Fast Camera Imaging of Hall Thruster Ignition

Hall thrusters provide efficient space propulsion by electrostatic acceleration of ions. Rotating electron clouds in the thruster overcome the space charge limitations of other methods. Images of the thruster start-up, taken with a fast camera, reveal a bright ionization period which settles into steady-state operation over 50 mu s. The cathode introduces azimuthal asymmetry, which persists for about 30 mu s into the ignition.