Micro-disperse particles as probes for plasma surface interaction

Powder particles have been used, for instance, as micro-probes for the dete rmination of the electric field in front of electrodes and substrates, as w ell as for the observation of energy fluxes between plasma and surfaces. By observing the position and movement of the particles dependent on the disc harge parameters, we obtained information on the electric field in front of the electrode to be in the order of 350 V/m. For this purpose an adapted m odel has been employed for determining the dust charge, which in our case w as of the order of 7000e. The equilibrium temperature of the particles, whi ch is a result of the different energy fluxes from the plasma, has been det ermined by temperature-dependent fluorescence of the micro-particles to be of the order of 100-200 degreesC. In case of an argon plasma the heating of the particles by charge carrier recombination could be identified as domin ant energetic contribution, while the losses are due to radiation and condu ction. The energy flux towards the particles is approximately 0.1 J/cm(2)s. (C) 2000 Elsevier Science B.V. All rights reserved.