| Paper | Title | Page |
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| MOPAB44 | Beam Halo Measurement Using a Combination of a Wire Scanner Type Beam Scraper and Some Beam Loss Monitors in J-PARC 3-GeV RCS | 143 |
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| Transverse beam halo is one of the most important beam parameters due to limit the performance of the high intensity beam accelerator. Therefore, the transverse beam halo measurement is required to increase the beam power of the J-PARC 3-GeV RCS. New beam halo monitor, which is combined a wire type beam scraper and some beam loss monitors, are installed in the extraction beam transport line. In order to use some beam loss monitors with a plurality of different sensitivities, it's ultra wide dynamic range can be achieved and beam profile including both of the beam core and halo can be obtained. | ||
| WEO2AB03 | Beam Instrumentation at the 1 MW Proton Beam of J-PARC RCS | 278 |
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| Rapid Cycling Synchrotron(RCS) of Japan Proton Accelerator Complex(J-PARC) is providing more than 300 kW of proton beam to Material and Life science Facility(MLF) and Main Ring(MR). Last summer shutdown, a new ion source was installed to increase output power to 1 MW. In order to achieve reliable operation of 1 MW, we need to reduce beam loss as well. Beam quality of such higher output power is also important for users. We present beam monitor systems for these purposes. | ||
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Slides WEO2AB03 [3.242 MB] | |
THO1LR02 |
Recent Commissioning of High-Intensity Proton Beams in J-PARC Main Ring | |
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| In the J-PARC, the main ring (MR) provides high power proton beams of 240 kW (1.24·1014 protons per pulse) to the neutrino experiment. The linac energy was upgraded from 181 MeV to 400 MeV in 2013, and its current is going to be from 30 mA to 50 mA in 2014. If the beam losses are minimized and localized in the MR, the MR will have the capability to provide over 300 kW after the upstream upgrades. Based on the upgrades and improvements of the 3-50BT and the MR in 2013 and 2014, following approaches have been tested and commissioned: 2nd harmonic RFs under the faster rise-up time improvement of the injection kickers, to increase bunching factor; intra-bunch feed-back system and chromaticity patterned correction, to suppress instability; intra-bunch feed-back, tail and reflection improvement of the injection kickers, and 6D matching between the 3-50BT and the MR, to reduce injection losses; achromatic tuning at the collimator section of the 3-50BT to cut beam halo effectively; collimator upgrades, aperture enlargement at dispersion peaks, and momentum spread control, to localize beam losses in the collimator section; new operation point survey. | ||
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Slides THO1LR02 [2.553 MB] | |
| THO3AB02 | Dynamic Correction of Extraction Beam Displacement by Field Ringing of Extraction Pulsed Kicker Magnets in the J-PARC 3-GeV RCS | 389 |
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| The 3-GeV rapid cycling synchrotron (RCS) of J-PARC is designed for a high-intensity output beam power of 1MW. The RCS is extracted two bunches by using eight pulsed kicker and three DC septum magnets with 25Hz repetition. The extracted beam is simultaneously delivered to the material and life science experimental facility (MLF) as well as the 50-GeV main ring synchrotron (MR). The kicker magnets have the ringing of flat-top field and the ringing causes the position displacement. The displacement is big issue because it causes an emittance growth of the extracted beam directly. In the beam tuning, we performed a timing scan of each kicker magnet by using a shorter pulse beam in order to understand the characteristics of ringing field. We then carefully optimized the trigger timings of each kicker for the ringing compensation. We have successfully compensated the extracted beam displacements to (min., max.) = (1.1 mm, +0.6 mm) as compared to (14 mm, +10 mm) with no ringing compensation. The procedure for ringing compensation and experimental results are reported in this paper. | ||
| THO3AB03 | Pulse-to-pulse Transverse Beam Emittance Controlling for the MLF and MR in the 3-GeV RCS of J-PARC | 394 |
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| The 3-GeV RCS (Rapid Cycling Synchrotron) of J-PARC (Japan Proton Accelerator Research Complex) is a MW-class proton beam source for the muon and neutron production targets in the MLF (Material and Life Science Experimental Facility) as well as an injector for 50-GeV MR (Main Ring). Not only the beam intensity but RCS has to provide two different transverse sizes of the extracted beam for the MLF and MR even in simultaneous operation. Namely, a wider one for the MLF, while a narrower one for the MR. We proposed a pulse-to-pulse direct controlling of the transverse injection painting area so as to ensure a desired extracted beam emittance. The injection system design is capable of changing painting area between MLF and MR. The extracted beam profile for the MR is measured to be sufficiently narrower than that for the MLF and is also shown to be consistent with ORBIT beam simulations. It is thus one remarkable progress in recent high intensity multi-user machine to confirm that the beam parameters can be dynamically controlled and delivered as requested by the users even in simultaneous operation. A detail of both design and experimental studies are presented in this paper. | ||
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Slides THO3AB03 [2.225 MB] | |