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arXiv · 2303.07723

Modulational instability in large-amplitude linear laser wakefields

Alexander von Boetticher·Roman Walczak·Simon Hooker
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Abstract

We investigate the growth of ion density perturbations in large-amplitude linear laser wakefields via two-dimensional particle-in-cell simulations. Growth rates and wave numbers are found to be consistent with a longitudinal strong-field modulational instability (SFMI). We examine the transverse dependence of the instability for a Gaussian wakefield envelope and show that growth rates and wavenumbers can be maximised off-axis. On-axis growth rates are found to decrease with increasing ion mass or electron temperature. These results are in close agreement with the dispersion relation of a Langmuir wave with energy density that is large compared to the plasma thermal energy density. The implications for wakefield accelerators, in particular multi-pulse schemes, are discussed.

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Alexander von Boetticher, Roman Walczak, Simon Hooker. 2023-03-14. Modulational instability in large-amplitude linear laser wakefields. https://doi.org/10.1103/physreve.107.l023201

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