Although it has been studied for 75 years, the physics behind the formation of a sheath and a presheath at the interface between a plasma and a wall is still not fully understood. Under certain conditions, plasma can be treated as a multi-fluid continuum, and principles and techniques of classical fluid mechanics, thermodynamics, and  heat and mass transfer can be applied to study the plasma sheath and plasma-surface interaction.

The presence of dust particles in the sheath provides more challenge in this problem since dusts can significantly change the characteristics of the sheath. The interactions between dust particles and plasma, dust particles and electrode surface make things even more complicated. There have been many theoretical models on plasma sheaths. But few have made accurate predictions and none could fully explain the various phenomena seen in plasma sheaths near the electrode surface. This work is performed in collaboration with the theory group of CASPER. Our hope is to model the dust-plasma interactions, in particular, grain charging in dense and tenuous plasmas, as well as the sheath.