Research On Beam Performance Improvement Of High-current And High-voltage Accelerator

The performance of the electron beam plays a decisive role in normal operation of high-current and high-voltage electron accelerator. The electron beam from the gun can be focused, accelerated and extracted normally in the accelerating tube, which should need a high requirement on the accelerating environment. The beam problems in the accelerator, such as beam stability, focusing, space charge effect and so on, are mostly caused by the design of accelerating tube. So the key to solve the problems of beam is to do research on the physical design of accelerating tube. However, there are many kinds of physical phenomenons and problems about the accelerating tube in the high-current and high-voltage accelerator, such as full voltage effect, electronic load phenomenon and vacuum breakdown. The problems of accelerating tube is very complicated, for the emergence of one problem will lead to another problem. In order to improve the beam transmission of the high-current and high-voltage accelerator and to improve the the performance of the accelerator, the content of this research is about the optimal design for accelerating tube of high-voltage electron accelerator.The content of our research is based on the accelerating electric field of the accelerating tube. This study adopts the lens electric field acceleration method, which is different from the previous uniform electric field. Using the lens electric field acceleration can effectively inhibit the electronic load phenomenon, and the stability of electron beam transportation is improved. We prove the effectiveness of the lens electric field by theoretical analysis and simulation.In order to study the focusing ability of the accelerating tube, we have built an accelerating tube experimental platform to measure and to obtain the information of the electron beam from the experiment. The beam density distribution was reconstructed, and the focusing property of the lens electric field of the accelerating tube was analyzed. It is proved that the lens electric field is better than the uniform electric field on focusing.About the suppressing of space charge effect in the low energy section, we analyze the motion state and the force of the electrons in the accelerating tube from the theory. And the method of using the lens electric field acceleration in the low energy section of the accelerating tube is presented, which do better to restrain the space charge effect of electron beam.