46th International Workshop on High Energy Density Physics with Intense Ion and Laser Beams

In this talk, we report on several novel aspects of laser-driven electron acceleration at CALA. The main highlight is the demonstration of energy doubling and a record absolute energy-transfer efficiency from the LWFA to the PWFA stages in hybrid laser–plasma wakefield acceleration (LPWFA). The motivation behind this scheme is to overcome the emittance limits inherent to classical laser-wakefield acceleration (LWFA), which arise from strong plasma-electron heating by the transverse laser fields. By using a high-charge, low-quality LWFA electron beam and exploiting its unipolar fields to drive a strong wake in a second plasma-wakefield-acceleration (PWFA) stage, the scheme enables cold-injection concepts in an initially cold plasma to achieve ultralow-emittance beams. The experimental demonstration of a 16% beam-to-beam transfer efficiency, energy doubling in the PWFA stage, and reduced beam bandwidth and divergence provides strong evidence for the practical feasibility of this approach. In addition, I will present a new, highly flexible, length-scalable gas-jet design currently being commissioned at CALA. Finally, I will comment on new insights into the sources of shot-to-shot instabilities at the ATLAS-3000 PW laser facility.