Liquid Disorder Effects on the Solid He II Kapitza Resistance

Abstract

At temperatures T below the λ-point T < T _λ , several Kapitza resistance results R _K ∝ T ⁻³ indicate phonon transmission difficulties and provide some support for acoustic mismatch models (proposed in the past and reviewed in Ref. 1) and for more recent modifications^2–4 of the early models. Some measurements, however, show departures from the T ⁻³ law, particularly at increased heat fluxes q. The departures appear to be consistent with some aspects of early thermohydrodynamic theories of the solid-He II Kapitza resistance^5,6; however, the He II contributions appear to be very small and outside of the error limits of early data. More recent experiments indicate that the liquid He II temperature difference ΔT may cause noticeable departures from phonon transmission laws at large heat fluxes. Then the liquid contribution to the entire Kapitza temperature “drop” may reach several percent. Therefore we have conducted experiments at heat fluxes of the order of magnitude 0.5–5 W cm⁻² with the purpose of resolving further details of the liquid He II thermohydrodynamic aspects of the solid-He II Kapitza resistance.

Supported by the National Science Foundation.