Linear Accelerator Cavity Field Calculation by the Finite Element Method

The design of linear accelerator (linac) cavities necessitates the field solution of axisymmetric electromagnetic resonators. Mathematically this involves the solution of the one-component vector Helmholtz equation in cylindrical coordinates subject to boundary conditions which are dictated by the physics of the electromagnetic field problem. In this paper it is shown how the high-order polynomial, triangular, finite element method can be applied to field calculation in linac cavities of arbitrary longitud - inal cross section.