Theoretical study of influence of modification of the metal surface on magnitude of the field emission current in gradient-stable accelerating structures

Quantum-mechanical problem on electron motion through the model potential barrier of the metal-vacuum system with an additional near-surface dipole layer is considered. Taking into account the continuity conditions of the wave functions and their derivatives at the interface between the two media, general expressions of the coefficient of transparency of the potential barrier and a current density of field emission is obtained in the framework of this model. It is shown the influence of the effective thickness of the dipole layer of the metal surface on a value of the field emission current density.