@article{oai:repo.qst.go.jp:00048050,
 author = {S., Bulanov S. and Esarey, E. and B., Schroeder C. and ブラノフ, セルゲイ and Timur, Esirkepov and Kando, Masaki and Pegoraro, F. and P., Leemans W. and ブラノフ セルゲイ and エシロケポフ ティムル and 神門 正城},
 issue = {5},
 journal = {Physics of Plasmas},
 month = {Apr},
 note = {Radiation pressure acceleration (RPA) is a highly efficient mechanism of laser-driven ion acceleration,
with near complete transfer of the laser energy to the ions in the relativistic regime. However,
there is a fundamental limit on the maximum attainable ion energy, which is determined by the
group velocity of the laser. The tightly focused laser pulses have group velocities smaller than the
vacuum light speed, and, since they offer the high intensity needed for the RPA regime, it is plausible
that group velocity effects would manifest themselves in the experiments involving tightly
focused pulses and thin foils. However, in this case, finite spot size effects are important, and
another limiting factor, the transverse expansion of the target, may dominate over the group velocity
effect. As the laser pulse diffracts after passing the focus, the target expands accordingly due to
the transverse intensity profile of the laser. Due to this expansion, the areal density of the target
decreases, making it transparent for radiation and effectively terminating the acceleration. The off normal
incidence of the laser on the target, due either to the experimental setup, or to the deformation
of the target, will also lead to establishing a limit on maximum ion energy},
 pages = {056703-1--056703-13},
 title = {Radiation pressure acceleration: The factors limiting maximum attainable ion energy},
 volume = {23},
 year = {2016}
}