Short-wavelength radiation pulses with time-varying orbital angular momentum from tailored relativistic electron beams

In this Letter, we propose a novel, to the best of our knowledge, technique to generate short-wavelength radiation carrying time-varying orbital angular momentum (OAM) by tailoring relativistic beams in free-electron lasers. To manipulate the temporal properties of OAM beams, two time-delayed seed lasers with different OAM values are used to interact with the electron beam in the undulator. With this method, high-harmonic electron beam microbunching with a time-varying helical distribution can be tailored to match the time-varying instantaneous helical phase structure of the x ray beams. Theoretical and simulation results demonstrate that high-power x ray beams with time-varying OAM can be produced by the proposed technique, which opens new routes to scientific research in x ray science.& COPY; 2023 Optica Publishing Group

Automated summary

In this Letter, a novel technique is proposed to generate short-wavelength radiation with time-varying orbital angular momentum (OAM) by manipulating relativistic beams in free-electron lasers. Two time-delayed seed lasers with different OAM values are used to interact with the electron beam to manipulate the temporal properties of OAM beams. Theoretical and simulation results demonstrate the production of high-power x ray beams with time-varying OAM using this technique, opening new avenues for scientific research in x ray science.