BNL, Upton, Long Island, New York
Funding: Work supported by U.S. DOE, Contract No.DE-AC02-98CH10886
The NSLS-II light source is a proposed 3 GeV storage ring, with the potential for ultra-low emittance*. Despite the reduced emittance goal for the bare lattice, the closed orbit amplification factors are on average >50 in both planes, for random quadrupole alignment errors. The high chromaticity will also require strong sextupoles and the low 3 GeV energy will require large dynamic and momentum aperture to insure adequate lifetime. This will require tight alignment tolerances (~30microns) on the multipole magnets during installation. By specifying tight alignment tolerances of the magnets on the support girders, the random alignment tolerances of the girders in the tunnel can be significantly relaxed. Using beam based alignment to find the golden orbit through the quadrupole centers, the closed orbit offsets in the multipole magnets will then be reduced to essentially the alignment errors of the magnets, restoring much of the DA and lifetime of the bare lattice. Our R&D program to achieve these tight alignment tolerances of the magnets on the girders using a vibrating wire technique**, will be discussed and initial results presented.
*Work presented on behalf of the NSLS-II Design Team, CDR(2006) and CD2(2007).
**A. Jain, et al, International Workshop on Accelerator Alignment, Tsukuba, Japan, Feb.11-15, 2008.
BNL, Upton, Long Island, New York
Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
eRHIC, a future high luminosity electron-ion collider at BNL, will add polarized electrons to the list of colliding species in RHIC. A 10-to-30 GeV electron energy recovery linac will require up to six passes around the RHIC 3.8 km circumference. We are developing and testing small (3-to-5 mm gap) dipole and quadrupole magnets and vacuum chambers for cost-effective eRHIC passes. We are also studying the sensitivity of eRHIC pass optics to magnet and alignment errors in such a small-magnet structure. We present the magnetic and mechanical designs of the small gap eRHIC components and prototyping test results.
BNL, Upton, Long Island, New York
Funding: US DOE Office of Basic Energy Sciences
The design and measurement of the NSLS-II ring quadrupoles prototypes are presented. These magnets are part of a larger prototype program described in [1]. Advances in software, hardware, and manufacturing have led to some new level of insight in the quest for the perfect magnet design. Three geometric features are used to minimize the first three allowed harmonics by way of optimization. Validations through measurement and confidence levels in calculations are established.
BNL, Upton, Long Island, New York
Funding: US DOE Office of Basic Energy Sciences
NSLS-II is a new state-of-the-art medium energy synchrotron light source designed to deliver world leading brightness and flux with top-off operation for constant output. Design and engineering of NSLS-II began in 2005 and the beginning of construction and operations are expected to start in 2009 and 2015, respectively. The energy of the machine is 3Gev and the circumference 792 m. The chosen lattice requires tight on magnetic field tolerances for the ring magnets. These magnets have been designed with 3D Opera software. The required multipole field quality and alignment preclude the use of multifunctional sextupoles, leading to discrete corrector magnets in the storage ring. The corrector magnets are multifunctional and will provide horizontal and vertical steering as well as skew quadrupole. This paper describes the dipoles, quadrupoles, sextupoles, and corrector magnets design and prototyping status of the NSLS-II.
BNL, Upton, Long Island, New York
Funding: US DOE Office of Basic Energy Sciences
Discrete corrector magnets are used for the 230 horizontal and vertical steering magnets in the NSLS-II storage ring. A unique design incorporates both dipole and skew quad correctors for(DC) steering in the same magnet. Separate AC (orbit feedback) correctors have also been designed. Comparison with alternate designs are presented as well as prototype measurements
BNL, Upton, Long Island, New York
Funding: US DOE Office of Basic Energy Sciences
The Sextupole magnets for the National Synchrotron Light Source (NSLS-II) have stringent performance requirements. These magnets have a faceted pole profile departing from the classic shape due to constraint imposed by the vacuum tube. Three different geometric features were used as parameters to minimize unallowed harmonics. Prototypes were measured and have confirmed the good field quality.
BNL, Upton, Long Island, New York
IN2P3-LAPP, Annecy-le-Vieux
OXFORDphysics, Oxford, Oxon
CERN, Geneva
SLAC, Menlo Park, California
KEK, Ibaraki
Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-98CH10886.
