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

Gilljohann, M. F. and Ding, H. and Döpp, A. and Götzfried, J. and Schindler, S. and Schilling, G. and Corde, S. and Debus, A. and Heinemann, T. and Hidding, B. and Hooker, S. M. and Irman, A. and Kononenko, O. and Kurz, T. and Martinez De La Ossa, A. and Schramm, U. and Karsch, S. (2019) Direct observation of plasma waves and dynamics induced by laser-accelerated electron beams. Physical Review X, 9 (1). 011046. ISSN 2160-3308

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    Abstract

    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.