A large-diameter coaxial relativistic backward-wave oscillator is presented. The linearized Lorentz force equation, continuity equation, and Maxwell equations are used to calculate the system dispersion relations for a backward-wave oscillator with a dual-plate rippled-wall waveguide. The system also includes an infinitely thin relativistic electron beam propagating between the opposing plates. Using this theory, the influences of various system parameters on the beam-wave interaction, especially on the exponential growth rate of the wave, are discussed in detail. This theory is also used to design a large-diameter coaxial relativistic backward-wave oscillator in 3cm waveband.

In this paper the nonlinear neutron transport equation is derived. The collisions between neutrons are taken into account in this equation. In order to solve this equation we proposed the successive n-n collision expansion method.By using this method the equation is deduced to the form suitable for numerical computation. The numerical calculation is performed and the significance of the solution is discussed.