• J.-S. Oh, S. D. Jang, I.S. Ko, S. J. Kwon, W. Namkung, Y. G. Son, J.-H. Suh
  PAL, Pohang, Kyungbuk

Funding: Supported by the POSCO and the MOST, Korea

The PAL (Pohang Accelerator Laboratory) is persuading to construct a SASE-XFEL facility (PAL XFEL) that supplies coherent X-rays. The bright and stable electron beam is essential for the PAL XEL. The electron beams has to have an emittance of 1.2 mm-mrad, a peak current of 3.5 kA, and a low energy spread of 0.5 MeV. In order to provide reasonably stable SASE output, the RF stability of 0.02% rms is required for both RF phase and amplitude. This is a technologically challenging issue for PAL XFEL. An inverter technology is to be applied to charge the PFN of a new modulator. Therefore, a new inverter system should provide very stable charging performances. This paper presents the development of an ultra stable klystron-modulator with an inverter power supply.

• I.S. Ko
  PAL, Pohang, Kyungbuk

Pohang Accelerator Laboratory (PAL) has recently launched a new XFEL project based on SASE technology. This PAL-XFEL will utilize the existing 2.5 GeV injection linac to the storage ring by upgrading its energy up to 3.7 GeV initially and possibly up to 4.5 GeV later on. The wavelength covers up to 0.18 nm when the electron beam energy is 4.5 GeV. In-vacuum undulator will be used to generate FEL lasing. Overall design philosophy and some details will be presented.

• J.Y. Huang, Y.S. Bae, M.-H. Chun, Y.J. Han, S.-H. Jeong, H.-S. Kang, D.T. Kim, S.H. Kim, S.-C. Kim, I.S. Ko, H.J. Park, I.-S. Park, S.J. Park, Y.J. Park, S.Y. Rah, J.-H. Suh
  PAL, Pohang, Kyungbuk
• J.H. Hong, C. Kim
  POSTECH, Pohang, Kyungbuk

Funding: Work supported by Ministry of Science and Technology (MOST)

Beam diagnostics for PAL-XFEL physics calls for precision of femto-second in time structure and sub-micrometer in beam position measurement(BPM). Existing instruments can be used for standard diagnostics such as single bunch charge measurement, wire scanner or optical transition radiator for beam size measurement. Instead, major R&D efforts should be focused on the measurement of femto-second bunch structure using electro-optic crystal, coherent radiation and transverse deflecting cavity. Nanometer BPM technique being developed in collaboration with linear collider group will also be utilized for sub-micrometer BPM. Overall plan and the ongoing R&D activities will be presented.

• S.J. Park, J.Y. Huang, I.S. Ko, J.-S. Oh, Y.W. Parc, P.C.D. Park, J.H. Park
  PAL, Pohang, Kyungbuk
• C. Kim
  POSTECH, Pohang, Kyungbuk
• X.J. Wang
  BNL, Upton, Long Island, New York
• D. Xiang
  TUB, Beijing

Funding: Work supported by the MOST and the POSCO.

The PAL XFEL, an X-Ray Free Electron Laser (XFEL) project based on the Self-Amplified Spontaneous Emission (SASE), is under progress at the Pohang Accelerator Laboratory (PAL). Successful completion of the project is expected to impose stringent requirements on the beam qualities such as the normalized emittance (< 1.2 mm-mrad) and the un-correlated energy spread (~10(-5)). This requires careful and systematic planning for ensuring the generation and the preservation of high-brightness beams in the whole machine. The PPI (Pohang Photo-Injector) is to achieve these requirements with high reliability and stability. In this article, we discuss various physics and engineering issues involved in the design and construction of the PPI. We also report on the R&D status of photo-cathode RF gun at the PAL.