EPAC 2006 - Classification:04 Hadron Accelerators/T12 Beam Injection/Extraction and Transport

04 Hadron Accelerators

T12 Beam Injection/Extraction and Transport

Paper	Title	Page
TUZBPA02	Crystal Channelling in Accelerators	945
	V.M. Biryukov IHEP Protvino, Protvino, Moscow Region
	This presentation will begin with a description of the channelling of charged particles through crystals and the use of the channelling effect in accelerators etc. Results from use of crystals for beam deflection and extraction from synchrotrons in Russia, USA and CERN will also be given. Following this the potential advantage of crystals for collimation in high-energy high-intensity machines will be described.
	Transparencies
TUPLS104	Matching of High Intensity Ion Beams to an RFQ: Comparison of PARMTEQ and IGUN Simulations	1741
	R. Becker, R.A. Jameson IAP, Frankfurt-am-Main
	The classical way of matching an ion source to the low energy accelerator RFQ generally is performed by adjusting the matching optics of the LEBT to provide the rms ellipse twiss parameter requirements of the RFQ shaper section. By matching to the rms parameters (the equivalent rms beam method) the actual shape of the distribution plays a smaller role according to F. Sacherer. In many cases, however, the matching optics are creating not only aberrations to the ion beam but also a very non-elliptical shape of the emittance figure, and a more exact match may be required. As a way out, an ion extraction program (IGUN) has been modified to also take into account the rf-focusing of non-modulated RFQ vanes in the shaper section. This makes it feasible to use this program for the simulation from the ion source plasma until the beginning of modulation inside the RFQ, and it can also handle dc fields in the injection region of the RFQ. In order to demonstrate the differences of both approaches we apply them to well defined experimentally proved designs of RFQ shaper sections.
TUPLS105	Sputter Probes and Vapor Sources for ECR Ion Sources	1744
	M. Cavenago, A. Galatà, M. Sattin INFN/LNL, Legnaro, Padova T. Kulevoy, S. Petrenko ITEP, Moscow
	Sputter probes are a promising method for injecting controlled quantities of metallic elements inside ECRIS ion source, provided that sputter rate can be controlled, so that high charge states and low sample consumption rate will be attained. Moreover pressure at the probe and inside source should be different. With a simple differential pumping scheme and a sputter probe at 25 mm from ECRIS plasma, a 200 nA current of 120Sn¹⁸⁺ was easily obtained. Typical results (for Sn and Ti) of an inductively heated rf oven are discussed for comparison. Improvements of sputter probe concept and geometry are also described.
TUPLS106	Pulsed Bending Magnet of the J-PARC MR	1747
	K. Koseki, H. Kobayashi, H. Nakayama, K.O. Okamura, M.J. Shirakata, M. Tawada KEK, Ibaraki
	Japan Proton Accelerator Research Complex (J-PARC) is under construction with a collaboration between Japan Atomic Energy Agency (JAEA) and High Energy Accelerator Research Organization (KEK). The J-PARC consists of a 180 MeV linac, a 3 GeV rapid-cycle synchrotron (RCS) and a 50 GeV synchrotron (MR). The bunch trains, which extracted from the RCS, is delivered both to the “Materials and Life Science Facility” and to the MR, two beam transport lines, 3-NBT and 3-50BT, are constructed. The switching of bunch trains is performed by a pulsed bending magnet. The field strength of 1.21 Tesla with rise and fall time of less than 40 msec is required. It was found that an effect induced by eddy current, which flows at thick end-plates, disturbs the flatness of the magnetic field. A simple compensation circuit has been adopted for a cure. A result from a field measurement, which shows a sufficient flatness, is presented.
TUPLS107	Operation of the Opposite-Field Septum Magnet for the J-PARC Main-Ring Injection	1750
	I. Sakai, Y. Arakaki, K. Fan, Y. Saito, M. Tomizawa, M. Uota KEK, Ibaraki A.K. Kawasaki, H. Mori, A. Tokuchi NICHICON, Shiga Y. Morigaki, A. Nishikawa IHI/Yokohama, Kanagawa
	The opposite field septum magnet system has been applied to the injection system of the J-PARC 50-GeV proton synchrotron. The features of the system are a force-free structure, easy pulse excitation and the possibility of a large-aperture, thin-septum structure. The septum magnet has the structure of an inside-vacuum to eliminate the thickness of the vacuum-chamber walls and electric-insulation layer to make the septum thickness as thin as possible. However the magnet cores and return coils are outside of the vacuum to reduce the out-gassing rate of the vacuum system. Finally, the larger beam aperture than the full acceptance of the ring and larger separation angle can be obtained at the septum magnet for low-loss injection. In this paper we will introduce the methods to eliminate the error fields caused by fabrication errors and eddy current with pulse excitation and stability of high current power supply of 50 kA.
