Electrovacuum devices which action is based on formation and management on intensity and situation by one more electron beams are called as electron beam devices. Despite a big variety of electron beam devices as on the device, and to destination, between them is much in common. So, the electron beam device always contains three basic elements in a cylinder: the electronic searchlight forming an electron beam, or a beam, rejecting the receiver of electrons – the screen or system of electrodes of the electronic switchboard.
At the corresponding form of electrodes of a searchlight and a potential difference between them such non-uniform electric field which accelerates beam electrons towards the screen is created and at the same time makes its focusing. Focusing of an electronic beam is made twice: in points of F1 and F It testifies to existence in an electronic searchlight of two electron-optical systems: short-focus with focus in F1 point (it is formed by the cathode, the modulator and the first anode) and dlinnofokusny with focus in a point of F2 located in the screen plane (it is formed by the first and second anodes). The principle of action of both systems is absolutely identical therefore it is enough to consider action only one, for example dlinnofokusny system.
At a repeated meeting of an electron with this power line in a point In Eg will still have on it the accelerating effect, and Ev will promote a defocusing. But a vertical component in a point In less, than in a point And as the electron takes off from non-uniform electronic electric field, pressed to an axis. Besides, around a point In it has a high speed, than around a point And therefore the rejecting force influences an electron a smaller period.