Study of the Possibility of a Stable Increase in the Electron Beam Current Density Using a Tapered Glass Channel

The possibility of increasing the current density of a charged particle beam (focusing) by means of tapered glass channels without the use of external energy sources is actively translated into action today for positively charged ions. For electron beams, this possibility is not realized due to the lack of experimental data on the sliding interaction between electron beams and a dielectric surface. It is necessary to examine the compression of an electron beam by tapered capillaries depending on their geometrical parameters, as well as to study the temporal characteristics of the focusing process. In this work, the authors experimentally studied the compression of a 10 keV electron beam using a 15-mm-long tapered glass channel with an inlet-to-outlet inside diameter ratio of 1.15 mm/0.30 mm. The beam current density is shown to increase at the outlet of the capillary with the specified parameters by up to a factor of 2.7 for the position where the channel axis is parallel to that of the initial beam. This density increase is estimated for electrons that have lost no more than 1 keV of initial energy. It is also shown that the process of electron transmission by a tapered capillary is stable regardless of the orientation of the capillary with respect to the direction of the initial beam.