Author: Satoh, M.
Paper Title Page
MOOBC02 Status of Main Linac Cryomodule Development for Compact ERL Project 67
 
  • K. Umemori, K. Enami, T. Furuya, H. Sakai, M. Satoh, K. Shinoe
    KEK, Ibaraki, Japan
  • E. Cenni
    Sokendai, Ibaraki, Japan
  • M. Sawamura
    JAEA, Ibaraki-ken, Japan
 
  The Compact ERL, which is a test facility of ERL, is under construction at KEK, in Japan. For the main linac, one cryomodule, containing two 9-cell superconducting cavities, is under development. The cryomodule has been designed under High Pressure Gas Safety Code in Japan. Thermal design and cavity alignment have been also carefully considered. Two 9-cell cavities were already fabricated and their performances were confirmed by vertical tests. They satisfied ERL main linac specifications. Their accelerating field reached to 25 MV/m, without field limits. Two input couplers, three HOM absorbers and two Slide-Jack tuners are also under fabrication for the cryomodule. High power processing will be applied for input couplers, at a test stand using a 300 kW klystron. Cooling tolerance and HOM damping abilities were tested for HOM absorbers. Some performance studies were also applied for the tuner at room temperature condition. Cryomodule assembly is planned on this summer. After cooling tests and high power tests will be carried out, ERL beam operation will be started.  
slides icon Slides MOOBC02 [3.849 MB]  
 
MOPPC070 Field Emission Simulation for KEK-ERL 9-Cell Superconducting Cavity 295
 
  • E. Cenni
    Sokendai, Ibaraki, Japan
  • T. Furuya, H. Sakai, M. Satoh, K. Shinoe, K. Umemori
    KEK, Ibaraki, Japan
  • M. Sawamura
    JAEA/ERL, Ibaraki, Japan
 
  In order to develop the Energy Recovery Linac at KEK, we are studying the performance of L-band superconducting cavities by means of vertical tests. One of the limiting factor for the cavities performance is power losses due to field emitted electrons. With regard to this phenomena, a particle tracking code is used to study electron trajectories and deposited energy on the inner surface of the cavity. Different emitters location were tested within a range of accelerating field and phases in order to reproduce different scenario. The final goal of this study is to locate the sources of the electrons inside the cavity through a deeper understanding of the phenomena. To validate the results from the simulation the outcome data are compared with other particle tracking codes.  
 
MOPPR025 The BPM DAQ System Upgrade for SuperKEKB Injector Linac 834
 
  • M. Satoh, K. Furukawa, F. Miyahara, T. Suwada
    KEK, Ibaraki, Japan
  • T. Kudou, S. Kusano
    MELCO SC, Tsukuba, Japan
 
  The non-destructive beam position monitor (BPM) is indispensable diagnostic tool for the stable beam operation. In the KEK Linac, approximately nineteen BPMs with the strip-line type electrodes are used for the beam orbit measurement and feedback. In addition, some of them are also used for the beam energy feedback loops. The current DAQ system consists of the fast digital oscilloscopes. A signal from each electrode is analyzed with a predetermined response function up to 50 Hz. The beam position resolution of current system is limited to about 0.5 mm because of ADC resolution. Towards SuperKEKB project, we have a plan to upgrade the BPM DAQ system since the Linac should provide the smaller emittance beam. We will report the system description of the new DAQ system and the results of performance test in detail.  
 
TUPPC021 Design Study on KEK Injector Linac Upgrade for High-current and Low-emittance Beams 1206
 
  • H. Sugimoto, M. Satoh, M. Yoshida
    KEK, Ibaraki, Japan
 
  Injector linac at KEK is now under upgrading to produce high current (5nC for e-, 4nC for e+) and low emittance (20 mm mrad for e-, 6 mm mrad for e+) electron and positron beams to a SuperB collider called SuperKEKB. Emittance growth resulted from both wakefield at the acceleration structure and dispersive effects at the focusing structure are troublesome in keeping the beam quality during the beam propagation. In this study, a possible solution to mitigate these effects in the KEK injector linac is explored by considering bunch compression in an existing bending section, orbit correction to suppress the wakefield excitation, and beam optics design.  
 
