Hara, K.

Paper	Title	Page
MOPC120	J-PARC RCS Non-linear Frequency Sweep Analysis	346
	A. Schnase, K. Haga, K. Hasegawa, M. Nomura, F. Tamura, M. Yamamoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken S. Anami, E. Ezura, K. Hara, C. Ohmori, A. Takagi, M. Toda, M. Yoshii KEK, Ibaraki
	A standard method to measure the S21-transfer function of a system of amplifier and cavity involves a network analyzer and a linear or logarithmic frequency sweep. However, to characterize the transfer function of the broadband (Q=2) RCS RF system, we measure and analyze several harmonics at the same time under high power ramping conditions. A pattern driven DDS system generates frequency and amplitude as in accelerator operation. During the 20ms acceleration part of the cycle, a large memory oscilloscope captures the RF-signals. The data are analyzed off-line with a down-conversion process like in a multi-harmonic LLRF-system, resulting in multi-harmonic amplitude and phase information. Using this setup in the cavity test phase we were able to find and cure resonances before installation into the tunnel. We show examples. RCS is in the commissioning phase and has reached the milestone of acceleration to final energy and beam extraction. 10 RF systems are in operation, and the low-level RF system controls the fundamental h(2) and the second harmonic h(4). Using a multi-harmonic analysis during beam operation allows checking the RF system behavior with and without beam-loading.
MOPC126	Beam Acceleration with Full-digital LLRF Control System in the J-PARC RCS	364
	F. Tamura, K. Haga, K. Hasegawa, M. Nomura, A. Schnase, M. Yamamoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken S. Anami, E. Ezura, K. Hara, C. Ohmori, A. Takagi, M. Toda, M. Yoshii KEK, Ibaraki
	In the J-PARC RCS (Rapid Cycling Synchrotron) we employ a full-digital LLRF control system to accelerate an ultra-high intensity proton beam. The key feature is the multi-harmonic RF signal generation by using direct digital synthesis (DDS) technology. By employing a full-digital system, highly accurate, stable and reproductive RF voltages are generated in the wide-band RF cavities loaded by magnetic alloy (MA) cores. The beam commissioning of the J-PARC RCS has been started in October 2007. The accelerators, the linac and the RCS, show good stability. The beam orbit and the longitudinal beam shape and phase are reproductive from cycle to cycle especially thanks to the stability of the linac energy, the RCS bending field and the frequency and voltage of the RCS RF. This reproductivity makes the beam commissioning efficient. We present the examples of the orbit signals and the longitudinal current signals. Also, we discuss the longitudinal beam control performance and future plans.
MOPC132	Acceleration Voltage Pattern for J-PARC RCS	379
	M. Yamamoto, K. Hasegawa, M. Nomura, A. Schnase, F. Tamura JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken S. Anami, E. Ezura, K. Hara, C. Ohmori, A. Takagi, M. Toda, M. Yoshii KEK, Ibaraki
	The beam commissioning has been started at the J-PARC RCS. Some acceleration voltage patterns are tested to prevent the beam losses. The calculation code for the acceleration voltage pattern is usually based on the differential equation of the longitudinal synchrotron motion. We have developed the code based on the forward-difference equation which satisfies the synchronization with the bending magnetic field ramping accurately. This is very useful especially at the rapid cycling synchrotron where the ramping rate is high. The results of the test are described.
MOPC134	The Status of the J-PARC RF Systems	385
	M. Yoshii, S. Anami, E. Ezura, K. Hara, C. Ohmori, A. Takagi, M. Toda KEK, Ibaraki K. Haga, K. Hasegawa, M. Nomura, A. Schnase, F. Tamura, M. Yamamoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
	The first acceleration of a proton beam at the J-PARC Rapid Cycling Synchrotron started in October 2007. The R&D for magnetic alloy (MA) loaded rf-systems to realize a high field gradient accelerating system for a rapid cycling machine has been initiated in 1996 with the aim of surpassing standard ferrite loaded cavities. The RCS RF system is broad-band and designed to cover both the RCS accelerating frequency range and the second harmonic for bunch shape manipulation. The optimum Q value of the RCS cavities is approximately 2. This is realized by combining a high-Q parallel inductor with an un-cut core configuration. The beam commissioning of the 50GeV Main Ring synchrotron will start in May 2008. Acceleration and slow-beam extraction are planned for December 2008. In case of the MR RF system, the accelerating frequency swing is small. The Q-value in the order of 20 has been selected to reduce transient beam loading due to the multiple-batch injection scheme. The MR RF cavities realize the Q-value by a cut-core configuration. The details of the RF systems and the results of beam accelerations are summarized.
MOPD014	First Test Results of ILC/STF Cryogenic System at KEK	472
	S. Kaneda, T. Ichitani Taiyo Nippon Sanso Corporation, Kawasaki-city Kanagawa Pref. K. Hara, K. Hosoyama, A. Kabe, Y. Kojima, H. Nakai, K. Nakanishi KEK, Ibaraki T. Kanekiyo Hitachi Technologies and Services Co., Ltd., Kandatsu, Tsuchiura M. Noguchi Mayekawa MFG. Co., Ltd., Moriya S. Sakuma, K. Suzuki Taiyo Nippon Sanso Higashikanto Corporation, Hitachi-city, Ibaraki-Pref J. Yoshida Hitachi Plant Technologies, Ltd., Tokyo
	The STF (Superconducting RF Test Facility) cryogenic system, of which capacity is 30W at 2.0K, has been constructed and commissioned for testing STF cryomodule. In the first operation phase, the STF cryogenic system was successfully cooled down to maintain a superconducting RF cavity at the working temperature of 2.0K. Presented in this session will be the results of the first operation of the cryogenic system and the future collaboration plan among KEK and Japanese cryogenic industrial members.
