Experimental and theoretical studies of evaporation and condensation mechanism inHe3-He4mixture systems

Abstract

Evaporation and condensation of the mixed ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-${}_{}{}^4{}_{}{}^{}\mathrm{He}$ system ($0<\mathrm{}{X}_l<0.21\mathrm{}$) were studied at 1.58°K using the heat-pulse technique. The evaporation efficiency increased linearly, while the condensation efficiency decreased, with increasing ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ concentration in the liquid. Analysis based on a weak-coupling model of the surface state with the bulk excitations as an evaporation and condensation mechanism gave information on the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ trapped surface state which agrees with the surface-tension measurements. In addition, the results seem to suggest that accumulation of surface ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ does not essentially affect the evaporation of ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ atoms in the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-${}_{}{}^4{}_{}{}^{}\mathrm{He}$ mixture.