Generation and Characterization of Intense Ultralow-Emittance Electron Beams for Compact X-Ray Free-Electron Lasers

Area of Science:

• * Particle Physics
• * Accelerator Physics
• * X-ray Science

Background:

• * Transverse emittance is critical for linac-based X-ray free-electron lasers (FELs).
• * Achieving high beam quality is essential for generating powerful FEL radiation.
• * Compact and cost-effective FEL facilities are highly desirable.

Purpose of the Study:

• * To present novel high-resolution techniques for measuring electron beam emittance.
• * To report emittance measurement results from the SwissFEL facility.
• * To demonstrate the optimization of electron beam parameters for FEL applications.

Main Methods:

• * Implementation of novel high-resolution emittance measurement techniques.
• * Detailed electron beam optimization procedures.
• * Measurements conducted at the SwissFEL compact X-ray FEL facility.

Main Results:

• * Achieved slice emittance values as low as 200 nm for 200 pC, 30-40 fs electron beams.
• * Demonstrated ultra-low slice emittances of 100 nm for 10 pC, few fs electron beams.
• * Generated high-power FEL radiation at 0.1 nm using a 6 GeV electron beam.

Conclusions:

• * The achieved emittance values represent new standards for electron linear accelerators.
• * These results enable the generation of hard X-ray FEL pulses with lower-energy beams.
• * Paves the way for more compact and cost-effective FEL facilities.