2026/07/27 by Haiyang Li, Yixuan Liu, Tao Liu +1
paper · doi:10.1088/1402-4896/ae9141
Abstract Plasma-wakefield accelerators (PWFAs) offer a promising route to compact X-ray free electron lasers (FELs) due to their ultra high accelerating gradients. However, achieving high brightness, X-ray quality beams from PWFAs remains challenging due to emittance growth caused by nonlinear plasma fields, which significantly impacts on X-ray FEL generation. Here we propose an integrated PWFA based Fresh-Slice scheme to achieve high-power and ultra-short X-ray FEL pulses. Theoretical analyses demonstrate that an off-axis hollow plasma channel imparts a strong transverse temporal tilt to the electron bunch via its dipole wakefield. To compensate for the concomitant time-dependent quadrupole wakefield and preserve beam quality, a compact permanent magnet sextupole is employed immediately downstream. Using parameters of the Shanghai Soft X-ray FEL (SXFEL), simulations demonstrate the generation of soft X-ray pulses with duration below 3 fs and peak power above 10 GW—an order of magnitude above the self amplified spontaneous emission saturation power. This work is expected to be carried out at the SXFEL facility, which would provide a compact and efficient path toward plasma‑driven X‑ray sources, delivering the ultra‑short, high‑peak‑power pulses necessary for probing ultra-fast dynamics and other frontier scientific applications.