OBSERVATION OF SHEATH PHENOMENA IN MULTICOMPONENT PLASMA WITH NEGATIVE-IONS

Some properties of the steady state ion rich sheath and the sheath ind uced instability in a multicomponent plasma with negative ions are exp erimentally studied in a double plasma device. With increasing negativ e ion concentration the thickness of the sheath around the negatively biased separator grid increases. The sheath structure follows the modi fied Child law. The frequency of the sheath induced instability decrea ses when the negative ion concentration is increased. (C) 1998 Elsevie r Science B.V.