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Transverse instability analysis for the IPNS Upgrade

Description: The proposed 1-MW spallation neutron source upgrade calls for a 2-GeV rapidly-cycling synchrotron (RCS) with an intensity of 1.04{times}10{sup 14} protons per pulse. The potential exists for the excitation of collective, intensity-dependent transverse instabilities. These can normally be controlled by introducing a betatron tune shift or spread, where care is exercised to avoid single-particle resonance effects. Adjusting the chromaticity using sextupoles to vary the head-to-tail phase shift is compared to introducing Landau damping by octupoles. An option for a feedback system is also examined. The momentum spread used for the transverse analysis was obtained from the requirements for longitudinal stability.
Date: July 1, 1995
Creator: Harkay, K. & Cho, Y.
Partner: UNT Libraries Government Documents Department

Advanced Photon Source insertion device field quality and multipole error specification

Description: The Advanced Photon Source (APS) storage ring is a 7-GeV light source with forty straight sections. Intense x-ray beams will be delivered by insertion devices installed in these straight sections. Installation of insertion devices in the APS storage ring produces several effects which can degrade overall performance. Rigid ring performance requirements exist which can be used to set limits on insertion device field quality, i.e. the first- and second-field integrals of the transverse magnetic field. Individual multipole error specifications can be determined by considering the lifetime of the beam. For nominal operation of the APS storage ring, the vertical aperture corresponding to a 10-hour lifetime is approximately 3.35 mm, which limits the level of multipole error. We find that the skew-octupole error has the most significant effect on the reduction of the aperture; the reasons are discussed in this paper.
Date: July 1, 1995
Creator: Chae, Yong-Chul & Decker, G.
Partner: UNT Libraries Government Documents Department

A superconducting bending magnet system for a compact synchrotron light source

Description: High intensity, high energy X-rays for use in protein crystallography, nano-machining and medical applications, such as non invasive coronary angiography, can be produced by a 1.2 to 1.5 GeV electron storage ring compact light source with 6 to 8 tesla superconducting bending magnets. Because the bending magnets are to be superconducting, the storage ring energy can be over factor of two lower than a conventional storage ring that delivers same photon energy. The ring, which has superconducting bending magnets, is smaller in circumference and has the advantage of having fewer particles in the ring for a given x ray source intensity. The proposed storage ring is a separated function accelerator ring with six superconducting bending magnet units. Conventional quadruples and correction elements would be located between the bending magnets. Because the synchrotron radiation is generated in the bend, the superconducting bending magnets must have a warm vacuum chamber for the electron beam. Variations of a superferric magnet design have been studied for this application. This report presents a superferric H magnet design that can produce good quality magnetic field in a region that is 50 mm high by 100 mm wide. This modified superferric H magnet design has saturated iron poles but the magnetic flux is returned from one pole to the other through an unsaturated iron return path. The dipole magnet required for a compact storage ring must be physically short (380 mm long), and the field must fall off rapidly at the ends of the magnet. This report describes a preliminary design for a pair of 6.894 tesia, thirty degree bending magnets in a common vacuum vessel for use in a 1.5 GeV compact storage ring light source.
Date: July 1, 1995
Creator: Green, M.A.; Garren, A.A.; Leung, E.M.; Madura, D.D.; Cline, D.B.; Kolonko, J.J. et al.
Partner: UNT Libraries Government Documents Department

Polarization measurement and vertical aperture optimization for obtaining circularly polarized bend-magnet radiation

