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The Brown-Servranckx matching transformer for simultaneous RFQ to DTL H{sup +} and H{sup {minus}} matching

Description: The issue involved in simultaneous matching of H{sup +} and H{sup -} beams between an RFQ and DTL lies in the fact that both beams experience the same electric-field forces at a given position in the RFQ. Hence, the two beams are focused to the same correlation. However, matching to a DTL requires correlation of the opposite sign. The Brown-Servranckx quarter-wave ({lambda}/4) matching transformer system, which requires four quadrupoles, provides a method to simultaneously match H{sup +} and H{sup -} beams between an RFQ and a DTL. The method requires the use of a special RFQ section to obtain the Twiss parameter conditions {beta}{sup x}={beta}{sup y} and {alpha}{sub x}={alpha}{sub y}=0 at the exit of the RFQ. This matching between the RFQ and DTL is described.
Date: September 1, 1996
Creator: Wadlinger, E.A. & Garnett, R.W.
Partner: UNT Libraries Government Documents Department

Scientific potential and design considerations for an undulator beam line on Aladdin storage ring

Description: The unique features of undulator radiation, i.e., high photon flux and brightness, partial coherence, small beam divergence, spectral tunability, etc., mandate that undulators be included in the future plans for Aladdin. This will make it possible to perform the next generation of experiments in photon-stimulated spectroscopies. A team of scientists (see Appendix) has now been assembled to build an insertion device (ID) and the associated beam line at Aladdin. In considering the specifications for the ID, it was assumed that the ID beamline will be an SRC user facility. Consequently, design parameters were chosen with the intent of maximizing experimental flexibility consistent with a conservative design approach. A tunable {open_quotes}clamshell{close_quotes} undulator device was Chosen with a first harmonic tunable from 35 to 110 eV to operate on a 1 GeV storage ring. Higher harmonics will be utilized for experiments needing higher photon energies.
Date: April 8, 1985
Creator: Arko, A.J.; Bader, S.D.; Dehmer, J.L. & Kim, S.H.
Partner: UNT Libraries Government Documents Department

Switchyard in the Main Injector era conceptual design report

Description: This report presents elements of a design of the Switchyard and of the present fixed target beamlines in the era of the Main Injector (MI). It presumes that 800 GeV Tevatron beam will be transported to this area in the MI era, and permits it to share cycles with 120 GeV Main Injector beam if this option is desired. Geographically, the region discussed extends from the vicinity of AO to downstream points beyond which beam properties will be determined by the requirements of specific experiments. New neutrino lines not utilizing the present Switchyard (NuMI, BooNE) are not addressed. Similarly Main Injector beams upstream of AO are described fully in MI documentation and are unaffected by what is presented here. The timing both of the preparation of this report and of its recommendations for proceeding with construction relate to a desire to do required work in Transfer Hall and Enclosure B during the Main Injector construction shutdown (September 1997 - September 1998). As these areas are off-limits during any Tevatron operation, it is necessary for the fixed target program that work be completed here during this extended down period. The design presented here enables the operation of all beamlines in the manner specified in the current Laboratory plans for future fixed- target physics.
Date: August 1, 1997
Creator: Brown, C.; Kobilarcik, T.; Lucas, P.; Malensek, A.; Murphy, C.T. & Yang, M.-J.
Partner: UNT Libraries Government Documents Department

Overview of the APT high-energy beam transport and beam expanders

Description: The APT high energy beam transport (HEBT) and beam expanders convey the 1700-MeV, 100-mA cw proton beam from the linac to the tritium target/blanket assembly, or a tuning beam stop. The HEBT includes extensive beam diagnostics, collimators, and beam jitter correction, to monitor and control the 170-MW beam prior to expansion. A zero-degree beamline conveys the beam to the beam stop, and an achromatic bend conveys the beam to the tritium production target. Nonlinear beam expanders make use of higher-order multipole magnets and dithering dipoles to expand the beam to a uniform-density, 16-cm wide by 160-cm high rectangular profile on the tritium-production target. The overall optics design will be reviewed, and beam simulations will be presented.
Date: August 1, 1997
Creator: Shafer, R.E.; Blind, B. & Gray, E.R.
Partner: UNT Libraries Government Documents Department

