 
Summary: Thermal resistance of 4
He below but very near the
superfluid transition
Hanan Baddar, Guenter Ahlers, Kerry Kuehn, and Haiying Fu
Department of Physics and Quantum Institute,
University of California, Santa Barbara, CA 93106, USA
We report highresolution measurements at saturated vapor pressure of the
thermal resistivity R of superfluid 4He over the reducedtemperature range
3 × 107 < t 1  T/T < 3 × 105 (T is the transition temperature for
Q = 0) and heatcurrentdensity range 4 < Q < 200µW/cm2. For smaller
Q and t, no thermal resistance was detectable below Tc(Q) < T. For Q >
10µW/cm2 we find that the results can be described well by R = (t/t0)2.8
Kcm/W with t0 = (Q/Q0)0.904 and Q0 = 393 W/cm2. Thus R has an
incipient divergence at T which is, however, supplanted by Tc(Q) where R
remains finite. The results imply R Q(m1) with m = 3.53 ± 0.02. This
differs from the original assumption m = 3 of Gorter and Mellink, and
from experimental results obtained well below T. However, it agrees with
measurements by Leiderer and Pobell at larger currents and further below
but still close to T. Our measurements could not resolve a critical heat
current for the onset of resistance.
