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P: Fachverband Plasmaphysik

P 3: Dusty Plasmas

P 3.4: Vortrag

Montag, 8. März 2010, 17:30–17:45, B 302

Dust agglomeration induced by self-excited density waves in a complex Plasma — •Cheng-Ran Du, Hubertus Thomas, Alexei Ivlev, and Gregor Morfill — Max Planck Institute for Extraterrestrial Physics, D-85740 Garching, Germany

Dust agglomeration plays an important role in astrophysics, atmospheric science, fusion physics as well as dusty plasma physics. In a capacitively coupled rf discharge, microparticles can be dramatically accelerated by self-excited density waves at low gas pressure. Once the kinetic energy is high enough to overcome the interparticle repulsive potential energy, hitting collisions i.e. agglomerations happen. In our experiment a high-speed camera is used to record the particle motion in the density waves in an argon plasma. We employ Rutherford scattering theory to evaluate the mean particle charge by observing the particle trajectories in scattering collision events and estimate the minimal relative velocity for hitting collisions. Using Smoluchowski's equation, the total number of hitting collisions for a certain time in a limited area is estimated and compared with the number of the observed big particles. The results confirm that agglomeration is the mechanism of the formation of these big particles in our experiment.