Kim, S. H.

Paper	Title	Page
WEC3H102	Fabrication and Performance Test of the Cavity BPM for KEK ATF2 and PAL XFEL	336
	J. Y. Huang, W. H. Hwang, S. H. Kim, S. J. Park, Y. J. Park PAL, Pohang, Kyungbuk Y. Honda, I. Y. Inoue, T. Tauchi, J. Urakawa KEK, Ibaraki M. C. Ross Fermilab, Batavia, Illinois
	Precise, single shot measurement of the beam position with a sub-micrometer resolution is required for the next generation linear accelerators such as International Linear Collider (ILC) and X-ray Free Electron Laser (XFEL). As a pill-box cavity structure is sensitive to the transverse offset of the beam at the dipole-mode resonance, e.g., TM110-mode, a pill-box type cavity is a good candidate for the sub-micrometer beam position monitor (BPM). Test cavity BPM had been designed and tested in KEK successfully, and miscellaneous improvements for the final prototype fabrication and beam tests are performed in collaboration between KEK, SLAC and PAL. With the successful results of beam test in ATF, 41 cavity BPMs will be produced by PAL and installed in ATF2, which is an advanced beam-test line under construction as the extension of existing ATF for the beam studies on the final focus of the planned ILC program. Technical design considerations, fabrication and test results are described in this paper.
	Slides
THPMA063	Energy Stabilization of 2.5 GeV Linac using DeQing	717
	S. H. Kim, Y. J. Han, J. Y. Huang, S.-C. Kim, S. H. Nam, S. S. Park PAL, Pohang, Kyungbuk
	The 2.5 GeV electron linac of Pohang Accelerator Laboratory (PAL) employs 80 MW klystrons with matching 200 MW modulators as RF sources. Beam voltage stability of the klystron is directly related to a PFN (pulse forming network) charging voltage of the modulator. Therefore, a good regulation of a PFN charging voltage is essential in the modulator. The regulation of the klystron pulse voltage amplitude is made by controlling the PFN charging voltage. In a conventional resonant charging pulse modulator, the regulation is usually achieved by using a deQing circuit. The required beam voltage regulation of less than ± 0.5 %, without deQing circuit, has been achieved by using a SCR phase controller with a voltage regulator. For further improvement of the beam voltage stability for the PAL XFEL (x-ray free electron laser) linac, PAL is studying a deQing circuit aiming at the stabilization of less than 0.02%. A new deQing circuit has been developed with a compensation function which can reduce a charge voltage fluctuation by about several times. The design concept and performance of the deQing circuit will be discussed.
THPMA074	Operational Analysis of Klystron-Modulator System for PLS 2.5-GeV Electron Linac	740
	S. S. Park, J. Y. Huang, S. H. Kim, S.-C. Kim PAL, Pohang, Kyungbuk
	The klystron-modulator(K&M) system of the Pohang Accelerator Laboratory (PAL) generates high power microwaves for the acceleration of 2.5 GeV electron beams. There are 12 modules of K&M system to accelerate electron beams up to 2.5 GeV nominal beam energy. One module of the K&M system consists of the 200 MW modulator and an 80 MW S-band (2856 MHZ) klystron tube. The total accumulated high-voltage run-time of the oldest unit among the 12 K&M systems has reached nearly 92,300 hours as of June 2006. The overall system availability is well over 95%. In this paper, we review overall system performance of the high-power K&M system and the operational status of the klystrons and thyratron lifetimes, and overall system's availability will be analyzed for the period of 1994 to June 2006.
WEPMA083	Design of C-band Standing-wave Accelerating Structure	440
	S. H. Kim, M.-H. Cho, W. Namkung, B. Park, H. R. Yang POSTECH, Pohang, Kyungbuk S. D. Jang, J.-S. Oh, S. J. Park, Y. G. Son PAL, Pohang, Kyungbuk
	We design a C-band standing-wave accelerating structure for a compact electron linac. It is capable to produce electron beams with the beam energy of 4 MeV and the pulsed beam current of 50 mA. It is to be operated in the π/2 mode with the on-axis coupled structure. The beamline is composed of the E-gun and the accelerating column with 3 and half bunching cells and 9 and half normal cells. We design standing-wave RF cavities using the OMEGA3P code to implement the asymmetric magnetic coupling slots. For the beam dynamics study, we use the PARMELA code with the SUPERFISH fields configuration. Without the pre-buncher cavity and the focusing magnets, the lost beam power to the wall is 10 kW for the output beam power of 200 kW, while the transmission is 58%.
THPMA127	Development of L-band Electron Accelerator for Irradiation Source	821
	S. H. Kim, M.-H. Cho, S.-I. Moon, W. Namkung, B. Park, H. R. Yang POSTECH, Pohang, Kyungbuk S. D. Jang, J.-S. Oh, S. J. Park, Y. G. Son PAL, Pohang, Kyungbuk
	An intense L-band electron accelerator is under development for irradiation applications. It is capable of producing 10-MeV electron beams of 30 kW with the fully beam-loaded condition. The accelerator is powered by a pulsed klystron of 1.3 GHz and 25 MW with the 60-kW average power. The accelerating column, a traveling-wave structure, is operated with the 2π/3 mode and is installed vertically with other beam-line components. With the beam dynamics simulation, the beam transmission efficiency is over 90% and the beam size is enough to clear the apertures. Design details and the status of installation are presented for the L-band electron accelerator.