Enhanced laser intensity and ion acceleration due to self-focusing in relativistically transparent ultrathin targets

T. P. Frazer, R. Wilson, M. King, N. M. H. Butler, D. C. Carroll, M. J. Duff, A. Higginson, J. Jarrett, Z. E. Davidson, C. Armstrong, H. Liu, D. Neely, R. J. Gray, P. McKenna

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Laser-driven proton acceleration from ultrathin foils is investigated experimentally using F/3 and F/1 focusing. Higher energies achieved with F/3 are shown via simulations to result from self-focusing of the laser light in expanding foils that become relativistically transparent, enhancing the intensity. The increase in proton energy is maximised for an optimum initial target thickness, and thus expansion profile, with no enhancement occurring for targets that remain opaque, or with F/1 focusing to close to the laser wavelength. The effect is shown to depend on the drive laser pulse duration.
Original languageEnglish
Number of pages6
JournalPhysical Review Research
Publication statusAccepted/In press - 7 Sep 2020


  • laser driven proton accelerator
  • ultrathin foils
  • pulse amplification

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