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Space-Charge Effects in the Super B-Factory LER

Description: Space-charge effects in the low-energy ring of the proposedSuper-B Factory are studied using a weak-strong model of dynamics asimplemented in the code Marylie/Impact (MLI). The impact of space chargeappears noticeable but our results suggest the existence of workableregions of the tune space where the design emittance is minimallyaffected. However, additional studies are recommended to fullysubstantiate this conclusion.
Date: January 31, 2007
Creator: Venturini, Marco
Partner: UNT Libraries Government Documents Department

An effective longitudinal space-charge impedance model for beamswith non-uniform and non-axissymmetric transverse density

Description: Use of a one-dimensional model of longitudinal space-charge(SC) impedance has been proposed for studying the microbunchinginstability in single-pass delivery systems relevant for the nextgeneration of FELs. For beams with uniform transverse density andcircular cross-section of radius r_b the SC impedance can be expressed ina handy analytical form, making this model particularly convenient. Inthis report we show how with an appropriate choice of r_b one can usethis as an effective-beam model to approximate beams with non-axissymmetric and non-uniform transverse densities.
Date: June 29, 2007
Creator: Venturini, Marco
Partner: UNT Libraries Government Documents Department

Models of Longitudinal Space-Charge Impedance for the Study of theMicrobunching Instability

Description: A 1D model of space-charge impedance, assuming atransversely uniform beam with circular cross-section, has been proposedand is being extensively used in the modelling of the microbunchinginstability of relevance for the beam delivery systems of x-ray FELs. Inthis paper we investigate the limitation of the model when applied tostudying the effect of shot noise--one of the sources of themicrobunching instability. We make comparison witha fully 3D calculationand identify the upper end of the frequency spectrum for applicability ofthe 1D model. Relaxation of the assumptions regarding axis-symmetry anduniformity of the transverse density is also reviewed.
Date: March 10, 2008
Creator: Venturini, Marco
Partner: UNT Libraries Government Documents Department

Space-charge effects of the proposed high-intensity Fermilab booster

Description: Space-charge effects on beam stabilities are studied for the proposed two-ring high-intensity Fermilab booster destined for the muon collider. This includes microwave instabilities and rf potential-well distortions. For the first ring, ferrite insertion is suggested to cancel the space-charge distortion of the rf wave form. To control the inductance of the ferrite during ramping and to minimize resistive loss, perpendicular biasing to saturation is proposed.
Date: April 1, 1998
Creator: Ng, K.-Y. & Qian, Z.
Partner: UNT Libraries Government Documents Department

Solution of K-V envelope equations

Description: The envelope equations for a KV beam with space charge have been analyzed systematically by an e expansion followed by integrations. The focusing profile as a function of axial length is assumed to be symmetric but otherwise arbitrary. Given the bean current, emittance, and peak focusing field, we find the envelopes a(s) and b(s) and obtain <a>, a{sub max}, {sigma}, and {sigma}{sub 0}. Explicit results are presented for various truncations of the expansion. The zeroth order results correspond to those from the well-known smooth approximation; the same convenient format is retained for the higher order cases. The first order results, involving single correction terms, give 3--10 times better accuracy and are good to {approximately}1% at {sigma}{sub 0} = 70{degree}. Third order gives a factor of 10--30 improvement over the smooth approximation and derived quantities accurate to {approximately}1% at {sigma}{sub 0} = 112 {degree}. The first order expressions are convenient design tools. They lend themselves to variable energy problems and have been applied to the design, construction, and testing of ESQ accelerators at LBL.
Date: April 1, 1995
Creator: Anderson, O.A.
Partner: UNT Libraries Government Documents Department

Space Charge and Equilibrium Emittances in Damping Rings

Description: We present a model of dynamics to account for the possible impact of space charge on the equilibrium emittances in storage rings and apply the model to study the current design of the International Linear Collider (ILC) damping rings.
Date: June 21, 2006
Creator: Venturini, Marco; Oide, Katsunobu & Wolski, Andy
Partner: UNT Libraries Government Documents Department

Direct space-charge effects on the ILC damping rings: Task ForceReport

Description: In 2005 a global effort was initiated to conduct studies for a baseline recommendation for the various components of the International Linear Collider (ILC). Work for the damping rings was subdivided in a number of tasks. This Report contains the contribution to this effort by the Authors as Coordinators of the Task Force on space charge. (A slightly reduced version of this document can also be found as part of the ''Configuration Studies and Recommendations for the ILC Damping Rings'', Edts. A. Wolski, et al., LBNL-59449.) The studies documented in this Report were carried out for several of the reference lattices considered for the baseline recommendation. Space charge effects were found to be quite noticeable in the lattices with the longest circumference. Although it does not appear that they could prevent operation of any machine having such lattices they do favor a choice of a ring design with shorter ({approx}6km) circumference at 5 GeV.
Date: February 28, 2006
Creator: Venturini, Marco & Oide, Katsunobu
Partner: UNT Libraries Government Documents Department

