Following the last experimental campaign on JET, the data are being analysed to reveal the fundamental physics processes that will contribute to increasing the confidence for extrapolating to future devices. Here interpretative modelling tools are applied to advance our understanding. Extrapolations based on JET results provides more confidence in avoiding bursty transport that endangers the integrity of plasma facing components. At JET the first experiments providing a new method involving the creation of a small local plasma by firing a laser onto a plasma facing material and analysing the emitted light provided an in-situ method to detect hydrogen isotopes and measure the retention of fuel, compatible with the use of a remote handling facility.
Following first operations on the JT-60SA tokamak, analysis of the data obtained during the commissioning phase of the device are underway and activities have started to prepare the operating scenarios for the future experimental campaigns that will take place in 2026 and 2027.
The W7-X Stellarator continued to make progress in prolonging the high-performance phase and discharge duration in conditions relevant for reducing the heat loads to the plasma facing walls. To emulate reactor relevant conditions in the centre of the plasma, experiments with a large ratio of plasma pressure to magnetic pressure were undertaken at reduced magnetic field, and the plasma transport and loss mechanisms of fast particles were studied.
In 2024 experiments were performed in the tokamaks WEST, ASDEX Upgrade, MAST-U and TCV addressing areas of real time control, power and particle exhaust as well as avoiding large intermittent transport events to the walls to increase the lifetime of the plasma facing components. A particular focus was put on the startup of metallic devices with Tungsten as plasma facing components, in view of ITER changing the first wall from Beryllium to Tungsten. Experiments in several European linear devices (Pilot Surface Interaction (PSI-2) & MAGNUM-PSI in Netherlands) were carried out to complement the experiments in tokamaks. Improved numerical tools were applied to plasma wall interaction and exhaust processes in a reactor-like device to predict erosion, migration, and deposition of Plasma-Facing Materials. Such studies towards including Tritium retention remain critical for assessing the Plasma Facing Components lifetime, nuclear safety, and machine availability.
Activities relating to the concept design of the EU-DEMO have progressed. The work packages responsible for the system design and technology R&D have continued the maturation and down-selection of variants. Several studies were conducted by the DEMO Central Team to define the optimum EU-DEMO design space, which is heavily constrained by physics and technology, aiming to minimise either the machine size or the technical risks. The previous DEMO baseline indicated the unacceptably high divertor heat fluxes during inevitable re-attachment events, the high sensitivity of plasma performance to confinement assumptions, the relatively high toroidal field on axis, the large number of cycles leading to design-driving fatigue issues in the central solenoid (CS) and the lack of a viable solution for breeding blanket (BB) remote maintenance.
Addressing these issues have been at the core of the studies of low aspect ratio configurations in 2024. These studies revealed that the plasma volume is not significantly affected when reducing the aspect ratio.
The feasibility study of a volumetric neutron source, as recommended by the EUROfusion Breeding Blanket Working group, have been accelerated in 2024. It aimed at demonstrating the feasibility of technical and physics objectives, pre-conceptual design activities, defining preliminary configurations, timeline and required resources for further work. A review of the feasibility study was performed by the EUROfusion Scientific Advisory Committee and concluded that at the current stage there are so far no obvious technical or scientific showstoppers that prevent the conceptual design to be carried out.
