Extreme High Vacuum System of High Brightness Electron Source for ERL

by Mr Masahiro Yamamoto (KEK)

Friday 4 Feb 2011, 09:00 → 10:00 Europe/Zurich

30/7-018 - Kjell Johnsen Auditorium (CERN)

A compact test accelerator for Japan's future light source based on energy recovery linac (ERL) is under construction in KEK, aiming to demonstrate key technologies such as a high-brightness photocathode DC-gun and superconducting RF cavities. The accelerator commissioning of the compact ERL will be started by March 2013. We employ a DC-gun using GaAs-type photocathode which has a negative electron affinity (NEA) surface. The NEA surface plays an indispensable role to extract electrons from conduction band minimum into vacuum. It assures high quantum efficiency of photocathode and very low intrinsic emittance of the extrated beam. However, the NEA surface is extremely delicate against residual gas in vacuum. In order to extract mA-level beam currents continuously for more than several tens of hours, the pressure should be lower than the order of E-10 Pa. In this talk, recent achievements in the development of a 500-kV photocathode DC-gun and in the fundamental studies of its extreme high vacuum system will be presented.

Slides CERN_20110204_ver3.pdf