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Title: Design and delivery of the diamond double double bend achromat project

Abstract

A major project is underway at Diamond Light Source to remove one of the 24 Double Bend Achromat (DBA) Storage Ring cells and replace it with a Double Double Bend Achromat (DDBA). In this way a new Insertion Device (ID) straight can be created and so ID light can be produced and delivered to a beamline previously only capable of receiving Bending Magnet (BM) radiation. This project is in support of the micro-focus Protein Crystallography (MX) beamline VMX-m which is scheduled to take users towards the end of 2017. This paper describes the Engineering Design of the DDBA project in more detail and gives the current status of the project.

Authors:
; ;  [1]
  1. Diamond Light Source, Didcot, Oxfordshire, UK, OX11 0DE (United Kingdom)
Publication Date:
OSTI Identifier:
22608331
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1741; Journal Issue: 1; Conference: SRI2015: 12. international conference on synchrotron radiation instrumentation, New York, NY (United States), 6-10 Jul 2015; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; CRYSTALLOGRAPHY; CURRENTS; DESIGN; DIAMONDS; MAGNETS; SCHEDULES; STORAGE RINGS

Citation Formats

Kay, J., E-mail: jim.kay@diamond.ac.uk, Hammond, N. P., and Thomson, A. Design and delivery of the diamond double double bend achromat project. United States: N. p., 2016. Web. doi:10.1063/1.4952817.
Kay, J., E-mail: jim.kay@diamond.ac.uk, Hammond, N. P., & Thomson, A. Design and delivery of the diamond double double bend achromat project. United States. doi:10.1063/1.4952817.
Kay, J., E-mail: jim.kay@diamond.ac.uk, Hammond, N. P., and Thomson, A. 2016. "Design and delivery of the diamond double double bend achromat project". United States. doi:10.1063/1.4952817.
@article{osti_22608331,
title = {Design and delivery of the diamond double double bend achromat project},
author = {Kay, J., E-mail: jim.kay@diamond.ac.uk and Hammond, N. P. and Thomson, A.},
abstractNote = {A major project is underway at Diamond Light Source to remove one of the 24 Double Bend Achromat (DBA) Storage Ring cells and replace it with a Double Double Bend Achromat (DDBA). In this way a new Insertion Device (ID) straight can be created and so ID light can be produced and delivered to a beamline previously only capable of receiving Bending Magnet (BM) radiation. This project is in support of the micro-focus Protein Crystallography (MX) beamline VMX-m which is scheduled to take users towards the end of 2017. This paper describes the Engineering Design of the DDBA project in more detail and gives the current status of the project.},
doi = {10.1063/1.4952817},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1741,
place = {United States},
year = 2016,
month = 7
}
  • The Pohang Light Source (PLS) storage ring is a synchrotron light source with the emittance of 18.9 nm at 2.5 GeV and has delivered vacuum ultraviolet and soft x-rays during the past 15 years. We investigate a lattice design for the 3 GeV ring for an upgrade project that keeps the existing tunnel. We investigate a double bend achromat (DBA) structure that provides the reduction of emittance by a factor of 3 and the increase of the number of straight section by a factor of 2 than the existing PLS lattice. We present several characteristics on the beam dynamics, dynamicmore » aperture, and optics matching in the low-emittance lattice which includes squeezed space between magnets. Present PLS lattice has 12 long straight sections of 6.8 m long and the lattice is modified to provide the additional 12 short straight sections of 3.7 m long by eliminating a bending magnet in the middle of the cell of the present triplet bending achromat lattice. Thus, the new lattice consists of a total of 24 straight sections that consist of 12x6.8 and 12x3.7 m long straight sections, which can provide the spaces for the 4- and 2-m-long insertion devices. We present the design results in detail for a DBA lattice in 281.82 m long circumference. It is shown that the emittance of 6.2 nm in the lattice can be achieved by allowing nonzero dispersions in the straight sections. The lattice provides high brilliance at the photon energy of a few 10 keV that meets the requirements by synchrotron radiation users; however, it may require a strong focusing and become sensitive to machine errors and effects of insertion devices. Thus, we investigated the dynamic aperture in the lattice by a simulation method and achieved an optimal tune under the strength of sextupole magnets of 500 T/m{sup 2} for the low-emittance ring. We also performed the lattice tunings to restore the optics due to the errors in the low-emittance ring. In result, our designed lattice shows a good optimization in terms of emittance, brilliance, and circumference as a light source for a 3 GeV.« less
  • In a double bend achromat, Chasman-Green (CG) lattice represents the basic structure for low emittance synchrotron radiation sources. In the basic structure of CG lattice single focussing quadrupole (QF) magnet is used to form an achromat. In this paper, this CG lattice is discussed and an analytical relation is presented, showing the limitation of basic CG lattice to provide the theoretical minimum beam emittance in achromatic condition. To satisfy theoretical minimum beam emittance parameters, achromat having two, three, and four quadrupole structures is presented. In this structure, different arrangements of QF and defocusing quadruple (QD) are used. An analytical approachmore » assuming quadrupoles as thin lenses has been followed for studying these structures. A study of Indus-2 lattice in which QF-QD-QF configuration in the achromat part has been adopted is also presented.« less
  • Using a 1D steady-state free-space coherent synchrotron radiation (CSR) model, we identify a special design setting for a triple-bend isochronous achromat that yields vanishing emittance growth from CSR. When a more refined CSR model with transient effects is included in the analysis, numerical simulations show that the main effect of the transients is to shift the emittance growth minimum slightly, with the minimum changing only modestly.
  • Using a 1D steady-state free-space coherent synchrotron radiation (CSR) model, we identify a special design setting for a triple-bend isochronous achromat that yields vanishing emittance growth from CSR. When a more refined CSR model with transient effects is included in the analysis, numerical simulations show that the main effect of the transients is to shift the emittance growth minimum slightly, with the minimum changing only modestly.
  • The basic Chasman-Green or double focusing achromat (DFA) lattice, see Fig. 1, represents the most compact and economical of the structures used in low emittance electron storage rings. The main problem with this structure arises from the requirement to operate at zero (or slightly positive) chromaticity. This demands the use of strong sextupole fields, which drive third order structure resonances. These, in turn, place a restriction on the tune of the lattice, particularly in the radial plane. Unfortunately, the DFA structure, which, when operated in the low emittance mode has a fixed phase advance across the achromat, is not verymore » flexible in this regard. We will show, for example, that it is not possible to design for high-beta insertions while maintaining the desired tune. The triple bend achromat (TBA) structure utilizing combined function magnets, see Fig. 2, first described by Vignola as a candidate for the U.S. 6 GeV synchrotron radiation source, is the logical extension of the DFA lattice. Adding an extra bending magnet within the achromat permits the designer to tailor the phase advance across the achromat and the beta value in the insertion region while maintaining the desired tune shift across the cell. This paper details the difficulties with the DFA structure and shows how they are overcome in the TBA design. The principles are illustrated in two lattices which have been optimized for a 1.5 GeV synchrotron light source.« less