High power broadband CARM amplifier

Journal article

The simulation of an efficient, broadband cyclotron autoresonance maser (CARM) amplifier operating at a 4MW output power level is presented and discussed. The amplifier is based on a high current accelerator capable of generating a ∼35A pencil electron beam at an accelerating voltage of 450kV. The use of a beam trajectory modeling code has enabled optimisation of the beam transport system, with results showing a laminar beam profile and transverse velocity spread imparted via beam transport reduced to ∼3%. The low velocity spread was achieved without use of beam scraping, and therefore values presented for the interaction efficiency are a direct reflection of the overall system efficiency. A full 3D numerical model of the CARM amplifier was constructed within the PIC (particle-in-cell) code KARAT taking into account electron beam parameters derived from simulation and experiment. At a frequency of 12 GHz numerical simulations demonstrate 37dB gain and an interaction efficiency of 17%. In addition, a viable amplification bandwidth of 9 - 13GHz is apparent amounting to some 27% detuning from the centre frequency with a minimum gain and efficiency of 25dB and 10% respectively at the boundaries of the amplification band. This primary resonance coupled with the amplification bandwidth gives excellent correlation with the beam-wave dispersion character.

Authors: Speirs, D; Phelps, A; Konoplev, I; Cross, A; He, W

• Journal: ITG-Fachbericht
• Issue: 183
• Pages: 347-351
• Publication date: 2004-01-01
• ISSN: 0932-6022
• Language: English