Description: Using multilayer linear polarizers, we have studied the polarization state of radiation from bend magnet beamline 9.3.2 at Advanced Light Source as function of vertical oping angle at photon energies 367 and 722 eV. Both a fine slit and a coarse semi-aperture were stepped across the beam to accept different parts of the vertical radiation fan. Polarimetry yields the degree of linear polarization directly and the degree of circular polarization indirectly assuming an immeasurably small amount of unpolarized radiation based on close agreement of theory and experiment for linear polarization. Results are in good agreement with theoretical calculations, with departures from theory owing to uncertainty in effective aperture of the measured beam. The narrow 0.037 mrad aperture on the orbit plane transmits a beam whose degree of linear polarization exceeds 0.99 at these energies. The wide semi-aperture blocking the beam from above and below transmits a beam with a max figure of merit, given by the square root of flux times degree of circular polarization, when the aperture edge is on the orbit plane thus blocking only half of the total available flux.
Date: October 1, 1995
Creator: Kortright, J.B.; Rice, M. & Hussain, Z.
Partner: UNT Libraries Government Documents Department

Energy and angular distributions of radiation power from bending magnet and wiggler sources at a 6-GeV ring

Description: In order to design radiation ports and beam line components, it is essential to understand the distribution of power from a radiation source as a function of both the photon energy and the solid angle of emission. In this preliminary note, we assemble all the formula involved for the case of a bending magnet and a wiggler. Typical distributions are presented for the case of 6-Gev radiation.
Date: September 25, 1985
Creator: Shenoy, G.K. & Viccaro, P.J.
Partner: UNT Libraries Government Documents Department

Theorem on magnet fringe field

Description: Transverse particle motion in particle accelerators is governed almost totally by non-solenoidal magnets for which the body magnetic field can be expressed as a series expansion of the normal (b{sub n}) and skew (a{sub n}) multipoles, B{sub y} + iB{sub x} = {summation}(b{sub n} + ia{sub n})(x + iy){sup n}, where x, y, and z denote horizontal, vertical, and longitudinal (along the magnet) coordinates. Since the magnet length L is necessarily finite, deflections are actually proportional to ``field integrals`` such as {bar B}L {equivalent_to} {integral} B(x,y,z)dz where the integration range starts well before the magnet and ends well after it. For {bar a}{sub n}, {bar b}{sub n}, {bar B}{sub x}, and {bar B}{sub y} defined this way, the same expansion Eq. 1 is valid and the ``standard`` approximation is to neglect any deflections not described by this expansion, in spite of the fact that Maxwell`s equations demand the presence of longitudinal field components at the magnet ends. The purpose of this note is to provide a semi-quantitative estimate of the importance of {vert_bar}{Delta}p{sub {proportional_to}}{vert_bar}, the transverse deflection produced by the ion-gitudinal component of the fringe field at one magnet end relative to {vert_bar}{Delta}p{sub 0}{vert_bar}, the total deflection produced by passage through the whole magnet. To emphasize the generality and simplicity of the result it is given in the form of a theorem. The essence of the proof is an evaluation of the contribution of the longitudinal field B{sub x} from the vicinity of one magnet end since, along a path parallel to the magnet axis such as path BC.
Date: December 31, 1995
Creator: Wei, Jie & Talman, R.
Partner: UNT Libraries Government Documents Department

A preliminary analysis of the APS crotch design

Description: A preliminary design analysis of the absorber plate of the proposed crotch for the APS bending magnet radiation is presented. Various design aspects including thermal and structural considerations, material selection, geometry, and cooling method are discussed and a number of recommendations are made.
Date: March 1, 1990
Creator: Khounsary, A.M.
Partner: UNT Libraries Government Documents Department

6 GeV synchrotron x-ray source: Conceptual design report. Supplement A - characteristics of the insertion devices for the 6 GeV synchrotron source

Description: Historically, synchrotron radiation (SR) has been obtained primarily from bending-magnet (BM) sources. These continuous sources of electromagnetic radiation have contributed in a major way to our understanding of the structure and dynamics of biological, chemical and material systems. During the past few years, newer sources of SR based on sophisticated periodic magnetic structures, called insertion devices (IDs), have been developed. The electromagnetic radiation from these IDs can be used as a very versatile probe in scientific and technological research which is far superior to that based on a BM source.
Date: March 1, 1986
Partner: UNT Libraries Government Documents Department

