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:07252014090646708
Abstract
We present the first experimental evidence that the heat capacity of superfluid ^{4}He, at temperatures very close to the lambda transition temperature, T_{λ},is enhanced by a constant heat flux, Q. The heat capacity at constant Q, C_{Q},is predicted to diverge at a temperature T_{c}(Q) < T_{λ} at which superflow becomes unstable. In agreement with previous measurements, we find that dissipation enters our cell at a temperature, T_{DAS}(Q),below the theoretical value, T_{c}(Q). Our measurements of C_{Q} were taken using the discrete pulse method at fourteen different heat flux values in the range 1µW/cm^{2} ≤ Q≤ 4µW /cm^{2}. The excess heat capacity ∆C_{Q} we measure has the predicted scaling behavior as a function of T and Q:∆C_{Q} • t^{α} ∝ (Q/Q_{c})^{2}, where Q_{c}T) ~ t^{2ν} is the critical heat current that results from the inversion of the equation for T_{c}(Q). We find that if the theoretical value of T_{c}( Q) is correct, then ∆C_{Q} is considerably larger than anticipated. On the other hand,if T_{c}(Q)≈ T_{DAS}(Q),then ∆C_{Q} 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): 

Thesis Committee: 

Defense Date:  20 July 2000 
Record Number:  CaltechTHESIS:07252014090646708 
Persistent URL:  https://resolver.caltech.edu/CaltechTHESIS:07252014090646708 
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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