On the connection between secondary electron emission yield and the potential of an electron-beam-irradiated target

Abstract

An unambiguous correspondence between the potential of an insulated metal target, irradiated by a continuous electron beam, and secondary electron emission yield from the target, in the medium vacuum pressure range (at fore-vacuum pressures), is demonstrated. This connection allows one to estimate the secondary emission properties of the target material and to predict the beam-plasma parameters. Moreover, this can help to estimate the intensity and energy of the ion bombardment of the target when it is irradiated by the electron beam. The metallic target potential value was found to be dependent on its material (aluminum, stainless steel, titanium and copper), which is related to the secondary emission properties of the surface. Since an electrically insulated metal target can be regarded as an experimental model for exploring the effect of energetic electron beam bombardment of dielectric surfaces, this work also provides a firm basis for the study of electron-beam modification of dielectric materials. A method for estimation of the potential of a dielectric having a secondary emission yield less than 1 and irradiated by a dc electron beam in fore-vacuum pressures is proposed. This method is based on measurements of the ionic sheath length and plasma parameters near the surface of the target irradiated by the electron beam.