Azimuthal asymmetry in collective electron dynamics in relativistically transparent laser-foil interactions

Gray, Ross and MacLellan, David and Izquierdo, Bruno and Powell, Haydn and Carroll, David and Murphy, C.D. and Stockhausen, L.C. and Rusby, Dean and Scott, G. and Wilson, R. and Booth, Nicola and Symes, Dan and Hawkes, S. and Torres, R and Borghesi, M. and McKenna, Paul (2014) Azimuthal asymmetry in collective electron dynamics in relativistically transparent laser-foil interactions. New Journal of Physics, 16. ISSN 1367-2630

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    Abstract

    Asymmetry in the collective dynamics of ponderomotively-driven electrons in the interaction of an ultraintense laser pulse with a relativistically transparent target is demonstrated experimentally. The 2D prole of the beam of accelerated electrons is shown to change from an ellipse aligned along the laser polarisation direction in the case of limited transparency, to a double-lobe structure aligned perpendicular to it when a significant fraction of the laser pulse co-propagates with the electrons. The temporally-resolved dynamics of the interaction are investigated via particle-in-cell simulations. The results provide new insight into the collective response of charged particles to intense laser fields over an extended interaction volume, which is important for a wide range of applications, and in particular for the development of promising new ultraintense laser-driven ion acceleration mechanisms involving ultrathin target foils.