The trap of dust particles with different sizes in electronegative plasma sheaths

In this work, we have examined the dynamics of dust particles in the electronegative plasma sheath. For this, we have developed a 1D stationary and unmagnetized model. The electrons and the negative ions are considered in thermodynamic equilibrium, while the positive ions and the impurities (dust grains) are described by fluid equations model. The impurities are considered to have spherical forms; moreover their size distribution is given by Gaussian distribution. Several forces acting on the dust particles are taken into account. The numerical results show that the contribution of the neutral drag force is negligible compared to others forces. In addition, the electrostatic force acting on the nm particles is dominant. Also, we found that the suspension of dust grains in electrostatic sheath is only for a small dust radius interval for which the electrostatic force is balanced by the gravity and the ion drag forces.