Dust-acoustic waves in strongly coupled plasmas with variable dust charge

A generalized theory of dust-acoustic waves in strongly coupled dusty plasmas containing variable-charge dusts or impurities is given. Relaxation processes associated with the strong coupling, as well as dust-charge variation, are taken into account. It is shown that the dispersion and damping properties of the waves are strongly affected by dust-dust correlation, dust charging and viscoelastic relaxations, and dust-neutral collisions. Multiple transitions between positive to negative dispersions are also found and discussed.