Speaker
Description
SACLA, the most compact hard-X-ray free-electron laser, has delivered user beamtime reliably for more than a decade. To satisfy growing demand, a linac upgrade is planned to reach kHz-class repetition rates with higher brightness. At the heart of this program is a new injector derived from the existing pulsed DC gun with a thermionic cathode, chosen for its proven beam quality, stability and straightforward maintenance.
Here we report a detailed beam-dynamics study of a promising injector layout. A chain of velocity-bunching sections, followed by a single magnetic chicane and strict control of emittance growth, enables up to three orders of magnitude bunch compression while keeping the emittance increase below the sub-µm level. Performance optimization employs a genetic algorithm coupled to full 3D, space-charge-dominated tracking, allowing us to identify robust operating points and tolerance windows.
The resulting working points deliver bunch lengths and emittances comparable to those from state-of-the-art injectors based on RF photocathode guns, but within a DC-gun–centric architecture.
Footnotes
Published in Phys. Rev. Accel. Beams 28, 091601, 2025.
DOI: https://doi.org/10.1103/b7sd-jvxq
Funding Agency
VG acknowledges funding from Swedish Research Council (VR), 2022-03983.
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