Dust charge measurement in a strongly coupled dusty plasma produced by an rf discharge.

The electric charge on silica microparticles (5µm in diameter) levitating in the sheath of an rf discharge plasma is determined in a newly installed device for dusty plasma experiments at the IASST. The sheath potential profile is measured using an emissive probe and the electric field is obtained in order to determine the dust charge. The measured dust charge in the pressure range 0.50-5.0 Pa using the electric field value at the levitation height is found to be of the order of 10₄ elementary charges. Dust charge is also examined using the vertical resonance method which gives a similar order of charges. The experimentally measured charge is compared with the estimated values based on the orbital motion limited charging model. The coupling strength between the particles forming a 2D plasma crystal lattice is estimated using the measured dust charge. [ABSTRACT FROM AUTHOR]