Beam-matching design for suppressing beam losses in high-power klystrons

In order to suppress beam losses and radiations in high-power klystrons, the electron beam should be desinged to have the scalloping (i.e., the radial oscillation of beam envelope) as small as possible. This is done by matching the focusing field profile with beam trajectories (which are usually convergent). In this article, we report on the beam-matching simulations using a newly developed matching procedure with various beam radii and design solenoid magnets of S-band klystrons at Pohang Accelerator Laboratory (PAL).