Direct observation of plasma waves and dynamics induced by laser-accelerated electron beams

Journal article

Plasma wakefield acceleration (PWFA) is a novel acceleration technique with promising prospects for both particle colliders and light sources. However, PWFA research has so far been limited to a few large-scale accelerator facilities worldwide. Here, we present first results on plasma wakefield generation using electron beams accelerated with a 100-TW-class Ti:sapphire laser. Because of their ultrashort duration and high charge density, the laser-accelerated electron bunches are suitable to drive plasma waves at electron densities in the order of 10¹⁹ cm⁻³. We capture the beam-induced plasma dynamics with femtosecond resolution using few-cycle optical probing and, in addition to the plasma wave itself, we observe a distinctive transverse ion motion in its trail. This previously unobserved phenomenon can be explained by the ponderomotive force of the plasma wave acting on the ions, resulting in a modulation of the plasma density over many picoseconds. Because of the scaling laws of plasma wakefield generation, results obtained at high plasma density using high-current laser-accelerated electron beams can be readily scaled to low-density systems. Laser-driven PWFA experiments can thus act as miniature models for their larger, conventional counterparts. Furthermore, our results pave the way towards a novel generation of laser-driven PWFA, which can potentially provide ultralow emittance beams within a compact setup.

Authors: Gilljohann, M; Ding, H; Doepp, A; Goetzfried, J; Schindler, S

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Physical Society
• Journal: Physical Review X
• Volume: 9
• Issue: 1
• Article number: 011046
• Publication date: 2019-03-12
• Acceptance date: 2019-01-25
• DOI: 10.1103/PhysRevX.9.011046
• EISSN: 2160-3308
• Keywords: plasma acceleration and new acceleration techniques; particle acceleration in plasmas; plasma waves; laser driven electron acceleration; plasma-beam interactions; laser wakefield acceleration; laser-plasma interactions