Radiation pressure and gas drag forces on a melamine-formaldehyde microsphere in a dusty plasma

Abstract

Measurements are reported for the radiation pressure and gas drag forces acting on a single melamine-formaldehyde microsphere. The radiation pressure force coefficient q, which would be unity if all incident photons were absorbed, has the value qϭ0.94Ϯ0.11. For argon, the Epstein gas drag force coefficient ␦, which would be unity if impinging molecules underwent specular reflection, has the value ␦ϭ1.26Ϯ0.13 as measured with our single-particle laser acceleration method, or ␦ϭ1.44Ϯ0.19 as measured using the vertical resonance method.

Dislocation nucleation and motion observed in a plasma crystal

“…In this experiment, a plasma crystal was formed by melamine formaldehyde microspheres with a diameter of 8.09 ± 0.18 μm suspended in an rf discharge in argon at a low pressure of 3 mTorr. The neutral-gas damping rate was calculated [31] to be ν = 0.52 s −1 . The single-layer suspension included about 4000−5000 particles and had a diameter of about 50 − 60 mm; the interparticle spacing was b = 0.69 mm.…”

Observation of Temperature Peaks due to Strong Viscous Heating in a Dusty Plasma Flow

“…The dust particles filled only a single horizontal layer, and significant out-of-plane displacements [26] were not present, so that particles within the dust layer can be described as having mainly two-dimensional (2D) motion. As a single dust particle moved at a velocity V d , it experienced a frictional drag force −ν gas m d V d due to collisions with the gas atoms [27], where ν gas = 2.7 s −1 . The dust particles had an interparticle distance b = 0.50 mm, corresponding to a Wigner-Seitz radius [28] a = 0.26 mm.…”

“…In our experiment, instead of planar plates we used laser manipulation [23,27,[29][30][31][32][33] of the dust particles In our data analysis, we exploit the symmetry of the experiment, and divide the region of interest into 89 long narrow rectangular bins, with one example bin shown in (b). The particle data are converted to continuum data by averaging data for individual particles in each bin.…”

Viscoelasticity of 2D Liquids Quantified in a Dusty Plasma Experiment

“…After the 8.1 µm diameter microspheres were introduced into the plasma (which had an Argon pressure of 14 mTorr), they experienced a damping rate of ν f = 2.4 s −1 [31].…”