High-quality electron beams are critical for imaging experiments that provide detailed microscopic structural insights into materials. The Very-High-Frequency electron gun, capable of operating in continuous and pulsed modes, is a preferable option. In this paper, we employ a tungsten tip with an apex radius of curvature approximately 100nm as a cold field emission cathode in the VHF gun and measure the beam charge, transverse emittance, and energy spread to characterize the beam quality. In preliminary experiments, we have achieved a normalized transverse emittance of 54.01nm·rad. With an electron gun power of 37kW, we obtained astrongbeamcurrentofapproximately 6µA, which remained stable and continuous for several hours in a single experiment. By using an aperture to block electrons with large divergence angles and adjusting the solenoid’s focusing strength, we propose to converge the target-energy electron beam onto the aperture, increasing its transmission rate and optimizing the energy spread. Prior to optimization, the energy spread was approximately 3.57% at 536keV when using a 20µm diameter aperture.

High-quality electron beams are critical for imaging experiments that provide detailed microscopic structural insights into materials. The Very-High-Frequency electron gun, capable of operating in continuous and pulsed modes, is a preferable option. In this paper, we employ a tungsten tip with an apex radius of curvature approximately 100nm as a cold field emission cathode in the VHF gun and measure the beam charge, transverse emittance, and energy spread to characterize the beam quality. In preliminary experiments, we have achieved a normalized transverse emittance of 54.01nm·rad. With an electron gun power of 37kW, we obtained astrongbeamcurrentofapproximately 6µA, which remained stable and continuous for several hours in a single experiment. By using an aperture to block electrons with large divergence angles and adjusting the solenoid’s focusing strength, we propose to converge the target-energy electron beam onto the aperture, increasing its transmission rate and optimizing the energy spread. Prior to optimization, the energy spread was approximately 3.57% at 536keV when using a 20µm diameter aperture.