Charging of individual dust particles in contact with hot plasmas is studied by numerical methods. The dust particle is treated as a rigid solid body, composed by either perfectly insulating or conducting material. The collisionless plasma, consisting of electrons and singly charged ions, is simulated by Particle-in-Cell methods in two spatial dimensions. It is demonstrated that the surface con...

We study the role of dust-dust collisional charging in protoplanetary discs. We show that dust-dust collisional charging becomes an important process in determining the charge state of dust and gas, if there is dust enhancement and/or dust is fluffy, so that dust surface area per disc volume is locally increased. We solve the charge equilibrium equations for various disc environments and dust c...

Large dust grains can fluctuate dramatically in their local density, relative to the gas, in neutral, turbulent disks. Small, high-redshift galaxies (before reionization) represent ideal environments for this process. We show via simple arguments and simulations that order-of-magnitude fluctuations are expected in local abundances of large grains (> 100Å) under these conditions. This can have i...

Aims. In order to understand the first stages of planet formation, when tiny grains aggregate to form planetesimals, one needs to simultaneously model grain growth, vertical settling and radial migration of dust in protoplanetary disks. In this study, we implement an analytical prescription for grain growth into a 3D two-phase hydrodynamics code to understand its effects on the dust distributio...

Dust particles can be a useful plasma diagnostic tool. Sufficiently dust particles can be used as test grains for the visualization of the plasma potential distribution; larger dust particles can be used as specific probes to determine electron temperature. Here we report on diagnostic measurements carried out in a capacitively coupled planar rf discharge. The location of the sheath edge has be...

The effect of the conducting electrode on the interaction of dust grains in a an ion flow is discussed. It is shown that two grains levitat-ing above the electrode at the same height may attract one another. This results in the instability of a dust layer in a plasma sheath.

We perform an accurate modelling of orbital evolution of dust grains taking into account both the ejection parameters derived from the analysis of the dust tail of each considered parent comet (Fulle 1989), and the integration of the Newton equations in the context of a nine–body problem (Sun, seven major planets and the dust particle) plus solar radiation and wind forces. Among Short Period Co...

Measurements of the charge of dust grains have been performed in a quasineutral plasma over a wide range of grain sizes. A new method was established for measuring the charge on grains levitating in the striations of a dc glow discharge. A single dust particle is moved out of a dust cloud with the help of a focused laser beam. When it leaves the beam it returns back to the cloud, and the charge...

ISOCAM allowed the observation of diffuse interstellar regions where the transition from atomic to molecular gas takes place. In this contribution we report on spectacular variations of small dust grains abundance in such regions observed with ISOCAM. In the four cirrus-like clouds observed, we note a systematic disappearance of small dust grains in regions where CO emission starts to appear. W...