Spatial autoresonance cyclotron accelerator

A mechanism of electron acceleration scheme utilizing the spatial autoresonance phenomenon in combined axial guide magnetic field and a traveling electromagnetic wave with adiabatically varying parameters is analyzed. The acceleration is achieved due to the self-tendency of the particles to stay in the relativistic gyroresonance with the wave, despite the variation of systems parameters. As compared to other traveling wave cyclotron acceleration schemes, the spatial autoresonance accelerator does not require a precise initial frequency matching and a rigid tuning of the guide magnetic field for sustaining the resonance. The method is illustrated in the case of a microwave driver with a tapered axisymmetric waveguide geometry.