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Recently, a novel approach has been proposed to produce ultrashort, fully coherent high-repetition-rate EUV and X-ray radiation by combining an energy recovery linac (ERL) with the angular-dispersion-induced microbunching methodology. It is critical to maintain microbunching when the beam passes through bending magnets between the undulators, which results in difficulties supporting multiple beamlines. In this paper, the design of a multiplexed emitting system consisting of multi-bend achromats, matching sections and radiators to facilitate the multi-beamline operation is presented. Theoretical analysis and numerical simulations have been carried out and the results show that the microbunching and beam quality can be well maintained after four times of bending. Five radiation pulses with a central wavelength of 13.5 nm and peak power at the MW level have been produced by the same electron beam via this multiplexed emitting system. The proposed method holds potential in the multi-beamline operation of ERL- or storage-ring-based coherent light sources.

The Hefei Advanced Light Facility (HALF), recently approved by the Chinese government, is a soft X-ray and VUV light source based on diffraction-limited storage ring (DLSR), which has beam energy of 2.2 GeV and emittance goal of less than 100 pm·rad. The lattice design is the core of the storage ring physics design, and the selection of lattice is crucial to the storage ring performance and the related technology that will be used. The emittances of DLSRs are as low as hundreds or even tens of pm·rad and the insertion device radiation brightness is about 1.2 orders of magnitude higher than that of the third-generation light sources. Generally, increasing the number of bends is the most effective method to reduce the emittance and thus multi-bend achromat (MBA) lattices are used for designing DLSRs. In this paper, firstly, a conventional 6BA (six-bend achromat) lattice with distributed chromaticity correction was designed for the HALF storage ring, which has a circumference of 441.6 m with 18 identical cells. In this lattice design, the horizontal and vertical phase advances of each bend unit cell are about (0.4, 0.1)×2π, so that main nonlinear effects can be effectively cancelled over five identical unit cells based on higher-order achromat. The lattice has an ultra-low emittance of 74 pm·rad and a horizontal dynamic aperture (DA) of about 6 mm. Then two hybrid MBA lattices (HMBA) designed for HALF with 20 cells were briefly introduced, including an ESRF-EBS type H7BA lattice and a modified H6BA lattice, which have horizontal DAs larger than 10 mm. The latter is the present baseline lattice of HALF, which has a long straight section and a short one in each lattice cell. And the two central bend cells of the baseline lattice use longitudinal gradient bends and reverse bends to reduce the emittance and damping times. The H7BA lattice has a circumference of 441.6 m and a natural emittance of 84 pm·rad, and the circumference and natural emittance of the H6BA lattice are 480 m and 86 pm·rad. Compared to the conventional 6BA lattice designed in this paper, two HMBA lattices have larger DAs which can allow off-axis injection. The conventional 6BA lattice and H6BA lattice have shorter damping times than that of the H7BA lattice, which is beneficial for suppressing emittance increase due to intra-beam scattering. Besides, the H6BA lattice has much more straight sections than the other two lattices. So the present modified H6BA lattice is a better option for the HALF storage ring.

Recently, a novel approach has been proposed to produce ultrashort, fully coherent high-repetition-rate EUV and X-ray radiation by combining an energy recovery linac (ERL) with the angular-dispersion-induced microbunching methodology. It is critical to maintain microbunching when the beam passes through bending magnets between the undulators, which results in difficulties supporting multiple beamlines. In this paper, the design of a multiplexed emitting system consisting of multi-bend achromats, matching sections and radiators to facilitate the multi-beamline operation is presented. Theoretical analysis and numerical simulations have been carried out and the results show that the microbunching and beam quality can be well maintained after four times of bending. Five radiation pulses with a central wavelength of 13.5 nm and peak power at the MW level have been produced by the same electron beam via this multiplexed emitting system. The proposed method holds potential in the multi-beamline operation of ERL- or storage-ring-based coherent light sources., (open access.)

We present a lattice design for a low-emittance and high-brilliance 3 GeV synchrotron light source that has been widely investigated in the world. We show the design results for a MBA (Multi-Bend Achromat) lattice with an emittance of 1.3 nm and 282.4 m circumference. Each cell has 5 bending magnets that consist of outer two with bending angle of 4.5° and inner three with bending angle of 7°. The lattice is designed to be flexible and consists of 12 straight sections in which one straight section has a length of 5.9 m. We have studied the dynamic aperture in the lattice with machine errors. It is shown that the designed low-emittance lattice provides sufficient dynamic aperture after COD correction. We present the results of variations of emittance, energy spread and dynamic aperture due to in-vacuum undulators in the straight sections. We performed particle tracking after the beam injection to investigate the efficiency of the injection scheme. We show the designed results of an injection scheme that shows the space allocation in injection section and the particle motions of injected beam. Our designed lattice provides a good optimization in terms of the emittance and brilliance as a light source for 3 GeV energy and circumference of 28 m. [ABSTRACT FROM AUTHOR]

