Evaluation of a 4-gap extended interaction output circuit for a 50MW X-band klystron

A 50 MW, 12 GHz klystron based on the SLAC XL5 design has been developed and tested to full specifications. The 4-gap extended interaction output circuit is critical for the reduction of the electric field gradients to acceptable levels yielding reliable operation. A systematic cold test method for evaluating the as-built performance of the output circuit against the ideal simulated performance is described. The proposed method can be applied to any extended interaction output circuit with any number of gaps. Additionally, the analysis shows that this type of structure exhibits both standing-wave and traveling-wave characteristics.