JLab DC photoguns: a quest for higher operating voltage

by Carlos Hernandez-Garcia (Thomas Jefferson National Accelerator Facility)

Friday Sep 13, 2024, 11:00 AM → 12:00 PM Europe/Paris

100/0-A018 - Salle Library (IJCLab)

Obtaining field-emission-free operation in photoemission electron guns can be challenging. The Jefferson Lab CEBAF injector generates continuous-wave spin-polarized electron beams for nuclear physics experiments from delicate GaAs-based photocathodes biased at ~200 kV DC. High biasing voltages contribute to manage space charge forces in high-intensity electron beams. These combined factors impose stringent requirements on the photogun static and operational vacuum conditions. Any level of field emission from the photogun cathode electrode can degrade the vacuum inside the photogun leading to short photocathode quantum efficiency lifetime.  This contribution describes Jefferson Lab’s process, experience and technical challenges developing and operating some of the highest operational voltage DC photoguns to generate high-polarization and non-polarized, high-intensity electron beams for accelerator applications.

 

 

This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.