Radio-frequency (RF), electrodeless, neutraliser-free plasma thrusters are of interest to the electric propulsion community as they can provide extended lifetimes and power scaling, and reduce the complexity of subsystems through the removal of neutralisers compared to mature technologies like Hall effect and gridded ion thrusters. Helicon thrusters like the Helicon Double Layer Thruster (HDLT) fall within this category of RF, electrodeless, neutraliser-free devices and is being investigated via its experimental analog, the Chi Kung reactor. This midterm review presents the status of ongoing experiments probing the characteristics of an ion beam formed in the throat of a magnetic nozzle at the outlet of the thruster under different pressure and geometric conditions.