On the role of the quantum image forces on the initial stage of a picosecond gas discharge

Summary form only given. Certain results achieved while investigating vacuum and gas discharges can be interpreted in the supposition that on the cathode there are adsorbed nonmetal films consisting of gas atmosphere molecules. Consider the interface between a metal and a tunnel-thin dielectric film. For the case of an external electric field of strength E applied to the structure, the tunneling electron as a particle-wave locates in the field of the image quantum forces. In paper it is shown that for small thicknesses in the dielectric layer quite good is the approximation formula W_ie ≈-C_ie/ε(4x + x₀), where C_ie is the constant determined by the chosen system of units; ε is the permittivity of the adsorbed film; x₀ is the parameter determined by electronic polaron radius. Based on the electron polaron model the thermionic emission theory developed and the general expression for current density is obtained with concern to the quantum character of image forces: j= e3E_a²/8πhΦt_a²(y_a)[πbkT/sin(πbkT)]exp[-8π√2m*Θ³/3ehE_a Θ_a(y_a)], wheree is the elementary charge, Ea = E/ε is the average value of the electric field strength in the adsorbed film, h is the Planck´s constant, Φ is the work function of the cathode covered with adsorbate, k is Boltzmann´s constant, T is the absolute temperature, m* is the effective mass of an electron in the dielectric, t_a(y_a) θ_a(y_a) are tabulated functions, considering the electron polaron effect and expressed through elliptical integrals, b is the coefficient determined by the system parameters. As follows from the numerical calculations, in a strong electric field, consideration of the quantum character of image forces in the cathode-a- sorbed layer system tends to reduce the emission current in the total range of fields and temperatures.