Design Of The Electron Gun Used In The Diamond Amplifier For Thermionic Cathode System And Numerical Simulation Of The Emittance Measurement System

With the continuing development of accelerator technology, the demand of the beam quality become higher and higher, hoping to get beam with higher beam current, higher brightness but lower emittance. As a result, new methods to produce high qualitybeam has been paid great attention. The method of diamond amplifier forphotocathode would be a good chioce. Diamond amplifier for photocathode uses a photocathode electron gun to create the primary electron beam. Afterwards, primary electron beam reaches a metalized side of the specialized diamondwindow film and secondary electron beam will be discharged from the hydrogenatedside of the diamond film. The current densityof secondary electron beam could be twoorders of magnitude higher than the primary ones, while the emittance remaining the same.In this thesis, we use the thermionic electron gun to produce primary beam to study the diamond amplifier mechanism. Based on numerical simulation of the beam current amplified by diamond film, the first part focuses on the design of energy adjustable electron gun. After determining the electron gun design specifications, under the guidance of Pierce electron gun theory, a satisfactory structure of electron gun will be achieved using the softwatr OPERA after a series of adjustment of angles of the focus, distances between cathode and anode, the radius of the anode. Then, a numerical simulation will be carried out in OPERA to get beam current, beam path, distribution of electrical potential and field strength. The emittance will also be accessible after leading the structure of electron gun into CST. Finally, through the relationship between figures of radius, current and anode’s voltage, we can find that the structure of the electron gun meet the design requirements. It can be used in the diamond amplifier for thermionic cathode system.To measure the emittance of the electron gun, the second part of the theses is trying to design a measurement system of horizontal emittance. Through theoretical analysis, we choose solenoid as focus lens. And we use ASTRA to simulate the whole system. The emittance calculated from the equation sets is consistent with the the simulation value. It proves that the emittance measurement system can be used to measurement the emittance of the electron gun.In the end, the dissertation gives brief introduction and conclusion of the research, in the mean time, the future prospect of the study has also been indicated as a suggestion.