A 1-D MHD Model for the Axial Induced Electric Field During the Self Compression of a Cylindrical Plasma Column

Summary form only given. The radial compression of cylindrical plasmas induces acceleration voltages considerably higher than those used to charge the capacitor bank employed in the discharge. These phenomena typically occur in Z-pinches and plasma focus devices, where 100 keV X-rays are commonly observed in machines operated with charging voltages of 50 kV or less. Several accelerating mechanisms were discussed in the literature to explain this peculiarity and its effect on the discharge behavior. In this communication, a 1D MHD model for the time evolution of the plasma column dynamics is proposed to evaluate the accelerating potential along the symmetry axis, taking into account the plasma resistivity as well as the inverse skin effect. The total current circulating through the plasma column is calculated in a self consistent manner with the external circuit evolution. The numerical results of the model, which predicts electric fields of 100 kV/cm; convergent radial velocities of about 20 cm/mus for deuterium plasma columns of 2 mm in diameter; are satisfactorily compared with experimental results about the characteristic energy of the hard-X-rays generated by electron impact on the anode base