Dust particles in low-pressure plasmas: Formation and induced phenomena
Résumé
Solid dust particles from a few nanometers to centimeters can often be found in plasmas. This new species is at the origin of a wide variety of new plasma phenomena. These plasmas containing dust particles are called dusty or complex plasmas. They are encountered in many environments such as astrophysics, industrial processes, and fusion devices. Dust particles can come from regions in the plasma vicinity or can be formed in the plasma due to the presence of molecular precursors. These precursors can result from the presence of reactive gases (silane, methane, acetylene) or from material sputtering at the molecular level. Then, they initiate a complex succession of chemical and physical reactions, leading to the growth of dust particles. As long as precursors are available in the plasma phase, dust particle formation can be a cyclic phenomenon. Furthermore, as the dust particles are growing, they attach plasma free electrons, leading to a disturbance of plasma equilibrium when the dust particle density is high. New phenomena, like the occurrence of various instabilities are then observed. These behaviors seem to be present in many dusty plasmas created in different chemistries, experimental setups and conditions. In this presentation, we will discuss about these nearly universal phenomena and will principally focus on experiments related to dust successive generations and instabilities.