Final Report for "User Friendly Steering and Diagnostics for Modleing Heavy Ion Fusion Accelerators"

Description: The goal accomplished in thisproject was to improve the Synergia code by improving the integration of the Impact space charge algorithms into Synergia and improving the graphical user interface for analyzing results. We accomplished five tasks along these lines: (i) a refactoring of the Impact space charge algorithm to make it more accessible by other codes, (ii) development of the Forthon interface between Impact and Python, (iii) implementation of a Python-MPI interface to allow parallel space charge calculation, (iv) a new user-friendly interface for analyzing Synergia results, and (v) a toolkit for doing parallel analysis of Synergia results.
Date: October 15, 2007
Creator: Peter Stoltz, Douglas R Dechow, Scott Kruger, Brian Granger
Partner: UNT Libraries Government Documents Department

Single/Few Bunch Space Charge Effects at 8 GeV in the Fermilab Main Injector

Description: For Project X, it is planned to inject a beam of 3 10{sup 11} particles per bunch into the Main Injector. Therefore, at 8 GeV, there will be increased space charge tune shifts and an increased incoherent tune spread. In preparation for these higher intensity bunches exploratory studies have commenced looking at the transmission of different intensity bunches at different tunes. An experiment is described with results for bunch intensities between 20 and 300 10{sup 9} particles. To achieve the highest intensity bunches coalescing at 8 GeV is required, resulting in a longer bunch length. Comparisons show that similar transmission curves are obtained when the intensity and bunch length have increased by similar factors. This indicates the incoherent tune shifts are similar, as expected from theory. The results of these experiments will be used in conjugation with simulations to further study high intensity bunches in the Main Injector.
Date: May 1, 2012
Creator: Scott, D.J.; Capista, D.; Kourbanis, I.; Seiya, K.; Yang, M.-J. & /Fermilab
Partner: UNT Libraries Government Documents Department

Exact solution of the envelope equations for a matched quadrupole-focused beam in the low space-charged limit

Description: The Kapchinskij-Vladimirskij equations are widely used to study the evolution of the beam envelopes in a periodic system of quadrupole focusing cells. In this paper, we analyze the case of a matched beam. Our model is analogous to that used by Courant and Snyder [E.D. Courant and H.S. Snyder, Ann. Phys. 3, 1 (1958)]in obtaining a first-order approximate solution for a synchrotron. Here, we treat a linear machine and obtain an exact solution. The model uses a full occupancy, piecewise-constant focusing function and neglects space charge. There are solutions in an infinite number of bands as the focus strength is increased. We show that all these bands are stable. Our explicit results for the phase advance sigma and the envelope a(z) are exact for all phase advances except multiples of 180o, where the behavior is singular. We find that the peak envelope size is minimized at sigma = 90o. Actual operation in the higher bands would require very large, very accurate field strengths and would produce significantly larger envelope excursions.
Date: September 23, 2008
Creator: Anderson, O.A. & LoDestro, L.L.
Partner: UNT Libraries Government Documents Department

Exact solution of the envelope equations for a matchedquadrupole-focused beam in the zero space-charge limit

Description: The Kapchinskij-Vladimirskij equations are widely used to study the evolution of the beam envelopes in a periodic system of quadrupole focusing cells. In this paper, we analyze the case of a matched beam. Our model is analogous to that used by Courant and Snyder [E.D. Courant and H.S. Snyder, Ann. Phys. 3, 1 (1958)] in obtaining a first-order approximate solution for a synchrotron. Here, we treat a linear machine and obtain an exact solution. The model uses a full occupancy, piecewise-constant focusing function and neglects space charge. There are solutions in an infinite number of bands as the focus strength is increased. We show that all these bands are stable. Our explicit results for the phase advance {sigma} and the envelope a(z) are exact for all phase advances except multiples of 180{sup o}, where the behavior is singular. We find that the peak envelope size is minimized at {sigma} = 90{sup o}. Actual operation in the higher bands would require very large, very accurate field strengths and would produce significantly larger envelope excursions.
Date: November 7, 2008
Creator: Anderson, Oscar A. & LoDestro, L.L.
Partner: UNT Libraries Government Documents Department

Debunching and Capture in the LEB for the SSC

Description: The authors present the details of the capture process in the Low Energy Booster (LEB) for the SSC. They consider only the longitudinal dynamics. Space charge forces are computed quasistatically. The beam pipe is considered to be perfectly conducting. With respect to maximizing the capture efficiency and minimizing the space charge tune spread, initial few milliseconds are very important. They present only the first few milliseconds of the cycle, during which space charge effects are significant. For the numerical simulation they use the code ESME.
Date: May 1, 1991
Creator: Mahale, N. & Furman, M.
Partner: UNT Libraries Government Documents Department

Sheet beam model for intense space-charge: with application to Debye screening and the distribution of particle oscillation frequencies in a thermal equilibrium beam

