A viable model for power focussing in a lossy cylinder

Summary form only given. The authors are interested in controlling the power dissipation of a lossy cylinder of finite length when a field is applied on its surface and where the applied surface field is independent of the azimuthal angle. In addition the cylinder is assumed homogenous. A procedure is presented to show how this is accomplished. To begin, a field is assumed on the axis of the lossy cylinder such that the required dissipation inside the cylinder is obtained (or visa versa). An analytical evaluation of the source on the surface of the cylinder can then be carried out. The solution involves an inverse problem where the source is unknown and its response is specified. In this form, the source is continuous. A realization of the source (surface field) in terms of a discrete array is also given. This is done by assuming that the source is zero on the surface of the cylinder except at a finite number of points. The source can then be realized by applying voltages at these points and the values of the voltages correspond to the actual source on the surface. In a practical situation, the voltages are applied across a finite number of thin cylindrical slots cut in a metal encasing. Results are presented that show excellent agreement between the actual source and the discrete array in producing the field on the axis of the cylinder. Hyperthermia treatment of cancer in cylindrical objects such as limbs, and torsos are one potential application. Non-destructive testing of manufactured cylindrical products is another application where the energy is focused at a given region in the cylinder.