For the study of electron beams in high voltage electrical discharge at low pressures implemented the device JUPITER (Joint Uniersal Plasma and Ion Tecnologies Experimental Reactor) is based on the ideas of ion implantation dimensional (3DII) and a set of special strips acrylic determine with high precision geometry electron beams. Additionally we used the mapping program Matrox Inspector 2.0 to obtain the profile online (RGB line profile) and the KARAT code for conducting a threedimensional simulation electron movement test. This article presents a study of the geometry propagation of electron beams that allows conclusions about the spatial structure of the discharge and, in particular, about the size of region acceleration of electrons (cathode region).