Second sound very near T[sub [lambda]]

Journal Article · Fri Oct 01 04:00:00 EDT 1993 · Journal of Low Temperature Physics; (United States)

DOI:https://doi.org/10.1007/BF00682285· OSTI ID:5751242

Goldner, L S; Mulders, N; Ahlers, G ^[1]

---

1. Univ. of California, Santa Barbara, CA (United States)

The results of an experimental investigation of the evolution of planar, nonlinear, second-sound pulses in superfluid [sup 4]He, to within 650 nK of the [lambda]-transition, are presented. A new method for extracting the second-sound velocity and damping is demonstrated. As predicted from two-fluid hydrodynamics, the pulses are well modeled by the solutions of Burgers' equation. The second-sound velocity (u[sub 20]) and damping (D[sub 2]) are extracted from fits of the model to the data. Damping data are obtained in this fashion to 3 [times] 10[sup [minus]7] in reduced temperature at saturated vapor pressure; nearly two decades closer to T[sub [lambda]] then any previous measurements. The superfluid density is extracted from the u[sub 20] measurements and the critical exponent, [zeta], is determined. A study of very large amplitude pulses near T[sub [lambda]] is also presented. These pulses extend well beyond the range of validity of Burgers' equation. The amplitude of the shock that forms at the trailing edge of the pulse is observed to saturate as a function of heater power and then decrease suddenly, as has been previously observed away from T[sub [lambda]]. However, the pulse shapes are quite different from any previously observed.

• OSTI ID: 5751242
• Journal Information: Journal of Low Temperature Physics; (United States), Journal Name: Journal of Low Temperature Physics; (United States) Vol. 93:1-2; ISSN JLTPAC; ISSN 0022-2291
• Country of Publication: United States
• Language: English

Related Subjects

665420* -- Superfluidity-- (1992-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
DAMPING
EVEN-EVEN NUCLEI
FLUID MECHANICS
HELIUM 4
HELIUM ISOTOPES
HYDRODYNAMICS
ISOTOPES
LAMBDA POINT
LIGHT NUCLEI
MECHANICS
NUCLEI
PHYSICAL PROPERTIES
PULSES
SECOND SOUND
STABLE ISOTOPES
SUPERFLUIDITY
TEMPERATURE RANGE
TEMPERATURE RANGE 0000-0013 K
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE
VELOCITY