Ribbon Note The Focusing Of The Electron Gun Design

The generation and stable transport of electronic sheet beams comes within the scope of many subjects, such as microwave electronics, plasma electronics, Electromagnetic Fields and Microwave Techniques, vacuum technique, materials science, which is a complex fundamental utility research problem. Intensive and painstaking study of these problems can not only promote our fundamental research level in vacuum electronics field and improve our independent innovation ability, which has important science meaning, but provides electronic sources greatly wanted in millimeter wave electric vacuum devices and accelerators, thus break western countries'blockade on new techniques, meet the urgent need of our country's martial and civil electronic systems, which has great practical significance.Sheet electron beam have lots of attractive virtues. For example, when it was used in microwave tubes, it can carry higher currents than those with solid beams. Since sheet beam current would not be limited in perveance, which means current is increased by increasing the width of the beam. On the other hand, Sheet electron beam could greatly decrease the space charge force that might reduce the focusing requirement. Converting from cylindrical solid to sheet beam may permit substantial reduction in space charge effects on the efficiency of devices. The more high frequency we need smaller of the SWS (slow wave structure) section. We can use sheet electron beam in micrometer or microwave device, while ring or cylindrical electron beam can't be used in such device. Finally, sheet electron beam could put close to SWS, which makes the tubes more efficiently than ring or cylindrical electron beam tubes.At present, there are two main ways to produce an electronic sheet beam,①direct approach: the sheet beam is produced directly by the sheet beam gun, which is divided into rectangle sheet beam gun and elliptical sheet beam gun.②indirect approach: the sheet beam is produced by circular beam flying through the asymmetric solenoid lenses, and produced sheet beam by quadrode focused. This article mainly describes the theory research and particle modeling of the second way. First in this article, the potential distribution expression of infinite planar diode is deduced, based on the theory of Pierce gun. Secondly, the elliptical electronic sheet beam is cut out from the planar diode, which boundary conditions are also determined in this step. Thirdly, the equipotential surface distribution expression outside the beam is deduced through the solution of the physical equation which the beam satisfied.Then, in this article, first explores elliptical beam transformations with anisotropic lenses, followed focal properties of an elliptical solenoid lens, and then through the simulations of high-perveance beam transformation by elliptical solenoid lenses. Which make the electronic sheet beam gun design easier!Finally, we use the particle simulation software CST, to simulate an asymmetric elliptical solenoid can produce sheet electron beam, verify the non-symmetric solenoid can converted circular electron beam into elliptical sheet electron beam.