Mechanism of dust-acoustic instability in a direct current glow discharge plasma

An observation of low frequency waves spontaneously excited in a dc glow di scharge dusty plasma is reported. To analyze possible reasons for the insta bility observed, a linear dispersion relation which takes into account coll isions with neutrals, dust grain charge variations, ion drift, and forces a cting on dust particles is derived. Numerical analysis of the dispersion re lation shows that the observed instability is the result of dust charge var iations in the presence of external charge-dependent forces together with t he ion drift effect. (C) 2000 American Institute of Physics. [S1070-664X(00 )01005-3].