抄録
Numerical analysis for radiation level in a high-power backward wave oscillator with a finite-length slow-wave structure with end reflections has been made using an algorithm called the higher-order implicit difference method (HIDM). Spatial and temporal evolutions of a small localized disturbance in an RF field are followed by relativistic fluid equations and Maxwell equations. The radiation intensity of the oscillation decreases substantially with increasing energy spread beyond 10% of the beam.