Observations of structured and long-range transport in a large volume dusty (complex) plasma experiment

Abstract

DUPLEX—the DUsty PLasma EXperiment at the Naval Research Laboratory—is a large volume dc glow discharge plasma device. The DUPLEX chamber is a transparent polycarbonate cylinder that is 40 cm in radius and 80 cm in height. Argon dc glow discharge plasmas are generated between a grounded cathode and a biased anode. The anode and cathode are separated by 15 to 20 cm. Clouds of 1 μm diameter alumina microparticles are suspended in the plasma—with the highest density directly above the cathode. However, particles have been detected throughout the entire plasma volume. This article reports on previously unidentified, and possibly unknown, phenomena observed in a dusty plasma. Two specific features will be the focus of this article. First, large microparticle clouds—up to 15 cm in diameter in some locations—with highly complex internal structures are identified. Second, long range—20 to 30 cm distances—periodic transport of microparticles from one region of the plasma to another is identified. It is believed that the large size and nonconducting boundary of the DUPLEX chamber facilitates the observation of these phenomena.