Finite Elements based optimal design approach for high voltage pulse transformers

Summary form only given. High voltage pulse transformers are widely used in klystron modulators. For these topologies, the quality of the modulator output voltage is strongly dependent on the pulse transformer performance. An optimal design process of such transformers is a necessity, particularly when the specifications of the output voltage are tight such as in the case of the CLIC klystron modulator under study at CERN [1]. Using a sufficiently accurate analytical model to optimize a high voltage transformer design will yield the most efficient design process. The accuracy of the design can then be verified with a Finite Element Analysis as a final check. However in the case of high voltage transformers, it can be difficult to obtain an analytical model that is sufficiently accurate particularly due to effects of parasitic capacitance. As such, it would be desirable to find an efficient method to use only Finite Element Analysis to find an optimal design. This paper presents a new design approach for high voltage pulse transformers, based on a FEA dimensioning model only. For each iteration of the non-linear optimization process, the transformer parameters used to compute the objective and constraints functions are directly derived from the 2D FEA dimensioning model. Programming techniques to speed-up the FEA model evaluation for each iteration of the optimization procedure are presented.