Hollow Beam Klystron Design for the International Linear Collider

Summary form only given. In this talk, we describe a benchmark design for the ILC klystron to meet the requirements using the Trak and AKLSC codes. Trak is a fully relativistic 2D code for gun and collector design and AKLSC is an extension of the KLSC code for annular beams. We have added streamlined interfaces between the codes to create a unitized package for HBK design. We shall discuss injector design and optimization of the cavity geometries and configuration for minimum electric field and optimum efficiency. The challenge for gun design is to ensure moderate source current density with compensation for cathode cooling over the long pulse. These consideration lead to a space-charge-limited extractor with strong area convergence (> 10). The shape of the cathode and fringe magnetic field lines must be carefully designed to ensure a good match to the focusing solenoid with small beam transverse energy content.