CERN Accelerating science

Article
Title	Status of PPI (Pohang Photo-Injector) for PAL XFEL
Author(s)	Park, Sung-Ju ; Kim, Changbum ; Oh, Jong-Seok ; Park, Chong-Do ; Park Jang Ho ; Soo Ko In ; Wang, Xijie ; Woon Parc, Yong
Affiliation	(BNL/NSLS, Upton, Long Island, New York) ; (PAL, Pohang) ; (Pohang Photo-Injector)
Publication	2005
In:	21st IEEE Particle Accelerator Conference, Knoxville, TN, USA, 16 - 20 May 2005, pp.1733
Subject category	Accelerators and Storage Rings
Abstract	A X-Ray Free Electron Laser (XFEL) project based on the Self-Amplified Spontaneous Emission (SASE) is under progress at the Pohang Accelerator Laboratory (PAL). One of the critical R&D for the PAL XFEL* is to develop the Pohang Photo-Injector (PPI) which is required to deliver electron beams with normalized emittance < 1.5 mm-mrad. In order to achieve the required beam quality with high stability and reliability, we will use photocathode with quantum efficiency > 0.1 % and long lifetime. This will greatly lessen the laser energy requirement for producing flat-top UV pulses, and open the possibility of using only regenerative amplifiers (RGAs) to drive the photocathode RF gun. The RGAs can produce mJs output with much better stability than multi-pass amplifiers. Both the Cs2Te and Mg are under consideration for the possible photo-cathode. To demonstrate the suitability of the Mg and Cs2Te for the future 4th generation light source application, an improved BNL-type S-band RF gun with a high-performance load-lock system will be developed for the PPI. In this article, we present the design concept of the PPI, the expected performance, and report on its development status.