Description: A one-dimensional Vlasov-Poisson model for sheet beams is reviewed and extended to provide a simple framework for analysis of space-charge effects. Centroid and rms envelope equations including image charge effects are derived and reasonable parameter equivalences with commonly employed 2D transverse models of unbunched beams are established. This sheet beam model is then applied to analyze several problems of fundamental interest. A sheet beam thermal equilibrium distribution in a continuous focusing channel is constructed and shown to have analogous properties to two- d three-dimensional thermal equilibrium models in terms of the equilibrium structure and Deybe screening properties. The simpler formulation for sheet beams is exploited to explicitly calculate the distribution of particle oscillation frequencies within a thermal equilibrium beam. It is shown that as space-charge intensity increases, the frequency distribution becomes broad, suggesting that beams with strong space-charge can have improved stability.
Date: January 10, 2011
Creator: Lund, Steven M.; Friedman, Alex & Bazouin, Guillaume
Partner: UNT Libraries Government Documents Department

Space charge stopband correction

Description: It is speculated that the space charge effect cause beam emittance growth through the resonant envelope oscillation. Based on this theory, we propose an approach, called space charge stopband correction, to reduce such emittance growth by compensation of the half-integer stopband width of the resonant oscillation. It is illustrated with the Fermilab Booster model.
Date: September 1, 2005
Creator: Huang, Xiaobiao; U., /Fermilab /Indiana; Lee, S.Y. & U., /Indiana
Partner: UNT Libraries Government Documents Department

Analytic Solution of the Envelope Equations for an Undepressed Matched Beam in a FODO Quadrupole Channel

Description: In 1958, Courant and Snyder analyzed the problem of alternating-gradient beam transport and treated a model without focusing gaps or space charge. Recently we revisited their work and found the exact solution for matchedbeam envelopes in a linear quadrupole lattice [O.A. Anderson and L.L. LoDestro, Phys. Rev. ST Accel. Beams, 2009]. We extend that work here to include the effect of asymmetric drift spaces. We derive the solution and show exact envelopes for the first two solution bands and the peak envelope excursions as a function of the phase advancesigma up to 360o. In the second stable band, decreased occupancy requires higher focus field-strength and accentuates the remarkable compression effect predicted for the FD (gapless) model.
Date: April 29, 2009
Creator: Anderson, Oscar & LoDestro, L. L.
Partner: UNT Libraries Government Documents Department

Investigations of the Dynamics of Space Charged Dominated Beams

Description: We propose to perform investigations of the dynamics of space charge dominated beams. These investigations will support present activities such as the electron ring project at the University of Maryland as well as provide an improved basis for future accelerator designs. Computer simulations will provide the primary research element with improved code development being an integral part of the activities during the first period. We believe that one of the code development projects provides a unique strategy for the inclusion of longitudinal dynamics, and that this concept should provide a computationally rapid research tool.
Date: August 1, 2002
Creator: York, Richard C.
Partner: UNT Libraries Government Documents Department

THE TRANFT USER'S MANUAL.

Description: The Fortran program TRANFT simulates transverse instabilities in circular accelerators using fast Fourier transform algorithms. It may be used for any particle type. Forces from transverse wakefields, longitudinal wakefields, and transverse detuning wakes are included, with linear transverse space charge forces included as a special case. This note describes the algorithms and their implementation in TRANFT.
Date: August 30, 2006
Creator: BLASKIEWICZ, M.
Partner: UNT Libraries Government Documents Department

PARALLEL 3-D SPACE CHARGE CALCULATIONS IN THE UNIFIED ACCELERATOR LIBRARY.

Description: The paper presents the integration of the SIMBAD space charge module in the UAL framework. SIMBAD is a Particle-in-Cell (PIC) code. Its 3-D Parallel approach features an optimized load balancing scheme based on a genetic algorithm. The UAL framework enhances the SIMBAD standalone version with the interactive ROOT-based analysis environment and an open catalog of accelerator algorithms. The composite package addresses complex high intensity beam dynamics and has been developed as part of the FAIR SIS 100 project.
Date: June 26, 2006
Creator: D'IMPERIO, N.L.; LUCCIO, A.U. & MALITSKY, N.
Partner: UNT Libraries Government Documents Department

CHOICE OF PROTON DRIVER PARAMETERS FOR A NEUTRINO FACTORY.

Description: We discuss criteria for designing an optimal ''green field'' proton driver for a neutrino factory. The driver parameters are determined by considerations of space charge, power capabilities of the target, beam loading and available RF peak power.
Date: June 23, 2006
Creator: KIRK, H.G.; BERG, J.S.; FERNOW, R.C.; GALLARDO, J.C.; SIMOS, N. & WENG, W.
Partner: UNT Libraries Government Documents Department

Proton Bunching Options

Description: Muon Colliders need intense, very short, proton bunches. The requirements are presented and a number of possible bunching systems discussed. The best solution uses a small super-conducting buncher ring with 6 bunches that are taken though separate transports and combined on the target.
Date: October 19, 2009
Creator: Palmer, R.B.
Partner: UNT Libraries Government Documents Department