The coaxial cavity locked HPM tube and external HPM feedback stabilization

Summary Form only given, as follows. Relativistic electron beam interactions in high-power microwave (HPM) tubes have been studied. It has been shown that: (1) dense electrode and cavity plasmas are both sporadic and dynamic, making efforts to produce coherent, nonspiky, >100-ns HPM in subcentimeter gap tubes difficult; (2) intense and dynamic ion beams steal modulator energy and cause drastic modification of space charge field profiles; (3) intense electron-beam-wave interactions vary locally in a chaotic manner and suffer from poor HPM transmission and phase communication; and (4) applied magnetic field, pulse risetime, and low-ripple voltage plateau tuning is complicated by appreciable HPM fields and beam space charge and self-magnetic fields. To improve HPM pulse efficiency and stability, feedback stabilization by means of a vacuum channel between each perturbation, which is outside the beam-wave interaction region and thereby free of plasma, has been proposed. Several physical models based on the mechanism have been developed and supported by theory, computer simulation, and/or preliminary experiments.<>