• K. Fan, K. Ishii, H. Matsumoto, N. Matsumoto
  KEK, Ibaraki

Injection into the J-PARC main ring is implemented by 4 kickers and 2 pulsed septa at 3 GeV in a long straight section. To accommodate the injection beam of 54 pmm.mrad, both septa have large physical acceptance of 81 pmm.mrad. However, large aperture leads to large end fringe field interfereing the circulating beam and causing beam loss, which has been observed even at low beam intensity during the beam commissioning. To provide users a proton beam with high beam power, the injection beam intensity will increase greatly in future, which creates difficulties for the present injection system. To accommodate these high intensity beams with low beam loss, the injection system needs to be upgraded. Taking account the strong space charge effects, even larger physical is needed to reduce the localized beam loss, which creates severer end fringe leakage field. This paper will discuss the problems encountered in operating the present septa, and give an optimized design for the new septa.

• K. Fan, K. Ishii, H. Matsumoto, N. Matsumoto
  KEK, Ibaraki

The J-PARC is a high intensity proton accelerator complex, which consists of a LINAC, a Rapid Cycling Synchrotron (RCS) and a Main Ring (MR). The MR injection system employs a high-field septum to deflect the incoming beam from the RCS, which has been used for the beam commissioning study with low beam intensity successfully. Relative large beam losses in the injection area have been observed, which is proportional to the injection beam intensity. In future, the beam intensity will increase about 100 times to realize high beam power (~MW) operation required from neutrino experiments. The beam loss at the injection region is expected increase greatly due to the space charge effects, which creates severe radiation problems. Since the present injection septum coil is organic insulated, which will be destroyed under such a severe irradiation quickly. To cope with this problem, a new high radiation resistant injection septum magnet is developed, which uses inorganic insulation material (Mineral Insulated Cable - MIC) to prevent the septum from radiation damage. This paper investigates different effects caused by the MIC and gives an optimization design.

• T. Yokoi, K.J. Peach, H. Witte
  JAI, Oxford

PAMELA (Particle Accelerator for MEdicaL Application) aims to design a particle therapy facility using Non-scaling FFAG (Fixed Field Alternating Gradient) accelerator. In the beam extraction in PAMELA, the biggest challenge is the flexible energy variability, which is desirable for better dose field formation. The feature is a unique feature of PAMELA for a fixed field accelerator. To realize energy variable beam extraction, PAMELA employs vertical extraction using large a aperture kicker magnet. In the paper, the detail of the extraction scheme, hardware specifications are discussed.

• T. Adachi, T. Kawakubo
  KEK, Ibaraki
• T. Yoshii
  Nagaoka University of Technology, Nagaoka, Niigata

New acceleration system using an induction cell has been developed at KEK by using KEK 12-GeV PS*. We call an accelerator using the induction acceleration system "Digital Accelerator". The PS-Booster is now being renovated as the first Digital Accelerator (DA) by introducing the induction acceleration instead of rf**. Argon ion beam from the ECR ion source is injected to the DA by an electrostatic beam kicker. Another electrostatic device with the same structure is used for chopping the beam before injection. The accelerated beam is extracted by the existing extraction system, which comprises bump, septum and kicker magnets. Since these magnets are installed in a vacuum chamber, vacuum pressure deteriorates due to outgas from them. In order to reduce a beam loss in the DA ring, the pressure level is crucial especially for an ion beam. Therefore, we decided to put the septum magnet outside the vacuum chamber and insert a vacuum duct in the gap, since it dominantly contributes to the vacuum pressure more than the other magnets. This paper describes the electrostatic beam chopper, injection kicker and septum magnet containing the vacuum duct for the KEK DA and beam dynamics.

