Analysis of eddy currents in the walls of the ferrite tuned RF cavity for the TRIUMF Kaon Factory Booster Synchrotron

In the perpendicular biased ferrite tuned cavity of the proposed TRIUMF Kaon Factory Booster Synchrotron, magnetizing flux passes through the cavity walls. The equivalent circuit utilized is based on Faraday´s and Kirchoff´s laws. This equivalent circuit was used to obtain a first estimate of the eddy current loss in the walls of the RF resonator for the booster cavity and also used to determine the ratings for the power supply for perpendicular biasing of the ferrite in the RF cavity. By electrically isolating the cooling structure from the cavity walls and introducing slots in the walls, it is possible to bring to an acceptable level both the power loss and the maximal temperatures. Based on the measurements, an analytical model-essentially 3D-was derived and the eddy currents were predicted using the circuit analysis program PSpice. The calculated surface current and power distribution agree with measurements. PSpice can now be used to determine the effect of design changes on the eddy current and power distribution.<>