A MAGNETICALLY-NOZZLED, QUASI-STEADY, MULTIMEGAWATT, COAXIAL PLASMA THRUSTER

The Los Alamos National Laboratory Coaxial Thruster Experiment (CTX) h as been upgraded to enable 10 ms quasi-steady-state (QSS) operation of magnetohydrodynamic type thrusters at power levels from 1 to 40 MW, H ere we report on experimental observations and associated analysis for QSS discharges using deuterium, helium, and argon propellants, Measur ements of thruster current and voltage, magnetic field fluctuations, e lectron density and temperature, and plasma potential indicate true qu asi steady operation over 10 ms with propellant exhaust velocities of 1-2 x 10(5) m/s in helium and deuterium, The application of unique app lied magnetic nozzle configurations result in a substantial reduction of the measured anode fall potential, Data analysis and analytical MHD modeling imply an impulsive start in the propellant flow that is limi ted to the Alfven critical ionization velocity and the presence of an effective constriction or ''nozzling'' in the flow channel, This resea rch indicates that efficiency optimization of MHD class thrusters will most likely occur at megawatt power levels, This implies repetitively pulsed, high-power operation for near term, low-mean-power solar elec tric propulsion missions.