CERN Accelerating science

QUACO Phase-3 starts now

First QUACO winding mock-up at ElyttEnergy factory. (Image: QUACO)

The pre-commercial procurement (PCP) is an approach to public procurement of research and development (R&D) services. It challenges the industry to develop innovative solutions and it provides a first customer reference that enables companies to create competitive advantage on the market. In the past it has been extensively used in the ICT domain.

In 2016 was launched the QUACO PCP (Grant Agreement 689359) to demonstrate that industry could start working on innovative magnets from the conceptual phase. Pre-commercial procurement is a perfect instrument to prepare industry to build new large research infrastructures. Including the industry from the conceptual phase can reduce industrialization time and cost and creates competition while fostering competion.

PCPs bring together several research infrastructures with similar technical requirements allowing partners to avoid unnecessary duplication of design efforts, creating a bigger pool of expertise able to transfer knowledge form the labs to the industry and providing buying momentum for potential suppliers, thereby bridging the gap between cutting-edge research and development, and the existing market for novel technologies.

QUACO PCP will procure two pilot 3.8 m quadrupole magnets with two 90 mm apertures, an integrated gradient of 440 T with 120 T/m in the transverse plane, and which will have an operational temperature of 1.9 K. It is a joint effort of CEA, CERN, CIEMAT and NCBJ, under CERN coordination.

The Challenge started in September 2016 when four companies (Antec, Elytt, Sigmaphi and Tesla) obtained a work order for Phase 1. The main milestone was to create, from a functional specification, the preliminary concept of the magnet and the tooling and procedures needed to fabricate it. After the assessment of the work in June 2017, three of them (Antec, Elytt and Sigmaphi) were awarded the order for phase 2 where they had to move from concept to detailed design. The phase included the first mock-ups and the complete technical solutions.

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Mockups from Sigmaphi, Elytt and Antec. (Image: QUACO)

 

Huge electromagnetic forces are produced in the superconducting magnet windings due to high magnetic fields combined with high electrical currents. Antec explored the use of bladders and keys to obtain the needed pre-stress in its magnet. A technique developed and used only in research centres, not in the industry, and only in single aperture magnets. They also explored the use of an industrial robot to wind the superconducting coils, improving the flexibility, quickness and repeatability of the winding compared to the conventional winding technology.

Innovation from Elytt did not come from the magnet design in itself. They selected a classical solution using two independently collared apertures. Their innovation focused on design robustness, reduction of harmonics and mainly production technics to reduce the cost of the series. Creating flexible and reusable tooling several types of magnets can be built without extra effort and in less time.

Finally, Sigmaphi innovative solution consist on applying an azimuthal stress on coil poles by inserting stainless steel spacers into the pole. Aluminum collars around the coil: the high thermal shrinkage of aluminium between room temperature and 1,9K will limit the azimuthal stress decrease during cool-down in comparison with the collaring solution based on stainless steel laminations.

The three solutions were evaluated last summer and considered innovative and promising. Following the competitive tender for phase 3 only two of them could be awarded a work order.

On November it was adjudicated phase 3 to Elytt and Sigmaphi. Next year will be exciting for the accelerator community!

Pre-commercial procurement is a unique and novel procurement method in the field of accelerator components, and QUACO aims to demonstrate its full potential for success in this field.

The summary of the results can be found on https://quaco.web.cern.ch/

Linn Tvede, Giovanni Porcellana (CERN)
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QUACO Phase-3 starts now
10 Dec 2018

QUACO Phase-3 starts now

Following the competitive tender for phase-3, only two solutions could be awarded a work order. Three were evaluated and considered promising.

Quadrupole magnets for FCC-ee

Last summer, the first measurements of a twin quadrupole magnet for a future 100 km circular lepton collider (FCC-ee) were taken at CERN’s new magnetic measurement laboratory profiting from the excellent capabilities offered in the new building (Building 311).

Contrary to previous designs for twin aperture quadrupoles, currently used for example in the LHC cleaning insertions, the design team opted for a mechanically and magnetically coupled twin quadrupole. This approach, also implemented for the FCC-ee dipoles, offers significant energy savings and reduces the number of coils, thus simplifying the construction of these magnets, finally decreasing their cost.

