• J.H. Hong, M.S. Chae, I.S. Ko, S.-I. Moon, Y.W. Parc
  POSTECH, Pohang, Kyungbuk
• C. Kim, S.J. Park
  PAL, Pohang, Kyungbuk

A Brookhaven National Laboratory (BNL) type S-band photocathode RF gun is used at Pohang Accelerator Laboratory (PAL) to produce femtosecond tera hertz (fs-THz) radiation. In order to upgrade the fs-THz Facility at PAL, we need to develop the performance of the RF gun. The requirements for new RF gun are following: 1 nC beam charge, 60 Hz repetition frequency and 1 mm mrad normalized rms transverse emittance. A dual feed photocathode RF gun is designed satisfy these requirements. Two additional pumping ports are used to remove the field asymmetry. A large radius and short length of the iris increases the mode separation. The coupling scheme is changed to make the fabrication simpler. The RF gun structure had been modeled using 3D field solver to provide the desired RF parameters and to obtain the field profile. In this paper the new RF gun design and the cold test results will be presented.