Emittance growth from bend straight transitions for beams approaching thermal equilibrium

Description: In certain applications such as heavy ion fusion, intense beams with large space charge tune depressions will be transferred from linear transport sections into bent, transport, sections. In some. designs, such as recircutating induction accelerators, transport. through bends will occur over thousands of betatron periods and in some driver designs the final transports through a bend will occur over tens of betatron periods. Over such distances, non-linear space charge forces are expected to produce particle phase space distributions which are close to thermal equilibrium, especially with respect to lower order moments. Here we calculate the properties of thermal equilibrium beams in bends assuming uniform focusing, as a function of two dimensionless parameters. We also outline the calculation of the change in emittance for a beam that is initially in thermal equilibrium in a straight transport section. and that finally reaches thermal equilibrium in a bent system, using an energy conservation constrint to connect, the two states.
Date: August 19, 1998
Creator: Barnard, J. J. & Losic, B.
Partner: UNT Libraries Government Documents Department

The mechanical design for the second axis beam transport line for the DARHT facility

Description: This paper describes the mechanical design of the downstream beam transport line for the second axis of the Dual Axis Radiographic Hydrodynamic Test (DARHT II) facility. The DARHT II project is a collaboration between LANL, LBNL, and LLNL. DARHT II is a 20-MeV, 2000-Amperes, 2-&micro;sec pulse length linear induction accelerator designed to generate short bursts of x-rays for the purpose of radiographing dense objects. The downstream beam transport line is an 18-meter long region extending from the end of the accelerator to the bremsstrahlung target. Within this proposed transport line there are 17 conventional solenoid, quadrupole and dipole magnets; as well as several specialty magnets, which transport and focus the beam to the target and beam dumps. There is a high power beam dump, which is designed to absorb the 80-kJ of beam energy during accelerator start-up and operation. The beamline vacuum chamber has an 8-cm diameter aperture and operates at an average pressure of 10<sup>-7</sup> Torr.
Date: March 23, 1999
Creator: Bertolini, L R; Alford, O J; Paul, A C; Shang, C C & Westenkow, G A
Partner: UNT Libraries Government Documents Department

An overview of what is required and when for developing a beamline at the ALS

Description: This report discusses these topics: reviews required for developing a beamline at the ALS; work items and documentation required for the beamline design review; information to be communicated to the ALS staff before the beamline readiness review; work items and documentation required for the beamline readiness review; contacts for information, technical questions, and sources of additional information; and checklist of what is required and when for developing a beamline.
Date: August 1, 1995
Creator: Hussain, Z.
Partner: UNT Libraries Government Documents Department

Exact matched-beam envelopes for undepressed transport in a quadrupole lattice with unequal drift lengths and arbitrary field strength

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 exactsolution for matched-beam 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 gaps. We derive the exact envelopes and show results for various field strengths, occupancies eta,and gap-length ratios. We find the peak envelope excursion. It has a broad minimum as a function of the phase advance sigma (typically around 34o) over which it varies less than +-1percent. The phase-advance numbers also change little over the full range of gap ratios. However, the required field strengths vary appreciably. In the second stable band, the higher field strength necessitated by the lower occupancy accentuates the remarkable compression effect predicted for the FD (gapless) model.
Date: April 29, 2009
Creator: Anderson, O. A. & LoDestro, L. L.
Partner: UNT Libraries Government Documents Department

A simple drift-diffusion model for calculating the neutralization time of H- in xe gas for choppers placed in the LEBT

Description: The neutralization of H{sup -} beam with a gas like Xe is an important part of low energy beam transport (LEBT). It is well known that choppers which use an electric field when placed in the LEBT strongly affects the neutralization of H{sup -}. The question then naturally arises as to whether a magnetic chopper has a better neutralization time than an electric chopper. To answer this question, a simple 1-space, 1 time drift-diffusion model of H{sup -} beam in Xe gas has been used to calculate the neutralization times for the following scenarios: (a) a region initially cleared of Xe+ ions with an electric field but partially neutralized outside, (b) a region within and outside the chopper which is initially partially neutralized.
Date: March 1, 2010
Creator: Tan, Cheng-Yan
Partner: UNT Libraries Government Documents Department

