UTNL, Ibaraki
The University of Tokyo, Nuclear Professional School, Ibaraki-ken
A, Kawasaki, Kanagawa
AET Japan, Inc., Kawasaki-City
We are developing X-ray nondestructive testing (NDT) system using with portable X-band linac. This system uses 9.4 GHz X-band linac and 250 kW magnetron. Our system energy is 950 keV for Japanese regulation. Therefore we can use it on-site using local radiation protection. We measured electron beam and X-ray. We have started X-ray imaging test. We will use this system for condition based maintenance of pump-impeller at nuclear plants. The linac based X-ray source can generate pulsed X-ray. Therefore we can get still images without stopping rotation when x-ray repetition rate synchronizes impeller's rotaion rate. We are successfull in proof of principle using a simple fan and a synchronized circuit. We prepare real-time imaging for conventional pump. In this paper, we will explain the detail of this system and expermental results.
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
KEK/JAEA, Ibaraki-Ken
In the J-PARC RCS, we employ the longitudinal painting methods, the momentum offset injection method and applying the second harmonic RF voltages, to increase the bunching factor so that the space-charge tune shift is reduced. By the dual-harmonic operation with wide-band MA loaded cavities, in which each single cavity is driven by a superposition of the fundamental and the second harmonic RF signals, we can generate a large amplitude second harmonic RF voltage without extra cavities for the second harmonic RF. We present the results of the beam tests for the longitudinal painting in the J-PARC RCS. Also, we present the beam behavior at very high beam power.
KEK, Ibaraki
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
GUAS, Kanagawa
J-PARC RCS accelerates a high intensity beam using 11 sets of Magnetic Alloy loaded cavities. It supplies the proton beam to the MLF (Material Life Science Facility) for the neutron and muon experiments. For very high resolution muon experiments, a short proton beam bunch of few ten ns is necessary. To reduce the bunch width to several ten ns, a bunch rotation scheme before extraction will be useful. For the bunch width of few ten ns, a much higher RF voltage is also required. Based on a new magnetic alloy core technology, a design of a new RF cavity to increase the maximum RF voltage by a factor of two will be described in this paper.
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
LASTI, Hyogo
Hiroshima University, Graduate School of Science, Higashi-Hiroshima
KEK, Ibaraki
J-PARC, KEK & JAEA, Ibaraki-ken
The beam commissioning of the J-PARC 3-GeV RCS started in October 2007. The initial machine parameter tuning and underlying beam studies were completed in February 2008 through various beam dynamics measurements, such as optical functions, turn-by-turn beam positions, and transverse and logitudinal beam profiles. Now the RCS is in transition from the first commissioning phase to the next challenging stage and our efforts hereafter will be focused on higher beam power operations. In this paper, we describe experimental results obtained in the high intensity demonstrations in October 2008, together with the corresponding simulation results.
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
KEK, Ibaraki
KEK/JAEA, Ibaraki-Ken
J-PARC consists of a 181 MeV linac, a 3GeV Rapid Cycling Synchrotron (RCS) and a 50 GeV Synchrotron (MR). The RCS is designed to accelerate a high intensity proton beam. One of the key issues of the RCS RF system is how to achieve the very high accelerating field gradient of more than 20kV/m. This is impossible with conventional ferrite-loaded cavities. We reach this goal by the development of Magnetic Alloy (MA) core loaded RF cavities. We installed 10 RF cavities in the RCS tunnel on May 2007. The RCS beam commissioning was started on September 2007 and we successfully accelerated a proton beam up to 3GeV on October 2007. We also employed MA cores for MR RF cavities and use a cut core configuration to adjust the Q-value. The MR beam commissioning was started on May 2008. We didn't have any trouble caused by the MA cores during operation. We measured the impedance of the RF cavities several times at the shutdown periods. We show the results of impedance measurements. From these results, we can make an assumption about the core condition.
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
KEK, Ibaraki
KEK/JAEA, Ibaraki-Ken
The J-PARC Rapid Cycling Synchrotron (RCS) uses broadband magnetic alloy loaded cavities to create the acceleration voltages needed for rapid cycling at 25 Hz rate. Besides the desired second harmonic of the acceleration frequency, which is employed in the painting process of RCS injection, also unwanted harmonics can be found at the acceleration gaps of the cavities. Here, the effect of the vector sums of undesired harmonics during the acceleration process is estimated.
