Strong Stream Static Convergence Of Lab <sub> 6 </ Sub> Cathode Electron Gun

High current electron guns are widely used in high frequent devices, electron beam jointing, surface modification of materials and mechanical manufacture etc. Taking surface modification of materials for example, cross-sectional EPMA (Electron Probe Micro-Analyzer) and SEM (Scanning Electron Microscope) images of the untreated and irradiated samples give a direct observation on microstructures, suggest a corresponding improvement in mechanical properties. at the same time, it easy to operate, avoid to destroy the partings. So it is meaningful to study the e-guns with robust properties.In order to obtain reliable e-guns, it is very important to select materials of cathode, for it determine the life and stability of the guns. The previous experiments testify that the LaB6 has the properties of high conductivity, well stabilities of thermal and chemical, low work function and active cathode surface etc. So it is a perfect choice of cathodal materials.Traditional high current electron beam is always focused by the magnetic or electronic and magnetic hybrid method. Although the magnetic focusing technique is so mature, the problem that can not avoid is the insulation of high voltage and low voltage. So the structures are very complicated and can not satisfy the requirements the situation that has weight limitation, such as space weld. But the problem can be solved by pure electrostatic field focused e-guns.The classical ways to design an electron gun include theory design method, schematic method and experimental method. But the theory design method need fussy formula evolvement, the structure must be very simple, and the results are always complicated curves, so it's difficult to produce. The schematic and the experiment methods can not be satisfied the requirements for their high tolerance, so seldom to use now. As the development of computer technology and numerical technology, the popular way to design guns is to propose a prototype according to the requirements, and to simulate the model by computer, then, modify the model if necessary by the results of simulation, simulate again, until yield the reasonable results. This method saved the cost and time, reduce the blindness of experiments, improved the efficiency and precision of design.The main objective of this paper is to study that the different parameters how to effect the performance of high current electron guns focused by the pure electrostatic field with LaB6 cathode, and to make the e-guns with good performance. Firstly, design the prototype according to the demand, to yield 300mA current at the total voltage of 5000V, next to simulate the model by MAGIC software, and modify the model according to the results, and then simulate again. Mechanical design goes after getting the reasonable results. For the limitation of the power, there is only a direct power with 2500V. So modify the structure and some parameters to test at the total voltage 2000V. The tests indicate its coherence with the simulation. So the results of simulation at the total voltage of 5000V can be used in the detail structure design.