Dust Dynamics in Wake Channel

Dynamics of dust particles in an rf discharge plasma is studied. The plasma is produced in a glass tube of 16 mm in diameter and 680 mm in length. Dust particles are introduced into the plasma from the top of the glass tube. A sheath is formed near the bottom of the glass tube. A dust particle charged negatively in the plasma moves downward into the sheath and is observed to move upward against gravity, while two dust particles injected into the sheath interact each other and are observed to form a vertical pair along the ion stream. The lower dust particle is trapped in the wake potential formed by the upper dust particle in the ion flow. A pair of dust particles is observed to move upward together against gravity in the wake channel.