[en] Stark broadening of the spectral line HeII 6560 A by plasma was studied. The profiles of the line HeII 6560 A were calculated for different values of the electron concentration N_e. We used the quasi-static approximation to account for the perturbing ions and the impact approximation to describe the perturbing electrons. The electron concentration N_e in the central region of a current sheet plasma was deduced by comparing the experimentally obtained profiles of the line HeII 6560 A with the set of the theoretically calculated profiles of this line. (orig.)