Numerical Analysis of SGEMP Responses on Coaxial Cables Based on a New Mesh Tally in Monte-Carlo Methods

System-generated electromagnetic pulse (SGEMP) that is generated by X-ray irradiation on coaxial cables would deteriorate sensitive electronic systems inside spacecraft, thereby affecting normal operations and survival of spacecraft. In this article, the SGEMP responses on coaxial cables are numerically assessed by using an equivalent transmission line model. In the transmission line model, a key parameter for determining its input is the charge distribution on coaxial cables due to X-ray irradiation. To acquire the actual charge distribution on coaxial cables, we present a new mesh tally in an in- house Monte-Carlo software, JMCT. The new mesh tally counts the number of charges in the user-defined mesh cells for coaxial cables to evaluate their nonuniform actual charge distribution, which has the advantages of high computational efficiency and high flexibility, and further yields a more accurate input to predict the SGEMP responses on coaxial cables. To illustrate the accuracy of the proposed method, it is validated by simulating the charge distribution on a coaxial cable and its load currents in the X-ray illumination and comparing the results with those calculated by using the method presented in the reference. In addition, the proposed method is further applied to explore the effects of coaxial cables’ structural parameters on their load currents. The studies in this article would guide the radiation-hardened design of coaxial cables.