Dutch consortium builds high-power cooler for the Einstein Telescope

A Dutch consortium is taking a significant step forward in the development of vibration-free cooling for the Einstein Telescope. It is building the first high-power sorption cooler for the future observatory. This marks the first time the technology has been scaled up from compact applications to a cooling system with much greater cooling capacity. Sorption coolers have not yet been used on such a large scale anywhere else.

A silent solution to a major challenge

In order to measure gravitational waves, the mirrors and their suspension system at the Einstein Telescope must be cooled to extremely low temperatures. At the same time, the environment must remain completely vibration-free. Even the slightest vibration can affect the measurements. This makes cooling one of the greatest technological challenges for the future observatory.

The Zero-vibration Sorption Cryocooler consortium, comprising the University of Twente, Demcon kryoz and Cooll, is developing an innovative solution for this purpose on the initiative of Nikhef. The technology will be tested in the coming period at the Einstein Telescope’s test facility: the ETpathfinder at Maastricht University.

Cross-border collaboration

At the Belgian Einstein Telescope lab, ET-CRISTAL, in Liège, researchers have validated vibration-free (radiative & contactless) cooling technology, at full scale both experimentally and numerically, under conditions that meet the requirements of the Einstein Telescope. In this way, the Dutch and Belgian test facilities complement one another, and researchers in the Meuse-Rhine Euroregion are collaborating on a crucial technology for the future observatory.

From small coolers to a unique system

Sorption coolers are already used in compact cryogenic systems, for example in microscopes and communications satellites. For the Einstein Telescope, however, much greater cooling capacity is required to maintain the large, highly sensitive components at extremely low temperatures over long periods. That is why the consortium is scaling up the existing technology to a size that has not yet been applied on this scale.

A standard fridge uses a compressor that is constantly moving and therefore causes vibrations. A sorption cooler builds up the required pressure without such a mechanical component. This allows it to cool without the vibrations that would interfere with the Einstein Telescope’s measurements.

Project manager Adrie Visser at Demcon kryoz: “We expect one system to be fully integrated into the high-pressure laboratory in Twente by the summer. We can then begin testing, and if the results are positive, we can start work in parallel at the Einstein Telescope’s test facility in Maastricht. By the end of this year, we will have built the first complete system for the ETpathfinder there.”

Technology with an impact

For Romaine Kunst, thermal systems engineer at Demcon Kryoz, the project is more than just a contribution to the Einstein Telescope. “With this, we are making a major improvement on existing cooling techniques. For me personally, it’s a dream to continue developing our technology.

Space travel and astronomy are currently the main areas of application, but there are so many other research applications too. Think of medical imaging of samples that need to be cooled, or microscopes used in all sorts of scientific experiments. The vibration requirement is also highly relevant for quantum computers, at even lower temperatures.”

Six consortia are developing technologies for the Einstein Telescope

The consortium is one of six consortia developing technology for the Einstein Telescope. Together, 26 Dutch high-tech companies and research institutions are working on innovations in the fields of optics, vacuum technology, vibration-free cooling, vibration damping and thermal deformations. Over 12 million euros in funding has been made available for this purpose. The projects not only deliver essential technology for the Einstein Telescope, but also create new opportunities for the Dutch and Euregional high-tech sector.