Transverse beam emittance measurement of a high current DC electron gun: Simulation and experimental approaches

High-current DC electron guns play a vital role in high-power electromagnetic sources. Accurate determination of essential parameters, such as transverse emittance, is important because this parameter affects the quality of the output radiation. Due to the high cathode temperature and intense beam power, measuring beam parameters near the electron gun poses significant challenges. In this study, a beam profile monitoring system for transverse beam diagnostics was developed. The system was initially modeled and simulated using CST Studio Suite, and the validated design was subsequently fabricated. A pepper-pot mask combined with a YAG(Ce) scintillator screen was employed to measure the transverse beam parameters, enabling diagnostics of high-current electron beams near the electron gun. The simulation and experimental results were compared, demonstrating good agreement. For the 1.7 A electron beam, the difference between simulated and measured transverse emittance near the electron gun was less than 15%, and the corresponding RMS deviation was below 7%.