Paper | Title | Page |
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MOPAB02 | Progress in the Upgrade of the CERN PS Booster Recombination | 24 |
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The CERN PS Booster recombination lines (BT) will be upgraded following the extraction energy increase foreseen in 2018 and meant to reduce the direct space-charge tune shift in the PS injection for the future HL-LHC beams. Henceforth the main line elements, recombination septa, quadrupoles and dipoles must be scaled up to this energy. An increase in the beam rigidity by a factor 1.3 would require the same factor in the field integral of the septa, ∫Bdl, in order to bend the same angle and preserve the present recombination geometry, which is one of the main upgrade constraints. This paper describes the new optics, in particular in the new and longer septa. In addition we consider the upgrade of the so called BTM line that brings the beam to the external dump and where emittance measurements are taken thanks to three pairs of grids. The new proposed optics has also the advantage to simplify the design of the new dipoles. Here we study this new optics and the issues related to the emittance measurement at the new higher energy. | ||
MOPAB04 | An Overview of the Preparation and Characteristics of the ISIS Stripping Foil | 29 |
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The ISIS facility at the Rutherford Appleton Laboratory is a pulsed neutron and muon source, for materials and life science research. H− ions are injected into an 800 MeV, 50 Hz rapid cycling synchrotron from a 70 MeV linear accelerator, over ~130 turns by charge exchange injection. Up to 3·1013 protons per pulse can be accelerated, with the beam current of 240 μA split between the two spallation neutron targets. The 40 × 120 mm aluminium oxide stripping foils used for injection are manufactured on-site. This paper gives an overview of the preparation and characteristics of the ISIS foils, including measurements of foil thickness and elemental composition. Consideration is also given to the beam footprint on the foil and how this could be optimised. | ||
TUO1AB01 | High Gradient RF System for Upgrade of J-PARC | 162 |
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Magnetic alloy cavities are successfully used for J-PARC synchrotrons. These cavities generate much higher RF voltage than ordinary ferrite-loaded cavities. The MR (Main Ring) upgrade project aims to deliver the beam power of 750 kW to the neutrino experiment. It includes replacements of all RF cavities for high repetition rate of about 1 Hz. By the replacements, the total acceleration voltage will be doubled, while power supplies and amplifiers remain the same. The key issue is the development of a high gradient RF system using high impedance magnetic alloy, FT3L. A dedicated production system for the FT3L cores with 80 cm diameter was assembled in the J-PARC and demonstrated that we can produce material with two times higher muQf product compared to the cores used for present cavities. The first 5-cell FT3L cavity was assembled and the status of high power test is reported. | ||
TUO1AB02 | Upgrades of the RF Systems in the LHC Injector Complex | 165 |
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In the framework of the LHC Injector Upgrade (LIU) project the radio-frequency (RF) systems of the synchrotrons in the LHC injector chain will undergo significant improvements to reach the high beam intensity and quality required by the High-Luminosity (HL) LHC. Following the recent upgrade of the longitudinal beam control system in the PS Booster (PSB), tests with Finemet cavities are being performed in view of a complete replacement of the existing RF systems in the PSB by ones based on this technology. In the PS a similar wide-band Finemet cavity has been installed as a longitudinal damper. New 1-turn delay feedbacks on the main accelerating cavities to reduce their impedance have also been commissioned. Additional feedback and beam control improvements are foreseen. A major upgrade of the main RF system in the SPS by regrouping sections of its travelling wave cavities, increasing the number of cavities from four to six, will reduce beam-loading and allow higher intensities to be accelerated. The upgrade includes the installation of two new RF power plants and new feedback systems. All upgrades will be evaluated with respect to their expected benefits for the beams to the LHC. | ||
Slides TUO1AB02 [4.317 MB] | ||
TUO1AB03 |
Enhancements of the Fermilab Booster to Reduce Losses and Extend Lifetime: The Proton Improvement Plan | |
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The Proton Improvement Plan is a campaign of upgrades, improvements, and replacements of equipment in the Fermilab Proton Source to enable operation of the machines at higher throughput for an extended period. The Fermilab Proton Source is principally composed of a 400 MeV linac and Booster synchrotron. This talk will concentrate on a number of improvements in injection, extraction, and the RF systems. The notching system in the Booster has been rebuilt with shorter kickers and a dedicated absorber within the ring. The cogging system is also being changed to a system using fast magnetic feedback, replacing the previous system which used radial RF feedback. A laser-based H− neutralization system will be implemented in the linac's MEBT, largely eliminating the loss from notching. The Booster RF system is undergoing a comprehensive overhaul. The amplifier stages have all been replaced with a mostly solid-state system. The cavities are being comprehensively refurbished. Harmonic cavities will be added. The RF power systems of the drift tube linac are also under study, with possible implementation of a 200 MHz klystron, and likely implementation of a modern modulator. | ||
Slides TUO1AB03 [7.757 MB] | ||
TUO1AB04 | Current Status on ESS Medium Energy Beam Transport | 170 |
