Recent Publications

Mirror cleaning of the ITER Core Plasma Thomson Scattering system using 13.56-80 MHz discharges

Youpeng Wang, Artem M. Dmitriev, Laurent Marot, Paul Hiret, Maitane Amarika, Gorka Beaskoetxea, Aitor Marco, Jordi Puig, Laura Sanchez Garcia, Ernst Meyer

The First Mirror Unit (FMU) is a critical front-end component of the collection optics in the ITER Core Plasma Thomson Scattering (CPTS) diagnostic, responsible for monitoring electron density and temperature. Large-sized metallic first (M1) and second (M2) mirrors are integrated into the CPTS FMU to collect and reflect optical signals from the fusion plasma to downstream optics. Due to its proximity to the plasma, M1 requires periodic in-situ cleaning to prevent severe optical degradation caused primarily by deposition. A simplified full-scale 1:1 mock-up of the FMU was manufactured to experimentally assess the radio-frequency (RF) plasma parameters over a wide frequency range of 13.56-80MHz using a retarding field energy analyzer. With increasing pressure and frequency, the magnitude of the direct current (DC) self-bias, mean ion energy, and energy splitting decreased, while the ion flux increased. In addition, particular attention was given to the DC grounding effect by introducing quarter-wavelength shorted stubs as notch filters (NF). In this preliminary RF circuit design, one or both mirrors could be RF-powered, with the remaining surfaces acting as grounded electrodes. Based on the selected parameters, M1 cleaning experiments with DC grounding or self-bias were conducted, followed by elemental composition and reflectivity analysis via X-ray photoelectron spectroscopy and spectrophotometry. The complete removal of 20 nm alumina on M1 was achieved at 13.56 MHz for both configurations, and substantial heating of RF components and the chamber was observed at all frequencies. Moreover, compared with the self-bias case, structural material could be deposited on both mirrors after cleaning with NF, owing to enhanced wall sputtering and weaker mirror cleaning. The feasibility of powering both mirrors simultaneously with self-bias was also demonstrated. Finally, significant power reflection from the load was confirmed using an Octiv V/I probe, highlighting the need for improved power transfer in the CPTS mirror cleaning system.

A feasibility study of neutron spectrum reconstruction using synthetic activation data for JT-60SA

Katarzyna Mikszuta-Michalik, Alvaro Cubi, Marco Fabbri, Matteo Di Giacomo

This study presents a methodology for assessing neutronics models of JT-60SA by comparing simulated neutron spectra with spectra reconstructed from neutron activation measurements. The analysis was performed using synthetic data generated with the Monte Carlo N-Particle (MCNP) radiation transport code for an existing model, as the final detailed tokamak model remains under development. Rather than limiting the assessment to a direct comparison with activation measurement, the proposed approach incorporate neutron spectrum reconstruction as a complementary method to evaluate agreement between simulated and actual spectra. The analysis demonstrates the feasibility and potential of the methodology rather than reproducing experimental conditions. Several spectrum unfolding techniques were applied: Tikhonov Regularisation, Minimum Fisher Information, Maximum Entropy, and Maximum Likelihood. Results were additionally combined into an average reconstructed spectrum to reduce method-dependent differences. The MCNP-calculated spectrum for the P10 port was used in FISPACT-II, advanced nuclear simulation software, to simulate foil activation. The reconstructed spectra and FISPACT-II activities were compared against reference MCNP data. Irradiation was assumed to last the entire experimental campaign. Longer irradiation time limits the activation foil set and increases reconstruction uncertainty. Results demonstrate that the high-intensity region of the neutron spectrum can be reconstructed with an uncertainty below 25%. Performing reconstructions separately across distinct energy ranges enables accurate determination of dominant high-intensity peaks despite numerical challenges from large intensity gradients. Shorter irradiation time allows the use of additional dosimetry foils, reducing the overall reconstruction uncertainty to approximately 23% for the full spectrum. Individual unfolding methods reproduce different spectral regions with varying accuracy, whereas averaging results reduces the discrepancy between the reconstructed and reference spectra. The study demonstrates the potential of combining established reconstruction methods for complementary assessment of neutronics simulations and identifies the treatment of large spectral intensity gradients as an important area for further methodological development

Further development of JADE as a tool for validation and verification of nuclear data libraries and particle transport codes

Alex Valentine, Steven Bradnam, Jude Moorehead, Davide Laghi, Alberto Bittesnich, Marta Campos Fornes, Matteo Di Giacomo, Marco Fabbri, Allan Harte

Several international leading efforts are focused on the improvement of evaluations for nuclear data. This data captures all of the physics of nuclear interactions for which the applications are far ranging from medical applications to criticality simulations. Nuclear analysis in the field of fusion, commonly referred to as neutronics, is one such application, typically employing Monte Carlo methods that rely on continuous-energy, pointwise cross-section data. Historically, the most widely adopted and complete radiation transport code in this field is MCNP, however in recent years there has been an evident trend in exploration of alternatives, most notably OpenMC. Nuclear analysis is a critical driver of the design, operation, safety and decommissioning of future fusion power plants stressing the importance of confidence in the transport codes and underlying nuclear data used in prediction of the radiation environment. Here we present recent developments to the JADE tool - a framework originally conceived for verification and validation of nuclear data within MCNP, now extended to performing cross-code comparisons. In particular, the developments required for the complete integration of OpenMC are detailed. A demonstration of this capability is presented for several of the currently implemented computational and experimental OpenMC benchmarks, with results compared against MCNP with the FENDL-3.2c and ENDF/B-VIII.0 nuclear data libraries.

