The simulations of charged particle acceleration from gas target at 20 TW SOKOL-P laser with intensity of 5⋅1019 W/cm2V.A. Lykov, G.V. Baidin and D.V. TorshinEPJ Web of Conferences, 59 (2013) 17006DOI: https://doi.org/10.1051/epjconf/20135917006