Implementation of a frequency-agile, high power backward wave oscillator

Work at the University of New Mexico (UNM) has demonstrated how finite length effects in a high power vacuum backward wave oscillator (BWO) can be exploited to achieve frequency agility for constant beam and magnetic field parameters. This enhanced bandwidth is obtained through the axial displacement of the slow wave structure with respect to the cutoff neck "inlet" to the electrodynamic system. This paper describes progress on the implementation of this automatic displacement to facilitate the incorporation of a robust controller, as proposed by Abdallah, et al. (1996). The purpose of this controller is to demonstrate a "smart tube" where a variety of objectives, such as (i) maximizing the frequency bandwidth for a given constant power output, (ii) maximizing the radiated peak power at a given frequency, or (iii) maximizing the beam-to-microwave power conversion efficiency, can be achieved automatically.