The European laboratory for particle physics, CERN, is one of the largest research facilities in the world. In a current project, the North Area experimental facility is being brought up to the state of the art. MANGOLDT filter chokes play a decisive role in this.
The chokes from MANGOLDT, a member of the Reinhausen Group, ensure maximum safety and efficiency in electrical grids all over the world. But the job for (Laboratoire européen pour la physique des particules) near Geneva was something very special for the Aachen-based company. Founded in 1954, the European laboratory enables particle physicists to carry out cutting-edge international research using the most powerful particle accelerators in the world.
The research site, which covers around 600 hectares, is home to a gigantic complex of particle accelerators that are connected to each other via a tunnel system several kilometers long. There are also various experimental areas, such as the North Area which has been used for physics experiments since the 1970s as part of the Super Proton Synchrotron (SPS). As the facility is getting on in years, it has been undergoing renovation since 2021. Ivan Josifovic is leading the development of the main powering solution at CERN: “The power converters in the North Area will be replaced in the next few years so that it will once again be able to answer the open questions in particle physics.”
“We are very satisfied with the professional cooperation with Mangoldt. We always received a quick response to our questions.”
Ivan Josifovic, Project Manager CERN
Perfectly transformed
The POLARIS power converters developed by CERN are a key component. Their function is to precisely control the magnetic field of the particle accelerators in order to accelerate electrons and protons to almost the speed of light. To do this, they convert the alternating current from the power grid into direct current and pass it on to the particle accelerator’s electromagnets. However, the current is distorted during the conversion.
Ivan Josifovic explains it like this: “If you were to represent direct current graphically, it would be a straight line. The conversion causes it to line, so minimizing current deviations is critical across the accelerator.” To prevent outliers, CERN therefore relies on filter chokes from MANGOLDT in the North Area project. There are three chokes in each power converter. The first is a so-called DC-link filter choke, which draws the current from the power grid and passes it on to two high-frequency chokes for control of power exchange with the electromagnets. Ivan Josifovic from CERN says: “The high-frequency chokes have to work very precisely in order to smooth out the outliers.”
By precise work, Josifovic means the lowest possible deviation of the chokes. Michael Eßer, Head of Engineering at MANGOLDT, explains: “Inductivity could also be described as a kind of current brake.” This means that a lower inductance is used at higher frequencies in order to dampen the interference which enables the chokes to deliver the electrical voltage precisely to the magnets.
With the help of the chokes from MANGOLDT the magnetic field remains stable.
The experts at MANGOLDT achieve the low deviation through a special design. A choke has two main components: a core made of sheet iron and a winding consisting of coiled insulation material and aluminum or copper strip. The iron core is divided into several segments by special air gaps. Michael Eßer explains: “With the size and number of air gaps, we can adjust the inductance and meet CERN’s requirements.” In addition to inductivity, Josifovic believes another property is crucial: “The high-frequency chokes must not get hotter than 70 degrees Celsius during use. Otherwise this shortens their service life.”
To comply with this limit, MANGOLDT uses particularly thin sheet iron, as this generates very little waste heat. “We are very satisfied with the professional cooperation with MANGOLDT. We always received a quick response to our questions,” summarizes Josifovic. There is still a lot for MANGOLDT to do. A total of 3,750 chokes are needed in the POLARIS Power Converters to supply the magnets with electricity. The renovation work in the North Area will be completed in 2029.
YOUR CONTACT
If you have any questions about the chokes, Michael Eßer will be happy to help you: m.esser@reinhausen.com