Experimental Study and Analysis of an S-Band Multiple-Beam Klystron With 6% Bandwidth

We present experimental results and analyses of an eight-beam five-cavity multiple-beam klystron (MBK) operating at a center frequency of $\sim$3.2 GHz. The device met its performance goals in its first hardware implementation, generating a peak RF output power of 600 kW and a 3-dB bandwidth of $\sim$6%. The circuit was modeled with TESLA, a 2.5-D large-signal klystron/MBK code that was extended to enable simulations of the low- $Q$ multiple-gap cavities used to increase the bandwidth. Details of the model and underlying theory are described, and the simulation results are compared with experimental measurements. The good agreement between the model and the experiment provides a validation for our tools and techniques that will be used in the design of future devices.