Plasma wakefield dynamics of self-generated electron bunch trains

A new study reports on the successful generation of narrow, quasi-monoenergetic electron bunch trains with periodic energy spacing using downramp injection in a laser-driven wakefield accelerator.

The periodic energy spacing is achieved by relativistic lengthening of the wakefield during acceleration, while spatial periodicity is obtained through injection into multiple plasma periods. Phase-space rotation at the accelerator's end compresses individual bunches, creating distinct periodic spikes in the electron spectrum.

Particle-in-cell simulations corroborate the experimental findings, reproducing the formation and evolution of these periodic bunch trains and offering insights into the underlying plasma dynamics.