1,218 Matching Results

Search Results

Advanced search parameters have been applied.

Overview of the bump-magnet system at the LANSCE proton storage ring

Description: An upgrade program for increasing the stored beam current in the Proton Storage is presently under way. A part of the upgrade is the design and installation of a four-magnet beam-bumping system used for phase-space painting and minimizing interaction of the stored beam with the injection stripper foil. This paper describes the bump- magnet system including the relevant beam requirements, magnet specifications, power-cable specifications, pulsed-modulator requirements, and beam-tube eddy-current effects. The magnets are ferrite window-frame magnets with saddle windings. The series-pass pulsed modulators are programmable both in rise and fall time as well as amplitude. The peak current can be varied between 50 and 300 A. The pulsed-current rise-time is fixed at 1 ms, and the linear fall- time during which beam is injected into the ring can be varied between 0.5 and 1.5 ms.
Date: September 1, 1997
Creator: Rose, C.R.; Barlow, D.B.; Blind, B.; Neri, F.; Power, J.F. & Walstrom, P.L.
Partner: UNT Libraries Government Documents Department

Closed orbit response to quadrupole strength variation

Description: We derive two formulae relating the variation in closed orbit in a storage ring to variations in quadrupole strength, neglecting nonlinear and dispersive effects. These formulae correct results previously reported [1,2,3]. We compare the results of the formulae applied to the ATF with simulations using MAD, and consider their application to beam-based alignment.
Date: January 20, 2004
Creator: Wolski, Andrzej & Zimmermann, Frank
Partner: UNT Libraries Government Documents Department


Description: A formal expression is obtained for the energy loss per turn, of a rigid bunch of electrons, to a closed cylindrical cavity with quality factor Q. The expression is valid provided the diameter of the entrance and exit ports for the beam are small compared to the bunch length. The effect of the ports is studied in an independent computational method. The energy loss is numerically evaluated for a range of parameters of interest to electron storage rings.
Date: April 1, 1975
Creator: Henkin, Bruce M. & Sauer, Kenneth
Partner: UNT Libraries Government Documents Department


Description: An equilibrium theory of the length of intense electron bunches circulating in a storage ring is presented. The consequence of electrical interaction with various resonant structures is expressed in terms of quadratures over the impedance of the structures, and impedance functions for a variety of elements are evaluated. It is shown that elements having resonances at high frequency can, above transition, cause bunches to increase in length with increasing current. The parametric dependence of the bunch lengthening is found to be in good agreement with observations, and numerical estimates, which are in substantial agreement with experiment, are presented.
Date: August 7, 1970
Creator: Pellegrini, C. & Sessler, A.M.
Partner: UNT Libraries Government Documents Department

Flip-Flop Modes in Symmetric and Asymmetric Colliding-Beam Storage Rings

Description: A model of self-consistent beam blow-up in a colliding beam storage ring is described which explains the appearance of flip-flop modes in both symmetric and asymmetric beam systems. It derives the strong-strong steady-states and their stabilities from the weak-strong behavior. This model agrees well with the observed flip-flop behavior in storage rings, including the hysteresis seen when the beams are flipped from one asymmetric steady state to the other. It can be used to predict the behavior of proposed facilities in which the two colliding beams are characterized by different parameters.
Date: August 1, 1989
Creator: Tennyson, J.L.
Partner: UNT Libraries Government Documents Department

Reexamination of the ISABELLE box car stacking scheme

Description: Box car stacking of ISABELLE after acceleration of the fundamental frequency in the AGS is reviewed with the present ISABELLE parameters and examined with regard to longitudinal impedence requirements. The scheme results in an impedance tolerance of Z/n less than or equal to 30 $Omega$ compared to Z/n less than or equal to 5 $Omega$ obtained for rf stacking. However, to meet the claimed luminosity, the AGS performance demands are increased above those assumed in the ISABELLE proposal. (auth)
Date: August 26, 1975
Creator: Chasman, R.
Partner: UNT Libraries Government Documents Department

ISABELLE ring structure and performance

Description: A summary of the ISABELLE Ring Structure is presented. A phased approach to ISA operation is detailed. The initial performance potential indicates that p-p collisions at a wide range of energies and unequal energies in the two beams will be possible. The quasi 8-fold periodicity could be broken to allow a hi-luminosity set-up, which could be achieved by small changes in the insertion quadrupole strengths. A discussion is given of future ISA phases requiring the alteration of the physical layout of the insertions for various special experimental conditions. (auth)
Date: July 1, 1975
Creator: Month, M.
Partner: UNT Libraries Government Documents Department

