Plasma characterization in Hall thrusters by Langmuir probes

One of the main factors that limits the Hall thruster lifetime is the degradation of surfaces exposed to plasma caused by the flux of energetic ions. Since the magnetic field shapes the plasma properties inside the thruster channel, non-standard magnetic configurations have been proposed in recent years to substantially increase the thruster lifetime. The present article reports an experimental investigation of different magnetic topologies of a Hall thruster operating on xenon and krypton. Plasma properties were measured using probes installed on the channel walls and a fast diving probe. Data are analysed by means of a Bayesian methodology. Results show that magnetic shielding correctly reduces the interaction between the plasma and the channel walls, which can result in lower erosion rates. A comparison between xenon and krypton operation showed that magnetic shielding is less effective for krypton, as the grazing line presents higher temperatures. Fast probe results also show how krypton discharges present wider acceleration regions and higher temperatures inside the channel.