The FNAL Injector Upgrade Status

Description: The new FNAL H{sup -} injector upgrade is currently being tested before installation in the Spring 2012 shutdown of the accelerator complex. This line consists of an H{sup -} source, low energy beam transport (LEBT), 200 MHz RFQ and medium energy beam transport (MEBT). Beam measurements have been performed to validate the design before installation. The results of the beam measurements are presented in this paper.
Date: May 14, 2012
Creator: Tan, C.Y.; Bollinger, D.S.; Duel, K.L.; Karns, P.R.; Lackey, J.R.; Pellico, W.A et al.
Partner: UNT Libraries Government Documents Department

Chromatic Correction in the CEBAF Beam Transport System

Description: The CEBAF accelerator beam transport system contains 104 sextupoles to correct chromatic aberrations. We describe the layout of these elements and discuss schemes for suppressing chromatic errors. Analytic results for the required sextupole strengths are given and computations of chromatic aberrations are documented. Numerical results using two correction methods are provided.
Date: May 1, 1991
Creator: Douglas, David
Partner: UNT Libraries Government Documents Department

A Vlasov solver for collective effects in particle accerators

Description: Integration techniques based on Lie algebraic methods have been successfully used in beam transport codes for particle accelerators. Generally these methods have been applied to problems of single-particle beam dynamics. Here we present an application of Lie algebraic techniques to the development of a Vlasov solver suitable for problems of beam transport in the presence of non-negligible particle self-fields. The solver we discuss is suitable for modelling a variety of collective effects that may arise at high current. In particular, we consider the case of coherent synchrotron radiation effects in magnetic bunch compressors which can cause instabilities limiting performance of high current accelerators.
Date: February 1, 2009
Creator: Migliorati, M.; Schiavi, A.; Dattoli, G. & Venturini, M.
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

The Adiabatic Matching Section Solution for the Source Injector

Description: Typical designs for a Heavy Ion Fusion Power Plant require the source injector to deliver 100 beams, packed into an array with a spacing of 7 cm. When designing source injectors using a single large aperture source for each beam, the emitter surfaces are packed into an array with a spacing of 30 cm. Thus, the matching section of the source injector must not only prepare the beam for transport in a FODO lattice, but also funnel the beams together. This can be accomplished by an ESQ matching section in which each beam travels on average at a slight angle to the axis of the quadrupoles and uses the focusing effect of the FODO lattice to maintain the angle. At the end of the matching section, doublet steering is used to bring the beams parallel to each other for injection into the main accelerator. A specific solution of this type for an 84-beam source injector is presented. PACS: 41.75.Ak,41.85.Ar, 41.85.Ja
Date: September 15, 2000
Creator: Ahle, L.; Grote, D.P.; Halaxa, E.; Henestroza, E.; Kwan, J.W. & Mac Laren, S.A.
Partner: UNT Libraries Government Documents Department

A 3D Model for Ion Beam Formation and Transport Simulation

Description: In this paper, we present a three-dimensional model forself-consistently modeling ion beam formation from plasma ion sources andtransporting in low energy beam transport systems. A multi-sectionoverlapped computational domain has been used to break the originaltransport system into a number of weakly coupled subsystems. Within eachsubsystem, macro-particle tracking is used to obtain the charge densitydistribution in this subdomain. The three-dimensional Poisson equation issolved within the subdomain after each particle tracking to obtain theself-consistent space-charge forces and the particle tracking is repeateduntil the solution converges. Two new Poisson solvers based on acombination of the spectral method and the finite difference multigridmethod have been developed to solve the Poisson equation in cylindricalcoordinates for the straight beam transport section and in Frenet-Serretcoordinates for the bending magnet section. This model can have importantapplication in design and optimization of the low energy beam line opticsof the proposed Rare Isotope Accelerator (RIA) front end.
Date: February 7, 2006
Creator: Qiang, J.; Todd, D. & Leitner, D.
Partner: UNT Libraries Government Documents Department