JAEA/J-PARC, Tokai-mura
KEK, Ibaraki
Nippon Advanced Technology Co. Ltd., Ibaraki-prefecture
J-PARC RCS is in the beam commissioning period. Some longitudinal beam gymnastics and the acceleration has been successfully perfomed under the high intensity operation. We have developed a longitudinal particle tracking code, which includes beam loading and space charge effects. The comparison between the beam test result and the particle tracking simulation is described.
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
KEK/JAEA, Ibaraki-Ken
In order to observe two-dimensional beam profiles in the longitudinal phase space, the reconstruction techniques with the computer tomography algorithms can be adopted at the J-PARC RCS. On the assumption that the longitudinal profiles should not be disturbed for one period of the synchrotron oscillation, such two-dimensional profiles can be reconstructed easily from one-dimensional bunch beam profiles, which are measured for every turn by the wall current monitor. In this presentation, we introduce the experimental results and the comparison to the longitudinal beam tracking simulation, and we discuss the technical issues and applicability of this longitudinal tomography techniques.
JAEA/FEL, Ibaraki-ken
KEK, Ibaraki
JAEA/ERL, Ibaraki
HU/AdSM, Higashi-Hiroshima
Nagoya University, Nagoya
A 500-kV, 10-mA photocathode DC gun has been designed and is now under fabrication by the collaboration efforts of JAEA, KEK, Hiroshima Univ. and Nagoya Univ. The Cockcroft-Walton generator and the ceramic insulator are installed upright in the SF6 tank. We have adopted a multiple-stacked cylindrical ceramic insulator, because this type of ceramic insulator has shown good stability and robustness at the 200-kV Nagoya polarized gun and the 250-kV JAEA FEL gun. All the vacuum chambers are made of titanium alloy with very low out-gassing. The Cockcroft-Walton generator, the ceramic insulator, the vacuum chambers will be fabricated by April 2009 and a high-voltage test will be started soon later. Up-to-date status of the gun development will be presented in detail.
KEK, Ibaraki
JAEA/ERL, Ibaraki
JASRI/SPring-8, Hyogo-ken
ISSP/SRL, Chiba
UVSOR, Okazaki
HU/AdSM, Higashi-Hiroshima
Hiroshima University, Graduate School of Science, Higashi-Hiroshima
AIST, Tsukuba
Future synchrotron light source project using an energy recovery linac (ERL) is under proposal at the High Energy Accelerator Research Organization (KEK) in collaboration with several Japanese institutes such as the JAEA and the ISSP. We are on the way to develop such key technologies as the super-brilliant DC photo-injector and superconducting cavities that are suitable for both CW and high-current operations. We are also promoting the construction of the Compact ERL for demonstrating such key technologies. We report the latest status of our project, including update results from our photo-injector and from both superconducting cavities for the injector and the main linac, as well as the progress in the design and preparations for constructing the Compact ERL.
KEK, Ibaraki
KEK/JAEA, Ibaraki-Ken
J-PARC is a unique accelerator, because magnetic alloy (MA) loaded cavities are employed for the first time in the rf systems of high intensity proton synchrotrons. High field gradients of more than 20 kV/m are achieved covering the frequency range from 0.9 MHz to 3.4 MHz. The peak voltage of 45 kV per cavity is obtained by driving with two 600 kW tetrodes in push-pull. The first high intensity beam acceleration was successfully initiated at J-PARC RCS. Although RCS beam commissioning started with 10 rf systems, instead of 11 as designed, RCS succeeded in the acceleration of an intense proton beam, which is equivalent to 300 kW when operated at 25 Hz. The longitudinal painting based on the simulation with superimposed second harmonics and with phase and momentum manipulations was the key of success. In December 2008, the J-PARC MR beam is scheduled for its first acceleration up to 30 GeV, and the Material and Life Science facilities start the user operations. During the development stage of the MA cavities, some serious problems such as electrical breakdown on core surfaces occurred. The problems were solved in a short term, and all rf systems were completed on schedule.
HU/AdSM, Higashi-Hiroshima
Nagoya University, Nagoya
High brightness electron source is a key technology for future projects based on advanced accelerators. Although GaAs photo-cathode is very attractive because it can generate highly polarized and extremely high brightness electron beam, the limited operational life time is a technical issue. In Hiroshima University, a photo-cathode test bench is implemented for various studies of GaAs photo-cathode. Super high vacuum, 9E-9Pa, was achieved and the cathode was successfully activated by processes of heat cleaning technique and the alternate evaporation of Cs and oxygen. The quantum efficiency and its lifetime were investigated as a function of cathode temperature, simulating temperature rise by the high power cathode drive laser. Wavelength dependence was also investigated.