A complex plasma device of large surface area

A novel complex plasma device (YCOPEX) to create two-dimensional monolayer plasma crystals of a large surface area of 15x90 cm2 is described. The YCOPEX, in which a plasma is produced by a rf discharge of argon gas, is designed to utilize gravitational force to study fundamental physics of complex plasmas. The device may be used for observation of spatial change of a phase state, propagation of waves, and collisions of flowing dust particles with an obstacle. As an example of experiments, neutral drag forces on microspheres are measured using the gravitational force on those particles. The obtained neutral drag force agrees reasonably with the values estimated from Epstein's formula.