Triangular discretization method for the evaluation of RF-fields in cylindrically symmetric cavities

The design of rf accelerating structures nowadays is largely based on mesh-codes that solve for fields and eigenfrequencies in arbitrarily shaped cavities. The most developed codes deal with structures of cylindrical symmetry. However, no program is available that can solve for fields with azimuthal variation in cavities with dielectric and/or permeable insertions. Here we describe a discretization method Using an "orthogonal triangular double grid". The special mesh and the FIT-discretization /1,2/ enable the treatment of cavities with arbitrary material insertions and combines the features of SUPERFISH /3/ (triangular mesh, rotationally symmetric fields) and URMEL /4/ (rectangular mesh but field with or without azimuthal variation).