Dynamics of small dust clouds trapped in a magnetized anodic plasma

Abstract

Small dust clouds, which are confined in an anodic plasma, are studied with respect to their structure and their response to modulation of the anode bias. The dust cloud is displaced from the center of the discharge by a process similar to the void mechanism in radio-frequency discharges under microgravity. The top layers of the dust cloud are in a crystalline state and the cloud performs a slow rotation about the magnetic field direction. For modulation frequencies below 15Hz, a sloshing and stretching motion in the confining potential well is found. Spontaneously excited dust density waves are observed when the dust cloud exceeds a minimum size. The waves are characterized by sickle-shaped wave fronts. No standing waves were found. The wave dispersion shows an influence of the boundedness of the system in terms of a frequency cutoff.

Dust Clouds in Dc‐Generated Dusty Plasmas: Transport, Waves, and Three‐Dimensional Effects

“…Other studies by Ishihara and Sato on small clusters of organized particles (Coulomb clusters) [148], [149] have shown that it is possible to form quasi-crystalline structures in dc glow discharge dusty plasmas. Finally, it is noted that recent reports by Merlino [150] and Pilch, et al, [31] also have also provided evidence for the formation of strongly coupled structures in dc plasmas. Nonetheless, the rf glow discharge plasmas have generally proven to be an experimentally more favorable platform for the study of the solid-like dusty plasma crystals.…”

“…The contours of the particle clouds that are confined to the anode glow region of the plasma often form sharp boundaries that coincide with the potential structure of the anode glow. Therefore, in these cases, it is possible to make a direct, quantitative description of the confinement of the microparticles [31], [42].…”

“…In spite of these differences, dc-generated dusty plasmas have been shown to be an excellent platform for fundamental investigations of particle charging, [19], [20], [21], [22] a wide variety of collective effects including both dust-modified plasma waves [23], [24] and dust-driven waves, [25], [26], [27], [28], [29], [30], [31], [32] three-dimensional shaping effects, [33], [34], [35], [36], [37] and thermodynamic properties. [38], [39], [40], [41] The dc-generated dusty plasma enables a range of experimental studies that are distinct from, yet complementary with, studies in rf-generated dusty plasmas.…”

Structure and Phase Transitions of Yukawa Balls

“…MERLINO and coworkers confined dust in a magnetized anodic plasma [43,44] and investigated dust acoustic waves. Later, similar experiments on dust dynamics were performed in other discharges [45][46][47][48][49][50][51]. To produce 3D plasma crystals, a number of experiments have been performed under microgravity conditions.…”

Ion-dust streaming instability in a radially bounded dusty plasma

“…the wave can have finite frequency as the axial wavenumber k → 0 (see also [6]). Recently, this behavior was reported in a dusty plasma wave experiment [7]. Since the DA wave can be driven by ions streaming relative to the dust grains [8,9], it is of interest to investigate the conditions under which radial boundaries may affect the ion-dust streaming instability.…”