Characteristics of air showers with energy more than 1017 eV reconstructed by the Yakutsk array radio emission measurements

The paper presents results on the longitudinal development of air showers of ultra-high energies obtained from radio emission measurements at the Yakutsk array. The energy, the depth of maximum development of individual showers are determined and a statistical analysis of Xmax in order to estimate the fluctuation of air shower development σ(Xmax) in the energy region 1017-1018 eV is performed. It is shown that σ(Xmax) in the energy region 1017-1018 eV is equal to 50-60 g·cm-2, which doesn’t contradict with a mixed composition of cosmic rays - protons and helium nuclei. This is also indicated by data of the Xmax value dependence on energy