*K. Takayama, Phys. Rev. Lett. 98, 054801 (2007)
**K. Takayama, "KEK Digital Accelerator for Material and Biological Sciences", T. Iwashita, "Induction Acceleration System", in this conference

• G.A. Karamysheva, A.I. Papash
  JINR, Dubna, Moscow Region
• C.P. Welsch
  Cockcroft Institute, Warrington, Cheshire

The Ultra-Low energy Storage Ring (USR) within the future Facility for Low-energy Antiproton and Ion Research (FLAIR) will decelerate antiproton beams from 300 keV to energies of only 20 keV. Cooled beams will then be extracted and provided to external experiments. The large variety of planned experiments requires a highly flexible longitudinal time structure of the extracted bunches, ranging from ultra-short pulses in the nanosecond regime to quasi DC beams. This requires fast as well as slow extraction in order to cover whole range of envisaged beam parameters. A particular challenge was to combine elements for fast and slow extraction in one straight section of this electrostatic ring. In this contribution we present the results of beam dynamic simulations and describe the overall extraction scheme in detail.

• K. Satou, T. Toyama
  J-PARC, KEK & JAEA, Ibaraki-ken
• H. Harada, K. Yamamoto
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken

A single-wire proportional counter which has the maximum gain of 6·10⁴ is used as a beam loss monitor (p-BLM), thus low-level beam loss can be monitored. However, it involves gain reduction problem by the space charge effect. It is essential to estimate the space charge effect to utilize a proportional counter for beam loss monitoring. The calibration procedure is discussed for the p-BLMs for 3-50BT and MR. Measurements of residual dose were made and some nuclei were identified. Radiation from the short-life nucleus, Fe53 (T1/2=8.51m), may be a good index to predict a residual dose after a long term beam operation.

• P.C. Chiu, J. Chen, Y.K. Chen, Y.-S. Cheng, K.T. Hsu, K.H. Hu, C.H. Kuo
  NSRRC, Hsinchu

To keep and achieve desired performance of a modern synchrotron light source, it requires continuous efforts including good design of the accelerator, good performed subsystems and sophisticated feedback system. While some wonders happen unexpectedly and could deteriorate performance of the light source. For examples, some strong source occasionally occurred especially after long shut down or malfunction of some corrector power supply and it would result in increased noise level. Non ideal injection element will cause large perturbation as well. This report presents algorithms to spatially locate source and summarize some of our practical experience to identify the source.

• B. Goddard, W. Bartmann, C. Bracco, V. Kain, M. Meddahi, V. Mertens, J.A. Uythoven
  CERN, Geneva

The commissioning of the beam transfer systems for LHC included detailed aperture measurements in the injection regions and for the beam dump systems. The measurements, mainly single pass, were made using systematic scans of different oscillation phases and amplitudes, and the results compared with the expectations from the physical aperture model of the LHC. In this paper the measurements and results are presented and compared with the specified apertures in these critical areas.

• O. Dressler, M.V. Hartrott
  Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Elektronen-Speicherring BESSY II, Berlin
• N. Hauge
  Danfysik A/S, Jyllinge

The pre-accelerator microtron supplies an electron beam at 10⁵ MeV for the Metrology Light Source (MLS) of the Physikalisch-Technische Bundesanstalt (PTB) in Berlin. The beam is delivered via the transfer line to the injection septum and then into the storage ring. This septum magnet has its stainless steel vacuum beam pipe placed inside a laminated silicon iron magnet core. Hence, the pulsed magnetic field (half sine) used for the beam deflection must propagate through the thin metallic beam pipe. During the commissioning of the injection process, it became apparent that the calculated nominal pulse current for this energy and geometry had to be increased by 30 % to achieve proper beam transfer and accumulation. Two problems were apparent. Firstly, the injected beam trajectory had to be set at an angle away from the main beam axis. Secondly, the beam transfer from the septum entrance to exit was disturbed. As a first measure, the septum current pulse length was extended from 35 to 10⁷ μs. Further on, the septum magnet was insulated from the transfer line beam pipe by a ceramic brake. This paper reports on measurements of pulsed magnetic fields inside the septum magnet.

* Commissioning and Operation of the Metrology Light Source, J. Feikes et al., BESSY, Berlin, Germany; R. Klein, G. Ulm, Physikalisch-Technische Bundesanstalt, Berlin, Germany; EPAC08, Genoa, Italy.

