octupole

Paper	Title	Other Keywords	Page
MOPLT122	Dynamical Aperture Study for the NLC Main Damping Rings	wiggler, damping, dynamic-aperture, lattice	824
	M. Venturini, S. Marks, A. Wolski LBNL, Berkeley, California
	A sufficiently large acceptance is critical for the NLC Main Damping Rings (MDR) as the high power carried by the beams demands very high injection efficiency. Both chromatic sextupoles and wiggler insertions, needed for damping, are substantial sources of nonlinearities limiting the dynamical aperture. We report on our latest studies on single particle dynamics for the MDR current lattice with and without inclusion of lattice errors and with attention paid to working point optimization. The possibility to use octupole magnets for compensation is also explored.
WEOALH02	Multiturn Extraction Based on Trapping in Stable Islands at CERN PS: Recent Measurement Advances	extraction, proton, resonance, emittance	173
	M. Giovannozzi, R. Cappi, S.G. Gilardoni, M. Martini, E. Métral, A. Sakumi, R.R. Steerenberg CERN, Geneva A.-S. Müller FZK-ISS-ANKA, Karlsruhe
	Recently a novel approach to perform multi-turn extraction was proposed based on beam splitting in the transverse phase space by means of trapping inside stable islands. During the year 2002 run, preliminary measurements at the CERN Proton Synchrotron with a low-intensity, single-bunch, proton beam, confirmed the possibility of generating various beamlets starting from a single Gaussian beam. The experimental campaign continued also in the year 2003 run to assess a number of key issues, such as feasibility of trapping with high-intensity beam, capture efficiency, and multi-turn extraction proper. The experimental results are presented and discussed in detail in this paper.
	Video of talk
	Transparencies
WEPKF022	Electro-mechanical Aspects of the Interconnection of the LHC Superconducting Corrector Magnets	quadrupole, sextupole, dipole, monitoring	1645
	J.-P.G. Tock, D. Bozzini, F. Laurent, S. Russenschuck, B. Skoczen CERN, Geneva
	In addition to the main 1232 bending dipoles and 474 focusing and defocusing quadrupoles, more than 6800 superconducting corrector magnets are included in the LHC machine. They are housed in the superfluid helium enclosures of the main cryomagnets. Among them, the closed orbit correctors (sextupole and octupole) are integrated in the main quadrupole helium vessel and they are powered via an externally routed cryogenic line (line N). During the assembly, these corrector magnets have to be connected according to a complex electrical scheme based on the optical requirements of the LHC machine. Along the 27-km long LHC machine, 440 interconnection boxes are installed and will allow the powering of the correctors by means of a 42-wires auxiliary bus-bar cable, of which the corresponding wires have to be routed to the SSS from the interconnection box. Stringent requirements in terms of volume, mechanical resistance, electrical conductance and insulation, reliability, and respect of the electrical schematics apply during the assembly and splicing of the junctions inside the line-N box. The activities and their sequence, aiming at ensuring the fulfilment of these requirements are presented. The planned activities (assembly, ultrasonic welding, general and electrical inspection, and electrical qualification) and the interactions between the various intervening teams are described.
WEPKF034	The Modified DAFNE Wigglers	wiggler, sextupole, collider, betatron	1678
	S. Guiducci, S. Bertolucci, M. Incurvati, M.A. Preger, P. Raimondi, C. Sanelli, F. Sgamma INFN/LNF, Frascati (Roma)
	Modifications to the pole shape of a spare wiggler have been tested to increase the width of the good field region, with the aim of reducing the effect of nonlinearities affecting the dynamic aperture and the beam-beam interaction. Additional plates realized with the same material of the pole have been machined in several shapes and glued on the poles. Accurate measurements of the vertical field component on the horizontal symmetry plane of the magnet have been performed to find the best profile. The particle motion inside the measured field has been simulated to minimize the field integral on the trajectory, to determine the wiggler transfer matrix and to estimate the amount of non linear contributions. All wigglers in the collider have been modified to the optimized pole shape. Measurements with beam performed with the modified wigglers show a significant reduction of nonlinearities.
