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This paper summarizes preliminary experimental and theoretical research that was directed toward the study of quasi-steady-state power flow in a large, unoptimized, multimegawatt coaxial plasma thruster. The paper addresses large coaxial thruster operation and includes evaluation and interpretation of the experimental results with a view to the development of efficient, steady-state, megawatt-class magnetoplasmadynamic (MPD) thrusters. Experimental studies utilized the Coaxial Thruster Experiment (CTX) facility at the Los Alamos National Laboratory. The unoptimized thruster, 1 m in length with inner and outer tungsten-coated electrode diameters of 0.37 and 0.56 m, respectively, was operated over a range of peak power levels (nominally 10-40 MW) in order to ascertain high-power performance scaling. In addition to pure self-field operation, an unoptimized applied magnetic field configuration, with adjustable flux densities, was used to form a rudimentary, annular magnetic nozzle. In this initial research, an accurate power balance was precluded due to the lack of spatial resolution of power deposition on the electrodes. However, the data, together with a calorimetric IR data reduction algorithm, did quantify energy flux deposition on electrode surfaces and provided a qualitative picture of global power flow and thruster performance. Highlights of this study include the observations that the measured longitudinal flow velocity of the propellant was in essential agreement with the prediction of self-field nozzle theory, achieving Alfvenic flow velocities of approximately equal to 10 to the fifth power m/s. Furthermore, radiative emission was a negligible power loss mechanism (