Electron Dynamics and Anomalous Processes in Low- Temperature Plasmas

The role of electrons in the formation and behavior of plasmas is at once both obvious and incredibly subtle. Electrons are at the heart of plasma physics, and their complex interaction with electric and magnetic fields, together with the friction forces they experience due to collisional processes, leads to a remarkable richest and diversity in plasma properties. The disparity in spatial and temporal scales caused by just the electron mass leads to important plasma phenomena, and can result in non-local effects or instabilities that produce "anomalous" behavior: often defying intuition and conventional explanations. In this talk, we examine different plasma systems and show how a combination of experiment, theory and numerical simulation has allowed new insight into the underlying electron dynamics, and a better understanding of overall system operation. The plasmas considered are relevant to material processing and space propulsion applications, and include both well-established systems such as RF capacitively coupled plasmas and DC Hall thrusters, as well as emerging concepts using magnetic nozzles and accelerators based on RF biased electrodes. We also discuss recent advances in our understanding of charged particle collisions, and how external magnetic fields can influence electron dynamics to produce fundamentally new collisional behavior.