Spatially resolved Thomson scattering measurements of electron properties across the acceleration region of a high-power magnetically shielded Hall effect thruster

Noninvasive measurements of electron properties in a Hall effect thruster (HET) are needed to understand the physical processes in the acceleration region and to validate simulations. This paper presents spatially resolved laser Thomson scattering (LTS) measurements across the entire acceleration region of a HET. The test article is the H9, a 9 kW class magnetically shielded HET. The H9 is operated on krypton at a facility pressure of 1.2 × 10−5 Torr Kr (1.6 mPa). The thruster is operated at three discharge conditions: 171 V, 35 A, an inner coil current (Iic) of 4.11 A, and an outer coil current (Ioc) of 2.27 A as the baseline 6 kW condition; 154 V, 34.8 A, an Iic of 4.11 A, and an Ioc of 2.27 A to vary the discharge voltage; and 171 V, 34.4 A, an Iic of 4.52 A, and an Ioc of 2.5 A to vary the magnetic field strength. At each discharge condition, we measured axial profiles of electron density and electron temperature along the channel centerline from 5% to 95% of a channel length downstream of the channel exit plane. At the baseline condition, we also measure the axial profile of the azimuthal electron drift velocity. We measure a minimum electron density of 1.3 × 1017 m−3, peak electron temperatures around 40 eV, and a peak azimuthal electron drift velocity around 680 km/s. The results suggest the presence of anomalous electron heating and demonstrate that low discharge voltages allow LTS to access the entire acceleration region of a HET.