• D. Xiang, Y.-C. Du, W.-H. Huang, R. K. Li, Y. Lin, C.-X. Tang, L. X. Yan
  TUB, Beijing
• J. H. Park, S. J. Park
  PAL, Pohang, Kyungbuk

There are growing interests in generation, preservation and applications of high brightness electron beam. With the rapid development in the techniques for emittance compensation and laser shaping, we are approaching the limit-the uncorrelated thermal emittance. In this paper, we report the measurements of thermal emittance for Cu and Mg. The measurement is conducted in a field-free region. The energy spectrum and angular distribution of the electrons are measured immediately after its emission and further used to reconstruct the initial phase space and the corresponding thermal emittance. We also show how cathode surface roughness* and laser incidence angle as well as its polarization state** affect the quantum efficiency and thermal emittance.

*X. Z. He, High energy physics and nuclear physics,28(2004)1007.**Dao Xiang,et al, NIM A,562(2006)48.

• J. H. Park, J. Y. Huang, C. Kim, I. S. Ko, Y. W. Parc, S. J. Park
  PAL, Pohang, Kyungbuk
• D. Xiang
  TUB, Beijing

A high-brightness electron beam is emitted from a photo-cathode (PC) RF gun for use in the FIR (Far Infrared) facility being built at the Pohang Accelerator Laboratory (PAL). The beam dynamics study for the PAL XFEL injector is essencial to generate low emittance electron beam from the PC RF gun. The XFEL injector requires 1 nC beam with short bunch length and low emittance. This conditions are simulated with PARMELA code and then are realized on experimental conditions. The experimental conditions for the XFEL injector are measured with beam diagnostic devices such as ICT and Faraday cup for charge measurement, a spectrometer for beam energy measurement. In this article, we present the experimental approaches of the beam dynamics study for the XFEL injector.

wpjho@postech.ac.kr (Jangho Park)

• H. R. Yang, M.-H. Cho, S. H. Kim, S.-I. Moon, W. Namkung
  POSTECH, Pohang, Kyungbuk
• S. D. Jang, S. J. Kwon, J.-S. Oh, S. J. Park, Y. G. Son
  PAL, Pohang, Kyungbuk

An intense L-band electron accelerator is now being installed at PAL (Pohang Accelerator Laboratory) for initial tests. It is capable of producing 10-MeV electron beams with average 30 kW. This accelerator has a diode-type E-gun, a pre-buncher cavity, and an accelerating column with the built-in bunching section. We conduct simulational study for the commissioning scenario by the PARMELA code. At first, we observe the beam position and the beam current when the beam line is misaligned under no fields. Next, turning on focusing solenoids we observe the beam position change to check the alignments of the solenoids. Finally, varying RF power and phase of the pre-buncher we observe beam energy and beam power to obtain the optimum pre-buncher condition. In this paper, we present simulational results for each step. We also present commissioning strategies based on these results.

• S. H. Kim, M.-H. Cho, Y. M. Gil, S.-I. Moon, W. Namkung, H. R. Yang
  POSTECH, Pohang, Kyungbuk
• J. Jang, J.-S. Oh, S. J. Park
  PAL, Pohang, Kyungbuk

For a compact X-ray source, we designed a C-band standing-wave electron accelerator. It is capable of producing 4-MeV electron beams with 50-mA peak beam current. As an RF source, we use 5-GHz magnetron with duty factor of 0.08%. The accelerating structure is bi-periodic and on-axis coupled structure, operated with π/2-mode standing waves. Each cavity in the bunching and normal cell is designed by the MWS code and measured with aluminium prototype cavity. As per the dispersion relation derived from the measurement results, calibration factor obtained for the actual copper cavity.

• S. H. Kim, M.-H. Cho, W. Namkung, H. R. Yang
  POSTECH, Pohang, Kyungbuk
• S. D. Jang, S. J. Kwon, J.-S. Oh, S. J. Park, Y. G. Son
  PAL, Pohang, Kyungbuk

An intense L-band electron accelerator is designed and under development for CESC (Cheorwon Electron-beam Service Center) irradiation applications. It is capable of producing 10-MeV electron beams with average 30 kW. For an RF source, a Thales klystron is used with 1.3 GHz, pulsed 25 MW, and average 60 kW. The accelerator column, fabricated by IHEP in China, is operated with 2π/3 mode traveling-wave under the fully-beam-loaded condition. The modulator was fabricated with inverter power supplies. The klystron was assembled to the klystron tank with pulse transformer. The high-voltage pulse test was conducted for the klystron tube. In this paper, we present design details of the accelerator and current status.