Langmuir Probe Measurements in the Discharge Channel of a 6-kW Hall Thruster

Bryan Reid, Alec Gallimore
2008 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit   unpublished
In an effort to understand the role of neutral flow dynamics in the operation of Hall thrusters, a cylindrical Langmuir probe was used to measure the electron temperature, floating potential, and ion number density in the discharge channel of a 6-kW Hall thruster operating at 300 V and anode flow rates of 10, 20, and 30 mg/s. To isolate the effect of propellant flow rate, the cathode flow fraction and magnetic field topology were held constant while varying magnetic field strength to minimize
more » ... ength to minimize discharge current while maximizing thrust. The probe was inserted and removed from the discharge channel by a high-speed positioning system at nine radial locations. The peak ion density calculated by the thin sheath analysis technique was typically upstream of the peak electron temperature location by 3-5% of the channel length. The peak ion density calculated by the orbitalmotion limited analysis technique coincided with the peak electron temperature location. The peak electron temperature dropped by approximately 5 eV and moved downstream by 3-5% of the channel length for each addition of 10 mg/s. The electron cooling was attributed to increased electron-neutral collisions. The results indicate a strong dependence between neutral flow rate and the peak plasma property magnitude and location.
doi:10.2514/6.2008-4920 fatcat:3kgbmr4tcfejzihheiyms7z4ry