• M. Gu, Z.H. Chen, B. Liu, L. Ouyang, R. Wang, Y. Wu, Q. Yuan
  SINAP, Shanghai

The injection system composed of four kickers and two septa in the SSRF have been built and operated. The commissioning shows that fine injecting efficiency and smaller disturbance are carried out. The septum magnets are eddy current designs with a sheet of magnetic screening material around the stored electron beam to reduce the leakage field. The beam tube with RF finger flanges at each end is added to keep the continuity of impedance for the circulating beam. The pulser excite the septum with 60μsecond waveform of half sine-wave and 8kA peak current. Four identical kicker magnets provide the symmetric bump in 10 meter long straight sections. The excitation waveform is a 3.8μsecond half sine pulse up to 7 kA peak. The emphasis was on achieving the best possible tracking in time of the magnet field waveforms so that the residual closed orbit disturbance is minimized for top-up injection. The performance of the injection system with these pulsed magnets are described.

• J.C. Huang, C.-H. Chang, C.-S. Hwang, C.Y. Kuo, F.-Y. Lin, C.-S. Yang
  NSRRC, Hsinchu

Pulsed magnet system of Taiwan Photon source(TPS) requires a very low stray field to avoid parasitic magnetic field into the stored beam. The stray field from storage ring(SR) injection septum is required to be less than 0.2 Gauss. The most common method to protect parasitic magnetic field is to use high permeability and conductivity material, such as a Mu-metal. A 1.2 ms half-sine wave pulse of up to 8280A current peak are supply to a septum and would result in eddy current loss in magnet and conductor current diffusion during the rapid charging on magnet. Moreover, competition between eddy current loss and magnetic permeability would lead to a complex phenomena inside the mumetal shielding cabinet and shielding performance. In this study, the magnetic shielding performance of a shielding cabinet was examined in different shielding cabinet geometry and thickness. The results were calculated in Opera software and show that there is a significant suppression of SR septum stray field when round shielding cabinet is in use.

• R.P. Fliller, R. Heese, S. Kowalski, J. Rose, T.V. Shaftan, G.M. Wang
  BNL, Upton, Long Island, New York

The National Synchrotron Light Source II (NSLS-II) is a state of the art 3 GeV third generation light source currently under construction at Brookhaven National Laboratory. The NSLS-II injection system consists of a 200 MeV linac and a 3 GeV booster synchrotron. The injection system needs to deliver 7.5 nC in 80 - 150 bunches to the storage ring every minute to achieve current stability goals in the storage ring. This is a very stringent requirement that has not been demonstrated at an operating light source, though it should be achievable. To alleviate the charge requirement on the linac, we have designed a scheme to stack two bunch trains in the booster. In this paper we discuss this stacking scheme. The performance of the stacking scheme is studied in detail at injection and through a full booster ramp. We show the the ultimate performance of the stacking scheme is similar to a single bunch train in the booster if the linac emittance meets the requirements. Increasing the emittance of the linac beam degrades the performance, but still allows an overall increase of train charge vs. one bunch train.

• C.Y. Wu, J. Chen, Y.-S. Cheng, C.-S. Fann, K.T. Hsu, S.Y. Hsu, K.H. Hu, C.H. Kuo, D. Lee, K.-K. Lin
  NSRRC, Hsinchu
• K. Furukawa, J.-I. Odagiri
  KEK, Ibaraki

The EPICS embedded programmable logic controller (PLC) has been developed based on F3RP61-2L, a CPU module of a FA-M3R series PLC running Linux OS. The EPICS IOC resided in F3RP61-2L module can access the registers of sequence CPU modules and I/O modules of the PLC. The embedded EPICS PLC was applied to control the prototype of pulse magnet power supply and support functionality testing remotely. The system comprises various input/output modules and a CPU module with built-in Ethernet interface. The control information (status of the power supply, ON, OFF, warn up, reset, read/write voltage, etc.) can be accessed remotely using EPICS client tools. The EDM is selected to develop the GUI for itself. Efforts are summarized in this report.

