Three‐dimensional electromagnetic analysis of a vacuum window involving waveguides

Abstract

AbstractLocal heating of the pillbox‐type vacuum window employed in microwave heating of nuclear fusion apparatus TOKAMAK has been a problem when used under a high power, particularly under the ghost mode. This factor is used to determine the maximum power of the heating system. However, in the measurement in actual operation, only the electric field can be measured when the amplitude and reflection coefficient become small due to the loss. An analysis taking into consideration the dielectric loss is needed to determine the characteristics of the electromagnetic field distribution in the ghost mode. We have applied the spatial network method to the pillbox vacuum window excited by a rectangular waveguide. The method has a number of unique features as a time domain analysis method for three‐dimensional electromagnetic fields. After the basic treatment is described, the electromagnetic field of the ghost mode is simulated by the analysis taking into consideration the dielectric loss. The effectiveness of the three‐dimensional electromagnetic analysis for the entire system is presented.