Hall thrusters are plasma accelerators which produce thrust with a low-temperature, 𝐸𝐸×𝐵𝐵 plasma ring. Due to their high performance, they have become the most widely flown form of in-space propulsion. However, our ability to predict Hall thruster operation and life with simulations is limited by difficulties in modeling the “anomalous” loss of electron confinement due to plasma turbulence. This anomalous transport of electrons limits efficiency and determines the electric field profile, impacting nearly every aspect of the thruster. Past attempts to measure the anomalous transport have used perturbative plasma probes which alter the thruster operation, and model-based inference studies do not produce a unique solution.

In this work, laser scattering experiments are performed to non-perturbatively characterize the flow of momentum and heat through the Hall thruster plasma. Laser-induced fluorescence (LIF) velocimetry is employed to capture the electric field, while incoherent Thomson scattering (ITS) is used to directly measure the electron properties in a high-power, magnetically shielded Hall thruster. A method is devised to infer the cross-field transport, represented by the effective Hall parameter, directly from these laser measurements. The electron properties are investigated across a parametric map of operating conditions and propellants in one and two dimensions. It is found that electron temperatures are larger than previously expected and the principle of isothermal field lines does not hold. The resulting dataset is used to evaluate theories for turbulent forces and heat fluxes in the Hall thruster and hollow cathode plumes.