Hybrid LWFA-PWFA Plasma Photocathodes: A Pathway for Compact X-ray Light Sources

Plasma wakefields can sustain accelerating field gradients on the order of 100 GV/m, far exceeding those achievable in conventional particle accelerators based on radio-frequency technology. Such plasma wakefield accelerators can be driven either by high-power laser pulses (LWFA), or by high-current charged-particle beams (PWFA). The individual advantages of both approaches can also be combined in a compact hybrid scenario, where an LWFA generates electron drivers for a subsequent PWFA stage. This configuration provides a versatile novel platform for exploring advanced plasma-based accelerator concepts such as plasma photocathodes. Plasma photocathodes employ a laser pulse to ionise and inject electrons at controlled locations directly within the wakefield, thereby promising to generate electron beams with exceptionally low emittance and high brightness. Compact hybrid LWFA-PWFA plasma photocathodes therefore offer a pathway towards next-generation, miniaturized X-ray light sources. The talk will introduce the conceptual principles of hybrid plasma wakefield accelerators and plasma photocathode injection, and present recent progress from experiments and simulations.