Facelift for particle Accelerator

© Cern

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


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