Periodic Reporting for period 2 - SuperEMFL (Superconducting magnets for the European Magnet Field Laboratory)
Reporting period: 2022-07-01 to 2023-12-31
The magnetic field is a powerful thermodynamic parameter to influence the state of any material system, therefore it is an outstanding experimental tool for physics. Higher magnetic fields brought higher resolution for analyzing materials, more opportunities to discover new phases, properties or materials. To go beyond the conventional commercially available superconducting (SC) magnets, very large infrastructures such as the ones gathered within the European Magnetic Field Laboratory (EMFL) are necessary.
The SuperEMFL project is a design study aiming at adding an entirely new dimension to the EMFL through the development of novel SC magnets, using high temperature superconductor (HTS) materials that go beyond the commercial offer, providing the European high field user community with much higher superconducting fields.
This is meant to be achieved by combining high temperature superconductor (HTS) insert magnets, an emerging technology that can work in field above 25T, with low temperature superconductor (LTS) outsert magnets, a more developed and commercial technology but limited in field below 25 T. The project has two design magnetic field targets, 32+T and 40+T, combining either a single stack of HTS pancakes with a 19 T/150 mm LTS magnet or two nested HTS coils with a 15 T/ 250 mm LTS magnet. The particular choice of the project is to use no insulation but a metallic tape co-wound with the bare HTS tape. This so-called Metal as Insulation (MI) technology enables a self-protection feature of the HTS coil by allowing the electrical bypass of defects as well as better mechanical performances in a very compact winding.
The project is not just a technical development beyond the state-of-the-art of a series of magnets; those magnets have to be useful to EMFL users which are scientists leading various experiments under very high field and have for that purpose specific needs (peak field, experimental available volume, homogeneity to name a few) depending on their specialties and their working environment (facilities). This project is also about the implementation of those magnets at the EMFL facilities and a financial scheme to fund their fabrication, installation and operation costs, as many parameters that need to be evaluated.
The SuperEMFL project is a design study aiming at adding an entirely new dimension to the EMFL through the development of novel SC magnets, using high temperature superconductor (HTS) materials that go beyond the commercial offer, providing the European high field user community with much higher superconducting fields.
This is meant to be achieved by combining high temperature superconductor (HTS) insert magnets, an emerging technology that can work in field above 25T, with low temperature superconductor (LTS) outsert magnets, a more developed and commercial technology but limited in field below 25 T. The project has two design magnetic field targets, 32+T and 40+T, combining either a single stack of HTS pancakes with a 19 T/150 mm LTS magnet or two nested HTS coils with a 15 T/ 250 mm LTS magnet. The particular choice of the project is to use no insulation but a metallic tape co-wound with the bare HTS tape. This so-called Metal as Insulation (MI) technology enables a self-protection feature of the HTS coil by allowing the electrical bypass of defects as well as better mechanical performances in a very compact winding.
The project is not just a technical development beyond the state-of-the-art of a series of magnets; those magnets have to be useful to EMFL users which are scientists leading various experiments under very high field and have for that purpose specific needs (peak field, experimental available volume, homogeneity to name a few) depending on their specialties and their working environment (facilities). This project is also about the implementation of those magnets at the EMFL facilities and a financial scheme to fund their fabrication, installation and operation costs, as many parameters that need to be evaluated.
The last period focused on the tapes, coil manufacturing and coil testing, on the 40 T+ designs, the quench simulation tools (HTS alone and LTS/HTS), the interaction of LTS/HTS parts during a quench and on the operation of an HTS insert test coil into an existing LTS magnet, the protection scheme including mechanical reinforcement and the preparation of a scientific case in such LTS/HTS configuration to validate it as a user magnet.
The choice is to use a newly developed HTS tape with a particular enhancement of the critical current at low temperature and high magnetic field thanks to artificial pinning. A test coil consisting in an assembly of two double HTS pancakes (named 2 DP coil) was characterized under high magnetic field. This was also an opportunity to exchange about the winding technology between academic and industrial partners. The behaviour was as expected up to a background field of 15 T at which a mechanical damage occurred. Other characterizations (critical current Ic, delamination, joints, windability) were conducted in parallel on several tapes from different providers. A new 2 DP coil has been wound with a reinforced tape for for high field tests. Other valuable characterizations concerned the turn to turn resistance, the degradation of the Ic by strains and the delamination strength.
A set of simulation tools has been implemented and benchmarked, thanks to which a pre-design has been carried out targeting the 32+T and 40T+ range as a set of several HTS insert showing the possibility to prioritize homogeneity, peak field or bore size according to the users’ requirements. 40T can be reached with a single stack of pancakes but at the sake of a narrower central space considering the current performance of the HTS tapes. Only a design with nested coils enables to maximise the central space for experiment and reduce constrains. A simple version will be fabricated and tested in a large bore resistive magnet in the last part of the project as a proof of concept. Development and upgrade of the electro-thermal models were required because the peculiarities of the MI technology are not covered by the classical models. Applied to the interactions between HTS and LTS and in particular the mechanics during a quench of one to the other part, it led to the proposition of a specific mechanical reinforcement of the LTS outsert to accommodate the potential large axial forces that may be produced by a quench of the HTS insert.