Large equipment and facilities

Description: Component and design criteria are reviewed for a general purpose modular multiparticle spectrometer system. The study of hadronic interactions is emphasized, although the solenoidal magnet vertex detector system can be used for W bosons and other weak interaction processes. A general purpose spectrometer seems compatible with the requirements of the ISABELLE straight sections. (auth)
Date: January 1, 1975
Creator: Louttit, R.; Love, W. & Lindenbaum, S.J.
Partner: UNT Libraries Government Documents Department

Strong turbulence and the anomalous length of stored particle beams

Description: A theoretical analysis is made of the longitudinal stability of intense beams of charged particles in high energy storage rings. The effect of externally applied radiofrequency fields, i.e., synchrotron oscillations, is included. For electron and positron beams, the damping and quantum excitation due to particle radiation are also included. A criterion for the stability of small longitudinal plasma oscillations is derived and used to obtain the stable size of intense stored beams of electrons and positrons. (auth)
Date: November 1, 1975
Creator: Channell, P.J.
Partner: UNT Libraries Government Documents Department

Electron cloud development in the Proton Storage Ring and in theSpallation Neutron Source

Description: We have applied our simulation code "POSINST" to evaluatethe contribution to the growth rate of the electron-cloud instability inproton storage rings. Recent simulation results for the main features ofthe electron cloud in the storage ring of the Spallation Neutron Source(SNS) at Oak Ridge, and updated results for the Proton Storage Ring (PSR)at Los Alamos are presented in this paper. A key ingredient in our modelis a detailed description of the secondary emitted-electron energyspectrum. A refined model for the secondary emission process includingthe so-called true secondary, rediffused and backscattered electrons hasrecently been included in the electron-cloud code.
Date: October 8, 2002
Creator: Pivi, M.T.F. & Furman, M.A.
Partner: UNT Libraries Government Documents Department

Modeling Incoherent Electron Cloud Effects

Description: Incoherent electron effects could seriously limit the beam lifetime in proton or ion storage rings, such as LHC, SPS, or RHIC, or blow up the vertical emittance of positron beams, e.g., at the B factories or in linear-collider damping rings. Different approaches to modeling these effects each have their own merits and drawbacks. We describe several simulation codes which simplify the descriptions of the beam-electron interaction and of the accelerator structure in various different ways, and present results for a toy model of the SPS. In addition, we present evidence that for positron beams the interplay of incoherent electron-cloud effects and synchrotron radiation can lead to a significant increase in vertical equilibrium emittance. The magnitude of a few incoherent e+e- scattering processes is also estimated. Options for future code development are reviewed.
Date: June 18, 2007
Creator: Vay, Jean-Luc; Benedetto, E.; Fischer, W.; Franchetti, G.; Ohmi, K.; Schulte, D. et al.
Partner: UNT Libraries Government Documents Department


Description: We present a model for producing stable broadband coherent synchrotron radiation (CSR) in the terahertz frequency region in an electron storage ring. The model includes distortion of bunch shape from the synchrotron radiation (SR), enhancing higher frequency coherent emission and limits to stable emission due to a microbunching instability excited by the SR. We use this model to optimize the performance of a source for CSR emission.
Date: June 13, 2003
Creator: Sannibale, Fernando; Byrd, John M.; Loftsdottir, Agusta; Martin, MichaelC. & Venturini, Marco
Partner: UNT Libraries Government Documents Department

Particle-beam profiling techniques on the APS storage ring

Description: Characterization of the Advanced Photon Source storage ring particle beams includes transverse and longitudinal profile measurements using synchrotron radiation-based techniques. Both optical (OSR) and x-ray synchrotron radiation stations are now installed. Spatial resolution of about {sigma}=55{mu}m was obtained at low current in the visible field initially. This is expected to improve during commissioning. UV/visible light from the storage ring bending magnet was used to measure the particle beam with a resolution of {sigma}{approximately}80{mu}m and allow operation at 100 mA with the initial x-ray pinhole setup. Early OSR measurements of beam size are consistent with 8.2 nm-rad emittance and 2-3% vertical coupling. Early results with the x-ray pinhole camera are also presented.
Date: December 31, 1996
Creator: Yang, B.X. & Lumpkin, A.H.
Partner: UNT Libraries Government Documents Department

Magnetic measurement data of the 0.8-m prototype quadrupole magnets for the APS storage ring