TUPLS108	Realization of Thick Hybrid Type Carbon Stripper Foils with High Durability at 1800K for RCS of J-PARC	1753
	I. Sugai, K. Hara, H. Kawakami, M. Oyaizu, A. Takagi, Y. Takeda KEK, Ibaraki T. Hattori, K.K. Kawasaki RLNR, Tokyo Y. Irie, J. Kamiya, M. Kinsho JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
	The J-PARC requires thick carbon stripper foils (250-500 ug/cm²) to strip electrons from the H-beam supplied by the linac before injection into a 3 GeV Rapid Cycling Synchrotron. The 200 MeV H^- beam from the linac has a pulse length of 0.5 ms with a repetition rate of 25 Hz and an average beam current of 335 uA. By much energy deposition of these high-intensity H^- and circulating bunched beams, commercially available best stripper foils (CM) will break in a very short time and even a diamond foil will rupture at around 1800K by MW class accelerators. We have realized for first time the hybrid boron doped carbon stripper foils with long life time for J-PARC. The foils of 250-500 ug/cm² were made by a controlled DC arc-discharge method. The lifetime was tested by using 3.2 MeV Ne⁺ DC beam of 2.5 uA and 750 keV H^- DC beam of 500 uA, in which a significant amount of energy was deposited in the foils. The maximum lifetime was extremely long, 120- and 480-times than those of diamond and CM foils. The foils were also free from any shrinkage, and showed low thickness reduction rate even at high temperature of 1800K during long time irradiation of 90h.
TUPLS109	Present Status of the L3BT for J-PARC	1756
	T. Ohkawa JAEA, Ibaraki-ken M. Ikegami KEK, Ibaraki J. Qiang LBNL, Berkeley, California
	L3BT is a beam transport line from J-PARC (Japan Proton Accelerator Research Complex) linac to the succeeding 3-GeV RCS (Rapid Cycling Synchrotron). The construction of the L3BT has been almost finished. The beam commissioning of the L3BT will be started soon. On the other hand we have performed 3D particle simulations with PARMILA and IMPACT to evaluate the performance of the halo scraping, momentum compaction and beam diagnostics. In this paper, results of the beam simulation of the L3BT are presented. The construction status of the L3BT is also presented in brief.
TUPLS110	Measurement of the Extraction Kicker System in J-PARC RCS	1759
	J. Kamiya, M. Kinsho, M. Kuramochi, T. Takayanagi, O. Takeda, T. Ueno, M. Watanabe, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
	Kicker magnet system in the J-PARC RCS is now under construction at JAEA (Japan Atomic Energy Agency). Their role in RCS is to kick the accelerated 3 GeV proton beam to the following extraction line at a repetition rate of 25 Hz. There are three kinds of kicker magnets (S, M, L), distinguished by the difference in the size of their apertures. The specification of 2 % is required on the magnetic field in terms of homogeneity in time and space from the beam optical point of view. The required flatness of the temporal uniformity was accomplished by superposing the waveforms of the two kicker magnet. The required specification to the special uniformity is also very severe to achieve because our kicker magnet is designed with a large aperture in order to accept a maximum beam power of 1 MW. We established the search coil as a detector and 3-axes stage to perform magnetic field mapping. In order to reduce the signal noises and detect the stable output signals, matching register and integrated circuit were carefully selected. The 3-axes stage was precisely aligned. The distribution of the magnetic field (By) and integrated BL were systematically measured for the three types of kickers. J. Kamiya et al. “Magnetic field measurement of the extraction kicker magnet in J-PARC RCS,” submitted for publication to the proceedings of the 19th International Conference on Magnet Technology.
TUPLS111	Experimental Results of the Shift Bump Magnet in the J-PARC 3-GeV RCS	1762
	T. Takayanagi, Y. Irie, J. Kamiya, M. Kinsho, M. Kuramochi, O. Takeda, T. Ueno, M. Watanabe, Y. Yamazaki, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
	The shift bump magnet produces a fixed main bump orbit to merge the injection beam into the circulating beam. In order to control the injection beam for the short injection time (500 microseconds) with sufficient accuracy, the shift bump magnet needs a wide uniform magnetic field and the high speed exciting pattern of the high current. The magnetic field design and the structural analysis of the shift bump magnets have been performed using three-dimensional electromagnetic analysis code and mechanical analysis code, respectively. The magnetic field distributions were measured with a long search coil, thus giving a BL product over a magnet gap area. The temperature distributions at the various points of the magnet were measured by thermocouples over 24 hours till they saturated. General trend of these measurements agrees well with calculations.
