Particles as probes for complex plasmas in front of biased surfaces

Abstract

An interesting aspect in the research of complex (dusty) plasmas is the experimental study of the interaction of micro-particles with the surrounding plasma for diagnostic purposes. Local electric fields can be determined from the behaviour of particles in the plasma, e.g. particles may serve as electrostatic probes. Since in many cases of applications in plasma technology it is of great interest to describe the electric field conditions in front of floating or biased surfaces, the confinement and behaviour of test particles is studied in front of floating walls inserted into a plasma as well as in front of additionally biased surfaces. For the latter case, the behaviour of particles in front of an adaptive electrode, which allows for an efficient confinement and manipulation of the grains, has been experimentally studied in dependence on the discharge parameters and on different bias conditions of the electrode. The effect of the partially biased surface (dc, rf) on the charged micro-particles has been investigated by particle falling experiments. In addition to the experiments we also investigate the particle behaviour numerically by molecular dynamics, in combination with a fluid and particlein-cell description of the plasma.

Temperature of Particulates in Low‐Pressure rf‐Plasmas in Ar, Ar/H2 and Ar/N2 Mixtures

“…The Adaptive Electrode (AE) [18,19] is the most prominent component of PULVA-INP, it consists of more than 100 square pixels with an area of 7 · 7 mm 2 which each can be biased individually in real-time. The injected micro-particles can be confined above the bottom electrode, using the biasing options of the AE as shown in fig.…”

“…Related plasma parameters for PULVA-INP have previously been published [19,20]. If more electrons and ions reach the particle surface also their recombination rate is increased, which is by far the most important energy source for heating of the grains [4,11,12,21] in an inert argon discharge.…”

Behavior of a porous particle in a radiofrequency plasma under pulsed argon ion beam bombardment

“…So far, particles levitating in a plasma sheath have been manipulated, e.g., with an electric probe [10], with the help of laser beams [11], by time-varying electric fields of an adaptive electrode [12] and by periodic variation of the bias voltage [13]. Once the motion parameters like resonance frequency of the particles or their relative position with respect to the sheath are known, several plasma properties, like sheath thickness and the shape and strength of the electric field in the sheath, and/or particle properties like charge or mass can be determined [14].…”

Transport control of dust particles via the electrical asymmetry effect: experiment, simulation and modelling

“…This correlation analysis of the dust equilibrium position combined with the spatial electric field profile is applicable as a diagnostic tool to estimate plasma parameters, i.e. the dust particles can serve as electrostatic probes [38,39,[92][93][94]. The correlation analysis yields the maximum sheath extension as the only free fitting parameter, which depends on electron temperature and density (s max,p ∝ λ De /T ).…”