MOPP029	The First Measurement of Low-loss 9-cell Cavity in a Cryomodule at STF	610
	T. Saeki, M. Akemoto, S. Fukuda, F. Furuta, K. Hara, Y. Higashi, T. Higo, K. Hosoyama, H. Inoue, A. Kabe, H. Katagiri, S. Kazakov, Y. Kojima, H. Matsumoto, T. Matsumoto, S. Michizono, T. Miura, Y. Morozumi, H. Nakai, K. Nakanishi, N. Ohuchi, K. Saito, M. Satoh, T. Takenaka, K. Tsuchiya, H. Yamaoka, Y. Yano KEK, Ibaraki T. Kanekiyo Hitachi Technologies and Services Co., Ltd., Kandatsu, Tsuchiura J. Y. Zhai IHEP Beijing, Beijing
	We are constructing Superconducting RF Test Facility (STF) at KEK for the R&D of International Linear Collider (ILC) accelerator. In the beginning of year 2008, we installed one high-gradient Low-Loss (LL) type 9-cell cavity into a cryomodule at STF, where we assembled an input coupler and peripherals with the cavity in a clean room, and the assembled cavity packages were dressed with thermal shields and installed into a cryomodule. At the room-temperature, we performed the processing of capacitive-coupling input-coupler upto the RF power of 250 kW. At the temperature of 4 K, we measured the loaded Q of the cavity and the tuner was tested. At the temperature of 2 K, high-power RF was supplied from a klystron to the cavity and the performance of the cavity packeage was tested. This article presents the results of the first test of the Low-Loss (LL) 9-cell cavity package at 2 K in a cryomodule.
MOPP104	Possible Upgrade Scenario for J-PARC Ring RF	799
	C. Ohmori, K. Hara, A. Takagi, M. Toda, M. Yoshii KEK, Ibaraki K. Hasegawa, M. Nomura, A. Schnase, F. Tamura, M. Yamamoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
	The whole J-PARC RCS RF system is operational and during beam commissioning in 2007 the beam in RCS was successfully accelerated to final energy and then extracted. The Main Ring RF system has been installed in the tunnel. Both Ring RF systems are based on the new technology using magnetic alloy loaded cavities and have achieved higher field gradient than existing ferrite base RF systems in this frequency region. For the future upgrade of the J-PARC Main Ring, a short accelerating cycle is required to increase the average beam current. In this paper, a possible upgrade scenario for RF cavities based on improvements of the magnetic alloy ring cores will be described.
MOPP144	The First Cool-down Tests of the 6 Meter-Long-Cryomodules for Superconducting RF Test Facility (STF) at KEK	892
	N. Ohuchi, F. Furuta, K. Hara, H. Hayano, N. Higashi, Y. Higashi, H. Hisamatsu, K. Hosoyama, E. Kako, Y. Kojima, M. Masuzawa, H. Matsumoto, H. Nakai, S. Noguchi, T. Saeki, K. Saito, T. Shishido, A. Terashima, N. Toge, K. Tsuchiya, K. Yokoya KEK, Ibaraki M. H. Tsai NSRRC, Hsinchu Q. J. Xu IHEP Beijing, Beijing
	KEK is presently constructing the Superconducting RF Test Facility (STF) as the center of the ILC-R&D in Asia from 2005. In this project, KEK aims to get the manufacturing and operational experiences of the RF cavity and cryomodule toward the ILC, and two cryomodules have been developed. These cryomodules are 6 meter long and have 4 nine-cell cavities in each cryostat. The basic cross section designs of the cryomodules are almost same as the design of TESLA type-III, however, each cryostat has the different type of cavities, TESLA type and Low-Loss type. The tests for the cryomodules are planed to be performed at three steps. In the first test, measurements of the cryogenic performances of these cryomodules are the main objective. One nine-cell cavity was assembled in each cryostat and the cool-down of the two cryomodules was performed. In the following tests, the four nine-cell cavities will be assembled in each cryostat as the complete integration and the beam test will be performed. In this paper, we will report the design of the cryomodules and the cryogenic performances at the first cold test.
THXM02	Development of the KEK-B Superconducting Crab Cavity	2927
	K. Hosoyama, K. Akai, K. Ebihara, T. Furuya, K. Hara, T. Honma, A. Kabe, Y. Kojima, S. Mitsunobu, Y. Morita, H. Nakai, K. Nakanishi, M. Ono, Y. Yamamoto KEK, Ibaraki H. Hara, K. Okubo, K. Sennyu, T. Yanagisawa MHI, Kobe
	The development of the KEK-B superconducting crab cavity, including the design, production, tests and latest parameter performances should be described in this talk.
	Slides