Vector-based feedback of continuous wave radiofrequency compression cavity for ultrafast electron diffraction

• Published in: Structural dynamics (Melville, N.Y.) Vol. 11; no. 2; pp. 024303 - 024303-10
• Main Authors: Sutter, Thomas M., Lee, Joshua S. H., Kulkarni, Atharva V., Musumeci, Pietro, Kogar, Anshul
• Format: Journal Article
• Language: English
• Published: United States American Institute of Physics, Inc 01.03.2024; American Crystallographic Association/AIP; American Crystallographic Association; AIP Publishing LLC and ACA
• Subjects: Beams (radiation); Condensed matter physics; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Continuous radiation; Demodulators; Electron diffraction; Energy; Equilibrium; Feedback loops; Lasers; Longitudinal waves; Pulse compression; Pump probe experiments; Quadratures; Radio frequency; Radiofrequency cavities; Temporal resolution; Ultrafast electron diffraction; Wave diffraction
• ISSN: 2329-7778; 2329-7778
• DOI: 10.1063/4.0000231

The temporal resolution of ultrafast electron diffraction at weakly relativistic beam energies ( ≲100 keV) suffers from space-charge induced electron pulse broadening. We describe the implementation of a radio frequency (RF) cavity operating in the continuous wave regime to compress high repetition rate electron bunches from a 40.4 kV DC photoinjector for ultrafast electron diffraction applications. Active stabilization of the RF amplitude and phase through a feedback loop based on the demodulated in-phase and quadrature components of the RF signal is demonstrated. This scheme yields 144 ± 19 fs RMS temporal resolution in pump–probe studies.