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arXiv · 1701.05682

Laser opacity in underdense preplasma of solid targets due to quantum electrodynamics effects

W. -M. Wang·P. Gibbon·Z. -M. Sheng·Y. -T. Li·J. Zhang
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Abstract

We investigate how next-generation laser pulses at 10 PW $-$ 200 PW interact with a solid target in the presence of a relativistically underdense preplasma produced by amplified spontaneous emission (ASE). Laser hole boring and relativistic transparency are strongly restrained due to the generation of electron-positron pairs and $γ$-ray photons via quantum electrodynamics (QED) processes. A pair plasma with a density above the initial preplasma density is formed, counteracting the electron-free channel produced by the hole boring. This pair-dominated plasma can block the laser transport and trigger an avalanche-like QED cascade, efficiently transfering the laser energy to photons. This renders a 1-$\rmμm$-scalelength, underdense preplasma completely opaque to laser pulses at this power level. The QED-induced opacity therefore sets much higher contrast requirements for such pulse in solid-target experiments than expected by classical plasma physics. Our simulations show for example, that proton acceleration from the rear of a solid with a preplasma would be strongly impaired.

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W. -M. Wang, P. Gibbon, Z. -M. Sheng, Y. -T. Li, J. Zhang. 2017-01-20. Laser opacity in underdense preplasma of solid targets due to quantum electrodynamics effects. https://doi.org/10.1103/physreve.96.013201

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