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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

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 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

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

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

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

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

Fabrication and Measurement of 12 GeV Prototype Quadrupoles at Thomas Jefferson National Accelerator Facility

Description: Jefferson Lab's Continuous Electron Beam Accelerator Facility (CEBAF) currently has a maximum beam energy of 6 GeV. The 12 GeV Upgrade Project will double the existing energy and is currently scheduled for completion in 2014. This doubling of energy requires modifications to the beam transport system which includes the addition of several new magnet designs and modifications to many existing designs. Prototyping efforts have been concluded for two different designs of quadrupole magnets required for the upgrade. The design, fabrication and measurement will be discussed.
Date: May 1, 2009
Creator: Tommy Hiatt, Mark Wiseman, Kenneth Baggett, J. Beck, Leigh Harwood, Joseph Meyers, Jeffrey Dail
Partner: UNT Libraries Government Documents Department

Attempted RIAPMTQ Benchmarking Study of the ANL RIA Low-Beta LinacDesign

Description: The objective of this work is to compare the simulation results of the RIAPMTQ code with those of the ANL simulation code for the low-beta section of an ANL RIA Driver Linac design. However, the approach taken is not precisely that of a direct comparison of the two simulations of the same linac section, which is what one would normally expect to do. The reason is that the RFQ design approach used by the ANL codes and the LANL codes are approximately but not exactly the same, particularly at the ends of the RFQ, and it did not appear to be easy to make the two RFQ designs exactly identical. The effects on the beam of the different RFQ design approaches are not expected to be large, as long as the beam is properly matched at the transitions. What was done in the RIAPMTQ input file to compensate for the RFQ design difference was to use TRACE3D to adjust the four solenoid strengths and the two matching rf cavities in the MEBT (the beam transport system between the end of the RFQ and the beginning of the superconducting linac) to obtain the same match (Courant-Snyder parameters) into the superconducting linac as was obtained from the ANL code. We also matched the beam into the RFQ. The result is that we generate a RIAPMTQ input file for the low-beta section of the linac, which is not exactly identical to, but should be near to that of the ANL design. Then, what we wish to compare from the two codes are the rms emittances at the beginning of the superconducting linac, and the beam losses in the first or prestripper section of the superconducting (SC) linac. In this report, we describe the procedure and present the results. Section 2 gives the procedures ...
Date: January 1, 2007
Creator: Billen, J.; Qiang, J. & Wangler, T.
Partner: UNT Libraries Government Documents Department

A laser-wire beam-energy and beam-profile monitor at the BNL linac

Description: In 2009 a beam-energy monitor was installed in the high energy beam transport (HEBT) line at the Brookhaven National Lab linac. This device measures the energies of electrons stripped from the 40mA H{sup -} beam by background gas. Electrons are stripped by the 2.0x10{sup -7}torr residual gas at a rate of {approx}1.5x10{sup -8}/cm. Since beam electrons have the same velocities as beam protons, the beam proton energy is deduced by multiplying the electron energy by m{sub p}/m{sub e}=1836. A 183.6MeV H{sup -} beam produces 100keV electrons. In 2010 we installed an optics plates containing a laser and scanning optics to add beam-profile measurement capability via photodetachment. Our 100mJ/pulse, Q-switched laser neutralizes 70% of the beam during its 10ns pulse. This paper describes the upgrades to the detector and gives profile and energy measurements.
Date: March 28, 2011
Creator: Connolly, R.; Degen, C.; DeSanto, L.; Meng, W.; Michnoff, R.; Minty, M. et al.
Partner: UNT Libraries Government Documents Department

Simple Beam-Optic Simulations and Proposed Mechanical Mitigation for the Triplet Oscillation Problem

Description: The purpose of these simulations is to gain a better understanding of the relative contributions to the beam perturbation from the main horizontal oscillation modes (yawing and rolling) of Q1, Q2, and Q3. For this purpose, a simple beam transport program was implemented with an EXCEL spreadsheet to calculate the horizontal beam envelop through the Q1, Q2, Q3 triplet up to the IP, with the possibility of specifying horizontal displacements of the singlets. For now, the weak focusing properties of D0 and DX have been ignored, but could easily be included in the future if necessary. In a first simulation, quadrupole strengths have been adopted that correspond to {beta}* = 2m at the IP. The parameters used listed in Table 1 were obtained from references [1] and [2].
Date: May 1, 2008
Creator: Thieberger,P.; Montag, C.; Snydstrup, L.; Trbojevic, D. & Tuozzolo, J.
Partner: UNT Libraries Government Documents Department

ION TRAPPING AND CATHODE BOMBARDMENT BY TRAPPED IONS IN DC PHOTOGUNS.

Description: DC photoguns are used to produce high-quality, high-intensity electron beams for accelerator driven applications. Ion bombardment is believed to be the major cause of degradation of the photocathode efficiency. Additionally to ions produced in the accelerating cathode-anode gap, the electron beam can ionize the residual gas in the transport line. These ions are trapped transversely within the beam and can drift back to the accelerating gap and contribute to the bombardment rate of the cathode. This paper proposes a method to reduce the flow of ions produced in the beam transport line and drifting back to the cathode-anode gap by introducing a positive potential barrier that repels the trapped ions. The reduced ion bombardment rate and increased life time of photocathodes will reduce the downtime required to service photoinjectors and associated costs.
Date: June 25, 2007
Creator: POZDEYEV,E.
Partner: UNT Libraries Government Documents Department