Plasma detachment from a magnetic nozzle

Electrodless and gridless plasma thruster are currently considered for micro propulsion applications. These thrusters, such as the Helicon thruster, are appealing because they do not require a neutralizer, and are insensitive to grid erosion. However, they use for plasma confinement and acceleration magnetic nozzles. An important issue is then to understand the detachment of the plasma from this nozzle, which affects the beam divergence and thus the thruster Isp. In this study, we consider this problem, using ray-tracing model and 2 dimensional Particle in Cell modelling. The goal is to determine the relevant parameters which control the plasma expansion and detachment, and how they can affect the beam divergence.