Pic simulation And Analytic modelling Of both Long and Short-pulse Magnetically Insulated Transmission Lines

Abstract

It is crucial to have appropriate tools for MITL design. This need is emphasized by the number of new pulsed power accelerators presently in the feasibility-study and design stages. MITL systems are essential components of most of these accelerators. MITLs are typically modeled by Telegrapher`s equations that treat electrons only through a voltage and current-dependent loss front current. The electron flow behind the loss front in a MITL system must also be included adequately in a model if it is to accurately determine the power and energy available to the load of a MITL. Often electromagnetic, relativistic PIC simulations must be done to characterize specific MITL designs. However, rather than concentrate on simulations of a specific geometry, they have recently done ensembles of simulations of generic MITL systems and have found patterns in the results that validate the use of a generalized set of Telegrapher`s equations which include electron flow. The fit to this pattern provides the value of a parameter, determined by the electron dynamics, used in the model. The simulations have also demonstrated features whose assumption makes the analytic model very simple to implement. One of these simplifying assumptions is that the flow impedance is essentially constant, nearlymore » independent of load impedance even in a short line. The new modeling equations should prove useful for the accurate characterization of MITLs, allowing one to easily predict load power and energy for a variety of system designs. The authors show a number of sample calculations from the model with corresponding simulation results for comparison.« less