Observations on negative ion plasmas

Experimental observations that may have general interest are presented concerning a low micrometre size dust particles pressure plasma ( approximately=10-4 Torr) that consists of three components: positively charged ions, negatively charged ions and electrons ('negative ion plasmas'). These observations include Langmuir probe characteristics and sheaths that are germane to such a plasma. Properties of plasma waves in a negative ion plasma such as phase velocity, dispersion and soliton propagation are described.