Plasma Acceleration in an Electrical Discharge by the Self-Induced Magnetic Field

An electrical discharge is considered between two electrodes arranged axisymmetrically in the absence of an external magnetic field. Discharge currents are used up to 2500 A in a steady state and in the presence of a nitrogen-flow rate of the order of a few hundred milligrams per second. The interaction of the discharge with its self-induced magnetic field is examined and the importance of magnetoplasmadynamic effects in the acceleration of plasma is determined quantitatively. After a brief consideration of the analytical background several experiments are discussed and the corresponding results are analyzed. It has been determined that the self-magnetic field makes a substantial contribution, as high as 60% or higher in certain cases, to the acceleration of plasma. The particularly effective mechanism in these experiments seems to be the self-induced compression of the plasma in the discharge in front of the cathode. Further experimental results are presented from measurements of the momentum flux and of the velocity in the plasma flow. These measurements are constructively correlated with the forces which accelerate the plasma.