To meet the beam requirements, the magnet team came up with a design as shown in Figure.1. The two apertures have opposite polarities, allowing for both focusing and defocusing gradient for the two beams. For each aperture, there are four poles, but there are only two coils in total. This innovative design thus creates a flux in the central yoke parts, while the sides act as return legs for the field. The top and bottom halves of the yoke are kept together with a non-magnetic spacer in the centre.

Fig. 1: magnet design cross-section (Credits: Attilio Milanese@CERN)

As Attilio Milanese, a CERN expert that leads the design effort explains: “The inter-beam distance dictates the overall cross-section of the twin quadrupole; the coil is dimensioned to keep the current density, and consequently the power consumption, reasonably low. The magnetic coupling between the two apertures brings a 50% saving in power consumption with respect to a traditional design”. It has been estimated that thanks to the novel design, at the highest beam energies of 175 GeV foreseen for FCC-ee, the total power for the quadrupole magnets can be kept below 30 MW. Finally, the new design puts the coil far from the midplane radiation.

To understand the performance and future industrialization needed for FCC-ee, a short model has been constructed and tested at CERN (see Fig.2). The team measured the strength of the integral field, the field quality, and the magnetic axis for different current levels. As Carlo Petrone, in charge of these tests explains: “It was one of the firsts magnets tested in our new measurement laboratory. Additional effort was required due to the commissioning phase of the instrumentation to yield accurate magnetic measurement results. Furthermore, to fully qualify the FCC-ee twin-quadrupole magnet, different magnetic measurement systems have been used at different current cycles. This was required to achieve the accuracy required for taking decisions on the future design improvements”.

First results have been promising about the efficiency of this design and match very well the simulated data with a precision of 1% up to 200 amperes excitation current. The two apertures provide a similar magnetic field quality, within 0.1‰, even before individual trimming.

In the next months, the team will further analyze the data, explore in detail all the parameters of the new design and make any necessary improvements towards the final conceptual design of the FCC-ee quadrupoles as key components of this machine.

Fig. 2: FCC-ee quadrupole test magnet installed on the magnetic measurement bench in the laboratory 311 at CERN. (Credits: Stephan Russenschuck, CERN)

Daniela Antonio (CERN)
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Power tests of HL-LHC quadrupole

Fig. 1:

In July, the fourth short model of the Nb3Sn quadrupole for the HL-LHC interaction regions was tested in SM18. This is the first magnet with the final Bruker-OST Restacked Rod Process (RRP®) conductor, with 108/127 layout, which shall be used for eight out of ten magnets of this series. As the third model tested one year ago, this was fully manufactured and assembled in CERN’s laboratory 927.

The magnet reached nominal current (7 TeV operation) with one quench, and ultimate current (7.5 TeV operation) after five quenches. “It has been the fastest training of the short models tested so far, approaching the performance of HQ, the magnet developed in the 2000’s by LARP that is the father of MQXF” – says J. Carlos Perez, in charge of the 927 magnet laboratory. The most relevant parameter for operation is the training after thermal cycle, since it provides an indication of the magnet behavior after installation. For this model no quench was required to reach 7.5 TeV operation, proving a perfect memory of the training.

Fig.2:

Magnetic measurements confirmed a low value of the first order harmonics, already observed in the US prototype and in the third short model. This dodecapole component is 0.05% of the main field, whereas it should be not larger than 0.01%. A fine-tuning, foreseen in the initial design shall be carried out to recenter this unwanted harmonic around zero.  This will be done through a modification of shims around the coil by a mere 0.125 mm.

The coils of the fifth and last short model have been manufactured, and the magnet, named MQXSF6, will be assembled in autumn. These coils are made with the final Bruker-EAS Powder-In-Tube (PIT) conductor, which will be used for one prototype and for two series magnet. “The MQXFS6 magnet will complete the short model programme of the HL-LHC Nb3Sn quadrupoles” – says G. de Rijk, in charge of the MSC/MDT section leading the short models and the correctors of HL-LHC – “but we remain ready to continue further work on short models, should we need additional information to be fed in the full size magnets”. The construction of the first full size CERN prototype MQXFBP1 is ongoing, and the second US prototype MQXFAP2 is undergoing cool-down for a test to start in a few weeks in BNL.

Chris Edmonds (University of Liverpool)
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