A hydrodynamic model is established to study the interactions of a dust particle with a radio-frequency (rf) sheath, taking into account the influence of the spatial inhomogeneity of the ~rf! sheath, as well as the influence of the ion-neutral collisions. Numerical results are obtained for the charge on the dust particle and for the spatial distribution of the induced potential around this particle, based on a self-consistent modeling of the sheath parameters such as the sheath electric field, the ion velocity, and the ion and electron densities. The induced potential exhibits the familiar oscillatory structure of a wake potential, which is, however, strongly damped due to the collisional effects. The spatial inhomogeneity of the rf sheath gives rise to a further damping of the induced potential, as well as to a reduction of the oscillations at large distances from the dust particle.

A self-consistent fluid model is proposed for describing collisionless radio-frequency ~rf! sheaths driven by a sinusoidal current source. This model includes all time-dependent terms in ion fluid equations, which are commonly ignored in some analytical models and numerical simulations. Moreover, an equivalent circuit model is introduced to determine self-consistently the relationship between the instantaneous potential at a rf-biased electrode and the sheath thickness. The time-dependent voltage wave form, the sheath thickness and the ion flux at the electrode as well as the spatiotemporal variations of the potential, the electric field and the ion density inside the sheath are calculated for various rf powers and ratios of the rf frequency to the ion plasma frequency. The ion energy distributions ~ IEDs! impinging on the rf-biased electrode are also calculated with the ion flux at the electrode. The numerical results show that the frequency ratio is a crucial parameter determining the spatiotemporal variations of the rf sheath and the shape of the IEDs.

The interactions of charged particles with carbon nanotubes are studied by means of the linearized hydrodynamic theory for electronic excitations on the nanotube surface. General expressions are derived for the induced potential, the self-energy, and the stopping power for a charged particle moving paraxially in a nanotube. Numerical results are obtained showing the influence of the damping factor, the nanotube radius, and the particle position on its self-energy and the stopping power. Results for stopping power in the linearized hydrodynamic model are compared with those obtained by means of the dielectric formalism in random-phase approximation, showing a close agreement between the two approaches for high speeds of charged particles.

The interactions of charged particles with cylindrical tubules are studied within the framework of the dielectric theory. Elementary excitations on a tubule are modeled by an infinitesimally thin layer of freeelectron gas, uniformly distributed over the surface of the tubule. The dielectric function of such a system, obtained from the random-phase approximation, exhibits a dimensional crossover from two-dimensional to one-dimensional electron gas, when the radius of the tubule decreases. Energy loss of a charged particle, moving paraxially in a tubule, can be divided into a single-particle excitation part and a resonant excitation part. It is shown that the resonant excitation modes on a tubule, which dominate the energy loss in the high-velocity regime, are quite different from those in a cylindrical cavity in a solid, described by a bulk dielectric function of the surrounding three-dimensional electron gas.

A self-consistent model is proposed to study nonlinear phenomena, such as secondary resonance and hysteresis in the vertical oscillations of a charged microparticle in a radio-frequency sheath. The motion of a single microparticle in the sheath is simulated by solving Newton's equation in which various forces acting on the particle are taken into account. The particle charging and the sheath electric field are described by a self-consistent model of the collisional radio-frequency sheath dynamics. It is found that the nonlinearity is related to the particle's charge, the sheath electric field, and the external excitation force, as well as the ion drag force and neutral-gas friction on the particle.