Microparticles in a collisional Rf plasma sheath under hypergravity conditions as probes for the electric field strength and the particle charge.

We used microparticles under hypergravity conditions, induced by a centrifuge, in order to measure nonintrusively and spatially resolved the electric field strength as well as the particle charge in the collisional rf plasma sheath. The measured electric field strengths demonstrate good agreement with the literature, while the particle charge shows decreasing values towards the electrode. We demonstrate that it is indeed possible to measure these important quantities without changing or disturbing the plasma.

Charge and charging of nanoparticles in a SiH4 rf-plasma.

Plasma-produced nanoparticles are of interest for many applications. They have very specific properties that can vary greatly from those in the atomic and bulk materials, including thermodynamic properties, such as a reduced melting temperature, and optical properties, such as blue-shifted blackbody radiation. Since a plasma is dominated by free electrons, charge related properties, like a reduced work function for electron attachment and increased work function for photo ionization, are of major importance.

Evolution of a dust void in a radio-frequency plasma sheath.

The onset and growth of a dust void are investigated in a radio-frequency (rf) sheath of a capacitively coupled argon plasma. A circularly symmetric void emerges and grows with increasing rf power and pressure in the central region of the dust cloud levitating in the sheath. Experimental measurements of the void diameter are compared with the predictions of a simple phenomenological theory, based on a balance of forces on dust grains.