| Paper | Title | Other Keywords | Page |
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| MOPP072 | Present Status of J-PARC LINAC LLRF Systems | linac, controls, operation, feedback | 224 |
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| The RF control systems have been developed for the J-PARC proton linac, which consists of 324-MHz and 972-MHz acceleration sections. From October 2006, we started the commissioning of the 324-MHz sections. Then the J-PARC 324-MHz 181-MeV proton linac had been operated nearly for 7 years, until May 2013. In the summer of 2013, we upgraded the J-PARC linac by adding 972-MHz acceleration sections. The output energy of the J-PARC linac was successfully upgraded to 400 MeV in December 2013, and then the operation of the J-PARC 400-MeV linac started. In the past 8 years of the J-PARC linac operation, no heavy troubles occurred in the RF control systems. Every year we made improvements on the RF control systems, according to the operation experiences. In this paper, the present status of the J-PARC 400-MeV linac RF control systems will be described in details, and an improvement plan for the LLRF systems in the future will also be introduced. | |||
| MOPP092 | Compact Timing System with FPGA for SPring-8 Linac | FPGA, linac, gun, injection | 270 |
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Funding: This reserch was supported by TAKUMI project. A new timing system for SPring-8 linac was developed. It is a test system to confirm the possibility of replacing the current NIM module-based system. Although fast logic circuits can be made easily with NIM modules, they become complicated when they are used in a large system. The timing system for SPring-8 linac has been getting larger and larger after several improvements for injection to New SUBARU (NS), top-up injection for storage ring, low repetition operation for saving energy, fast alternative injection and so on. In order to simplify the system, we adopted FPGA technology that can run at a clock over 500 MHz. The new system has 50 NIM inputs and outputs on the front panel, which is installed in an 8U rack-mount box. It only has gun trigger parts of current system, but includes all of the circuit components used in the current system such as and/or logics, counter delay, fan in/out etc. Three clock sources for Synchrotron injection, NS injection, and linac solo use are available in the FPGA, and they can be changed rapidly according to the trigger sources. We describe here the details of test timing system, the results of timing jitter measurements. |
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| MOPP093 | Evaluation of Beam Energy Fluctuations Caused by Phase Noises | linac, experiment, electron, cavity | 273 |
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| The SSB noises of the RF reference signal dominate the short-term instabilities of the RF phase of the carrier RF. This phase modulation finally results in beam energy fluctuation. This presentation gives a quantitative evaluation of the beam energy fluctuations in an electron linear accelerator caused by phase noises, comparing a theoretical analysis and experimental results. A simple model was introduced to understand how phase noises result in the relative phase difference between a beam bunch and accelerating RF fields. In the experiments, we measured the enhanced beam energy fluctuations by modulating the phase of the reference RF signals with an external signal. The interference between the accelerating RF phase modulation and the timing modulation of a beam bunch was found in the model analysis and also in the experimental results. | |||
| TUPP015 | Status on Airix Restart | electron, target, induction, operation | 462 |
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The Airix accelerator has been moved from Moronvilliers to Valduc to be part of the EPURE facility. Airix has been refurbished and restarted. This paper presents the first results and quantification of performances at its new location.
*M.Mouillet et al., “First results of AIRIX induction accelerator”,XXth LINAC cf.,p.491(2000) **H.Dzitko et al., "operationnal efficiency of Airix accelerator since its commissioning",IPAC2012,p.4017 |
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| TUPP029 | Diagnostics and Analysis Techniques for High Power X-Band Accelerating Structures | diagnostics, controls, klystron, operation | 490 |
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| The study of high gradient limitations due to RF breakdowns is extremely important for the CLIC project. A series of diagnostic tools and analysis techniques have been developed in order to monitor and characterize the behaviour of CLIC accelerating structures under high power operation in the first CERN X-band klystron-based test stand (Xbox1). The data collected during the last run on a TD26r05 structure are presented in this paper. From the analysis of the RF power and phases, the location of the breakdowns inside the structure could be determined. Other techniques based on the field emitted dark current signals collected by Faraday cups placed at the two extremities of the structure have also been investigated. The results of these analyses are reported and discussed. | |||
| TUPP067 | Chopper Operation for the Tandem Scrapers at the J-PARC Linac | linac, operation, cavity, software | 581 |
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| In the J-PARC linac, the energy upgrade from 181 MeV to 400 MeV by the installation of annular-ring coupled structure (ACS) cavities was successfully achieved in 2013. In the next stage, we will schedule the intensity upgrade by the increase of the beam current by improving the front-end in this summer. Then, the high heat load of the scraper, which stops the kicked-beam by the RF chopper, is predicted to damage the surface. Therefore, we prepare the tandem scrapers to suppress the heat load. The half of the kicked beam leads to a scraper and the residual is to the other. Its chopping expedient will be achieved by reversing the phase of the RF chopper on the periodic cycle at the low-level RF system. In this paper, I would like to introduce this system and present the result of the low-level test. | |||
| TUPP105 | Storage Ring as a Linac Beam Monitor – Its Operation and Contribution to the Stable Top-up Injection | linac, injection, synchrotron, storage-ring | 668 |
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| We have used the electron storage ring, NewSUBARU, as a beam monitor of the SPring-8 linac. The time and transverse profiles of the injected linac beam are recorded in a frame of a dual-sweep streak camera. A measurements through synchrotron or betatron oscillation in the ring gives multi-dimensional beam structure. The system functions as a final check of the linac beam. It gives the time profile and energy profile or transverse emittance, which includes Twiss parameters. It measures parameters of one linac bunch in a long macro pulse. A shot-by-shot measurement gives beam fluctuations. We report how we use the system and its contribution to the stable top-up operation. The beam loading effect on the bunch energy was obtained by bunch-by-bunch energy profile measurements. It confirmed the optimization of the ECS (Energy Compression System) parameters. The single shot bunch-by-bunch vertical emittance measurement proved the difference between the front bunch and the following bunches. The same measurement showed a timing jitter of the electron gun pulse although the rf synchronization was perfect. This jittering had made the injection efficiency unstable. | |||
| THPP005 | A New High Current and Single Bunch Injector at ELSA | booster, linac, electron, injection | 847 |
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| At the Electron Stretcher Facility ELSA of Bonn University, an increase of the maximum stored beam current from 20 mA to 200 mA is planned for the stretcher ring. In order to keep the desired duty cycle of the post acceleration mode at about 80 \% a new high current injector operating at 3 GHz has been built. It provides an electron beam with an energy of 20 MeV and a beam current of 800 mA in pulsed operation. A prebuncher, travelling wave buncher system and an energy compressing system are installed in order to enhance the beam acceptance of the linac and to reduce the energy spread in order to achieve an improved injection efficiency into the booster synchrotron. For studying accelerators impedances and beam instabilities the linac is able to produce single bunches with a pulse current of 2 A which will be accumulated in the stretcher ring. | |||