An innovative mirror unit for soft X-ray beamlines at MAX IV

An innovative mirror unit for soft X-ray beamlines at MAX IV

A new five-axis parallel kinematic mirror unit has been developed for MAX IV soft X-ray beamlines. Its development and technical characteristics are now described in a peer-reviewed article.

In an article published in March 2020 in the Journal of Synchrotron Radiation, a team from Uppsala University, MAX IV Laboratory, FMB Feinwerk und Messtechnik GmbH, and University of Tartu presents a five-axis parallel kinematic mirror unit specially developed for MAX IV soft X-ray beamlines. This new mirror unit has been created to address the unique stability requirements of 4th-generation synchrotrons such as MAX IV.

A picture of the new mirror unit at the Veritas beamline.

MAX IV has pioneered the development of the 4th-generation synchrotrons thanks to the implementation of the multi-bend achromat technology, a system based on the use of several sequential bending magnets in place of a single large magnet. Thanks to the introduction of this technology, the emittance has decreased by one order of magnitude, resulting in increased brightness. The multi-bend achromat system has also brought new challenges for the construction of beamlines. Decreased emittance of the storage ring has allowed for a smaller beam size, which, in turn, means higher requirements for electron beam stability, as well as for mechanical stability of the beamline components.

To meet the new requirements for electron and mechanical stability, MAX IV implemented a stability policy that defines the mechanical properties of those beamline components responsible for beam transport and sample manipulation. These new requirements have triggered the development of new, dedicated components such as this mirror unit.

Traditionally, beamline components tend to be rather large, resulting from designs that favour modularity and maintainability over dimensions. In contrast, in this new five-axis parallel kinematic mirror unit system for soft X-ray beamlines, every component has been developed with the aim of being as small as possible in order to reduce weight and increase the stiffness of the system.

“The major part of the development was done before the beamlines were built. It was essential that Veritas, HIPPIE, and Bloch did this together as we needed to spread the development cost over as many units as possible”, explains Marcus Agåker, researcher at Department of Physics and Astronomy at Uppsala University and first author of the paper. “FinEstBeAMS also joined the project, allowing us to place an order with an even higher number of units to FMB Feinwerk und Messtechnik GmbH.”

Peter Sjöblom, research engineer at MAX IV and one of the authors of the article, explains that with reduced size and weight come several advantages. This design makes it easier to push mechanical resonance frequencies higher up in the spectra. Furthermore, the compact design means having fewer surfaces and fewer joints that can potentially create virtual leaks and compromise the vacuum system.

A lighter and more space-efficient setup is also easier to move and adjust. As Peter explains, the reduced beam size in 4th-generation synchrotrons requires high accuracy when aligning the beamline optics, and this system was developed to allow such fine and accurate motions.

The new mirror unit is now commercially available through FMB Feinwerk und Messtechnik GmbH. At MAX IV it has been implemented at Bloch, HIPPIE, Veritas, FinEstBeAMS, SoftiMAX, FlexPES, MAXPEEM, and NanoMAX beamlines.

Header image: Veritas is one of the beamlines at MAX IV used for testing the prototype of the new five-axis parallel kinematic mirror.

Read the article here:

Agaker, M., Mueller, F., Norsk Jensen, B., Ahnberg, K., Sjoblom, P., Deiwiks, J., Henniger, H., Parna, R., Knudsen, J., Thiagarajan, B. & Sathe, C.
A five-axis parallel kinematic mirror unit for soft X-ray beamlines at MAX IV
J. Synchrotron Rad. (2020). 27, 262-271.

More on the beamlines adopting this mirror unit: