Development of the Radiofrequency Section of a Ku-band Multiple-Beam Klystron. Issue 6 (1st November 2016) - Bandyopadhyay, A.K.
ABSTRACT: The multiple-beam klystrons (MBKs) are well known for some distinct performance advantages over their single-beam versions. The advantages of the MBKs include higher average power, relatively lower operating voltages, higher bandwidth, and low individual beam current. However, the design of the MBKs is more extensive and requires thorough and careful three-dimensional electromagnetic simulations and analysis. In this article, design of a four-beam klystron compatible with a predesigned electron gun is reported. Starting with simple analytical approach, detailed design and electromagnetic simulation results of the radiofrequency (RF) cavities are presented. Uniformity of the RF coupling between the external circuitry and the cavity RF field has been investigated in detail with the help of commercially available three-dimensional electromagnetic design code. A cold-test model of the RF cavity has been fabricated and its resonant frequency has been characterized experimentally. Design of the individual cavities, electromagnetic analysis of the same, simulation results of the beam-wave interaction, as well as the experimental frequency characterization of a fabricated cavity is presented in this paper.