Langmuir Probes and Dust Particle Trajectories: Characterizing a Complex Plasma Employing Minimally Perturbative Methods

The Langmuir probe has been used for a century to diagnose plasma parameters such as electron temperature and electron density. The ability of the Langmuir probe to calculate the plasma potential at specific points enables mapping of the electric field within an experimental plasma environment. Orbital Motion Limited (OML) theory is a variation of the theory of collectors in gaseous discharges derived for instruments like the Langmuir probe. OML then applies to the dielectric particles used in usual dusty plasma experiments. As such the particles themselves also map the field-forces in a plasma environment and can also be used to diagnose other plasma parameters in the same manner as a Langmuir probe in a minimally perturbative manner when compared to the disturbances created by use of the Langmuir probe. This presentation will examine the results of an experiment comparing the potential maps derived from the Langmuir probe and from a dust drop technique.