Development Of High-intensity,Low-energy Electron Gun And Its Experimental Platform

Terahertz(THz)has a wide range of application prospects.Free Electron Laser(FEL)is the method which can obtain the highest THz power currently and has been widely valued at home and abroad.An External Cathode Independently Tunable Cells RF Gun(EC-ITC RF GUN)is adopted in a compact THz facility(FEL-THz)due to its compactness,low-cost,large-charge and high intensity.As the electron injecting source of RF gun,the high-intensity,low-energy electron gun needs to generate maximum beam current of 3.2 A at low energy of 15 keV with other requirements such as large compression ratio and low energy spread,which creates difficulties for development of high-intensity,low-energy electron gun because of strong space charge effect.A double-anode gridded structure is adopted in the designed highintensity,low-energy electron gun which controls the beam current easily while maintains energy spread less than 0.5%,with high perveance and high compression ratio.Design method of the triode gun is studied,and influence of the grid on the beam flow is analyzed intensively.Segmental modeling is adopted in the simulation of CST,and the segmental modeling is verified by the calculation of beam transport capacity.Structure dimensions of the electron gun are optimized by CST simulation and verified by Opera simulation finally.The influence of different grid mesh hole structures on the beam current is also studied in this dissertation.Measurement for key Parameters of the high-intensity,low-energy electron gun is studied in this dissertation.The designed electron gun experimental platform is applicable for measurement of low-energy electron beams with beam energy of 0.5keV~20keV and beam current less than 10 A,and can measure the beam current,beam spot size,beam emittance and beam energy spectrum accurately.The principle of beam energy spectrum measurement is based on the retarding electric field.A beam scraper is adopted to reduce the energy deviation and additional energy spread caused by space charge forces.Focusing electric field generated by a focusing electrode can correct the retarding electric field and improve the energy spectrum measurement accuracy in the beam spectrum measurement device.CST simulation is used to optimize the structural dimensions of the beam spectrum measurement device and the beam energy resolution can reach 0.2%.