High-Bunch-Charge and High-Energy-Gain Inverse-Cherenkov Particle Accelerator With Prebunched Beam

Dielectric laser accelerator (DLA) is a promising candidate for next-generation on-chip particle accelerator. However, practical applications of DLA to date have been restricted due to low accelerated bunch charge and low energy gain, especially for subrelativistic particles. To break through these limitations, here we propose a multistage DLA scheme with inverse Cherenkov effect. The first stage, formed by a pair of symmetric dielectric prisms, is to prebunch a long (tens to hundreds of laser-wavelengths) electron beam with relatively high bunch charge (several to tens of femto-coulombs) via velocity bunching. The subsequent stages, consisting of pairs of dielectric prism stacks, are to fulfill cascade acceleration of the prebunched beam. The synchronization of subrelativistic particles with laser field is realized via adjusting the prism angles in each stack. With theoretical analyses and simulations, we obtain an energy gain of more than 400 keV for an electron beam with initial energy of 100 keV. Compared with that of a non-prebunched beam, the accelerated bunch charge of a prebunched beam is more than four times higher. This proposed scheme affords an effective way of developing an on-chip particle accelerator with high energy gain and high bunch charge.