Bandwidth Extension of an S-band, Fundamental-Mode Eight-Beam Klystron

We present the design of a five-cavity, broadband, high-power multiple-beam klystron (MBK) operating in S-band. The MBK uses a 32 A, 45 kV eight-beam electron gun as presented in K. T. Nguyen et al. (2004) whose design has been successfully tested in a previous narrowband MBK circuit stated in K. T. Nguyen et al. (2004) and D. K. Abe et al. (2005). The circuit was optimized using the 3D particle-in-cell code MAGIC; the predicted performance includes a 3-dB bandwidth of 6.7%, peak power of ~600 kW and a gain of 33 dB. This circuit performance represents a three-fold increase in the bandwidth-power product relative to our previous circuit