• K. Miyoshi, Y. Muroya, A. Sakumi, T. Ueda, M. Uesaka
  The University of Tokyo, Nuclear Professional School, Ibaraki-ken
• K. Kambe
  UTNL, Ibaraki

Multi-Alkali photocathode has the good possibility as a electron source which has high quantum efficiency and low workfunction. However the surface of the cathode is sensitive over the electric field of 100[MV/m] in a RFgun, the amount of dark current is not negligible. In order to reduce such a dark current, we consider the valance of the electric field between half-cell and full-cell of BNL-IV RF gun by numerical simulation using GPT code. In this work we will show that high quality electron beam can be transported on the condition that appled electric field in half and full cell is about 50[MV/m] and 150[MV/m] respectively.