Influence of laser irradiated spot size on energetic electron injection and proton acceleration in foil targets

Paul McKenna, David Carroll, Mireille Coury, A.P.L. Robinson, Xiaohui Yuan, Ceri Mae Brenner, Matthias Burza, Ross Gray, Mark Quinn, David Neely, Olivier Tresca, Kate Lancaster, YT Li, XX Lin, CG Wahlstrom

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The influence of irradiated spot size on laser energy coupling to electrons, and subsequently to protons, in the interaction of intense laser pulses with foil targets is investigated experimentally. Proton acceleration is characterized for laser intensities ranging from 2 x 10(18) - 6 x 10(20) W/cm(2), by (1) variation of the laser energy for a fixed irradiated spot size, and (2) by variation of the spot size for a fixed energy. At a given laser pulse intensity, the maximum proton energy is higher under defocus illumination compared to tight focus and the results are explained in terms of geometrical changes to the hot electron injection
Original languageEnglish
Article number074105
JournalApplied Physics Letters
Issue number7
Publication statusPublished - 13 Feb 2012


  • electron injection
  • proton acceleration
  • lasers
  • laser irradiation

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