• J. Skaritka, J. Bengtsson, G. Danby, G. Ganetis, W. Guo, R.C. Gupta, J.W. Jackson, A.K. Jain, S.L. Kramer, S. Krinsky, Y. Li, W. Meng, B. Nash, S. Ozaki, M. Rehak, S. Sharma, C.J. Spataro, F.J. Willeke
  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.

• W. Guo, S.L. Kramer, S. Krinsky, Y. Li, B. Nash, T. Tanabe
  BNL, Upton, Long Island, New York

Funding: NSLS-II, Brookhaven National Laboratory

NSLS-II, the third-generation light source which will be built at BNL is designed and optimized for 3 GeV energy, ultra-small emittance and high intensity of 500 mA. It will provide very bright synchrotron radiation over a large spectral range from IR to hard X-rays. Damping wigglers (DWs) are deployed to reduce the emittance of 2 nm by factors of 2-4, as well as for intense radiation sources for users. The linear and nonlinear effects induced by the DWs are integrated into the lattice design. In this paper, we discuss the linear and nonlinear optimization with DWs, and present a solution satisfying the injection and lifetime requirements. Our approach could be applied to the other light sources with strong insertion devices.

• B. Nash, S.L. Kramer
  BNL, Upton, Long Island, New York

The Touschek effect limits the lifetime for NSLS-II. The basic mechanism is Coulomb scattering resulting in a longitudinal momentum outside the momentum aperture. The momentum aperture results from a combination of the initial betatron oscillations after the scatter and the non-linear properties determining the resultant stability. We find that higher order multipole errors may reduce the momentum aperture, particularly for scattered particles with energy loss. The resultant drop in Touschek lifetime is minimized, however, due to less scattering in the dispersive regions. We describe these mechanisms, and present calculations for NSLS-II using a realistic lattice model including damping wigglers and engineering tolerances.

• B. Nash, W. Guo
  BNL, Upton, Long Island, New York

Successful operation of NSLS-II requires sufficient dynamic aperture for injection, as well as momentum aperture for Touschek lifetime. We explore the dependence of momentum and dynamic aperture on higher-order multipole field errors in the quadrupoles and sextupoles. We add random and systematic multipole errors to the quadrupoles and sextupoles and compute the effect on dynamic aperture. We find that the strongest effect is at negative momentum, due to larger closed orbit excursions. Adding all the errors based on the NSLS-II specifications, we find adequate dynamic and momentum aperture.

• L.-H. Yu, B. Nash
  BNL, Upton, Long Island, New York

We present a newly developed method to analyze some non-linear dynamics problems such as the Henon map using a linear matrix analysis method in linear algebra. Using the Henon map as an example, we analyze the spectral structure, the tune-amplitude dependence, the variation of tune and amplitude during the particle motion, etc., using the method of analysis of eigenvectors in Jordan spaces which is widely used in conventional linear algebra.

• A. Blednykh, S. Krinsky, B. Nash, L.-H. Yu
  BNL, Upton, Long Island, New York

For the NSLS-II storage ring with damping wigglers but without a Landau cavity, the low-current bunch length is 4.5mm. We have studied bunch lengthening and estimated the microwave instability threshold using the multi-particle tracking code TRANFT. An estimate of the pseudo-Green’s function for a 0.5mm driving bunch was obtained for most components of the vacuum system by using the 3D code GdfidL. With our present computer resources, certain components were too large and had too complex geometry to allow the wake for such a short bunch to be computed using GdFidL. In these cases, the actual 3D geometry was approximated by a structure having circular cross-section, and the pseudo-Green’s function was computed using the 2D code ABCI. It was found that the dominant geometric wake is due to the tapers for the in-vacuum undulators. The resistive wall wake is also important. The effect of pseudo-Green’s functions corresponding to an even shorter driving bunch (0.05mm) was investigated using the program ECHO to compute the wake of tapers with circular cross-section. Our results suggest that the microwave threshold will occur at an average single-bunch current greater than 5mA.

• B. Nash, S. Krinsky
  BNL, Upton, Long Island, New York

Single large angle Coulomb scattering is referred to as Touschek scattering. In addition to causing particle loss when the scattered particles are outside the momentum aperture, the process also results in a non-Gaussian tail, which is an equilibrium between the Touschek scattering and radiation damping. Here we present an analytical calculation for this equilibrium distribution.

• B. Nash
  SLAC, Menlo Park, California

We describe a set of tools that interface to the Tracy particle tracking library. The state of the machine including misalignments, multipole errors and corrector settings is captured in a 'flat' file, or 'machine' file. There are three types of tools designed around this flat file: 1) flat file creation tools. 2) flat file manipulation tools. 3) tracking tools. We describe the status of these tools, and give some examples of how they have been used in the design process for NSLS-II.