Positively charged particles in dusty plasmas - art. no. 056407

The trapping of dust particles has been observed in a dc abnormal glow disc harge dominated by electron attachment. A dust cloud of several tens of pos itively charged particles was found to form in the anode sheath region. An analysis of the experimental conditions revealed that these particles were positively charged due to emission process, in contrast to most other exper iments on the levitation of dust particles in gas-discharge plasmas where n egatively charged particles are found. An estimate of the particle charge, taking into account the processes of photoelectron and secondary electron e mission from the particle surface, is in agreement with the experimental me asured values.