Time-domain numerical computations of electromagnetic fields in cylindrical co-ordinates using the transmission line matrix: Evaluation of radiation losses from a charge bunch passing through a pill-box resonator

Abstract

The two-dimensional transmission line matrix (TLM) numerical method has been adapted to compute electromagnetic field distributions in cylindrical co-ordinates and it is applied to evaluate the radiation loss from a charge bunch passing through a ‘pill-box’ resonator. The computer program has been developed to calculate not only the total energy lost to the resonator but also that component of it which exists in the TM 010 mode. The numerically computed results are shown to agree very well with the analytically derived values as found in the literature which, therefore, establishes the degree of accuracy that is obtained with the TLM method. The particular features of computational simplicity, numerical stability and the inherently time-domain solutions produced by the TLM method are cited as additional, attractive reasons for using this numerical procedure in solving such problems.