An investigation of electrostatic properties of dust grains in a complex plasma.

Explanation of the electrostatic behavior of dust grains in complex plasmas requires a knowledge of their basic properties such as electrostatic charge and dipole moment. While the measurement of the charge on symmetric dust grains in laboratory experiments has been performed, dust grains in astrophysical and laboratory plasmas are not necessarily spherically symmetric: the grains are typically elongated or aggregates consisting of many small subunits. Many of the previous works on grain charge assume a uniform plasma condition, though in the sheath of the rf discharge, there is an ion ow toward the boundary of the plasma. In this study, we present models for these complex plasma environments, where dust aggregates and dust structures formed in a laboratory plasma. Their basic properties are investigated experimentally and by employing computer models examining 3D structures of aggregates under di erent plasma conditions. The results support the previous experimental and numerical predictions for aggregates in these environments.