Document Type


Publication Date




Publication Title

Review of Scientific Instruments




104703 (6 pages)


Nuclear physics experiments performed at the Continuous Electron Beam Accelerator Facility (CEBAF) at the Jefferson Lab require a DC high voltage photogun to generate polarized electron beams from GaAs photocathodes. The photogun uses a tapered ceramic insulator that extends into the vacuum chamber and mechanically holds the cathode electrode. Increasing the operating voltage from nominal −130 kV to −200 kV will provide lower beam emittance, better transmission through injector apertures, and improved photocathode lifetime. This desire to increase the photogun operating voltage led to the design of a triple-point-junction shield electrode which minimizes the electric field at the delicate insulator-metal-vacuum interface and linearizes the potential across the insulator, thus reducing the risk of arcing along the ceramic insulator. This work describes the results obtained using COMSOL® electrostatic-field simulation software and presents the high voltage conditioning results of the upgraded −200 kV CEBAF photogun. Published by AIP Publishing.


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Original Publication Citation

Palacios-Serrano, G., Hannon, F., Hernandez-Garcia, C., Poelker, M., & Baumgart, H. (2018). Electrostatic design and conditioning of a triple point junction shield for a -200 kV DC high voltage photogun. Review of Scientific Instruments, 89, 104703. doi:10.1063/1.5048700


0000-0002-5331-6127 (Palacios-Serrono)

Available for download on Thursday, October 03, 2019