Pushing the MAX IV 3 GeV storage ring brightness and coherence towards the limit of its magnetic lattice

Abstract

The MAX IV 3 GeV storage ring is presently being commissioned and crucial parameters such as machine functions, emittance, and stored current have either already been reached or are approaching their design specifications. Once the baseline performance has been achieved, a campaign will be launched to further improve the brightness and coherence of this storage ring for typical X-ray users. During recent years, several such improvements have been designed. Common to these approaches is that they attempt to improve the storage ring performance using existing hardware provided for the baseline design. Such improvements therefore present more short-term upgrades. In this paper, however, we investigate medium-term improvements assuming power supplies can be exchanged in an attempt to push the brightness and coherence of the storage ring to the limit of what can be achieved without exchanging the magnetic lattice itself. We outline optics requirements, the optics optimization process, and summarize achievable parameters and expected performance. Published by Elsevier B.V. 1 This is an important restriction in the MAX IV 3 GeV storage ring because most magnets in the achromat are connected in series to a common power supply for the entire family. 2 The transverse focusing gradients are provided by the shape of the dipole iron poles, however, the pole-face strips (PFSs) installed in each dipole allow a ±4% variation of this gradient, sufficient to move about ±0.5 in tune space.

First optics and beam dynamics studies on the MAX IV 3 GeV storage ring

“…Furthermore, with such dispersion bumps ensuring good lifetime, the emittance coupling can be reduced from the original design target of 8 pm rad to 2 pm rad which is expected to significantly increase the brightness for a typical MAX IV IVU beamline [31]. Along this line of reasoning, we hope to be able to also experiment with a harder focusing optics designed to further increase photon brightness and coherence from IDs installed in this storage ring [49][50][51] to ensure MAX IV remains competitive as other MBA-based storage rings come online.…”

MAX IV Laboratory

“…Emittance reduction by a factor of more than two and a corresponding increase in brightness is also conceivable [ 68 ] through moderate changes in the magnet lattice. Together with changes to the injection scheme, these could enable the use of advanced insertion devices with a reduced horizontal aperture, such as the APPLE-X undulators currently being prototyped [ 69 ] in connection to the Soft X-ray Laser project [ 70 ].…”

Chemical Limits on X-ray Nanobeam Studies in Water

“…26−29 The BCDI method requires extremely high flux densities when applied to small and industrially relevant nanoparticles, 30 and the recently constructed fourth-generation synchrotron sources are expected to enable this by providing brighter and higher-quality X-ray beams. 31,32 A potential problem with studying condensed liquid systems with increasingly bright and focused X-ray beams is the chemical environment created by the beam itself. Most compounds ionize under X-ray illumination, an effect that is more important in condensed liquid phases than in the gas phase, as the rate of energy deposition is larger and the diffusion of radiolysis products slower.…”

“…While X-rays typically offer lower spatial resolution than electrons do, their penetrating power seems to allow application to complex environments and operating conditions . This is part of the motivation for recently investing in modern nanofocus instruments at most of the world’s synchrotrons, − enabling operando experiments with a variety of nanobeam techniques. − In particular, BCDI has been increasingly applied to problems in heterogeneous catalysis, electrocatalysis, − and complex electrochemical energy conversion systems. − The BCDI method requires extremely high flux densities when applied to small and industrially relevant nanoparticles, and the recently constructed fourth-generation synchrotron sources are expected to enable this by providing brighter and higher-quality X-ray beams. , …”