• S.-C. Kim, K.R. Kim, S.H. Nam, C.D. Park, Y.G. Son, C.W. Sung
  PAL, Pohang, Kyungbuk

Lattice of the Storage Ring (SR) is changed from TDB to DBA, and beam energy is enhanced from 2.5 GeV to 3.0 GeV at the Pohang Light Source upgrade (PLS-II). Therefore all magnet specification and number have to change compare with exist PLS SR. At the PLS-II, Magnet Power Supplies (MPS) must be re-designed according to magnet specification of the PLS-II. Newly development MPSs are adopted switching type power conversion technology. High current unipolar MPSs are parallel operation type of unit module buck type power supply, and low current bipolar MPSs are H-bridge type. All MPSs are performed ± 10 ppm output current stability and adopted full digital controller. In this paper, we report on the development and characteristics of the MPS for PLS-II SR.

• L. Sermeus, M.J. Barnes, T. Fowler
  CERN, Geneva

A five-turn continuous extraction is currently used to transfer the proton beam from the CERN PS to the SPS. This extraction uses an electrostatic septum to cut the filament beam into five slices, causing losses of about 15 %. These losses would be an even greater drawback when the beam intensity is further increased for the CERN Neutrinos to Gran Sasso facility. To overcome this, a Multi-Turn Extraction (MTE) has been implemented, in which the beam is separated, prior to extraction, into a central beam core and four islands. Each beamlet is extracted using a set of kickers and a magnetic septum. For the kickers two new pulse generators have been built, each containing a lumped element Pulse Forming Network (PFN) of 12.5 Ohms, 80 kV and 10.5 μs. For cost reasons existing 15 Ω transmission line kicker magnets are reused. The PFN characteristic impedance deliberately mismatches that of the magnets to allow a higher maximum kick. The PFN design has been optimised such that undesirable side-effects of the impedance mismatch on kick rise-time and flat-top remain within acceptable limits. The kicker systems put in place for the current first phase of MTE are presented.

• J. Pasternak, M. Aslaninejad
  Imperial College of Science and Technology, Department of Physics, London
• J.S. Berg
  BNL, Upton, Long Island, New York
• D.J. Kelliher, S. Machida
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon
• J. Pasternak
  STFC/RAL, Chilton, Didcot, Oxon
• H. Witte
  JAI, Oxford

Nonscaling FFAG is required for the muon acceleration in the Neutrino Factory, which baseline design is under investigation in the International Design Study (IDS-NF). In order to inject/extract the muon beam with a very large emittance, several strong kickers with a very large aperture are required distributed in many lattice cells. Once the sufficient orbit separation is obtained by the kickers, the final degree of separation from the lattice is made by the septum, which needs to be superconducting. The geometry of the symmetric solutions allowing to inject/extract both signs of muons is presented. The preliminary design of the kicker and septum magnets is given.

• S. Sorge, O. Boine-Frankenheim, G. Franchetti
  GSI, Darmstadt
• A. Bolshakov
  ITEP, Moscow

The heavy ion synchrotron SIS-100 will play a key role within the future FAIR project underway at GSI. Although this synchrotron is optimized for fast extraction, also slow extraction will be used. Slow extraction is based on beam excitation due to a third order resonance. The spread in the particle momenta generating a tune spread causes particle loss leading to an irradiation of the machine especially in a high-current operation. A major part of the losses is assumed to occur at the electro-static separator. In the present study we apply a tracking method to model the extraction process to predict the losses, where, in a first step, high current effects are not taken into account.

• Y. Arakaki, S. Murasugi, R. Muto, K. Okamura, Y. Shirakabe, M. Tomizawa
  KEK, Ibaraki
• D. Horikawa, I. Sakai
  University of Fukui, Faculty of Engineering, Fukui
• M. Nishikawa
  Nippon Advanced Technology Co. Ltd., Ibaraki-prefecture

The two electrostatic septa are one of the most important device for the slow extraction in 50GeV proton synchrotron. We have developed the thin ribbon type septum in order to reduce the beam loss. If alignment of ribbons is poor, the effective thickness seen from the beam become large, and it would increase the beam-hitting rate. The alignment of ribbon over 1.5m long septa was measured by a laser-focus displacement meter. The achieved effective thickness of septa is estimated to be 0.075mm and 0.080mm respectively. We will report a high voltage conditioning and a performance under beam commissioning.

