Particle manipulation in plasma device & Dynamics of binary complex plasma [thesis]

Ke Jiang
A complex plasma is a suspension of nano- to micron-sized dust particles immersed in a plasma with ions, electrons and neutral gas molecules. Dust particles acquire a few thousands of electron charges by absorbing the surrounding electrons and ions, and consequently interact with each other via a dynamically-screened Coulomb potential. Dust particles in a complex plasma can be controlled through a low frequency electrostatic distortion. We studied the transport velocity of the particles as we
more » ... e particles as we modulate the frequency and phase of the applied voltage by a segmented electrode. We used molecular dynamics to simulate our experimental observations, using plasma conditions from independent particle-in-cell simulations. We found that the transport of dust particles controlled by low-frequency modulation in our simulations are in good agreement with our experimental findings. This work is in the aim of, on one hand, providing a potential technique for addressing the dust contamination issues in plasma processing reactors and on the other hand, providing a setup for investigating large two-dimensional complex plasma systems where boundary effects can be avoided. We then proceeded to study the non-additivity effect in a complex plasma containing two different sizes of dust particles (binary complex plasma). For dust particles of type 1 and 2, the 1-2 (inter-species) interaction is always more repulsive than the geometric mean of 1-1 and 2-2 interactions. This asymmetry in the mutual interaction is called positive non-additivity. We used Langevin dynamics simulations for the Yukawa interacting particles characterized by positive non-additivity. We found that the two types of particles can separate into fluid-fluid phases and the growth of characteristic domain length follows a simple power law with an exponent of about 1/3 until the coupling strength is small enough, which is in a good agreement with the Lifshitz-Slyozov growth law for the initial diffusive regime of phase separation. We then used Langevin dynamics simulation [...]
doi:10.5282/edoc.13346 fatcat:ixtxo3r4vfhlbfztg66fk7mihq