Description:
<jats:p>An analytical and numerical study is presented herewith to get an insight into the excitation of forward and backward waves caused by an intense relativistic electron beam in a rippled wall plasma filled waveguide with weak modulation. The numerical results of growth rate are derived in the case of weak modulation at kz=π/z0 (the π point). Numerical results also show that no excitation of waves takes place if relativistic factor of the beam γ&lt;(1+μ20s/R20k20)1/2. For γ≳(1−μ20s/R20k20)−1/2, the beam excites both forward and backward waves, and only forward waves if (1+μ20s/R20k20)1/2&lt;γ&lt; (1−μ20s/R20k20)−1/2. The dependence of the frequency of the generated forward waves on beam energy is also studied numerically and the results are compared with those of the experiment [IEEE Trans. Plasma Sci. PS-18, 490 (1990)]. The effect of corrugation depth of rippled wall plasma filled backward wave oscillator (BWO) on minimum frequency generated is also studied.</jats:p>