Measurements on an Experimental

An experimental arrangement is described which electromagnetically generates and accelerates ionized gas by inductive coupling between the circuit and the gas. Measurements are made of energy coupled from the circuit to the plasma and of energy, momentum, and velocity of the ac-celerated gas. Energy on the order of 20 to 40 j is transferred to the plasma; this represents about 5 to 10 % of the energy available for transfer, and J to \ of this appears as energy of directed motion of the gas. The gas velocities measured 10 cm beyond the acceleration coil are in the range between 0.5 X 104 and 1.5 X 104 m/sec, whereas the corresponding momenta are from 2 to 11 gm-cm/sec-cm2 of flow. High speed photographs of the radial compression of the plasma within the coil indicate tha t this radial compression is influential in determining the ult imate operating characteristics of this type of accelerator. Suggestions are made concerning improvement of efficiency. FOR MANY years studies have been made of systems in which energy is transferred from a circuit to an ionized gas by induction. An early description and analysis of con-tinuously driven, induction, or electrodeless discharges was given by Thomson (l),1 and the theory and use of such dis-charges have received frequent attention since Thomson'