Plasma characterization of a Hall effect thruster for a negative ion source concept

The characterization of the plasma generated by a Hall Effect thruster operating in Nitrogen and Hydrogen is presented. Measurements of the spatial profiles of the electron temperature and density of the plume have been obtained by scanning the region outside the exit plane of the thruster through a Langmuir probe. The measurements are aimed to determine the best position of a caesiated target in order to maximize the surface production of negative Hydrogen ions. The thruster has been designed as a tunable plasma source for a novel concept of a negative ion source, which could in principle benefit from some positive features of the Hall Effect thrtister; like the possibility of tuning the ion energy and the good uniformity of particle density at the channel exit, thanks to the axisymmetric magnetic field.