Abruptly autofocused electron beam generation through electron-plasmon interactions

Electron Airy beams and electron vortex beams are commonly generated using phase masks that imprint a transverse modulation on the particle wave function. Plasmons sustained by nanostructured conductors facilitate substantial interactions with free electrons, enabling considerable transverse modulation of the electron wave function. Consequently, electron Airy and vortex beams can also be produced through interactions between electrons and structured plasmonic fields. Here we illustrate the generation mechanism of the electron ring Airy vortex beams by allowing electrons to traverse an Airy plasmon field with phase singularities and calculate the excitation intensity probability. Subsequently, we numerically investigate the autofocus behavior of the generated Airy vortex beams. Our findings indicate that electrons in the ℓ = 1 channel exhibit the highest excitation probability and produce optimized autofocused ring-shaped Airy vortex beams in our proposed scheme. Furthermore, the number of exchanging plasmons does not significantly influence the position of the primary Airy ring in the initial plane, yet it markedly affects the focal distance and spot size in the focal planes. Our study supports the utilization of chiral plasmons sustained by externally illuminated thin films as a method for generating autofocused chiral electrons, resulting in remarkably large diffracted beam fractions in attainable conditions.