ANALYSIS OF THE AXIALLY-SYMMETRIC HARD MAGNETIC PISTON

The use of a magnetic piston to push plasma through a duct is analyzed. The magnetic piston is formed by sending a current step down a capacitively loaded helical transmission line which is entwined around the plasma duct. The radial component of the fringing B-field associated with the current step irteracts with the conducting plasma to produce a body force in it. The fringing B-field thus acts as a piston on the plasma. The magnetic piston is analyzed by a model which enables properties of the system such as plasma pressure and velocity to be computed in terms of design parameters. The analysis is for the steady-state case (the velocity of the piston equals the plasma velocity). The analysis involves the simultaneous solution of the energy balance for the system together with the normal shock relationships. Numerical computations are presented for design parameters for the cases in which capacitors are originally charged and uncharged, using hydrogen at 300 deg K as the plasma. (N.W.R.)