Application of Method of Characteristics to IEMP Cable Response

We have demonstrated the ability of MOC to solve transmission line problems, with space and time varying parameters. As a practical application, we developed a computer code for obtaining the response of a long cable subject to a ¿-environment when the far end of the cable is terminated either in a pure resistive load or in an impulse-response impedance. For cables without air gaps the current drive and the distributed conductance induced by the ¿-radiation are both proportional to the incident ¿-intensity. For cables with a small air gap next to the metal shield, the current drive induced by the ¿-radiation is affected by the induced air conductivity such that io(x,t) is proportional to the incident ¿-intensity or its time derivative according to dePlomb´s criteria. The effect of air gap tends to reduce the peak value of short-circuit current response at x = o. When the resultant distributed conductance G of the cable, with or without an air gap, induced by the ¿-radiation is of the order of 10-4 mho/m or smaller, the cable acts as a linear network and a Norton (Thevenin) equivalent circuit can be employed at the input terminal.