Abstract
In the continuing efforts to reduce the beam emittance of an electron storage ring composed of theoretical minimum emittance (TME) lattice, down to a level of several tens of picometers, nonlinear dynamics grows to be a great challenge to the performance of the storage ring because of the strong sextupoles needed to compensate for its large global natural chomaticities coupled with its small average dispersion function. To help in dealing with the challenge of nonlinear optimization, we propose a novel variation of theoretical minimum emittance (TME) lattice, named as ``modified-TME'' lattice, with minimal emittance about 3 times of the exact theoretical minimum, while with more compact layout, lower phase advance per cell, smaller natural chromaticities, and more relaxed optical functions than that in a TME cell, by using horizontally defocusing quadrupole closer to the dipole or simply combined-function dipole with horizontally defocusing gradient. We present approximate scaling formulas to describe the relationships of the design parameters in a modified-TME cell. The applications of modified-TME lattice in the PEP-X storage ring design are illustrated and the proposed lattice appears a good candidate for synchrotron radiation light source with extremely low emittance.
Highlights
Emittance is one of the most important parameters for electron storage rings
The bending angle of the dipole in the matching cell is set to 3À1=3 of that in the standard cell to preserve the minimal emittance [3,7]. Other than this type of lattice, double bend achromat (DBA) and triple bend achromat (TBA) lattices are usually adopted in the low-emittance synchrotron radiation storage ring design
We demonstrate that a modified-theoretical minimum emittance (TME) cell promises more compact layout than a conventional-TME cell in the Appendix; and in Sec
Summary
Emittance is one of the most important parameters for electron storage rings. Extremely low emittance allows high luminosity in colliders or high brightness in synchrotron light sources. The bending angle of the dipole in the matching cell is set to 3À1=3 of that in the standard cell to preserve the minimal emittance [3,7] Other than this type of lattice, double bend achromat (DBA) and triple bend achromat (TBA) lattices are usually adopted in the low-emittance synchrotron radiation storage ring design. Due to the found scaling law, the natural chromaticities of such a modifiedTME cell can be exactly solved with a simplified model The properties of such a lattice configuration are summarized and compared with that of a TME cell, and it shows that this type of lattice appears a good candidate for storage ring-based light source with extreme-low emittance. An empirical scaling law for the relationship between r and Dr for a modified-TME cell with combined-function defocusing dipole is presented Applications of such a type of lattice in PEP-X light source storage design are presented as demonstration
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Physical Review Special Topics - Accelerators and Beams
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