TUPLS112	Present Status of Injection and Extraction System of 3 GeV RCS at J-PARC	1765
	M. Yoshimoto, Y. Irie, J. Kamiya, M. Kinsho, F. Noda, P.K. Saha, T. Takayanagi, O. Takeda, M. Watanabe JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
	The injection and extraction system for 3GeV RCS (Rapid Cycling Synchrotron) at J-PARC (Japan Proton Accelerator Research Complex) have many challenging issues, in order to realize MW beam in the RCS ring. The system is consisted in 3 parts, such as the injection line, the dump line, and the extraction line. And they are constructed from many kinds of components, such as DC and pulse magnets, a charge exchange system, beam monitors, titanium and ceramic vacuum chamber, a beam dump, and so on. Up to now, final designs are accomplished and developments and experiments of some components are carried out. In this presentation, summary of the injection and extraction system, recent status of developments, and beam commissioning scheme for beam injection and extraction are introduced.
TUPLS113	Designs of Septum Magnet at 3 GeV RCS in J-PARC	1768
	M. Yoshimoto, Y. Irie, J. Kamiya, M. Kinsho, T. Takayanagi, O. Takeda, M. Watanabe JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken H. Fujimori, S. Igarashi, H. Nakayama KEK, Ibaraki
	3 GeV RCS (Rapid Cycling Synchrotron) at J-PARC (Japan Proton Accelerator Research Complex) consists in many kinds of septum magnets. There are two septum magnets to inject the beam into the ring, three septum magnets to extract the beam for the users, and two septum magnets to dump the beam which can not be exchanged its charge at the first foil. In order to reduce the magnetic leakage field from the septum magnets at the beam orbit in the ring, the silicon steel sheets are set at the outside of the septum magnets for the magnetic shields. However sufficient spaces to set the thick magnetic shields are not securable at the divergent duct areas. Therefore the vacuum chambers are made by the magnetic stainless steel and the leakage fields in the chambers can be reduced. As results of the 3D field calculations by TOSCA, the magnetic leakage field can be suppressed to a few Gauss or less.
TUPLS114	An Improvement of Matching Circuit of RF Kicker Electrodes	1771
	T. Kurita, S. Fukumoto, S.H. Hatori WERC, Tsuruga , Fukui S. Ninomiya KEK, Ibaraki
	Beam extraction system at accelerator of The Wakasa Wan Energy Research Center employs RF knockout technology. Narrow band RF noise is applied to the transverse kicker electrodes to increase betatron amplitude of the beam. Recently some improvements of the beam extraction system are introduced: To improve the shape of the spill, a feedback control of noise amplitude is introduced. The feedback control system works as an attenuator, therefore it is necessary to enhance the noise amplitude of the kicker electrodes to obtain agreeable effect on the spill shape. In order to obtain a higher voltage, we revamp the matching circuit at the electrodes. By introducing the resonating characteristic at the matching circuit, we obtained 3 times more amplitude at the electrodes. General shape of the spill is improved by this work, and extraction efficiency at a real operating condition is also improved.
TUPLS115	Transverse Phase Space Painting for the CSNS Injection	1774
	J. Qiu, J. Tang, S. Wang IHEP Beijing, Beijing J. Wei BNL, Upton, Long Island, New York
	The CSNS accelerators consist of an 80 MeV proton Linac, and a 1.6 GeV rapid cycling synchrotron (RCS). The ring accumulates 1.88*1013 protons via H－stripping injection in the phase CSNS-I. The injected beam is painted into the large transverse phase space to alleviate space-charge effects. The uniformity of beam emittance is important in reducing the tune shift/spread due to space charge effect. The paper introduces two parameters to evaluate the uniformity of a distribution. To satisfy the low-loss design criteria, extensive comparison of different painting scenarios has been carried out by using the simulation code ORBIT. This paper gives detailed studies on painting schemes and the dependence on the lattice tune, the injection peak current, and also chopping rate.
TUPLS116	Extraction System Design for the CSNS/RCS	1777
	J. Tang, Y. Chen, Y.L. Chi, Y.L. Jiang, W. Kang, J.B. Pang, Q. Qin, S. Wang, W. Wang IHEP Beijing, Beijing J. Wei BNL, Upton, Long Island, New York
	The CSNS extraction system takes use one of the four dispersion-free straight sections. Five vertical kickers and one Lambertson septum magnet are used for the one-turn extraction. The rise time of less 250 ns and the total kicking angle of 20 mrad are required for the kickers that are grouped into two tanks. The design for the kicker magnets and the PFN is also given. To reduce the low beam loss in the extraction channels due to large halo emittance, large apertures are used for both the kickers and septum. Stray magnetic field inside and at the two ends of the circulating path of the Lambertson magnet and its effect to the beam has been studied.
