Design of the radio frequency section of a multiple beam klystron working in the J-band frequency range
The multiple beam klystrons (MBK) offer some distinct advantages over their single beam versions including higher average power, relatively lower operating voltages, higher bandwidth and low individual beam current. In this paper the design of the radio frequency (RF) section of a multiple beam klystron working in the J band frequency range is presented. The RF design and simulation has been carried out using a 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. Design of the individual cavities, simulation results of the beam wave interaction as well as the frequency characterization of the fabricated cavity is presented in this paper.
Development of the Radiofrequency Section of a Ku-band Multiple-Beam Klystron
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.
Electron gun design for fundamental mode S-band multiple-beam amplifiers
This paper describes the detailed design of an eight-beam electron gun for use in S-band multiple-beam amplifiers operating in the fundamental mode. The gun operating voltage is 45 kV with a total beam current of 32 A, evenly divided among the beamlets. Each individual beam has a perveance of 0.42 mpervs making a total beam perveance of 3.35 mpervs. The optimized electron gun is singly convergent using a four-fold symmetry with the four inner and four outer emitters interlaced 90/spl deg/ apart. The emitter current density has been kept below 10 A/cm/sup 2/ (space-charge limited). The cathode is magnetically shielded and the longitudinal magnetic field in the interaction region is in the range of 1.1-1.8 kG. The design of the magnetic focusing system minimizes beam corkscrewing as well as electron interception on the tunnel walls. Beam optics simulations of the gun indicate excellent beam transport characteristics with a final beam-to-tunnel radial fill factor of less than 0.45. The primary computational tools used in the design process were the three-dimensional gun code MICHELLE, and the magnetostatics code MAXWELL-3D.