The interfacing of an HTS insert within an LTS magnet was developed, providing de facto a test bench. A series of quench-test measurements using a 2DP coil were performed up to 19 T, providing valuable information about the HTS/LTS coupling. A first scientific pilot experiment assessed the HTS/LTS magnet as a user magnet.
A user survey and a subsequent workshop showed a strong interest and support of our community with a clear idea of what can be expected and done. The facilities inventory is on-going bearing in mind the definition of the need and investment to implement such a magnet. Several workshops with other facilities were conducted for dissemination.
The choice is to use a newly developed HTS tape with a particular enhancement of the critical current at low temperature and high magnetic field thanks to artificial pinning. A test coil consisting in an assembly of two double HTS pancakes (named 2 DP coil) was characterized under high magnetic field. This was also an opportunity to exchange about the winding technology between academic and industrial partners. The behaviour was as expected up to a background field of 15 T at which a mechanical damage occurred. Other characterizations (critical current Ic, delamination, joints, windability) were conducted in parallel on several tapes from different providers. A new 2 DP coil has been wound with a reinforced tape for for high field tests. Other valuable characterizations concerned the turn to turn resistance, the degradation of the Ic by strains and the delamination strength.
A set of simulation tools has been implemented and benchmarked, thanks to which a pre-design has been carried out targeting the 32+T and 40T+ range as a set of several HTS insert showing the possibility to prioritize homogeneity, peak field or bore size according to the users’ requirements. 40T can be reached with a single stack of pancakes but at the sake of a narrower central space considering the current performance of the HTS tapes. Only a design with nested coils enables to maximise the central space for experiment and reduce constrains. A simple version will be fabricated and tested in a large bore resistive magnet in the last part of the project as a proof of concept. Development and upgrade of the electro-thermal models were required because the peculiarities of the MI technology are not covered by the classical models. Applied to the interactions between HTS and LTS and in particular the mechanics during a quench of one to the other part, it led to the proposition of a specific mechanical reinforcement of the LTS outsert to accommodate the potential large axial forces that may be produced by a quench of the HTS insert.
The interfacing of an HTS insert within an LTS magnet was developed, providing de facto a test bench. A series of quench-test measurements using a 2DP coil were performed up to 19 T, providing valuable information about the HTS/LTS coupling. A first scientific pilot experiment assessed the HTS/LTS magnet as a user magnet.
A user survey and a subsequent workshop showed a strong interest and support of our community with a clear idea of what can be expected and done. The facilities inventory is on-going bearing in mind the definition of the need and investment to implement such a magnet. Several workshops with other facilities were conducted for dissemination.
The SuperEMFL project generates specific know-how, models, the design of 32+ and 40+ T all-superconducting user magnets (TRL 7) and a scenario for implementing such equipment and its derivatives within EMFL as main outcomes.
The use of HTS inserts to generate field efficiently introduces a change of paradigm. New experimental possibilities are expected, in particular long duration and very low noise experiments. The large resulting reduction of operating costs for high field experiments will also considerably increase the EMFL capacity to host user experiments. The improvement of the EMFL environmental impact as well as the optimization of resources and energy are some major benefits of the project.
The development of the HTS technology is now widely competitive with projects at 40 T in Europe, the USA and China. We are reaching other communities beyond EMFL throughout workshops and conferences, which show their strong interest by submitting their own projects to leverage the HTS technology, i.e. the neutron beamline facilities, the CERN with its Muon Collider project, the fusion community… And we are involved.
The innovation impacts being pursued are developing an industrial technology to go beyond the current limit of commercial superconducting fields, giving the industrial partners a competitive advantage, understanding and modeling the quench events in HTS magnets and opening the high magnetic fields as a research tool to the bio- and life sciences.
Several PhD students and post-doctoral fellows have and are being trained throughout the SuperEMFL project, increasing their skills and value on the labor market, but also helping to prepare a future generation for HTS technology that will allow Europe to play an important role in this strategic technology. Currently, the fusion start-ups and technical cryogenics companies are fighting to hire skilled manpower.
The use of HTS inserts to generate field efficiently introduces a change of paradigm. New experimental possibilities are expected, in particular long duration and very low noise experiments. The large resulting reduction of operating costs for high field experiments will also considerably increase the EMFL capacity to host user experiments. The improvement of the EMFL environmental impact as well as the optimization of resources and energy are some major benefits of the project.
The development of the HTS technology is now widely competitive with projects at 40 T in Europe, the USA and China. We are reaching other communities beyond EMFL throughout workshops and conferences, which show their strong interest by submitting their own projects to leverage the HTS technology, i.e. the neutron beamline facilities, the CERN with its Muon Collider project, the fusion community… And we are involved.
The innovation impacts being pursued are developing an industrial technology to go beyond the current limit of commercial superconducting fields, giving the industrial partners a competitive advantage, understanding and modeling the quench events in HTS magnets and opening the high magnetic fields as a research tool to the bio- and life sciences.
Several PhD students and post-doctoral fellows have and are being trained throughout the SuperEMFL project, increasing their skills and value on the labor market, but also helping to prepare a future generation for HTS technology that will allow Europe to play an important role in this strategic technology. Currently, the fusion start-ups and technical cryogenics companies are fighting to hire skilled manpower.