TUPLS117	Beam Transport Lines for the CSNS	1780
	J. Tang, G.H. Wei, C. Zhang IHEP Beijing, Beijing J. Wei BNL, Upton, Long Island, New York
	This paper presents the design of two beam transport lines at the CSNS: one is the injection line from the linac to the RCS and the other is the target line from the RCS to the target station. In the injection beam line, space charge effects, transverse halo collimation, momentum tail collimation and debunching are the main concerned topics. A new method of using triplet cells and stripping foils is used to collimate transverse halo. A long straight section is reserved for the future upgrading linac and debuncher. In the target beam line, large halo emittance, beam stability at the target due to kicker failures and beam jitters, shielding of back-scattering neutrons from the target are main concerned topics. Special bi-gap magnets will be used to reduce beam losses in the collimators in front of the target.
TUPLS118	Injection System Design for the CSNS/RCS	1783
	J. Tang, Y. Chen, Y.L. Chi, Y.L. Jiang, W. Kang, J.B. Pang, Q. Qin, J. Qiu, L. Shen, S. Wang IHEP Beijing, Beijing J. Wei BNL, Upton, Long Island, New York
	The CSNS injection system is designed to take one uninterrupted long drift in one of the four dispersion-free straight sections to host all the injection devices. Painting bumper magnets are used for both horizontal and vertical phase space painting. Closed-orbit bumper magnets are used for facilitating the installation of the injection septa and decreasing proton traversal in the stripping foil. Even with large beam emittance of about 300 pmm.mrad used, BSNS/RCS still approaches the space charge limit during the injection/trapping phase for the accumulated particles of 1.9*10¹³ and at the low injection energy of 80 MeV. Uniform-like beam distribution by well-designed painting scheme is then obtained to decrease the tune shift/spread. ORBIT code is used for the 3D simulations. Upgrading to higher injection energy has also been considered.
TUPLS119	Design Study of the Axial Injection System of C400 Cyclotron	1786
	V. Shevtsov, V. Aleksandrov, Yu. Kazarinov JINR, Dubna, Moscow Region Y. Jongen, D. Vandeplassche IBA, Louvain-la-Neuve
	Computer modeling results on the axial injection system design are given. Results of simulations of the Carbon, Hydrogen and Helium ion beam injection are presented.
TUPLS122	Implementation of the Proposed Multiturn Extraction at the CERN Proton Synchrotron	1789
	M. Giovannozzi CERN, Geneva
	Following the positive results of the three-year measurement campaign at the CERN Proton Synchrotron concerning beam splitting with stable islands in the transverse phase space, the study of a possible implementation of the proposed multi-turn extraction was undertaken. The novel approach would allow a substantial reduction of beam losses, with respect to the present scheme, when delivering the high-intensity proton beams required for the planned CERN Neutrino to Gran Sasso Project. Major modifications to the ring layout are foreseen, such as a new design of the extraction bumps including also the installation of three additional kickers to create a closed-bump over the five turns used to extract the split beam. The ring aperture was reviewed and improvements are proposed to reduce possible beam losses between beam splitting and extraction. The goal consists of implementing the proposed changes by the end of the 2007/2008 PS shutdown and to commission the novel extraction during the 2008 physics run.
TUPLS123	Design of the LHC Beam Dump Entrance Window	1792
	R. Veness, B. Goddard, S.J. Mathot, A. Presland CERN, Geneva L. Massidda CRS4, PULA
	7 TeV proton beams from the LHC are ejected through a 600 m long beam dump transfer line vacuum chamber to a beam dump block. The dump block is contained within an inert gas-filled vessel to prevent a possible fire risk. The dump vessel and transfer line are separated by a 600 mm diameter window, which must withstand both the static pressure load and thermal shock from the passage of the LHC beam. In a previous paper* the functional requirements and conceptual design of this window were outlined. This paper describes the analysis leading to the final design of the window. The choice of materials is explained and tests performed on the prototype window are summarized. *A. Presland et al. "A large diameter entrance window for the LHC beam dump line". Proc. PAC 2005, 1698-1700.
TUPLS125	Spin Transport from AGS to RHIC with Two Partial Snakes in AGS	1795
	W.W. MacKay, A.U. Luccio, N. Tsoupas BNL, Upton, Long Island, New York J. Takano RIKEN, Saitama
	The stable spin direction in the RHIC rings is vertical. With one or two strong helical Siberian snakes in the AGS, the stable spin direction at extraction is not vertical. Interleaved vertical and horizontal bends in the transport line between AGS and the RHIC rings also tend to tip the spin away from the vertical. In order to preserve polarization in RHIC, we examine several options to improve the matching of the stable spin direction during beam transfer from the AGS to each of the RHIC rings. While the matching is not perfect, the most economical method appears to be a lowering of the injection energy by one unit of G*gamma to 45.5.