• G.H. Wei
  KEK/JAEA, Ibaraki-Ken
• A. Ando, Y. Hashimoto, T. Koseki, J. Takano
  J-PARC, KEK & JAEA, Ibaraki-ken
• S. Igarashi, K. Ishii, M. Tomizawa, M. Uota
  KEK, Ibaraki
• P.K. Saha, K. Satou, M.J. Shirakata
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken

The beam commissioning of J-PARC (Japan Proton Accelerator Research Complex) MR (Main Ring) was started from May 2008 and is in progress. As usual, injection tuning is in the first stage and strongly related to other tuning items. Starting with design schemes, making adjustment due to leakage field influence from injection septum, doing envelope matching considering dilution of beam profile in Main Ring are reported in this paper. The 'Without bump' scheme was got on June 15th 2008, while 'With bump' scheme on February 15th 2009. Beam orbit betatron oscillation to the MR close orbit which cause by injection error is less than 1 mm both in horizontal and vertical direction. Meanwhile, Beam Optics matching for 3 GeV beam from 350BT to MR has been well done too, which is also very important.

* T. Koseki, Challenges and Solutions for J-PARC Commissioning and Early Operation, in these proceedings

• G.H. Wei
  KEK/JAEA, Ibaraki-Ken
• A. Ando, T. Koseki, J. Takano
  J-PARC, KEK & JAEA, Ibaraki-ken
• K. Fan, S. Igarashi, K. Ishii, T. Nakadaira, M. Tomizawa, M. Uota
  KEK, Ibaraki
• H. Harada, P.K. Saha
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken

The beam commissioning of J-PARC/MR has been started from May 2008 and is in progress*. One key purpose of MR commissioning is the 30 GeV beam fast extraction to Neutrino beam line, which reflect the overall commissioning result. In the MR, the third straight section is assigned for the fast extraction. 5 kickers and 8 septa were installed there, which can give beam a bipolar kick to inside or outside of MR. Inside kick means beam to Neutrino Oscillation Experiment, while outside kick means beam dumped to abort line. However before commissioning, the measured magnetic field distribution of each septa shows non-linear profile along the horizontal direction. In order to find the influence, a simulation with these measured field has been performed. Depends on this study and some OPI (Operation Interface) made by code SAD for orbit modification online, fast extraction of 30 GeV beam to Neutrino line has been achieved on April 23rd 2009. Beam orbit have been tuned to less than 0.5 mm and 0.1 mrad in both horizontal and vertical at the beginning of Neutrino line, which is also the end of MR fast extraction. And so far, 100 kW continual operation to neutrino line have been achieved, too.

* T. Koseki, "Challenges and Solutions for J-PARC Commissioning and Early Operation", in these proceedings

• J. Borburgh, B. Balhan, M.J. Barnes, T. Fowler, M. Hourican, M. Palm, A. Prost, L. Sermeus, T. Stadlbauer
  CERN, Geneva
• F. Hinterschuster
  TU Vienna, Wien
• T. Kramer
  EBG MedAustron, Wr. Neustadt

The MedAustron facility, to be built in Wiener Neustadt (Austria), will provide protons and different types of ions for cancer therapy and research. Ten different types of bumpers, septa and kickers will be used in the low energy beam transfer line, the synchrotron and the high energy extraction lines. They are presently being designed in collaboration with CERN. Both 2D and 3D finite element simulations have been carried out to verify and optimize the field strength and homogeneity for each type of magnet and, where applicable, the transient field response. The detailed designs for the injection and dump bumpers, the magnetic septa and the fast chopper dipoles are presented. A novel design for the electrostatic septa is outlined.

