Modeling of a helicon plasma source

Abstract

Summary form given only, as follows. The helicon plasma discharge has proven to be a robust and efficient plasma source, which has been extensively studied. However, recent experiments with the space propulsion-oriented helicon source show new interesting data. VX-10 experiment demonstrates different performance of the discharge for pure hydrogen, deuterium and helium. Even more puzzling behavior was observed for two-gas mixtures. To study the helicon discharge we have developed zero dimensional models, which allow calculating main parameters of neutral gas and plasma species. Each of these models includes a set of dozen strongly coupled non-linear ordinary differential equations, which account for important plasma chemistry in the volume and for wall/boundary effects. This model is bundled with a separate 1D-model for a mixed collisional neutral gas flow in the volume of the helicon source. We use both models to explain various experimental observations and scans, to identify of the channels of mass and energy loss, and to give recommendations for the performance gain of the plasma source. Finally, we will present further improved fully kinetic model for the collisional gas and plasma dynamics in the discharge during continuous RF heating in the non-uniform magnetic field. Its results demonstrate importance of the kinetic corrections due to strong deviation of the distribution functions of all species from the Maxwellian, in agreement with the RPA data.