The problem of impulsive heating of dust grains in cold, dense interstellar clouds is revisited theoretically, with the aim to better understand leading mechanisms of the explosive desorption of icy mantles. It is rigorously shown that if the heating of a reactive medium occurs within a sufficiently localized spot (e.g., heating of mantles by cosmic rays), then the subsequent thermal evolution is characterized by a single dimensionless number λ. This number identifies a bifurcation between two distinct regimes: When λ exceeds a critical value (threshold), the heat equation exhibits the explosive solution, i.e., the thermal (chemical) explosion is triggered. Otherwise, thermal diffusion causes the deposited heat to spread over the entire grain -this regime is commonly known as the whole-grain heating. The theory allows us to find a critical combination of the physical parameters that govern the explosion of icy mantles due to impulsive spot heating. In particular, the calculations suggest that heavy cosmic ray species (e.g., iron ions) colliding with dust are able to trigger the explosion. Based on the recently calculated local cosmic-ray spectra, the expected rate of the explosive desorption is estimated. The efficiency of the desorption, which affects all solid species independent of their binding energy, is shown to be comparable with other cosmic-ray desorption mechanisms typically considered in the literature. Also, the theory allows us to estimate maximum abundances of reactive species that may be stored in the mantles, which provides important constraints on available astrochemical models.

For a homogeneous partially ionized plasma subject to a uniform electric field E, several methods and models are used to calculate the distribution function f(v) for ions subject to charge-exchange collisions. The exact solution for f(v), based on the energy-dependent cross section for Ar, is obtained by Monte Carlo (MC) simulation. This is compared to the MC results for f(v), based on either a constant cross section σ or a constant collision frequency ν. The constant-σ model is found to accurately represent f(v) for any value of E, whereas the constant-ν results are qualitatively incorrect for large fields. Under the constant-σ assumption, a simple, easily solvable ordinary differential equation is obtained which reproduces the MC results with good accuracy.

The theory of mode-coupling instability in 2D plasma crystal is combined with a self-consistent model of plasma wakes. The wake model is based on the solution of a kinetic equation for ions, providing realistic representation of their kinetics for the sheath environment. Furthermore, the self-consistent approach allows us to express the interparticle interaction via experimentally measurable parameters. It is suggested that distinct features of dispersion relations predicted by different wake models can be identified experimentally.

We study the effects of the particle-wake interactions on the dispersion and polarization of dust lattice wave modes in two-dimensional plasma crystals. Most notably, the wake-induced coupling between the modes causes the branches to "attract" each other, and their polarizations become elliptical. Upon the mode hybridization the major axes of the ellipses (remaining mutually orthogonal) rotate by 45°. To demonstrate the importance of the obtained results for experiments, we plot representative particle trajectories and spectral densities of the longitudinal and transverse waves. These characteristics reveal distinct fingerprints of the mixed polarization. Furthermore, we show that at strong coupling the hybrid mode is significantly shifted towards smaller wave numbers, away from the border of the first Brillouin zone (where the hybrid mode is localized for a weak coupling).