CERN Accelerating science

EuPRAXIA marks two years of research into plasma accelerators

The Horizon 2020 Project EuPRAXIA has just passed the halfway mark. The consortium led by DESY is preparing a conceptual design report of a highly compact and cost-effective European facility with multi-GeV electron beams using plasma as the acceleration medium. The accelerator facility will be based on a laser and/or a beam driven plasma acceleration approach and will be used for photon science, high-energy physics detector tests, and other applications such as compact X-ray sources.

The EuPRAXIA consortium has held its second Yearly Meeting and Collaboration Week from 20th to 24th November 2017 at the Instituto Superior Técnico in Lisbon. All partners gathered to discuss the status of each of the work packages and of the project as a whole. The Collaboration Board of EuPRAXIA approved the incorporation of Queen’s University Belfast (UK) and the Ferdinand-Braun-Institute of Berlin (Germany) as associated partners. With these new additions, the number of partners in EuPRAXIA now rises to 40.

The event in Lisbon was also the occasion for the first meeting of EuPRAXIA’s Scientific Advisory Committee (SAC). The SAC, composed of eight international experts in laser and accelerator science, was in charge of assessing the status of the project and providing a set of recommendations.

The Scientific Advisory Committee of EuPRAXIA presenting its conclusions in Lisbon (Image: EuPRAXIA)

Coordinator Ralph Assmann and the principal researchers of EuPRAXIA gave a summary of the status of the project and their respective work packages.

Current research within the consortium aims to improve the beam quality and to demonstrate the benefit of size and cost of a plasma accelerator versus established radio frequency (RF) technology.

Beam quality is essential in order to show that plasma accelerator technology is usable. In EuPRAXIA, two approaches are being used to address the beam quality. The first is to improve the technical components and plasma accelerator schemes already producing GeV class beams; this includes improved laser technology and feedback loops. The second is to start with a high-quality beam from a small RF injector and boost it to high energy. The latter approach is fully stageable, offering a path to high energy while the starting beam quality is assured. However, it brings out new issues, like sub-femtosecond beam synchronization, for which new solutions are needed and new ideas are being implemented. 

The project has identified nine different technical scenarios to achieve the target performance of the EuPRAXIA facility, defining the baseline parameters for the operation of lasers, RF injectors, and plasma accelerators. Several partners are assessing the viability of the different schemes through advanced start-to-end simulations and experiments at various European facilities.

The consortium has also made significant progress in developing the applications where a plasma-based accelerator would have a large impact, namely as a driver for a Free Electron Laser and as a test bed for high-energy physics detectors. 

EuPRAXIA is now ready to take on the second iteration of its general layout and start evaluating the cost construction and operation of the facility. The proposed solutions must offer significant benefits with respect to RF-based accelerators, e.g. fitting constrained spaces and being cost-effective, including having lower operational costs.

The design study is site independent, although five possible sites have been discussed. The construction of EuPRAXIA will be decided after 2019, and its location will be based on the facilities and expertise available at all the supporting laboratories. Even though the facility would be built in one central site, all the project partners would commission parts at their local facilities.

The final conceptual design report, which will include a detail implementation model, will be submitted in October 2019 and if construction is approved it could start operations as soon as 2025.

Although there are still major challenges ahead, the progress made in the first half of the project gives us the confidence to look forward to the delivery of an excellent Conceptual Design Report for a highly compact and cost-effective plasma accelerator facility with industrial beam quality.

Maurizio Vretenar (CERN)
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Physics of Star Wars: Science or Fiction?

Light sabres, hyper speed and droids – how do they all connect with the latest accelerator research? With the imminent launch of “The Last Jedi”, Professor Carsten Welsch, Head of Physics at the University of Liverpool and Head of Communication for the Cockcroft Institute, has explored the “Physics of Star Wars” in an event on 27th November designed to introduce cutting-edge accelerator science to hundreds of secondary school children, undergraduate and PhD students, as well as university staff.

The day started with a lecture which first presented iconic scenes from the movies to then explain what is possible with current technology and what remains fiction. For example, a lightsabre, as shown in the film, wouldn’t be possible according to the laws of physics, but there are many exciting applications using lasers. There is a link to advances in lasers and laser acceleration being studied by an international collaboration within the EuPRAXIA project. This programme is developing the world’s first plasma accelerator with industry beam quality. It uses a high intensity laser pulse to drive an electron beam and accelerate this to high energies. Applications in science or industry that are close to a light sabre include for example 3D printing of metals and laser cutting.

Professor Welsch said: “In the very first movie from 1977, the rebels have used proton torpedoes that make the Death Star explode as their lasers wouldn’t penetrate the shields. I linked that to our use of ‘proton torpedoes’ in cancer therapy. Within the pan-European OMA project we are using proton beams to target something that is hidden very deep inside the body and very difficult to target and destroy.”

 OMA Fellow Jacinta Yab explaining the use of ‘proton torpedoes’ in cancer therapy (Image credit: QUASAR Group)

 The light and dark side of the Force in Star Wars was an ideal opportunity to talk about matter and antimatter interactions which are currently being explored at CERN’s AD and ELENA storage rings, as well as within the brand-new Marie Sklodowska-Curie research network AVA. Finally, participants learned about how high energy colliders, such as the LHC, its high luminosity upgrade or a potential Future Circular Collider (FCC) as it is being studied within the EuroCirCol project, can provide fantastic opportunities to study the force(s).

High school students participating in hands-on activities during ‘Physics of Star Wars’ event. (Image credit: QUASAR Group)

After the lecture, all participants were given the opportunity to understand the science behind Star Wars through numerous hands-on activities in the university’s award-winning Central Teaching Laboratory. This included laser graffiti, augmented reality experiments with Star Wars droids and virtual accelerators using AcceleratAR, and even two full-scale planetariums which fully immersed participants into the world of Star Wars, deflecting charged particle beams using Helmholtz coils.

Professor Welsch and members of his QUASAR Group had the kind permission of Lucasfilm to use film excerpts; these were complemented by Lego Star Wars models, a real cantina as found in the movies, storm troopers and even Darth Vader himself! Many photographs from the exciting day can be found on Twitter at

Lucasfilm had no involvement in the preparation or delivery of the event which was organised only by staff and students from the University of Liverpool.


Header image: Prof Carsten Welsch presenting the ‘Physics of Star Wars’ (Image credit: QUASAR Group)

Massimo Sorbi (CERN, INFN), Marco Statera (INFN) and Ezio Todesco (CERN)
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