Theoretical study of the folded waveguide

A three-dimensional (3-D) algorithm for solving Maxwell's equations is applied to the analysis of folded waveguides used for fusion plasma heating at the ion cyclotron resonance frequency (ICRF). In this method a finite-difference method is used with a successive overrelaxation (SOR) convergence scheme and a method of treating boundaries that allows the cavity to have an arbitrary shape. A rigorous analysis of the magnetic-field structure in the folded waveguide is presented. The results are compared with experimental measurements in vacuum. To study breakdown problems, a much simpler two-dimensional (2-D) model is adopted. It is found from the 2-D analysis that the geometry, shape, and thickness of the vanes play an important role in avoiding voltage breakdown problems.<
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