Generating Single-Spike Hard X-Ray Pulses with Nonlinear Bunch Compression in Free-Electron Lasers

Area of Science:

• Physics
• Materials Science
• Chemistry

Background:

• Free-electron lasers (FELs) are crucial for generating high-intensity X-rays.
• Producing single-spike X-ray pulses is essential for advanced experiments requiring precise temporal resolution.

Purpose of the Study:

• To develop a simple and effective method for generating single-spike hard X-ray pulses.
• To demonstrate this method at the Linac Coherent Light Source (LCLS).

Main Methods:

• Nonlinear bunch compression technique.
• Utilizing a 20-pC bunch charge.
• Demonstration in the hard X-ray regime at 5.6 and 9 keV.

Main Results:

• Approximately 50% of FEL shots contained a single-spike spectrum.
• Single-spike shots at 5.6 keV had a mean pulse energy of ~10 μJ with 70% intensity fluctuation.
• Pulse duration (FWHM) was evaluated to be at the 200-attosecond level.

Conclusions:

• The developed method is effective for generating single-spike hard X-ray pulses.
• This advancement enables new possibilities in ultrafast X-ray science.
• The LCLS can reliably produce ultrashort X-ray pulses for demanding applications.