Coherent Thomson backscattering from laser-driven relativistic ultra-thin electron layers

Abstract

The generation of laser-driven dense relativistic electron layers from ultra-thin foils and their use for coherent Thomson backscattering is discussed, applying analytic theory and one-dimensional particle-in-cell simulation. The blow-out regime is explored in which all foil electrons are separated from ions by direct laser action. The electrons follow the light wave close to its leading front. Single electron solutions are applied to initial acceleration, phase switching, and second-stage boosting. Coherently reflected light shows Doppler-shifted spectra, chirped over several octaves. The Doppler shift is found to be proportional to γ_x^2=1/(1-β_x^2), where β_x is the electron velocity component in normal direction of the electron layer which is also the direction of the driving laser pulse. Due to transverse electron momentum p_y, the Doppler shift by 4*γ_x^2=4*γ^2/(1+(p_y/mc)^2) ~= 2*γis significantly smaller than full shift of 4*γ^2. Methods to turn p_y -> 0 and to recover the full Doppler shift are proposed and verified by 1D-PIC simulation. These methods open new ways to design intense single attosecond pulses.

10 pages, 8 figures, submitted to the special issue "Fundamental Physics with Ultra-High Fields" in The European Physical Journal D

References in corpus (4)

• Theory of high harmonic generation in relativistic laser interaction with overdense plasma
• Relativistic Doppler effect: universal spectra and zeptosecond pulses
• The reflectivity of relativistic ultra-thin electron layers
• Acceleration of ultra-thin electron layer. Analytical treatment compared with 1D-PIC simulation

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• Recoil Effects on Reflection from Relativistic Mirrors in Laser Plasmas
• Acceleration of ultra-thin electron layer. Analytical treatment compared with 1D-PIC simulation
• Coherent radiation reaction effects in laser-vacuum acceleration of electron bunches
• Determination of Carrier-Envelope Phase of Relativistic Few-Cycle Laser Pulses by Thomson Backscattering Spectroscopy
• Coherent keV backscattering from plasma-wave boosted relativistic electron mirrors
• Laser-nucleus interactions in the sudden regime
• Rate for Laser-Induced Nuclear Dipole Absorption