The distribution study of dust particles in Capacitively Coupled Radio Frequency (CCRF) discharges

In the research of dusty plasmas, the spatial distribution of dust particles is relevant for research and applications. The work is about the micrometer-sized dust particle moving observation in dusty plasmas, which were sprinkled into a Capacitively Coupled Radio Frequency(CCRF) discharge chamber. A three-dimensional fluid simulation study was also performed. It found that the dust particles were distributed in multiple layers, like a "bowl". When the pressure is fixed at 5pa and the RF power increases from 2w to 10w, the dust particles move upward as a whole, but the dust cloud volume is compressed. When the fixed RF power is 2w, the dust particles move overall downward as the air pressure increases, but the dust cloud volume changes less. The dust cavity first appears in the lower layer of dust particles, and as the pressure or power increases, the upper layer gradually appears again. When the inner diameter of the groove on the lower plate is small(2mm), the diameter of the dust cavity increases rapidly with the increase of the pressure. After reaching the maximum value, the diameter of the dust cavity gradually decreases as the pressure continues to increase until the dust cavity disappears.