ABSTRACT
Extended-interaction klystrons (EIKs) are resonant cavity-based circuits. First proposed by Chodorow and Wessel-Berg [1], the EIK has evolved into a compact device of choice for the THz regime. Similar to klystrons, EIKs are comprised of an input cavity, which imparts a velocity modulation on the beam to start the beam bunching process, one or more idler cavities to improve beam bunching (gain) and/or bandwidth, and an output cavity to extract RF power from the optimally bunched beam. The key difference between a standard klystron and an EIK is that EIK cavities have several interaction gaps versus one for a standard klystron, which raises the cavity interaction impedance. The higher cavity interaction impedance is a key factor in compensating for the unavoidable lower beam current at higher operating frequencies. This is because beam current tends to scale as ~1/ f2 for any given beam-forming approach.