Electromagnetic analysis of beams for the ITER ECH Upper Launcher

P. Platania, A. Simonetto, J.M. Arroyo, E. Carbonell, N. Casal, M. Choe, D. Farina, G. Garre, M. Henderson, M. Jimenez, et al.

Overview of Achievements and Outlook of the IFMIF/EVEDA Project

Kazuo Hasegawa, Atsushi Kasugai, Keitaro Kondo, Kai Masuda, Satoshi Sato, Kentaro Ochiai, Hervé Dzitko, Fabio Cismondi, Yann Carin, Dominique Gex, et al.

The Engineering Validation and Engineering Design Activities for the International Fusion Materials Irradiation Facility (IFMIF/EVEDA) project have been conducted as one of the three projects (IFMIF/EVEDA, IFERC and JT60SA) within the Broader Approach (BA) agreement between EURATOM and the Japanese government since 2007. The IFMIF is intended to deliver accelerator-based deuterium-lithium (D-Li) neutrons at energies and intensities to sufficient to enable the qualification of candidate materials for future fusion energy reactors, such as DEMO. The primary objective of the IFMIF/EVEDA project is twofold: (i) to develop a detailed engineering design of the IFMIF and (ii) to validate its major components, namely the Accelerator Facility, the Lithium Target Facility and the Test Facility. During Phase I of the BA, which concluded in March 2020, the Engineering Validation Activity (EVA) for the Lithium Target Facility and the Test Facility were successfully completed through the construction and testing of prototypes. In contrast, the EVA for the Accelerator Facility, implemented through the Linear IFMIF Prototype Accelerator (LIPAc), remains on-going. The current phase (Phase II) focuses on the continued commissioning of the LIPAc and the enhancement of some sub-systems to support the development of the Fusion Neutron Source Design (FNSD). This article presents an overview of the progress achieved in the LIPAc commissioning and FNSD activities and outlines the future directions of the activities.

Diagnostics for large tokamaks: from JET to JT-60SA 1

Carlo Sozzi, A Jokinen, G Phillips, K Tanaka, Juan Ayllon-Guerola, Andrea Belpane, Attila Buzás, Santiago Cabrera, mario - cavinato, Daniel Carralero, et al.

The main scientific purpose of JT-60SA is complementing ITER in the preparation of the operation of a DEMOnstration fusion reactor, in particular investigating the conditions for a controllable high beta steady-state regime able to optimize the fusion gain. In order to accomplish this task, a sequence of operation and machine enhancement periods in the next few years are planned to reach the target performance of the machine before a transition to a full tungsten wall. EUROfusion and Fusion for Energy are jointly contributing to the enhancement plan of JT-60SA, in particular, for what concerns the present contribution, to provide JT-60SA with state-of-art diagnostics in support of its scientific and technical objectives. This paper reports the status of the projects being implemented in view of the next scientific campaigns or under consideration through the various stages from feasibility to detailed design.

Analysis of background plasma behavior under external fields in the low energy beam transport section of LIPAC

Tomonobu Itagaki, Tomoya Akagi, Kai Masuda, Nicolas Chauvin, Luca Bellan, Fabio Cismondi, Hervé Dzitko, Yann Carin

Background plasma behaviour in the low energy transport section of the LIPAc is analysed with 3-dimensional particle-in-cell simulation. The simulation showed some characteristic effect under external field elements in the LEBT: a positive biased chopper absorbed the electron plasma in the surrounding drift region. Such absorption by the chopper is limited spatially by the solenoid lenses. However, some extent of electron plasma flows through the solenoid. Analytically estimated flux of the electron leakages through solenoid is compared to the simulation results. Results of experiments still show mysterious transient motion of beam pulse shape that is not shown in the simulations, while saturated state is roughly reproduced in it. Additionally, we developed a one-dimensional electron fluid simulation to investigate effects by thermalization of the background electron plasma, but this also could not reproduce the transient motion observed in the experiment. As a secondary outcome, the fluid simulation showed qualitatively close results to that of the particle in cell simulation in saturated states with much smaller computational resource.

