A 50-MW broadband plasma microwave amplifier

Computer simulation of a high power relativistic plasma microwave amplifier in a finite external magnetic field

“…The amplitude of the backward wave increased because of the reflection coefficient of the plasma wave from the end of the plasma waveguide grows with increasing frequency of the impinging wave [7]. Resonance values of the external magnetic field = 0.6, 1.2 and 1.8 at n = 3, 2, 1 in conformal with (1).…”

“…Some of the results obtained in those experiments (the plasma density ranges, the optimum length of the amplifier, etc) agree qualitatively with the linear and nonlinear theories of the microwave amplifier developed in [2], where a model of an ideal amplifier was considered, with no absorber, with a steady-state process, and without allowance for a reflection of electromagnetic waves from the junction between a waveguide filled with tubular plasma and a vacuum coaxial waveguide. Quantitative agreement with the experiments of [1] can be reached only when numerical model incorporates the presence of the microwave absorber, reflections from the waveguide ends, and the pulsed character of the process.…”

“…The geometry of the collector and of the vacuum output coaxial waveguide (see a right part of Fig. 1) was very close to those in the experiments of [1]. The radiation that reached the vacuum waveguide was assumed to be fully absorbed on its right end.…”

“…In computing the absorber we used a medium with the absorbing boundary conditions, calculated according to Berenger's Perfect Matched Layer method [4]. By properly choosing the parameters of this medium (sizes, gradients, conductivity) it was possible to make the absorption of the impinging wave nearly the same as that in real experiment [1].…”

“…In vacuum microwave electronics, the feedback factor is often lowered by placing a microwave absorber inside the device. The experimental implementation of the microwave amplifier in plasma electronics was described in [1]. Some of the results obtained in those experiments (the plasma density ranges, the optimum length of the amplifier, etc) agree qualitatively with the linear and nonlinear theories of the microwave amplifier developed in [2], where a model of an ideal amplifier was considered, with no absorber, with a steady-state process, and without allowance for a reflection of electromagnetic waves from the junction between a waveguide filled with tubular plasma and a vacuum coaxial waveguide.…”