Achromatic lattice comparison for light sources

Conference · Fri Jan 01 00:00:00 EST 1988

OSTI ID:6711917

Kramer, S L; Crosbie, E A; Cho, Y

The next generation of synchrotron light sources are being designed to support a large number of undulators and require long dispersion-free insertion regions. With less demand for radiation from the dipole magnets, the storage ring cost per undulator beam can be reduced by decreasing the number of dipole magnets and increasing the number of dispersion free straight sections. The two simplest achromatic lattices are the Chasman-Green or double-bend achromatic (DBA) and the three-bend achromat (TBA). The DBA in its simplest form consists of a single horizontally-focussing quadrupole between the two dipole magnets. Since this quadrupole strength is fixed by the achromatic condition, the natural emittance (/var epsilon//sub n/) may vary as the beta functions in the insertion region (IR) are varied. The expanded Chasman-Green (also DBA) uses multiple quadrupoles in the dispersive section to provide emittance control independent of the beta functions in the IR. Although this provides flexibility in the ID beta functions, the horizontal phase advance is constrained to /phi/ /approx equal/ 180/degree/ between approximately the centers of the dipole magnets. If small /var epsilon//sub n/ is required, the horizontal phase advance between the dipoles will be near one and the lattice properties will be dominated by this systematic resonance. The TBA lattice places a third dipole between the DBA dipoles, eliminating the 180/degree/ horizontal phase advance constraint. However, the requirement of small /var epsilon//sub n/ limits the range of tune, since /mu//sub x/ /approx equal/ 1.29 in the dipoles alone for /var epsilon//sub n/ near its minimum value. The minimum emittance is five times smaller for the TBA than for the DBA with the same number of periods and, therefore, its phase advance can be relaxed more than the DBA for the same natural emittance. 5 refs., 4 figs., 1 tab.

• Research Organization: Argonne National Lab., IL (USA)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6711917
• Report Number(s): CONF-880695-70; ON: DE89003937
• Resource Relation: Conference: 1. European particle accelerator conference, Rome, Italy, 7 Jun 1988; Other Information: Portions of this document are illegible in microfiche products
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
BEAM FOCUSING MAGNETS
COMPARATIVE EVALUATIONS
SYNCHROTRON RADIATION SOURCES
DESIGN
BETATRON OSCILLATIONS
STORAGE RINGS
BEAM DYNAMICS
ELECTRICAL EQUIPMENT
ELECTROMAGNETS
EQUIPMENT
MAGNETS
OSCILLATIONS
RADIATION SOURCES
430100* - Particle Accelerators- Design
Development
& Operation