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.
Highlights
Introduction & backgroundThe MAX IV 3 GeV storage ring is the first light source to make use of a multibend achromat lattice to reach ultralow emittance [1,2,3,4,5,6,7,8]
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
Once the design parameters are achieved, the electron beam brightness will be unmatched thanks to top-off injection keeping stored current constant at 500 mA and a bare lattice emittance of 328 pm rad that is expected to reduce towards ≈ 190 pm rad as additional insertion devices (IDs) are added and ID gaps are closed [10]
Summary
The MAX IV 3 GeV storage ring is the first light source to make use of a multibend achromat lattice to reach ultralow emittance [1,2,3,4,5,6,7,8]. An increase of brightness and coherence can be achieved by an improved matching of the electron beam to the intrinsic photon beam emerging from an ID as well as by reducing the bare lattice emittance The former has already been investigated in [12], whereas first studies related to the latter have been reported in [13] as a short-term upgrade plan. For the increase of brightness and coherence through lattice/optics improvements in the MAX IV 3 GeV storage ring, we pursue a staged approach. In a first stage a harder focusing optics was established while retaining achromaticity, all existing power supplies, and magnet cabling.1 The results from this first stage [13] showed how the horizontal focusing in the arcs can be increased reducing the dispersion and the lattice emittance. In this paper we detail the continued efforts to increase the brightness and coherence of the MAX IV 3 GeV storage ring in the context of the second stage of the upgrade approach
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More From: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
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