Vertical focusing of electron beams in the shf devices of klystron type

In the paper the method of electron flow transporting with help of inhomogeneous electric field able to do vertical focusing is described. Moreover inhomogeneous electric field can be created in the entrance unit of the shf-device of klystron type. The differential equation of trajectory with taking into account volume charge in the first approximation and Coulomb forces of pushing away is obtained, and it solution is shown. In approximation of thin lens the focus distance is determined, which is related with the device drift distance, as well as the expression allowing to estimate scattering circle value in Gaussian density