An overview of the major challenges, Tokamak Energy's approach to solving the problems and coil development programmes
by Dr Greg Brittles of Tokamak Energy

On the route to developing a source of clean fusion energy, Tokamak Energy (TE) is developing Spherical Tokamak (ST) technology employing high temperature superconducting (HTS) magnets as a key enabling component. TE has embarked on a program of developing HTS magnets based on REBCO coated conductors for ST’s up to fusion reactor scale magnet sets. This presentation will summarise the challenges and the progress of that program to date.

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R&D on Magnet System of the European DEMO tokamak
by Kamil Sedlak of Swiss Plasma Center (SPC), EPFL

Following ITER, the European DEMO tokamak should be the first fusion power plant delivering electricity to the grid. Its magnet system shall consist of 16 Toroidal Field (TF) coils, 5 modules of the Central Solenoid (CS) and 6 Poloidal Field (PF) coils. Several improvements with respect to the ITER magnets are being investigated within the R&D program, namely the usage of Nb3Sn conductors based on react & wind (RW) technology and hybrid CS solenoid with the high-grade conductors made of HTS with the magnetic field up to 16 T. Several conductor prototypes of these kinds (RW Nb3Sn and HTS) have been manufactured and tested in the SULTAN test facility. We will report on the design of these conductors and magnets, and also on the tests of the prototype samples.

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Investigating REBCO Irradiation for STEP
by Simon Chislett-McDonald of UKAEA

As the materials of choice for the STEP (Spherical Tokamak for Energy Production) primary magnets, the effect of radiation on the functional properties of REBCO tapes must be known. Qualitatively, it is understood that neutron fluence degrades superconductor critical current density, critical temperature, and irreversibility field – though the magnitude of the degradation varies between different tape types and depends on both the conditions of radiation and the conditions of magnet operation. Here, we present the UKAEA-STEP plans for the quantification of these radiation effects with the aims of 1) informing the choice of the optimal tape(s) for the STEP magnets and 2) characterising REBCO tapes under radiation to optimise magnet and shielding design.

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Development, qualification and lessons learned from conductor manufacture for ITER
by Neil Mitchell of Retired (formally Head of ITER Magnets)

During 35 years of the ITER project, we brought high current Nb3Sn and NbTi conductors from an early development phase to full industrialisation and production. In this presentation I will cover the main steps in this process, the main problems overcome and some lessons that could apply for the future for development of HTS conductors

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ITER Magnets and ITER Tokamak Assembly Status
by Min Liao of ITER Organization

ITER is the largest fully nuclear tokamak, with a target of 500MW of fusion power. It has been under construction at Cadarache since 2007, and has now reached the point where major on-site assembly activities are ongoing. The magnets represent by far the largest set of superconducting coils (Nb3Sn and NbTi) ever built and most have now been manufactured and many are on site. ITER has provided much experience on large scale industrialisation of what has previously been largely a research activity, and the nuclear aspects of the machine have brought many novelties to the magnet field regarding nuclear quality expectations, as well as adding large scale construction requirements to the more familiar constraints of cryogenic high voltage magnets. ITER is now facing some challenges regarding non-magnet tokamak components where quality standards have been deficient and recovery actions are now being implemented. Worldwide collaboration, such as the ITER cooperation, is seen as the way to work most efficiently and to achieve effective solutions to these scientific and technological challenges. However the improvement of organizational structure in some area, e.g, quality improvement as the integration approach for factory acceptance test and site acceptance test into a coherent and cost effective design, the mitigation and corrections will be able to build on the extensive experience gained so far.

Delivering Fusion Energy – the key role of magnets
by Howard Wilson of University of York

Fusion energy is rapidly accelerating its progress, as the urgency of addressing climate change drives a need to demonstrate its commercial viability by around 2050. This talk will focus on the challenges associated with achieving the fusion conditions, focusing on the magnetic confinement approach. We will explore the required plasma conditions in an accessible way, and discuss why the magnetic field plays such an important role in achieving these conditions. The consequences for the different approaches to magnetic confinement fusion will be explored, highlighting the similarities and differences between the conventional tokamak (e.g. JET and ITER) and the spherical tokamak (e.g. MAST-U, ST40 and STEP), and introducing the stellarator.

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Magnetics Challenges in Fusion
by Elizabeth Surrey of N/A (Retired UKAEA)

The magnetics challenge in developing fusion is two way: the challenges that fusion presents to magnetics and the challenges that feasibility present to fusion. The talk will discuss some examples, concentrating on the needs of fusion power plants.

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Validations of a High-Performance Computing model for HTS in Fusion.
by Neil Lamas and Oriol Fernández Serracanta of Barcelona’s institute of material sciences (ICMAB), Instituto de Ciencia de Materiales de Barcelona (ICMAB) and Barcelona Supercomputing Center – Centro Nacional de Supercomputación (BSC-CNS)

We implemented and validated “Magnet” an electromagnetic module of Alya, a high performance computing multiphysics simulation code; a module applied to simulate High Temperature Superconductors (HTS) for Fusion reactors development. Experimental measurements of in-field cooling and hysteresis losses were carried out, and compared to simulations in order to validate and upgrade the model .

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The CHIMERA Fusion Technology Facility magnet system
by Tom Barrett of UK AEA

The CHIMERA fusion technology test facility is under construction at the UKAEA site in South Yorkshire, UK. The facility will be uniquely capable of ‘semi-integral’ testing of fusion materials and component modules, up to the size of the ITER ‘test blanket’, under combined heating and magnetic load conditions. The unique capabilities of CHIMERA have led to the design and manufacture of a challenging and unusual magnet system. The main superconducting magnet is in a split pair arrangement, with coils on both lateral sides of the component test chamber. The central field for testing can be up to 4 Tesla, and a high field gradient leads to large static lateral forces up to 160 kN. The system also features a copper pulsed magnet, enabling fusion component prototypes to be subjected to repeated magnetic field pulses with ramp rate 12 T/s, to simulate loading conditions of a fusion plasma disruption. This talk gives an overview of the CHIMERA capabilities, with a focus on the design and challenges of the magnet system.

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