WEPKF040	Magnetic Field Measurement of Quadrupole Magnets for S-LSR	quadrupole, ion, superconductivity, lattice	1693
	T. Takeuchi, K. Noda, S. Shibuya NIRS, Chiba-shi H. Fadil, M. Ikegami, A. Noda, T. Shirai, H. Tongu Kyoto ICR, Uji, Kyoto
	S-LSR is a low energy ion storage/cooler ring. It has 12-quadrupole magnets (QM) with a bore radius of 70 mm and a maximum field gradient of 5 T/m. To suppress and control a magnetic flux in a fringing field of a bending magnet (BM), a field clamp with a thickness of 25 mm was installed in between BM and QM. The distance between the field clamp and QM is 80 mm. 3D calculation represented that the QM field is strongly influenced by the field clamp. Therefore, QMs were designed and optimized in considering the influence of the field clamp. Magnetic field measurements were performed by means of a Hall probe and a long search coil. A magnet field measurement by a Hall probe was carried out together with the field clamp and BM for S-LSR. For 12-quadrupole magnets, the measurement by the long search coil which moves in horizontal direction was carried out. The results for each measurements will be discussed.
WEPLT018	Nonlinear Dynamics Studies at the CERN Proton Synchrotron: Precise Measurements of Islands Parameters for the Novel Multi-turn Extraction	extraction, simulation, resonance, proton	1861
	M. Giovannozzi, P. Scaramuzzi CERN, Geneva
	Recently, a novel approach to perform multi-turn extraction from a circular accelerator was proposed. It is based on adiabatic capture of particles into islands of transverse phase space generated by nonlinear resonances. Sextupole and octupole magnets are used to generate these islands, while an appropriate slow variation of the linear tune allows particles to be trapped inside the islands. Intense experimental efforts showed that the approach is indeed performing rather well. However, good knowledge of the islands properties is a key ingredient for the success of this extraction type. In this paper, a series of measurements are presented dealing with the study of islands' parameters for the fourth-order resonance, such as detuning with amplitude, fixed points' position, betatron frequency, as well as detuning with amplitude inside the islands.
WEPLT030	Stability Diagrams for Landau Damping with Two-dimensional Betatron Tune Spread from Both Octupoles and Non-linear Space Charge applied to the LHC at Injection	space-charge, betatron, injection, damping	1897
	E. Métral, F. Ruggiero CERN, Geneva
	The joint effect of space-charge non-linearities and octupole lenses is discussed for the case of a quasi-parabolic transverse distribution of a monochromatic beam. The self-consistent non-linear space-charge tune shift corresponding to the above distribution function is first derived analytically. The exact dispersion relation is also given but not solved. Instead, noting that a good approximation of the non-linear space-charge tune shift is obtained considering only linear terms in the action variables, the dispersion relation is solved analytically in this approximate case. As expected, in the absence of external (octupolar) non-linearities, the result of Möhl and Schönauer is recovered: there is no stability region. In the absence of space charge, the stability diagrams of Berg and Ruggiero are also recovered. Finally, the new result is applied to the LHC at injection.
WEPLT064	2-nd Order Sextupole Effects on the Dynamic Aperture in HERA-e	resonance, sextupole, luminosity, optics	1993
	M. Vogt DESY, Hamburg
	During the first year after the luminosity upgrade HERA-e was operated in a mode for which the accessible area in transverse tune space was determined by resonances driven by sextupoles in 2-nd order. It turned out that with typical total incoherent beam beam tune shifts (.05,.08) for 2 IPs this space was too small for stable operation. We have used 2-nd order canonical perturbation theory to analyze the impact of the increased sextupole strengths in the upgraded lattice on the relevant resonance strengths and the detuning. Moreover, we have studied whether it is possible to compensate the resonances with localized octupole schemes (6 or 9 independent magnets) to 1-st and 2-nd order, computed the resulting detuning and compared the results with 6D tracking.