WEPPC011 Vertical Test Results for ERL 9-cell Cavities for Compact ERL Project 2227
 
  • K. Umemori, T. Furuya, H. Sakai, M. Satoh, K. Shinoe
    KEK, Ibaraki, Japan
  • E. Cenni
    Sokendai, Ibaraki, Japan
  • M. Sawamura
    JAEA, Ibaraki-ken, Japan
 
  The Compact ERL project, which is a test facility of ERL, is ongoing in Japan. At the first step of this project, main linac cavities accelerate electron beams by 30 MV. Two 9-cell cavities were fabricated for main linac cryomodule, under High Pressure Gas Safety Code in Japan. A series of surface treatments, such as annealing, pre-tuning, electro-polishing (EP), degreasing, high pressure rinsing by ultra-pure water, cavity assembly and baking, were applied for the cavities. For the final EP, current density was selected to be relatively low. Vertical tests were performed for both cavities. Their field successfully reached to 25 MV/m, without any field limitation. The Q-values were more than 1x1010, even at 20 MV/m. Field emission on-sets were to be 14 and 22 MV/m, for each cavities. Both cavities satisfied requirements for ERL main linac cavity. Details of vertical tests, with X-ray and temperature mapping data, are shown, in this paper. These cavities will be mounted with titanium He jackets, assembled and installed into a cryomodule.  
 
WEPPD065 Development of a Laser-based Alignment System Utilizing Fresnel Zone Plates at the KEKB Injector Linac 2672
 
  • T. Suwada, M. Satoh
    KEK, Ibaraki, Japan
  • K. Minoshima, S. Telada
    AIST, Tsukuba, Japan
 
  A new laser-based alignment system is under development in order to precisely align accelerator components along an ideal straight line at the 600-m-long KEKB injector linac. A well-known sequential three-point method with Fresnel zone plates and a CCD camera is revisited in the alignment system. The high-precision alignment system is strongly required in order to stably accelerate high-brightness electron and positron beams with high bunch charges and also to keep the beam stability with higher quality towards the Super B-factory at KEK. A new laser optics has been developed and the laser propagation characteristics has been systematically investigated at a 100-m-long straight section in vacuum. In this report, the experimental developments and investigations are reported along with the design of the new laser-based alignment system.  
 
TUPPR005 Linac Upgrade in Intensity and Emittance for SuperKEKB 1819
 
  • T. Higo, M. Akemoto, D.A. Arakawa, Y. Arakida, A. Enomoto, S. Fukuda, K. Furukawa, Y. Higashi, H. Honma, N. Iida, M. Ikeda, E. Kadokura, K. Kakihara, T. Kamitani, H. Katagiri, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Miura, F. Miyahara, T. Mori, H. Nakajima, K. Nakao, T. Natsui, Y. Ogawa, S. Ohsawa, M. Satoh, T. Shidara, A. Shirakawa, H. Sugimoto, T. Suwada, T. Takatomi, T. Takenaka, Y. Yano, K. Yokoyama, M. Yoshida, L. Zang, X. Zhou
    KEK, Ibaraki, Japan
  • D. Satoh
    TIT, Tokyo, Japan
 
  The SuperKEKB is designed to produce 40 times luminosity than that of the KEKB. In order to realize such a high luminosity, the injector linac should provide both electron and positron beams of about 4-5 nC/bunch, which is several times higher than before. In addition, their emittance requirement of the injection beam to the rings is 20 microns, which is a factor of a few tens smaller than before. The intensity and emittance of the electron beam are realized directly by developing the photo RF gun. In contrast, the positron intensity is increased by adopting a higher capture efficiency system with flux concentrator followed by large-aperture accelerators, while its emittance is reduced by a damping ring. For preserving such a low emittance of both beams toward the injection to the rings, the suppression of the emittance growth is crucial. To this end, the alignment of the accelerator components should be a few tens of microns, where we need an improvement by more than a factor 10. The beam-based alignment is definitely needed with better-resolution BPMs. In the present paper are reviewed the overall progress and perspective of the design and the associated component developments.