Electron acceleration in sub-relativistic wakefields driven by few-cycle laser pulses

Abstract

Using particle-in-cell simulations, we study the interaction of few-mJ-fewcycle laser pulses with an underdense plasma at resonant density. In this previously unexplored regime, it is found that group velocity dispersion is a key ingredient of the interaction. The concomitant effects of dispersion and plasma nonlinearities cause a deceleration of the wakefield phase velocity, which becomes sub-relativistic. Electron injection in this sub-relativistic wakefield is enhanced and leads to the production of a femtosecond electron bunch with a picocoulomb of charge in the 5-10 MeV energy range. Such an electron bunch is of great interest for application to ultrafast electron diffraction. In addition, in this dispersion dominated regime, it is shown that positively chirped laser pulses can be used as a tuning knob for compensating for plasma dispersion, increasing the laser amplitude during self-focusing and optimizing the trapped charge.

MeV femtosecond electron pulses from direct-field acceleration in low density atomic gases

“…2, but where x, y ∈ [−5λ 0 , 5λ 0 ] to reduce the computational load, simulating a 700-fs propagation takes about 40 hours on a supercomputer using some 128 processes. It corresponds to a distance of 0.2 mm away from the RPFLP focus, comparable to the longitudinal distances reached in similar PIC studies [25].…”

Capturing Structural Dynamics in Crystalline Silicon Using Chirped Electrons from a Laser Wakefield Accelerator

“…Finally, another way to decrease τ streak is to increase the electron energy E while keeping the resolution of the magnetic spectrometer the same. This may become possible in the near future with recent results showing that multi-MeV electrons can be generated3940.…”

Concept of a laser-plasma-based electron source for sub-10-fs electron diffraction

“…The laser beam is focused at the beginning of the plateau, down to a waist of 4.3 µm, so that the laser intensity is I = 2.6 × 10 18 W/cm 2 -the corresponding value of the normalized vector potential is a 0 = 1.1. The laser is polarized along the y-axis and propagates along the The physics of this interaction has been studied in details in a previous publication [38].…”