Attosecond-Angstrom free-electron-laser towards the cold beam limit.

Area of Science:

• Plasma physics
• Accelerator physics
• X-ray science

Background:

• High-quality electron beams are essential for generating X-ray pulses in free-electron lasers (FELs).
• Current linear accelerators (linacs) require kilometer-scale facilities for hard X-ray FELs.
• Plasma-based accelerators offer compact alternatives but have limitations in beam quality for advanced applications.

Purpose of the Study:

• To demonstrate the generation of significantly brighter electron beams using plasma photocathodes within plasma wakefield accelerators (PWFA).
• To show the feasibility of extracting, transporting, and injecting these high-quality beams into undulators without degradation.
• To explore the potential of these ultrabright beams for driving compact, high-performance hard X-ray FELs.

Main Methods:

• Generation of electron beams from plasma photocathodes in plasma wakefield accelerators (PWFA).
• Extraction, capture, and transport of the generated electron beams.
• Injection of the beams into undulators for X-ray pulse generation.

Main Results:

• Electron beams many orders of magnitude brighter than state-of-the-art were generated.
• Successful extraction, transport, and injection into undulators with minimal quality loss.
• Demonstrated capability to drive hard X-ray FELs near the cold beam limit, achieving saturation in a 10-meter undulator.
• Generation of coherent X-ray pulses of attosecond-Angstrom class.

Conclusions:

• Plasma wakefield accelerators can produce ultrabright electron beams suitable for compact hard X-ray FELs.
• This plasma-based approach enables advanced photon science, including observing electronic motion at atomic scales.
• Opens new avenues for higher photon energy FELs and compact scientific instrumentation.