Temporal survey of electron number density and electron temperature in the exhaust of a megawatt MPD-arc thruster.

Temporal and radial profiles are obtained 30 cm downstream from the anode for two peak arc currents (11.2 kA and 20 kA) and for various auxiliary magnetic fields (0, 1.0 T, and 2.0 T) using the Thomson scattering technique. Average density and temperature are relatively constant for over 100 microseconds with significant fluctuations. Radial profiles obtained are relatively flat for 4 cm from the axis. Compared to earlier 20 cm data, the exhaust density has decreased significantly, the average temperature has not changed, and the density ?hole' with an auxiliary magnetic field has enlarged.