Speaker
Description
High-signal-to-noise ultrafast electron diffraction (UED) demands probe electron beams with extremely high brightness and particularly ultralow transverse emittance. In the HUST-UED facility, the asymmetry of the RF gun cavity and the winding and installation errors of the focusing solenoid inevitably induce weak stray quadrupole field components. These non-axisymmetric fields introduce horizontal–vertical phase space coupling, limiting further improvements in beam quality. Here we present a compact aberration-correction scheme that combines normal and skew quadrupoles to generate compensation fields with precisely controlled strength and rotation via the independent regulation of their excitation currents. For various transverse beam sizes, the corrector effectively cancels stray quadrupole components from multiple sources, substantially suppressing transverse coupling aberrations. This work provides a practical and robust route to improving beam brightness and overall system performance in MeV-UED accelerators.
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