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Title: Identifying the electron–positron cascade regimes in high-intensity laser-matter interactions

Abstract

Strong-field quantum electrodynamics predicts electron-seeded electron–positron pair cascades when the electric field in the rest-frame of the seed electron approaches the Sauter–Schwinger field, i.e. $$\eta ={E}_{{\rm{RF}}}/{E}_{S}\sim 1$$. Electrons in the focus of next generation multi-PW lasers are expected to reach this threshold. We identify three distinct cascading regimes in the interaction of counter-propagating, circularly-polarised laser pulses with a thin foil by performing a comprehensive scan over the laser intensity (from 10 23 to 5 × 10 24 W cm –2) and initial foil target density (from 10 26 to 10 31 m –3). For low densities and intensities the number of pairs grows exponentially. If the intensity and target density are high enough the number density of created pairs reaches the relativistically-corrected critical density, the pair plasma efficiently absorbs the laser energy (through radiation reaction) and the cascade saturates. If the initial density is too high, such that the initial target is overdense, the cascade is suppressed by the skin effect. Here, we derive a semi-analytical model which predicts that dense pair plasmas are endemic features of these interactions for intensities above 10 24 W cm –2 provided the target's relativistic skin-depth is longer than the laser wavelength. Further, it shows that pair production is maximised in near-critical-density targets, providing a guide for near-term experiments.

Authors:
 [1]; ORCiD logo [2];  [1]
  1. Univ. of York, York (United Kingdom)
  2. Univ. of York, York (United Kingdom); SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1503402
Grant/Contract Number:  
AC02-76SF00515; EP/M018156/1
Resource Type:
Accepted Manuscript
Journal Name:
New Journal of Physics
Additional Journal Information:
Journal Volume: 21; Journal Issue: 1; Journal ID: ISSN 1367-2630
Publisher:
IOP Publishing
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; plasma physics; strong-field QED; high-intensity lasers

Citation Formats

Slade-Lowther, C., Del Sorbo, D., and Ridgers, Christopher P. Identifying the electron–positron cascade regimes in high-intensity laser-matter interactions. United States: N. p., 2019. Web. doi:10.1088/1367-2630/aafa39.
Slade-Lowther, C., Del Sorbo, D., & Ridgers, Christopher P. Identifying the electron–positron cascade regimes in high-intensity laser-matter interactions. United States. doi:10.1088/1367-2630/aafa39.
Slade-Lowther, C., Del Sorbo, D., and Ridgers, Christopher P. Wed . "Identifying the electron–positron cascade regimes in high-intensity laser-matter interactions". United States. doi:10.1088/1367-2630/aafa39. https://www.osti.gov/servlets/purl/1503402.
@article{osti_1503402,
title = {Identifying the electron–positron cascade regimes in high-intensity laser-matter interactions},
author = {Slade-Lowther, C. and Del Sorbo, D. and Ridgers, Christopher P.},
abstractNote = {Strong-field quantum electrodynamics predicts electron-seeded electron–positron pair cascades when the electric field in the rest-frame of the seed electron approaches the Sauter–Schwinger field, i.e. $\eta ={E}_{{\rm{RF}}}/{E}_{S}\sim 1$. Electrons in the focus of next generation multi-PW lasers are expected to reach this threshold. We identify three distinct cascading regimes in the interaction of counter-propagating, circularly-polarised laser pulses with a thin foil by performing a comprehensive scan over the laser intensity (from 1023 to 5 × 1024 W cm–2) and initial foil target density (from 1026 to 1031 m–3). For low densities and intensities the number of pairs grows exponentially. If the intensity and target density are high enough the number density of created pairs reaches the relativistically-corrected critical density, the pair plasma efficiently absorbs the laser energy (through radiation reaction) and the cascade saturates. If the initial density is too high, such that the initial target is overdense, the cascade is suppressed by the skin effect. Here, we derive a semi-analytical model which predicts that dense pair plasmas are endemic features of these interactions for intensities above 1024 W cm–2 provided the target's relativistic skin-depth is longer than the laser wavelength. Further, it shows that pair production is maximised in near-critical-density targets, providing a guide for near-term experiments.},
doi = {10.1088/1367-2630/aafa39},
journal = {New Journal of Physics},
number = 1,
volume = 21,
place = {United States},
year = {2019},
month = {1}
}

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