Author(s): XIANG Nong, HU Yemin OU Jing 1 Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China 2 Center for Integrated Plasma Studies, University of Colorado Boulder, 30309 Colorado, USA
Pages: 385-391
Year: 2011 Issue:  4
Journal: Plasma Science and Technology
Keyword:  sheath; Bohm criterion; two-ion-species plasma;
Abstract: <正> The sheaths of a plasma containing two species of positive ion generated in a lowpressure discharge(～mTorr)are studied using a fluid model.It is shown analytically that for theweakly collisional presheath,as long as the ion-ion streaming instability is absent,each ion speciesenters the sheath satisfying each individual Bohm criterion.The fluid equations of electrons andions,including the time derivative terms,are solved numerically to follow the temporal evolutionof the plasma and sheath.Our numerical results show that in the parameter range explored,theion-ion streaming instability is not observed,and each ion species has its own Bohm criterionindependent of the relative concentrations of the two ion species.In addition,the RF sheath isstudied numerically and the similar conclusion is drawn.