ,constant heat Tλ
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Goodstein, David L.
Thesis Committee:
  • Goodstein, David L. (chair)
  • Cross, Michael Clifford (co-chair)
  • Eisenstein, James P.
  • Yeh, Nai-Chang
Defense Date:20 July 2000
Record Number:CaltechTHESIS:07252014-090646708
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8606
Deposited By: Dan Anguka
Deposited On:25 Jul 2014 17:34
Last Modified:12 Sep 2022 22:20

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