KEK, Ibaraki
S1 global will be operated at STF in KEK, where total 8 cavities will be installed. The digital llrf system to control the vector sum of the field gradients to be flat has been developed. All the digital llrf system including rf monitoring, piezo-control system will be shown. The new llrf system suitable for the DRFS scheme, which is also studied during S1 grobal, is also under development.
KEK, Ibaraki
The compact ERL(cERL) is the energy recovery linac(ERL) test facility that is under construction at KEK. The stability of accelerating electric field of 0.1% rms in amplitude and 0.1deg. in phase is required for LLRF system. The status of LLRF system for cERL will be reported.
KEK, Ibaraki
UVSOR, Okazaki
JAEA/ERL, Ibaraki
JASRI/SPring-8, Hyogo-ken
HU/AdSM, Higashi-Hiroshima
ISSP/SRL, Chiba
Yamaguchi University, Ube-Shi
Nagoya University, Nagoya
Hiroshima University, Graduate School of Science, Higashi-Hiroshima
Tohoku University, School of Scinece, Sendai
AIST, Tsukuba
Future synchrotron light source using a 5-GeV-class energy recovery linac (ERL) is under proposal by our Japanese collaboration team, and we are conducting active R&D efforts for that. We are developing super-brilliant DC photocathode guns, two types of cryomodules for both injector and main superconducting linacs, 1.3 GHz high CW-power rf sources, and other important components. We are also constructing a compact ERL for demonstrating the recirculation of low-emittance, high-current beams using those key components. We present our recent progress in this project.
KEK, Ibaraki
This paper describes a long-pulse 1.3 GHz klystron modulator that was recently developed for the Superconducting RF Test Facility (STF) at High Energy Accelerator Research Organization (KEK). The modulators is a direct-switched-type design with a 1:15 step-up transformer and a bouncer circuit to compensate for the output pulse droop within ±0.5%; it can drive a klystron with up to 10 MW peak power, 1.5 ms rf pulse width, and up to 5 pps repetition rate. The main features of this modulator are the use of four 50 kW switching power supplies in parallel to charge the storage capacitors to 10 kV, self-healing-type capacitor to realize a compact storage capacitor bank, and a highly reliable IGBT switch which enables elimination of a crowbar circuit. Design considerations and its performance are presented. An IEGT (Injection Enhanced Gate Transistor) switch, composed of six series devices with a rating of 4.5 kV and 2100 A-DC, has been also developed and tested for R&D to realize a compact modulator.
KEK, Ibaraki
Under the CERN-SLAC-KEK collaboration, we have been developing the high gradient TW accelerator structures. One of the main focuses is the feasibility study of CLIC accelerator structure at X-band. A high power facility, Nextef*, was established at KEK in 2007. A few structures have been tested, including an un-damped disk-loaded structure successfully tested beyond 100 MV/m, a heavily damped structure to be tested from late 2009 and a structure made in a quadrant configuration. These structures follow the same accelerating-mode RF parameter profile, called CLIC-C**, but show different features at high gradient operation. Various observables, such as dark current, vacuum activities, light emission, breakdown rate, and so on, are measured. We discuss the high gradient phenomena related to these observables and the possible improvement for stable operation at a higher gradient.
* T. Higo et al., THP038, LINAC06,2006.
**A. Grudiev, http://indico.cern.ch/conferenceDisplay.py?confId=30911
KEK, Ibaraki
ERL (Energy Recovery Linac) of 5GeV energy is a future plan in KEK and in order to study the technical feasibility, construction of a compact ERL machine (cERL) is considered. Beam energy and current of cERL are 245MeV and 100mA, respectively. As 1.3 GHz frequency and super conducting cavity are chosen for the RF system, similar technology with KEK STF is employed. From 2008, KEK started the preparation of cERL and one RF unit of injector linac is introduced in this fiscal 2009. A new cw klystron of 300kW out put power, 150kW Y-type circulator and high power water load were developed in FY2009. DC power supply was under manufacturing. Preliminary test of HLRF and the high power couplers are scheduled in the Photon Factory site by making use of the old DC power supply. For main accelerator, we also introduced a 30kW IOT and a 35kW klystron and a DC power supply. At the same time, cERL is determined to be constructed in the East Counter Hall in KEK and the design layout is preceded. In this paper, the recent RF source development of cERL is described. Layout of the east counter hall, where cERL is constructed, is progressed and shown in this report.
KEK, Ibaraki
Mitsubishi Electric Corp., Communication Systems Center, Amagasaki City, Hyogo
The L-band inductive output tube (IOT) without trolly was developed to operate under higher applied voltage. The operation frequency of conventional IOTs is tuned using its trolly. This mechanism is based on the lower frequency IOT. However it causes less insulation voltage of the ceramics since the electric insulation oil is not available for its trolly and the length of the insulation ceramics is limited because it is a part of the resonant cavity. In case of IOTs, it is important to increase the applied voltage for higher output power since the grid gap is very narrow and its area cannot be increased to keep the gain. Thus we developed an IOT which has a longer insulating ceramic and the input cavity is filled with vacuum to use the electric insulation oil. Further the dielectric waveguide can solve to feed the input microwave to the cathode grid without trolly. These new features of the IOT is very effective for the fixed frequency application such as the accelerator, for example the energy recovery linac. The design and the experimental results will be presented in this report.
KEK, Ibaraki
The next generation B-factory 'SuperKEKB' project whose target luminosity is 8 ×1035 cm-2s-1 is under consideration. A 'nano-beam scheme' is introduced to the SuperKEKB. In the scheme, an electron beam (Energy = 7 GeV, Charge = 3-4 nC/bunch, Vertical emittance =2.8 x 10-5 m) and a positron beam (Energy = 4 GeV, Charge = 4 nC/bunch, Vertical emittance = 1.6 x 10-5 m), are required at the end of injector linac. They are quite challenging targets for the present linac. In order to meet the requirements, we will introduce some new components to the linac. They are a photo-cathode RF gun for an electron beam, a positron capture section using new L-band cavities, a newly designed positron-generation target system and a damping ring for a positron beam. This presentation shows a strategy of our injector upgrade.
NIRS, Chiba-shi
AEC, Chiba
Based on more than ten years of experience of the carbon cancer therapy with HIMAC, we have proposed a new treatment facility for the further development of the therapy with HIMAC. This facility will consist of three treatment rooms: two rooms equipped with horizontal and vertical beam-delivery systems and one room with a rotating gantry. For the beam-delivery system of the new treatment facility, a 3D hybrid raster-scanning method with gated irradiation with patient's respiration has been proposed. A R&D study has been carried out toward the practical use of the proposed method. In the R&D study, we have improved the beam control of the size, the position and the time structure for the proposed scanning method with the irradiation gated with patient's respiration. Further, owing to the intensity upgrade of the HIMAC synchrotron, we can successfully extend the flattop duration, which can complete one fractional irradiation with one operation period. The building construction of the new treatment facility will be completed at March 2010 and treatment of 1st patient is scheduled at March 2011. We will report the recent progress on the new treatment facility project at HIMAC.
