Tuning of betatron radiation in laser-plasma accelerators via multimodal laser propagation through capillary waveguides

The betatron radiation from laser-plasma accelerated electrons in dielectric capillary waveguides is investigated. The multimode laser propagation is responsible for a modulated plasma wakefield structure, which affects the electron transverse dynamics, therefore influencing the betatron radi- ation spectra. Such a phenomenon can be exploited to tune the energy spectrum of the betatron radiation by controlling the excitation of the capillary modes.