Dipole magnets for the SLAC 50 GeV A-Line upgrade

Description: The SLAC A-Line is a transport system originally designed to deliver electron beams of up to 25 GeV to fixed target experiments in End Station A. To raise the beam energy capability of the A-Line to 52 GeV, the eight original bending magnets, plus four more of the same type, have been modified by reducing their gaps and adding trim windings to compensate for energy loss due to synchrotron radiation. In this paper the authors describe the modifications that have been completed, and they compare test and measurement results with predicted performance.
Date: May 1, 1995
Creator: Erickson, R.; DeBarger, S.; Spencer, C.M. & Wolf, Z.
Partner: UNT Libraries Government Documents Department

ETA-II experiments for determining advanced radiographic capabilities of induction linacs

Description: LLNL has proposed a multi-pulsed, multi-line of sight radiographic machine based on induction linac technology to be the core of the advanced hydrotest facility (AHF) being considered by the Department of Energy. In order to test the new technologies being developed for AHF we have recommissioned the Experimental Test Accelerator (ETA II). We will conduct our initial experiments using kickers and large angle bending optics at the ETA II facility. Our current status and our proposed experimental schedule will be presented.
Date: May 1, 1997
Creator: Weir, J.T.; Caporaso, G.J.; Clark, J.C.; Kirbie, H.C.; Chen, Y.-J.; Lund, S.M. et al.
Partner: UNT Libraries Government Documents Department

Strength and shape of the magnetic field of the Fermilab Main Injector dipoles

Description: Measurements of 230 6-meter and 136 4-meter dipoles constructed for the Fermilab Main Injector were carried out as part of the magnet production effort. An automated measurement system provided data on magnetic field strength and shape using several partially redundant systems. Results of these measurements are available for each individual magnet for use in accelerator modelling. In this report we will summarise the results on all of the magnets to characterise the properties which will govern accelerator operation.
Date: April 8, 1999
Creator: al., D.J. Harding et
Partner: UNT Libraries Government Documents Department

Progress on the study of self-interaction of a bunch in a bend

Description: When a short (mm-length) bunch with high (nC-regime) charge is transported through a magnetic bending system, self-interaction via coherent synchrotron radiation and space charge may cause emittance growth. Earlier the authors studied analytically the shielded transient self-interaction of a rigid-line bunch entering from a straight path to a circular orbit, and estimated the concomitant emittance degradation in parts of Jefferson Lab`s infrared free-electron laser (IR-FEL). In this paper, they generalize their earlier results by calculating the curvature-induced steady-state longitudinal wakefield on particles with transverse offsets from the design orbit. Recent progress in developing a self-consistent simulation are also presented.
Date: December 31, 1997
Creator: Li, R.; Bohm, C.L. & Bisognano, J.J.
Partner: UNT Libraries Government Documents Department

Setting reference targets

Description: Reference Targets are used to represent virtual quantities like the magnetic axis of a magnet or the definition of a coordinate system. To explain the function of reference targets in the sequence of the alignment process, this paper will first briefly discuss the geometry of the trajectory design space and of the surveying space, then continue with an overview of a typical alignment process. This is followed by a discussion on magnet fiducialization. While the magnetic measurement methods to determine the magnetic centerline are only listed (they will be discussed in detail in a subsequent talk), emphasis is given to the optical/mechanical methods and to the task of transferring the centerline position to reference targets.
Date: April 1, 1997
Creator: Ruland, R.E.
Partner: UNT Libraries Government Documents Department

A comparison of three different ray trace programs for x-ray and infrared synchrotron beamline designs

Description: There are a number of ray trace programs currently used for the design of synchrotron beamlines. While several of these programs have been written and used mostly within the programmer`s institution, many have also been available to the general public. This paper discusses three such programs. One is a commercial product oriented for the general optical designer (not specifically for synchrotron beamlines). One is designed for synchrotron beamlines and is free with restricted availability. Finally, one is designed for synchrotron beamlines and is used primarily in one institution. The wealth of information from general optical materials and components catalogs is readily available in the commercial program for general optical designs. This makes the design of an infrared beamline easier from the standpoint of component selection. However, this program is not easily configured for synchrotron beamline designs, particularly for a bending magnet source. The synchrotron ray trace programs offer a variety of sources, but generally are not as easy to use from the standpoint of the user interface. This paper shows ray traces of the same beamline Optikwerks, SHADOW, and RAY, and compares the results.
Date: July 1, 1997
Creator: Irick, S.C. & Jung, C.R.
Partner: UNT Libraries Government Documents Department

