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

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 q = 0.94 +/- 0.11. For argon, the Epstein gas drag force coefficient delta, which would be unity if impinging molecules underwent specular reflection, has the value delta = 1.26 +/- 0.13 as measured with our single-particle laser acceleration method, or delta = 1.44 +/- 0. 19 as measured using the vertical resonance method. (C) 2003 American Institute of Physics.