Advanced light source vacuum policy and vacuum guidelines for beamlines and experiment endstations

Description: The purpose of this document is to: (1) Explain the ALS vacuum policy and specifications for beamlines and experiment endstations. (2) Provide guidelines related to ALS vacuum policy to assist in designing beamlines which are in accordance with ALS vacuum policy. This document supersedes LSBL-116. The Advanced Light Source is a third generation synchrotron radiation source whose beam lifetime depends on the quality of the vacuum in the storage ring and the connecting beamlines. The storage ring and most of the beamlines share a common vacuum and are operated under ultra-high-vacuum (UHV) conditions. All endstations and beamline equipment must be operated so as to avoid contamination of beamline components, and must include proper safeguards to protect the storage ring vacuum from an accidental break in the beamline or endstation vacuum systems. The primary gas load during operation is due to thermal desorption and electron/photon induced desorption of contaminants from the interior of the vacuum vessel and its components. The desorption rates are considerably higher for hydrocarbon contamination, thus considerable emphasis is placed on eliminating these sources of contaminants. All vacuum components in a beamline and endstation must meet the ALS vacuum specifications. The vacuum design of both beamlines and endstations must be approved by the ALS Beamline Review Committee (BRC) before vacuum connections to the storage ring are made. The vacuum design is first checked during the Beamline Design Review (BDR) held before construction of the beamline equipment begins. Any deviation from the ALS vacuum specifications must be approved by the BRC prior to installation of the equipment on the ALS floor. Any modification that is incorporated into a vacuum assembly without the written approval of the BRC is done at the user`s risk and may lead to rejection of the whole assembly.
Date: August 1, 1995
Creator: Hussain, Z.
Partner: UNT Libraries Government Documents Department

Some practical aspects of undulator radiation properties

Description: It is important to be able to accurately predict the spectral and angular distribution of undulator radiation properties when designing beamlines; at new synchrotron radiation facilities or when performing radiation experiments at already existing beamlines. In practice, the particle beam emittance and beam energy spread must be taken into account in modeling these properties. The undulators fabricated today are made with small RMS phase errors, making them perform almost as, ideal devices. Calculation tools for numerical modeling of undulator radiation sources (ideal and nonideal) will be discussed, and the excellent agreement with experimentally obtained absolute spectral flux measurements of undulator A at the Advanced Photon Source verifies the high accuracy of the computer codes and the high quality of the undulators being built today. Our focus here is on flux properties useful in practical beamline designs, and the chosen examples demonstrate the versatility of computer programs available to beamline designers and experimentalists.
Date: November 1996
Creator: Ilinski, P.; Dejus, R. J.; Gluskin, E. & Morrison, T. I.
Partner: UNT Libraries Government Documents Department

High intensity proton acceleration at the Brookhaven AGS -- An update

Description: The AGS accelerator complex is into its third year of 60+ {times} 10{sup 12} (teraproton = Tp) per cycle operation. The hardware making up the complex as configured in 1997 is briefly mentioned. The present level of accelerator performance is discussed. This includes beam transfer efficiencies at each step in the acceleration process, i.e. losses; which are a serious issue at this intensity level. Progress made in understanding beam behavior at the Linac-to-Booster (LtB) injection, at the Booster-to-AGS (BtA) transfer as well as across the 450 ms AGS accumulation porch is presented. The state of transition crossing, with the gamma-tr jump is described. Coherent effects including those driven by space charge are important at all of these steps.
Date: July 1, 1997
Creator: Ahrens, L.; Alessi, J. & Blaskiewicz, M.
Partner: UNT Libraries Government Documents Department

Overview of the national spallation neutron source with emphasis on the target station

Description: The technologies that are being utilized to design and build a state-of-the-art neutron spallation source, the National Spallation Neutron Source (NSNS), are discussed. Emphasis is given to the technology issues that present the greatest scientific challenges. The present facility configuration, ongoing analysis and the planned hardware research and development program are also described.
Date: June 1, 1997
Creator: Gabriel, T.A.; Barnes, J.N. & Charlton, L.A.
Partner: UNT Libraries Government Documents Department