Do Fluctuations Determine the Ion Mobility in He II near Tλ?

  • D. M. Sitton
  • F. E. Moss


Measurements of the zero-field ionic mobility µ in the roton region and near T λ of superfluid helium have been obtained from the characteristics of space-chargelimited discharges. The results for negative ions were obtained from the dc current I = CµV 2 of a planar diode using an 8-Ci tritium ion source. The source was plated on a 1-in.-diameter by 0.005-in.-thick OFHC copper disk which faced a collector at a distance of 0.5 cm. The source was maintained at a fixed voltage, V = − 8.00 V, which ensured space charge limitation for all currents measured, a condition which we checked at various temperatures by observing that IV 2. The geometric constant C was determined by matching the data to a known value of µ at a single temperature. The results for positive ions were obtained from tungsten field emission points and have been reported previously.1 These data have been compared to the recent data of Schwarz2 and Ahlers and Gamota.3 Over the range from 1.4°K to T λ tabular comparison with Schwarz’s data shows a point-by-point variation of no more than ± 1%.


Superfluid Helium Geometric Constant Fixed Voltage Planar Diode Inverse Mobility 


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  1. 1.
    D.M. Sitton and F. Moss, Phys. Lett. 34A, 159 (1971).CrossRefGoogle Scholar
  2. 2.
    K.W. Schwarz, Phys. Rev. (to be published).Google Scholar
  3. 3.
    G. Ahlers and G. Gamota, Phys. Lett. 38A, 65 (1972).CrossRefGoogle Scholar
  4. 4.
    D.T. Grimsrud and F. Scaramuzzi, in Proc. 10th Intern. Conf. Low Temp. Phys., 1966, VINITI, Moscow (1967), Vol. I., p. 197.Google Scholar
  5. 5.
    J.A. Tyson and D.H. Douglass, Phys. Rev. Lett. 17, 472 (1966).ADSCrossRefGoogle Scholar
  6. 6.
    D.S. Greywall and G. Ahlers, Phys. Rev. Lett. 28, 1251 (1972).ADSCrossRefGoogle Scholar
  7. 7.
    R.W.H. Webeler and G. Allen, Phys. Rev. A5, 1820 (1972).ADSCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 1974

Authors and Affiliations

  • D. M. Sitton
    • 1
  • F. E. Moss
    • 2
  1. 1.Department of Aerospace Engineering and Engineering PhysicsUniversity of VirginiaCharlottesvilleUSA
  2. 2.Department of PhysicsUniversity of Missouri—St. LouisSt. LouisUSA

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