THE OPTIMIZATION OF A TRIODE ELECTRON-GUN WITH A THERMIONIC CATHODE

This paper describes the systematic method of an electron gun optimiza tion. The properties and quality of high power electron beams formed b y an electron pun were evaluated by measuring the electron beam emitta nce as a very sensitive figure-of-merit. Our objective was to decrease the electron beam emittance by identifying the most significant facto rs which influence the electron beam quality and selecting the most pr eferable set of these factor levels. For this purpose we used the expe rimental design method based on Taguchi techniques for quality enginee ring. This technique proved to be a useful tool in identifying the sig nificant factors, optimizing its levels and decreasing the electron be am emittance. As a result of our experiments we have obtained an optim ized electron gun which produces an electron beam with an emittance by one order of magnitude lower than the emittance of a currently used b eam. It was proven that the repeatability of electron beam characteris tics after each cathode replacement is quire satisfactory provided tha t the cathode is placed in its optimum position.