Results are presented for a set of experiments performed in different types of gas-discharge plasma under ground bounded and microgravity conditions. Effective structural (pair correlation function) and transport (diffusion constant, formation of dust vortices) characteristics of the system of microparticles (dusty plasma) have been measured in a set of experiments in dc- and rf gas-discharge plasmas in ground-based and microgravity conditions on the board of Russian ''Mir'' Space Station and International Space Station.

First we report on the experiment performed in dc discharge plasma under ground-based conditions. The basic plasma parameters were: Ne gas at pressure p = 0.4-1 Torr, the current I = 3 mA, the electron temperature T_e= 2-5 eV, plasma number density n_e =n_i =5 10⁹ cm^-3. Basic purpose of these experiments was to study the properties of dust structures in a state close to gaseous one. The effective coupling parameters retrieved from these measurements as a function of neutral pressure were obtained. The complex plasma was in a weakly coupled ''gaseous'' state in this case as the parameter was in the range from 10 to 20.