Description: From magnetic measurement data of the two 0.8-m prototype quadrupole magnets (P-SRQ-1 and P-SRQ-2) and the study of the geometries for the pole-end bevels and pole chamfers, the following conclusions have been made. Mechanical stability of the magnet poles has been achieved by modification of the weld procedures between two quadrants of the magnets. Stability of the magnet-pole positions was measured optically and was also concluded from the fact that the allowed coefficients, mainly sextupole and octupole terms, were independent of the magnet excitation currents. Unallowed multipole field coefficients for the second magnet, without correction of the magnet-pole positions, are smaller than for the first magnet. The field gradient integrals of the two magnets at 400A differ by less than 5 {times} 10{sup {minus}4} for r = 2.5 cm. This indicates that an acceptable magnet assembly procedure has been established. The 2-D calculations and ``body`` measurements for allowed coefficients after the main field, b{sub 5} and b{sub 9}, agree within 1.2 {times} 10{sup {minus}4} at r = 2.5 cm. This implies that the 2-D design geometry is basically correct and acceptable. As expected for a magnet with long and narrow poles, saturation effects of pole shims have been observed. In order to reduce fabrication cost for the end-plates, the geometries for the pole-end bevels and pole chamfers have been studied. By choosing a bevel angle of 61{degree}, instead of 45{degree}, it is possible to have acceptable allowed coefficients with dimensions of pole-chamfers up to 16.5 mm. This allows the design of the end-plate as one piece without removable pole-tip.
Date: July 1, 1995
Creator: Kim, S.H.
Partner: UNT Libraries Government Documents Department

Undulators on a 6-GeV ring general considerations

Description: In, designing undulators on a 6-GeV storage ring the primary consideration will be the power that such devices will deliver. The beam line design should be capable of handling large powers that such undulators will deliver. Specifically, in a beam line in the front end we have masks (fixed and movable) followed by various optical components. Many thermal designs are now being developed to improve on the capability of various components to handle a greater beat load than ever been possible before. For example, designs for rotating optics and liquid metal cooled optics are actively pursued in the MST division.
Date: April 16, 1985
Creator: Shenoy, G.K.
Partner: UNT Libraries Government Documents Department

Status of the PEP-II B-factory high energy ring

Description: The 9 GeV High Energy Ring (HER) of the PEP-II B Factory is an electron storage ring under construction at SLAC. Significant progress has been made in the last year on all systems. As of mid 1996, all 192 dipoles have been installed, with installation of the quadrupoles underway. The vacuum system, for design currents up to 3 A average, is in production using a recently commissioned e-beam welder. Beam instrumentation systems are being fabricated. The interaction region will bring the HER beam into collision with the 3 GeV beam of the Low Energy Ring; design of this section of the HER is in an advanced stage. 8 refs., 3 figs., 1 tab.
Date: January 1, 1996
Creator: Wienands, U.; Reuter, E.; Bellomo, P.; Daly, E.; Fisher, A.; Gracia, J. et al.
Partner: UNT Libraries Government Documents Department

Progress on PEP-II magnet power conversion system

Description: The various power systems for supplying the PEP-II DC magnets rely exclusively on switchmode conversion, utilizing a variety of means depending on the requirements. All of the larger power supplies, ranging from 10 to 200 kW, are powered from DC sources utilizing rectified 480 V AC. Choppers can be used for the series connected strings, but for smaller groups and individual magnets, inverters driving high-frequency transformers with rectifiers comprise the best approach. All of the various systems use a ``building block`` approach of multiple standard-size units connected in series or parallel to most cost-effectively deal with a great range of voltage and current requirements. Utilization of existing infrastructure from PEP-I has been a cost-effective determinant. Equipment is being purchased either off-the-shelf, through performance specification, or by hardware purchase based on design-through-prototype. The corrector magnet power system, utilizing inexpensive, off-the-shelf, four-quadrant switching motor-controllers, has already proven very reliable: 120 of the total of 900 units have been running on the injection system for four months with no failures.
Date: June 4, 1996
Creator: Bellomo, P.; Genova, L.; Jackson, T. & Shimer, D.
Partner: UNT Libraries Government Documents Department

The vacuum system for the PEP II high energy ring straight sections

Description: The six straight sections of the PEP II High Energy Ring (HER) serve various functions: lattice tuning, beam injection and abort, providing space for rf cavities, longitudinal and transverse feedback, beam diagnostics and the interaction point. A stainless steel vacuum system has been designed; prototypes are currently being built. Cooling is required due to radiation coming from the last arc dipole and resistive losses in the vacuum chamber. Although the nominal beam current of the HER is 1 A the vacuum system is designed for 3 A to provide margin and an upgrade path. 5 refs., 7 figs.
Date: January 1, 1995
Creator: Wienands, U.; Daly, E.; Kulikov, A.; Kurita, N.; Nordby, M.; Perkins, C. et al.
Partner: UNT Libraries Government Documents Department