Measurements of thermal diffusivity of impurity-helium solids

Thermal diffusivity of the Kr - and N-2 - impurity-helium solids (IHS) has been measured for the samples, immersed into liquid helium in the temperature range of 2.2 - 4.2 K. It has been found that the thermal diffusivity for both solids does not differ from that of liquid helium when the convection is absent even for the case when the samples were compact 10 times as compared to their initial volume. It should be emphasized that the presence of less than 0.5% mole fraction, of a rare gas in the form of IHS allows us to suppress completely any convection in liquid helium (this effect was not observed when deuterium was used as an impurity). INS can be used as a specific porous medium for investigations of critical phenomena of the He-I - He-II phase transition, as the He-aerogel systems.