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The European Spallation Source, ESS, uses a high power linear accelerator for producing intense beams of neutrons. During last year the ESS linac cost was reevaluated, as a consequence important modifications were introduced to the linac design that affected Medium Energy Beam Transport (MEBT) section. RFQ output beam energy increased from 3 MeV to 3.62 MeV, and beam current under nominal conditions was increased from 50 to 62.5mA. The considered MEBT is being designed primarily to match the RFQ output beam characteristics to the DTL input both transversally and longitudinally. For this purpose a set of eleven quadrupoles is used to match the beam characteristics transversally, combined with three 352.2 MHz CCL type buncher cavities, which are used to adjust the beam in order to fulfill the required longitudinal parameters. Finally, thermo-mechanical calculations for adjustable halo scraping blades, with significant impact on the HEBT, will be discussed. | ||
Slides TUO1AB04 [5.290 MB] | ||
WEO3AB02 | Status of Preparations for a 10 us H− Laser-Assisted Stripping Experiment | 299 |
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At the Spallation Neutron Source accelerator preparations are underway for a 10 us laser-assisted H− stripping experiment. This is a three orders of magnitude increase in pulse duration compared the to initial 2006 proof of principle experiment. The focus of the experiment is the validation of methods that reduce the average laser power requirement, including laser-ion beam temporal matching, ion beam dispersion tailoring, and specialized longitudinal and transverse optics. In this presentation we report on the status of preparations and the anticipated schedule for the experiment. | ||
Slides WEO3AB02 [7.250 MB] | ||
WEO3AB03 |
The Design and Construction Status of Injection and Extraction System for CSNS/RCS | |
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The China Spallation Neutron Source (CSNS) accelerator consists of an 80MeV H− linac and a 1.6GeV proton Rapid Cycling Synchrotron(RCS), and it provides 100 kW beam to neutron target. The injection and extraction systems play an important role in the RCS. The H− stripping painting and single turn extraction are adopted in the RCS. Now the hardware of the injection and extraction systems are being fabricated and tested. The design of the injection system and extraction system of the RCS are introduced, including some simulation study and optimization. The construction status of hardware is also described, including the test results of hardware of the injection and extraction systems. | ||
Slides WEO3AB03 [5.085 MB] | ||
WEO4AB01 | Radio Frequency Quadrupole for Landau Damping in Accelerators. Analytical and numerical studies. | 315 |
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It is proposed to use a radio frequency quadrupole (RFQ) to introduce a longitudinal spread of the betatron frequency for Landau damping of transverse beam instabilities in circular accelerators. The existing theory of stability diagrams for Landau damping is applied to the case of an RFQ. As an example, the required quadrupolar strength is calculated for stabilizing the Large Hadron Collider (LHC) beams at 7 TeV. It is shown that this strength can be provided by a superconducting RF device which is only a few meters long. Furthermore, the stabilizing effect of such a device is proven numerically by means of the PyHEADTAIL macroparticle tracking code for the case of a slow head-tail instability observed in the LHC at 3.5 TeV. | ||
Slides WEO4AB01 [1.991 MB] | ||
WEO4AB02 | New PSB H− Injection and 2 GeV Transfer to the CERN PS | 320 |
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At CERN Linac4 is being commissioned as first step in the LHC injector upgrade to provide 160 MeV H− ions. In order to fully deploy its potential, the PSB conventional multiturn injection will be replaced by a charge exchange injection. An expected brightness improvement of about a factor 2 would then be difficult to digest at PS injection due to space charge. Therefore the transfer energy between PSB and PS will be increased at the same time from 1.4 to 2 GeV. This paper describes the new PSB injection system and the status of its test stand. Modifications of the PSB extraction and recombination septa and kickers in the transfer line are shown. A new focussing structure for the transfer lines to match the horizontal dispersion at PS injection and the design of a new eddy current septum for the PS injection are presented. | ||
Slides WEO4AB02 [2.867 MB] | ||
WEO4AB03 |
Study on the Beam Distribution and Painting Range during the Injection Process for CSNS/RCS | |
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Funding: Work supported by National Natural Science Foundation of China (11205185, 11175020, 11175193) In this paper, firstly, we studied the beam distribution during the injection process for the Rapid Cycling Synchrotron of the China Spallation Neutron Source (CSNS/RCS). The injection processes with and without the space charge were both simulated by the code ORBIT, and the beam distribution of each turn can be obtained. Then, the particle motion during the injection process can be studied and the beam aperture which was required can be obtained. Secondly, the injection processes for different transverse phase space painting ranges were discussed and simulated. Then, the optimized painting range for CSNS/RCS can be obtained. |
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Slides WEO4AB03 [0.977 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. | ||
Slides THO3AB03 [2.225 MB] | ||
THO3AB04 | Modeling and Feedback Design Techniques for Controlling Intra-bunch Instabilities at CERN SPS Ring | 399 |
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Funding: Work supported by the U.S. Department of Energy under contract # DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP). The feedback control of intra-bunch instabilities driven by electron-clouds or strong head-tail coupling (transverse mode coupled instabilities TMCI) requires bandwidth sufficient to sense the vertical position and apply multiple corrections within a nanosecond-scale bunch. These requirements impose challenges and limits in the design and implementation of the feedback system. This paper presents model-based design techniques for feedback systems to address the stabilization of the transverse bunch dynamics. These techniques include in the design the effect of noise and signals perturbing the bunch motion. They also include realistic limitations such as bandwidth, nonlinearities in the hardware and maximum power deliverable. Robustness of the system is evaluated as a function of parameter variations of the bunch. |
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Slides THO3AB04 [2.153 MB] | ||