From Event: SPIE Optical Engineering + Applications, 2016
We have constructed an electron gun that delivers highly charged femtosecond electron pulses to a target with kHz
repetition rate. Electron pulses are generated by femtosecond laser pulses in a photoemission process and are accelerated
up to 100 kV and compressed to sub-picosecond duration. Compression is essential to compensate for the space charge
effect that increases the size of electron pulses in all directions significantly. The pulses are compressed transversely by
magnetic lenses and longitudinally by the longitudinal electric field of a radio-frequency cavity. The longitudinal
compression is achieved by decelerating the electrons in the leading edge of the pulse, and accelerating the electrons in
the trailing edge of the pulse. This results in the pulse compressing and reaching the minimum pulse duration at a known
distance from the compression cavity. The short pulse duration and high repetition rate will be essential to observe subpicosecond
dynamic processes in molecules in gas phase with a good signal to noise ratio. A streak camera, consisting of
a millimeter-sized parallel plate capacitor, was used to measure the pulse duration in situ.
Omid Zandi, Kyle J. Wilkin, Alice J. DeSimone, Jie Yang, and Martin Centurion, "Femtosecond electron pulse generation and measurement for diffractive imaging of isolated molecules," Proc. SPIE 9956, Ultrafast Nonlinear Imaging and Spectroscopy IV, 995602 (Presented at SPIE Optical Engineering + Applications: August 28, 2016; Published: 26 September 2016); https://doi.org/10.1117/12.2237381.
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