A possible approach of realizing multi-stage laser-driven acceleration with Bessel beam is explored. With using a set of annular slits, Bessel beam is truncated and structured into several separate sections during its transportation, leading to the possibility of accelerating electrons stage by stage. Bessel beam is regarded as diffraction-free beam, allowing a very long acceleration distance in contrast to the Gaussian beam. In this paper, the transportation characteristics of the structured Bessel beam is analyzed based on scalar diffraction theory, as well as the acceleration mechanism is demonstrated numerically.

High brightness beams of gamma rays produced with laser Compton scattering have the potential to realize photo-transmutation through (γ,n) reaction, implying an efficient method to dispose long-lived fission products. Preliminary investigations have been carried out in understanding the feasibility of development of a transmutation facility to repose nuclear waste. A laser Compton scattering experimental setup based on a storage ring started to generate gamma-ray beams for studying the coupling of gamma photons and nuclear giant resonance. This paper demonstrates the dependency of nuclear transmutation efficiency on target dimensions and gamma ray features. ¹⁹⁷Au sample was adopted in our experiment, and experimental results correspond to the theoretical estimations.

Electrons undergoing half-cyclotron rotation emitts a half-cycle electromagnetic wave. A novel light source based on such short-pulse radiation is under developing at Institute of Free Electron Laser Osaka university. In this presentation, the experiments to amplify the radiation in the optical resonator will be discussed.