Experimental considerations in electron beam transport on a nanophotonic chip using alternating phase focusing

TL;DR

This paper explores the experimental considerations for electron beam transport on a nanophotonic chip using alternating phase focusing, emphasizing the importance of timing and angle alignment for effective electron transmission.

Contribution

It provides new insights from simulations and experiments on how to optimize electron transport in nanophotonic accelerators using alternating phase focusing techniques.

Findings

Transmission depends on temporal overlap of electron and laser pulses

Incidence angle affects electron transmission efficiency

Time delay scans reveal potential imprecisions and parasitic effects

Abstract

Not long after the laser was invented, it has been marked as a candidate source of strong, high-frequency electromagnetic radiation for acceleration of particles. Indeed, while the complex particle accelerator facilities today are an astonishing culmination of decades of work contributed by generations of physicists, engineers, and a host of scientists, new trends and acceleration technologies have been recently proposed and demonstrated. One of these technologies involves the miniaturization of particle accelerators, which is achieved by replacing the radio-frequency electromagnetic fields accelerating the particles with fields in the optical frequency range, using lasers. This entails using nanophotonics structures to provide the required field distribution. Recently, individual elements towards the nanophotonics counterpart of RF accelerators have been demonstrated. Similarly, active electron transport through such a structure has been shown, which was based on the concept of alternating phase focusing. In this contribution, we discuss and augment on the recently-demonstrated principle of alternating phase focusing using optical frequencies, and provide new insights from relevant simulations and experiments. In particular, we show how to identify possible imprecisions and parasitic effects from time delay scans and discuss how the transmission of electrons through the nanometric structure depends on the temporal overlap between electron and laser pulses, and show how the incidence angle of the electron beam can affect the measured transmission of electrons through the structure.