WEPLT078	The IFMIF High Energy Beam Transport Line	target, linac, simulation, space-charge	2032
	D. Uriot, R. Duperrier, J. Payet CEA/DSM/DAPNIA, Gif-sur-Yvette
	The IFMIF project (International Fusion Materials Irradiation Facility) requests two linacs designed to accelerate 125 mA deuteron beams up to 40 MeV. The linac has to work in CW mode and uses one RFQ and 10 DTL tanks. After extraction and transport, the deuteron beams with strong internal space charge forces have to be bunched, accelerated and transported to target for the production of high neutron flux. This paper presents the high energy beam transport line which provides a flat rectangular beam profile on the liquid lithium target. Transverse uniformisation is obtained by using non-linear mutipole lenses (octupoles and duodecapoles). Beam dynamics with and without errors has been study.
WEPLT106	Growth and Suppression Time of an Ion-related Vertical Instability	factory, storage-ring, photon, betatron	2098
	T. Miyajima, Y. Kobayashi, S. Nagahashi KEK, Ibaraki
	In the KEK Photon Factory electron storage ring, a vertical instability has been observed in a multi-bunch operation mode. The instability can be suppressed by octupole magnetic field in routine operation. Since the instability depends on a vacuum condition in the ring, it seems that it is an ion-related phenomenon. In order to study this instability, we measured the growth and the suppression time of it with the pulse octupole magnet system, which can produce the octupole field with rise and fall time of around 1.2msec. We obtained the result that the instability was grown slowly compared with to suppress it, and the growth time depended on the fill pattern of the bunch train and the beam current per bunch.
WEPLT136	Lattice Studies For The MAX-IV Storage Rings	lattice, dynamic-aperture, closed-orbit, sextupole	2155
	H. Tarawneh, M. Eriksson, L.-J. Lindgren, S. Werin MAX-lab, Lund B. Anderberg AMACC, Uppsala E.J. Wallén ESRF, Grenoble
	The lattice for the future MAX-IV storage rings at MAX-Lab has been studied, The MAX IV facility consists of two similar rings operated at 1.5 GeV and 3 GeV electron energies, The ring consists of 12 supercells each built up by 5 unit cells and matching sections. The high periodicity of the lattice combined with the high gradients in the small gap dipole magnets yield a small emittance of 1 nm.rad, good dynamic aperture and momentum acceptance. In the matching section, a soft end dipole magnet is introduced to reduce the synchrotron radiation power hitting the upstream straight section.
THPLT183	Results from the Commissioning of the NSRL Beam Transfer Line at BNL	target, beam-transport, optics, ion	2879
	N. Tsoupas, S. Bellavia, R. Bonati, K.A. Brown, I.-H. Chiang, C. Gardner, D. Gassner, S. Jao, I. Marneris, A. McNerney, D. Phillips, P. Pile, R. Prigl, A. Rusek, L. Snydstrup BNL, Upton, Long Island, New York
	The NASA SPACE RADIATION LABORATORY (NSRL) has started operations at the Brookhaven National Laboratory in 2003. The NSRL facility will be used by NASA to study radiation effects. The NSRL facility utilizes proton and heavy-ion beams of energies from 50 to 3000 MeV/n which are accelerated by the AGS_Booster synchrotron accelerator. The beams were extracted[1] ,and transported to a sample which is located 100 m downstream. To date, protons, 12C, 56Fe, 48Ti ion beams of various magnetic rigidities have been transported to the sample location. The NSRL beam transport line has been designed to employ octupole magnetic elements[2] which transform the normal (Gaussian) beam distribution on the sample into a beam with rectangular cross section, and uniformly distributed over the sample. No beam-collimation is applied along any point of the NSRL beam transport line and the beam focusing on the sample is purely magnetic. The experimental and theoretical horizontal and vertical beam envelopes of the first order optics will be presented. The theoretical beam profiles and uniformities at the location of the sample, when the magnetic octupoles are excited (third order optics), will be compared with the experimentally measured ones.