TheMAX IV 3 GeV storage ring, currently under construction, pursues the goal of low electron beam emittance by using a multi-bend achromat magnet lattice, which is realised by having several consecutive magnet elements precisionmachined out of a common solid iron block, 2.3-3.4 m long. With this magnet design solution, instead of having 1320 individual magnets, the MAX IV 3 GeV storage ring is built up using 140 integrated 'magnet block' units, containing all these magnet elements. Major features of this magnet block design are compactness, vibration stability and that the alignment of magnet elements within each unit is given by the mechanical accuracy of the CNC machining rather than individual field measurement and adjustment. This article presents practical engineering details of implementing this magnet design solution, and mechanical + magnetic field measurement results from the magnet production series. At the time of writing (spring 2014), the production series, which is totally outsourced to industry, is roughly half way through, with mechanical/magnetic QA conforming to specifications. It is the conclusion of the authors that the MAX IV magnet block concept, which has sometimes been described as new or innovative, is from a manufacturing point of view simply a collection of known mature production methods and measurement procedures, which can be executed at fixed cost with a low level of risk. [ABSTRACT FROM AUTHOR]

The lattice design and beam dynamics optimization for Sirius, a new lowemittance synchrotron light source presently under construction at the Brazilian Synchrotron Light Laboratory (LNLS) in Campinas, Brazil, is presented. The electron storage ring is based on a five-bend achromat (5BA) design achieving a bare lattice emittance of 0.28 nm rad for a 3 GeV beam. The circumference of 518 m contains 20 achromatic straight sections of alternating 7 m and 6 m in length. An innovative approach is adopted to enhance the performance of the storage ring dipoles by combining low-field (0.58 T) magnets for the main beam deflection with a very short 2 T permanent-magnet superbend sandwiched in the center dipole. This superbend creates 12 keV critical photon energy dipole sources with modest total energy loss from dipoles. In addition it also creates a longitudinal dipole field gradient that reduces the emittance by about 10%. The optimized dynamic aperture allows for top-up operation with off-axis injection and the optimized energy acceptance allows for a total beam lifetime of around 11 h at nominal current with a third-harmonic cavity. [ABSTRACT FROM AUTHOR]

In the design of multi-bend achromat (MBA) lattices for diffraction-limited storage rings (DLSRs), usually, many magnet parameters need to be adjusted, and the constraints to be satisfied can be stringent. When using an evolutionary algorithm to optimize such a complicated lattice, there can be only few or even none of lattice solutions satisfying the constraints in the early evolution stage of the algorithm, which may significantly affect the optimization result. Therefore, the techniques for constraint handling in an evolutionary algorithm will be important for better optimizing MBA lattices. In this paper, three typical constraint handling methods that are incorporated into a multi-objective particle swarm optimization algorithm are used to optimize a hybrid 7BA lattice for a 2.2 GeV DLSR. In this lattice optimization, the impacts of the population size of the algorithm and the constraint condition on the optimization result are studied for these methods, and comparisons are also made among these methods. It is shown that, in general, the penalty function method is a better constraint handling method for optimizing MBA lattices. From the optimization result obtained by the penalty function method, a lattice with a natural emittance of about 84 pm ⋅ rad is selected, which has large dynamic aperture and momentum aperture. [ABSTRACT FROM AUTHOR]

The hybrid multi-bend achromat (MBA) lattice concept, proposed by ESRF EBS, has been used in some diffraction-limited storage ring (DLSR) designs due to both the lower emittance and the better nonlinear performance achieved. In this paper, to reduce the emittance for a given storage ring circumference, we extended the hybrid MBA lattice from the typical hybrid 7BA to a hybrid 10BA with three additional combined function bending magnets in the lattice center, since the emittance scales inversely with the third power of the number of bending magnets. For the hybrid 10BA lattice, two kinds of phase advances between dispersion bumps have been studied in designing a DLSR with an energy of 2.4 GeV and a circumference of 324 m. The dynamic aperture of the designed DLSR with a natural emittance of 120 ∼ 130 pm ⋅ rad is large, and the momentum aperture is also acceptable. [ABSTRACT FROM AUTHOR]

The lattice design and beam dynamics optimization for Sirius, a new low-emittance synchrotron light source presently under construction at the Brazilian Synchrotron Light Laboratory (LNLS) in Campinas, Brazil, is presented. The electron storage ring is based on a five-bend achromat (5BA) design achieving a bare lattice emittance of 0.28 nm rad for a 3 GeV beam. The circumference of 518 m contains 20 achromatic straight sections of alternating 7 m and 6 m in length. An innovative approach is adopted to enhance the performance of the storage ring dipoles by combining low-field (0.58 T) magnets for the main beam deflection with a very short 2 T permanent-magnet superbend sandwiched in the center dipole. This superbend creates 12 keV critical photon energy dipole sources with modest total energy loss from dipoles. In addition it also creates a longitudinal dipole field gradient that reduces the emittance by about 10%. The optimized dynamic aperture allows for top-up operation with off-axis injection and the optimized energy acceptance allows for a total beam lifetime of around 11 h at nominal current with a third-harmonic cavity.