Toward a Laser-Driven Traveling-Wave Linac on a Chip

Abstract

Restricted by pulse dispersion, dephasing, and bunch deflection, it has been a challenging task to realize high-gain particle acceleration and bunch focusing by using an ultrashort-pulse laser to drive an integrable acceleration structure, which is necessary to develop an on-chip particle accelerator for practical applications. Here we propose a laser-driven traveling-wave linac (linear accelerator), which uses the cascade reflection and refraction of an ultrashort laser pulse on a microscale dielectric structure to achieve long-range laser-particle interaction, avoiding waveguide dispersion, and enhancing sustainable acceleration gradient. It is scalable and extensible, and can realize full-course particle acceleration by using a single laser source via the inverse Cherenkov effect. With this accelerator scheme, we further propose a dynamic synchronization and focusing method, which not only counteracts dephasing but also restrains the bunch spread and deflection caused by space-charge and emittance effects, realizing stable bunch transport and acceleration in a tiny-size bunch channel without resorting to the need for external focusing equipment. This accelerator scheme paves the way toward a high-efficiency laser-driven all-dielectric on-chip particle accelerator for practical applications.