Working Group 2 summary: Space charge effects in bending systems

Description: At the start of the Workshop, the authors asked the Working Group 2 participants to concentrate on three basic goals: (1) survey the status of how comprehensively the physics concerning space-charge effects in bends is understood and how complete is the available ensemble of analytic and computational tools; (2) guided by data from experiments and operational experience, identify sources of, and cures for, beam degradation; and (3) review space-charge physics in rings and the limitations it introduces. As the Workshop unfolded, the third goal naturally folded into the other two goals, and these goals, they believe, were fulfilled in that the Working Group was able to compile an end product consisting of a set of recommendations for potentially fruitful future work. This summary constitutes an overview of the deliberations of the Working Group, and it is their hope that the summary clarifies the motivation for the recommended work listed at the end. The summary is organized according to the two aforementioned goals, and the prime topics of discussion appear as subsections under these goals.
Date: February 1, 2000
Creator: Bohn, C.L. & Emma, P.J.
Partner: UNT Libraries Government Documents Department

Large aperture magnets for a future high power proton synchrotron

Description: A high intensity, high power proton synchrotron is currently under consideration at Fermilab. The machine--known as the Proton Driver--would accelerate 3 x 10{sup 13} protons from 400 MeV to 12 GeV (stage I) or 16 GeV (stage II) and ultimately deliver in excess of 1 MW of beam power. To minimize losses and insure beam stability, the space charge-induced tune shift must be kept well below 0.5. This is accomplished by spreading out bunches both longitudinally and transversely. While the former strategy favors high voltage low frequency RF, the latter leads to magnets with unconventionally large apertures. This requirement, combined with a 1.5 T bending field and rapid cycling operation results in a number of serious but not insurmountable challenges. In this paper, they discuss the design of the Proton Driver magnets and the rationale behind it.
Date: August 14, 2001
Creator: Mills, Jean-Francois Ostiguy and Frederick M.
Partner: UNT Libraries Government Documents Department

Design, construction, and procurement methodology of magnets for the 7-GeV Advanced Photon Source

Description: All major magnets of the Advanced Photon Source (APS) have now been measured and installed in the facility. This paper describes the mechanical design, construction, and procurement philosophy and methodology, and lessons learned from the construction and procurement of more than 1500 magnets for the APS storage ring, injector synchrotron ring, and positron accumulator ring.
Date: June 1995
Creator: Gorski, A.; Argyrakis, J. & Biggs, J.
Partner: UNT Libraries Government Documents Department

Permanent dipole magnets for the 8 GeV transfer line at FNAL

Description: The transfer line that will serve to transport 8 GeV protons from the Booster to the new Fermilab Main Injector has been built using permanent magnets. A total of 46 horizontal bend dipoles and 5 vertical bend dipoles were built for this beamline; 67 gradient magnets were also built. The magnets were built using magnetized strontium ferrite bricks. Thermal compensation of these bricks was effected by use of a nickel-iron alloy. The dipole magnets were built with a mean integrated strength of 0.56954 T-m, and an rms spread of 0.06%. The magnets were thermally cycled from 20{degrees}C to 0{degrees}C to condition the ferrite against irreversible thermal losses, and the compensation was measured with a flipcoil. The magnet strength was adjusted by varying the number of bricks installed at the magnet ends. Details of the assembly process and a summary of magnetic measurements are presented here.
Date: June 1, 1997
Creator: Glass, H.D.; Brown, B.C.; Foster, G.W.; Fowler, W.B. & Haggard, J.E.
Partner: UNT Libraries Government Documents Department