Measurement of the angle, temperature and flux of fast electrons emitted from intense laser-solid interactions

Rusby, D. R. and Wilson, L. A. and Gray, R. J. and Dance, R. J. and Butler, N. M H and MacLellan, D. A. and Scott, G. G. and Bagnoud, V. and Zielbauer, B. and McKenna, P. and Neely, D. (2015) Measurement of the angle, temperature and flux of fast electrons emitted from intense laser-solid interactions. Journal of Plasma Physics, 81 (5). 475810505. ISSN 0022-3778

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    Abstract

    High-intensity laser-solid interactions generate relativistic electrons, as well as high-energy (multi-MeV) ions and X-rays. The directionality, spectra and total number of electrons that escape atarget-foil is dependent on the absorption, transport and rear-side sheath conditions. Measuring the electrons escaping the target will aid in improving our understanding of these absorption processes and the rear-surface sheath fields that retard the escaping electrons and accelerate ions via the target normal sheath acceleration (TNSA) mechanism. A comprehensive Geant4 study was performed to help analyse measurements made with a wrap-around diagnostic that surrounds the target and uses differential filtering with a FUJI-film image plate detector. The contribution of secondary sources such as X-rays and protons to the measured signal have been taken into account to aid in the retrieval of the electron signal. Angular and spectral data from a high-intensity laser-solid interaction are presented and accompanied by simulations. The total number of emitted electrons has been measured as 2.6 × 1013 with an estimated total energy of 12 ± 1 J from a 100 mu;m Cu target with140 J of incident laser energy during a 4 × 1020 W cm-2 interaction.