LOA Seminar: Aaron Liberman (Weizmann): Direct Imaging of Wakefields Generated by Structured Light

1 Weizmann Institute of Science

2 LOA

Since their inception, laser-wakefield accelerators (LWFAs) have shown their capability to produce high-quality, monoenergetic electron beams. Yet, the push toward higher electron energies and more efficient accelerators is constrained by several limitations. Foremost among these are the dephasing and diffraction limits.  A promising strategy to address these issues involves using structured light to modulate the on-axis propagation velocity in LWFAs. By pairing the diffraction-resistant properties of Bessel beams with spatio-temporal pulse shaping, this approach offers an unprecedented combination of extended acceleration lengths and strong acceleration gradients.

Here we present the first experimental observation of wakefields driven by such structured beams. Spatio-temporally tailored pulses are directed through a specialized focusing mirror to form a quasi-Bessel beam, and the resulting wakefield is directly probed using femtosecond relativistic electron microscopy. Simulations corroborate the experimental data, offering novel insights into this underexplored regime. We show an experimental demonstration of the ability to modify the on-axis propagation velocity of the wakefield. We track the wakefield’s evolution throughout the focal region and examine how specific spatio-temporal manipulations influence both its structure and propagation velocity. Finally, we present the first results using such wakefields to accelerate electrons. These findings establish a foundation for harnessing structured-light-based strategies to overcome dephasing in LWFA.