Search

Transport of dust particles was studied in radio frequency (RF) plasmas. Dust particles of two sizes were injected in the plasmas. The plasmas were generated by applying a pulse-time modulated RF voltage. The pulse-time modulation made it possible to change the electron temperature in the plasmas. The electron temperature dominates the charges of the dust particles and the electric fields around the sheath where the dust particles are levitated. The equilibrium position of the dust particles can be determined by forces on them derived from the charges and the electric fields. In this research, it was clearly shown to change the position of the dust particles and drop them from the plasmas by the pulsed-time modulation. Furthermore, the modulated RF plasma worked as sieves of the dust particles. It was possible to drop larger dust particles from the plasma, while smaller ones remain in the plasmas.

The formation of dust particles in low-pressure plasmas is a 3-step process. The first one corresponds to nucleation and growth of nanoparticles by chain reactions between ions and gas molecules, the second one is agglomeration of the nanoparticles to form larger particles, and finally, the particles grow by radical deposition on their surfaces. In this work, the nucleation time for carbon dust particles was studied in low pressure acetylene/argon radio frequency (RF) plasmas. Since the self-bias voltage on a powered electrode was drastically affected by the transition from the nucleation to the agglomeration phases, the nucleation time was measured by observing the self-bias voltage time evolution. The nucleation time increases with the gas temperature and decreases when the gas pressure and the RF power are increased. A kinetic model, involving balance between diffusion and charging times of the nanoparticles as well as the chain reactions, is used to explain the exponential dependence of the nucleation...

Accepted: 2011-05-28, 資料番号: SA1003080000