High-Speed Imaging of Dusty Plasma Instabilities

PosterInternational audienceWhen a high-density of dust particles is trapped in a plasma, it often triggers unstable behaviours. This effect is mainly due to the strong drop in the free electron density due to dust particle charging effect. These instabilities have typical frequencies of about a few Hz up to several hundreds Hz, depending of the dust particle characteristics (size, density) and the discharge parameters (pressure, power). These instabilities are clearly visible on both the dust cloud and the plasma light emission. To analyse finely dust particle motion or spatiotemporal plasma changes, high-speed imaging (up to several thousands frames per second) appears to be an efficient diagnostics. In this work several types of dusty plasma instabilities are analysed thanks to this method. Experiments are performed in a capacitively-coupled rf discharge where dust particles are grown by polymer sputtering. We will present results on dust particle dynamics and plasma light oscillations specially during dust particle growth instabilities and void instabilities. Other types of observed unstable phenomena, like rotating plasma spheroids, will also be addressed. We will point out that all these instabilities have a strong nonlinear nature