[en] Kinetic phenomena in superfluid He³--He⁴ solutions are investigated by calculating the velocities and damping of first and second sound in the hydrodynamic as well as in the kinetic regime. The results point to the presence of velocity dispersion of second sound and to its substantial absorption in the transition frequency region. The calculation procedure employed has made it possible to write down in explicit form all the dissipation coefficients of the phonon-impurity system of a superfluid He³--He⁴ solution. The times contained in the dissipation coefficients for low-density solutions differ by more than an order of magnitude from those of an earlier theory. The calculation results are compared with the available experimental data

[en] An equation is obtained, taking into consideration nonlinearity and dispersion of waves in films of superfluid helium. It is shown that solutions differed in their properties from solitons in usual liquid can exist in films of superfluid helium

[en] This is a theoretical study of the size effects in a d approximately xi(T) - wide plane-parallel capillary with B- and A-phases of superfluid ³He in terms of the Ginzburg-Landau approach. Equations for the order parameter amplitudes are derived. The B-phase in capillaries is shown to have two modifications: B₁ and B₂. In the B₂-phase there are only pairs with projections of the orbital moment on the normal to the surface m sub(L)=+-J. At lower temperatures there exists a B₂-phase in which there are also pairs with m sub(L)=0. In sufficiently high magnetic fields the range of existence of the A₁-phase in capillaries is narrower

[en] An equation that takes account of both nonlinearity and wave dispersion in a superfluid helium film is obtained. It is shown that in a superfluid helium film solitons may exist with properties differing from those of solitons in conventional fluids

[en] All diffusion coefficients of superfluid ³ He - ⁴ He mixtures and the diffusion matrix of a tree-component gas of classical particles were calculated using the common approach. The comparison of all the results obtained made it possible to explain their physical sense. The diffusion flow of the gas of thermal excitations was shown to determine the nonaddictive of the thermal conductivity coefficient in the mixtures. The expression obtained for the coefficient of spin diffusion essentially differs from the earlier empirical formula that includes the coefficient of mass diffusion. The calculation results were compared with experimental data

[en] The size effects in a plane-parallel capillary of width dapprox.xi(T) in the B and A phases of superfluid He³ are studied theoretically using the Ginzburg-Landau approach. Equations are obtained for the amplitudes of the order parameter. It is shown that in capillaries the B phase has two modifications: B₁ and B₂. Only pairs with projections of the orbital angular momentum on the normal to the surface m/sub L/ = +- 1 are present in the B₁ phase. The B₂ phase, which also contains pairs with m/sub L/ = 0, exists at lower temperatures. In very strong magnetic fields the region of existence of the A₁ phase in the capillaries becomes narrower

[en] The effective coefficient of thermal conductivity of condensed matter containing two-component gas of thermal excitations and scattering centres was calculated. The result obtained is also true for any relations between interaction rates of different type thermal excitations and scattering centres. The effective coefficient of thermal conductivity is shown to involve not only the partial and flow terms but also the term associated with diffusion of the gas of thermal excitations. From the expressions obtained, which are valid at any dispersion laws, the effective coefficients of thermal conductivity due to thermal excitations of solids and quantum liquids (longitudinal and transverse phonons, phonons and magnons, phonons and rotons). Based on general relations, the limiting cased of setting up an equilibrium between thermal excitations of different types in a fast or slow manner have been considered for the above systems, that permits to refine the results given in literature and to define the field of their applications

[en] Equations have been obtained for long wave perturbations in films of binary solutions of superfluid liquids. They show that in such films there may be oscillations of two types representing coupled oscillations of the film thickness, temperature, and concentration. Nonlinear simple waves of the third sound are considered with allowance for the contribution due to the temperature finiteness

[en] The sound absorption coefficient at high pressures and the roton-induced renormalization of the first sound velocity are calculated using the expression for a mass operator, which was earlier derived by the authors. It is shown that the kinetic theory of sound propagation in He 2 changes essentially with the pressure rise. The calculation is compared with the available experimental results

[en] Various steady states of ³ He - ⁴ He quantum solutions are studied. The interaction between quasi-particles is consistently taken into consideration in terms of the hydrodynamic Hamiltonian. The chemical potential, the atomic pressure and the inertial mass of the impuriton gas are calculated. The Knudsen effect in the quantum impuriton gas is investigated with consideration for the interaction and the non-square dispersion law. The results of the theoretical calculations are compared to experimental data