Capacitance of an array of thick rods parallel to the ground - application to the ion cyclotron resonance frequency antenna of the Joint European Torus

A variational evaluation of the electrostatic capacitance of an array of thick metal rods parallel to the ground is presented. A straightforward procedure allowing unlimited numerical accuracy is given, as well as a simple analytical approximation sufficient for all practical purposes. The method is applied to the Faraday shield of the JET ICRF antenna, where it yields a correction of order 40% to the classical thin wire formula. (Author)