The Accelerator Test Facility (ATF2) at KEK is a scaled down version of the final focus design proposed for the future linear colliders (LC) and aims to experimentally verify the final focus (FF) technology needed to obtain very small, stable beam spots at a LC interaction point. Initially the ATF2 FF is made using conventional (warm) quadrupole and sextupole magnets; however, we propose to upgrade the FF by replacing some of the conventional magnets with new superconducting magnets constructed with the same technology as those of the International Linear Collider baseline FF magnets*. With the superconducting magnet upgrade we can look to achieve smaller interaction point beta-functions and to study superconducting magnet vibration stability in an accelerator environment. Therefore for the ATF2 R&D magnet we endeavor to incorporate cryostat design features that facilitate monitoring of the cold mass movement via interferometric techniques. The design status of the ATF2 superconducting upgrade magnets is reported in this paper.
*International Linear Collider Reference Design Report, ILC-REPORT-2007-001, August 2007.
BNL, Upton, Long Island, New York
Funding: US DOE Office of Basic Energy Sciences
This paper will describe the requirements, the design and the prototype test results of the magnets for the new synchrotron radiation source NSLS-II now under construction at BNL. Several innovations have been incorporated in the design, in manufacturing and in the alignment procedures of the magnets. Prototypes of these magnets have been built in industry. A dipole design has been developed with a maximized magnetic length which is longer than the mechanical length. The quadrupole and sextupole magnets of NSLS-II must be aligned and positioned to better than 30 microns, a level never achieved before in such accelerators. The paper will present a brief status of the progress made in the techniques developed to measure and achieve these demanding requirements. Another concern has been the distortion of field quality due to the small (150 mm) axial spacing between the iron-yoke of two adjacent magnets. Calculations (in 3-D) and the result of systematic measurements of the field quality in the presence of other magnets and other machine components in close proximity will be presented.
BNL, Upton, Long Island, New York
Funding: Work supported by Brookhaven Science Associates, LLC underContract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In order to cross more rapidly the 82 weak resonances caused by the horizontal tune and the partial snakes, we plan to jump the horizontal tune 82 times during the acceleration cycle, 41 up and 41 down*. To achieve this, the magnets creating this tune jump will pulse on in 100 micro-seconds, hold the current flat for about four milli-seconds and zero the current in another 100 micro-seconds. The magnets are old laminated beam transport magnets with longitudinal shims closing the aperture to reduce inductance and power supply current. The power supply uses a high voltage capacitor discharge to raise the magnet current, which is then switched to a low voltage supply, and then the current is switched back to the high voltage capacitor to zero the current. The current in each of the magnet pulses must match the order of magnitude change in proton momentum during the acceleration cycle. The magnet, power supply and cabling will be described with coast saving features and operational experience.
*Overcome Horizontal Depolarizing Resonances in the AGS with Tune Jump
BNL, Upton, Long Island, New York
CERN, Geneva
Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In the article we review the nonlinear beam dynamics from nonlinear magnetic fields in the Relativistic Heavy Ion Collider. The nonlinear magnetic fields include the magnetic field errors in the interaction regions, chromatic sextupoles, and sextupole component from arc dipoles. Their effects on the beam dynamics and long-term dynamic apertures are evaluated. The online measurement and correction methods for the IR nonlinear errors, nonlinear chromaticity, and horizontal third order resonance are reviewed. The overall strategy for the nonlinear effect correction in the RHIC is discussed.
BNL, Upton, Long Island, New York
Funding: Work performed under the auspices of the US DOE.
The existence of multipolar components in the dipole and quadrupole magnets is one of the factors limiting the beam stability in the RHIC operations. Therefore, the statistical properties of the non-linear fields are crucial for understanding the beam behavior and for achieving the superior performance in RHIC. In an earlier work*, the field quality analysis of the RHIC interaction regions (IR) was presented. Furthermore, a procedure for developing non-linear IR models constructed from measured multipolar data of RHIC IR magnets was described. However, the field quality in the regions outside of the RHIC IR regions had not yet been addressed. In this paper, we present the statistical analysis of multipolar components in the magnetic fields of the RHIC arc regions. The emphasis is on the lower order components, especially the sextupole in the arc dipole and the 12-pole in the quadrupole magnets, since they are shown to have the strongest effects on the beam stability. Finally, the inclusion of the measured multipolar components data of RHIC arc regions and their statistical properties into tracking models is discussed.
*J. Beebe-Wang and A. Jain, “Realistic Non-linear Model and Field Quality Analysis in RHIC Interaction Regions”, proc. of PAC 2007, page 4309-4311 (2007)