Excitation of low-frequency dust density waves in flowing complex plasmas

We study low frequency dust density waves excited in the microparticle streams of the Plasmakristall-4 chamber under microgravity conditions on board the International Space Station. Dispersion relations and instability conditions are analyzed for the dust density modes propagating along the axial electric field and in the reversed direction, revealing some important implications for the dust diagnostics. The results clearly point out to the Havnes parameter as a key factor for the excitation of the dust density modes.