Author: Kurisu, H.
Paper Title Page
TUODB02 Extreme High Vacuum System of High Brightness Electron Source for ERL 979
 
  • M. Yamamoto, T. Honda, Y. Honda, T. Miyajima, Y. Saito, Y. Tanimoto, T. Uchiyama
    KEK, Ibaraki, Japan
  • H. Akimichi, H. Yoshida
    AIST, Tsukuba, Japan
  • H. Kurisu
    Yamaguchi University, Ube-Shi, Japan
  
  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. A DC-gun using GaAs-type pho­to­cath­ode which has a neg­a­tive elec­tron affin­i­ty (NEA) sur­face is em­ployed. The NEA sur­face plays an in­dis­pens­able role to ex­tract elec­trons from con­duc­tion band min­i­mum into vac­u­um. It as­sures high quan­tum ef­fi­cien­cy of the pho­to­cath­ode and very low in­trin­sic emit­tance of the ex­tract­ed 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 ·10-10 Pa to avid the back­bom­bard­ment of pos­i­tive ions pro­duced by the col­li­sion of ac­cel­er­at­ed elec­trons with resid­u­al gas molecules in the beam path. 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.  
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