• F. Méot
  CEA, Gif-sur-Yvette
• J.S. Berg
  BNL, Upton, Long Island, New York
• Y. Giboudot
  Brunel University, Middlesex
• D.J. Kelliher, S. Machida
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon
• B.J.A. Shepherd
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• S.C. Tygier
  UMAN, Manchester

The EMMA (Electron Model for Many Applications) FFAG experiment at Daresbury will involve on-line modeling (a ‘‘Virtual EMMA'') based on stepwise ray-tracing methods. Various aspects of the code of concern and of its interfacing to real world - machine and users - are addressed.

• B.D. Muratori, J.K. Jones, A. Kalinin, A.J. Moss, Y.M. Saveliev, R.J. Smith, S.L. Smith, S.I. Tzenov, A.E. Wheelhouse
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• G. Cox
  STFC/DL, Daresbury, Warrington, Cheshire
• D.J. Holder
  Cockcroft Institute, Warrington, Cheshire
• D.J. Kelliher, S. Machida
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon

The first results from commissioning EMMA - the Electron Model of Many Applications- are summarised in this paper. EMMA is a 10 to 20 MeV electron ring designed to test our understanding of beam dynamics in a relativistic linear non-scaling fixed field alternating gradient accelerator (FFAG). EMMA will be the world's first non-scaling FFAG and the paper will outline the characteristics of the beam injected in to the accelerator as well as summarising the results of the extensive EMMA systems commissioning. The paper will report on the results of simulations of this commissioning and on the progress made with beam commissioning.

• S.I. Tzenov, J.K. Jones, B.D. Muratori
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• Y. Giboudot
  Brunel University, Middlesex

Described in the paper are systematic procedures to inject and keep the beam on the reference trajectory for a fixed energy, as applied to the EMMA non scaling FFAG accelerator. The notion of accelerated orbits in FFAG accelerators has been introduced and some of their properties have been studies in detail.

• S.W. Jang, E.-S. Kim
  Kyungpook National University, Daegu

Proton Engineering Frontier Project (PEFP) Linac has a plan of the addition of 1 GeV RCS ring. The lattice of the rapid cycling synchrotron is affected by a non-linear beam dynamics. In this study, we investigated about non-linear dynamics due to sextupoles in PEFP RCS. Notably, we investigated about 3rd integer resonance due to sextupoles. To slowly and continuously extract the proton beam, we utilize the 3rd integer resonance. For the reason, we investigated non linear beam dynamics due to 3rd integer resonance and slow extraction system by using of MAD8.

• N. Golubeva, V. Balandin, W. Decking
  DESY, Hamburg

We consider a beam line, in which pure betatron oscillations are transversely uncoupled, but which has nonzero horizontal and vertical dispersions simultaneously. We show that transverse oscillations in such a beam line could be chromatically coupled if the horizontal dispersion is nonzero in the vertical bending magnets and vice versa. We also show that the ability of sextupoles to generate chromatic coupling terms depends on the relation between sextupole tilt angles and the direction of the dispersion vector at the sextupole locations. We discuss different approaches to the setup of sextupole tilt angles depending on chromatic aberrations taken for correction. As a practical application we consider the usage of tilted sextupoles in the design of the beam switchyard at the European XFEL Facility.

• A.Y. Molodozhentsev, T. Koseki, M. Tomizawa
  KEK, Ibaraki
• A. Ando
  J-PARC, KEK & JAEA, Ibaraki-ken

During the early J-PARC Main Ring commissioning the emittance growth at the injection energy, caused by the field leakage of the slow extraction septums, has been observed. By using the measured field data in the J-PARC Main Ring computational model we perform the analysis of the resonance excitation for the 'bare' working points around the 3rd order horizontal resonance, used for the slow extraction of the accelerated beam. The space charge effects of the low energy beam with the moderate beam power are taken into this analysis. Some possible ways to reduce the transverse emittance dilution and the particle losses during the machine operation for the 'hadron' experiments are discussed.