Plasma Effects on the SGEMP Space-Charge Boundary Layer

The system-generated electromagnetic pulse (SGEMP) code MEEC-3D has been used to study plasma effects on the electromagnetic fields near a conducting surface exposed to a pulse of X-rays. It is shown that plasma convection to the surface and subsequent space-charge barrier breakdown is the predominant mechanism for altering SGEMP fields in the X-ray deposition region. The presence of the neutral plasma reduces the prompt time-phased magnetic field and the time derivative of the dipole moment. Late-time magnetic fields are more intense and the pulse width increases with the plasma present. Quenching of the surface electric fields results in an increase of net current emitted from the surface.