ITER water cooled lithium lead Test Blanket System transient thermal-hydraulic analysis

Tommaso Glingler, Gianfranco Caruso, Danilo Nicola Dongiovanni, Salvatore d’Amico, Italo Ricapito, Paul Wouters, Francesca Fantini, Joelle Elbez-Uzan, Sandrine Rosanvallon, Matteo D'Onorio

The planned experimental activities of the ITER Test Blanket Module program will be a key step in understanding the physics and technologies required for tritium breeding blankets, which are essential for achieving tritium self-sufficiency in a demonstration fusion power reactor. The ITER Test Blanket Module program foresees the installation and operation of different breeding blanket concepts, such as the Water-Cooled Lithium Lead and the Helium-Cooled Pebble Bed, to demonstrate tritium breeding, high-grade heat extraction, and integrated system operation under ITER conditions. The objective of this paper is to provide an overview of the thermal-hydraulic analyses performed in the frame of EUROfusion, for the Water Cooled Lead Lithium Test Blanket Module, with emphasis on the main phenomena occurring during representative accident sequences. The main figure of merit is that the structural integrity of confinement barriers is preserved. Accident scenarios were analyzed using MELCOR version 1.8.6 for fusion applications. The main sequences considered, were identified through an extensive failure mode and effect analysis, include ex-vessel Loss of Coolant Accident and Loss of Heat Sink. The results highlight the robustness of the current design.

Accomplishment of high duty cycle beam commissioning of Linear IFMIF Prototype Accelerator (LIPAc) at 5 MeV, 125 mA D+

Tomoya Akagi, Florian Benedetti, Yann Carin, Janic Chambrillon, Fabio Cismondi, Andrea De Franco, Hervé Dzitko, Takashi Ebisawa, Dominique Gex, Kazuo Hasegawa, et al.

The Linear IFMIF Prototype Accelerator (LIPAc) is being commissioned under the Broader Approach agreement between Europe and Japan to validate the low-energy section of the accelerator for the International Fusion Materials Irradiation Facility (IFMIF). LIPAc is designed to accelerate a 125 mA deuteron beam up to 9 MeV in continuous-wave (CW) operation. This paper reports the results of high-duty cycle beam commissioning at 5 MeV in the Phase B+ configuration using the RFQ. A maximum duty cycle of 8.75% and a beam current of 119 mA were achieved, corresponding to an average RFQ beam power of 40–45 kW, which is among the highest average beam powers achieved by operational RFQs. The commissioning also identified the RFQ RF couplers as the bottleneck for further duty cycle increases, leading to the preparation of brazed high-duty couplers. These achievements establish a solid foundation for the next commissioning phase, including SRF linac integration and a path toward CW operation to demonstrate the IFMIF accelerator concept.

Evaluating the structural reliability of piping systems for ITER Port Cell 16: Design challenges and optimization in Test Blanket Systems

E. García-Blanco, F. Tata-Ducru, D. Guerra, J.P. Martins, F. Fantini, A. Portone, I. Ricapito, R. Rotella, J. Van der Laan

Instrumentation integration and dynamic force reconstruction in the TBM attachment

Eduardo Rodríguez-López, David Alonso, Victor Domínguez, Luis Maqueda, Magdalena Roca, Fernando Rueda, Pablo Ruiz, Alejandro Vázquez, Álvaro Yáñez, Joelle Vallory, et al.

European test blanket modules: An overview of fabrication technologies development and EUROFER97 steel supply

Milan Zmitko, Yves Poitevin, Laurent Forest, Antonella Li Puma, Rémi Boullon, Jérôme Tosi, Denis Sornin, Philippe Emonot, Emmanuel Rigal, Laurence Cogneau, et al.

The design of the EC upper launcher and EX-vessel waveguide systems for ITER

S. Julià, F. Albajar, M. Jimenez, T. Cicero, P. Estebanez, R. Morón Ballester, I. Eletxigerra, A. San Vicente, C. Gómez, E. Carbonell, et al.

The electron cyclotron (EC) upper launcher (UL) and ex-vessel waveguide (EW) are integral components of the ITER EC system (Sanchez et al 2025 Qualification of the European gyrotrons and power supplies of the ECH and CD system of ITER IAEA FEC ), which plays a key role in achieving and maintaining the high temperatures required for nuclear fusion within the tokamak, providing plasma heating and current drive, and magnetohydrodynamics stabilization, which are crucial for ITER’s operational success. The fusion for energy contribution to the current ITER baseline configuration comprises four ULs and five sets of EWs. The UL and EW systems, currently in its final design phase under the frame of a procurement agreement between Europe and ITER organization, have released the final design documentation package, which is here described, as input to the final design gate review that took place in July 2025. The full set of documents released is composed by: (1) a design description (DD) dossier composed by a UL & EW DD document and supported by a set of 3D models, drawings and diagrams; (2) a design justification dossier encompassing a set of end-to-end engineering analyses verifying the functionality and structural integrity of the components according to the applicable requirements, and the RAMI analysis of both systems; and (3) a product lifecycle dossier covering documentation for subsequent phases including manufacturing, assembly, installation, commissioning, operations, maintenance and decommissioning. Furthermore, the validation of the design is supported by currently on-going activities of prototyping and testing of the most critical components.

The research plan for the ITER TBM program

Luciano M. Giancarli, Mu-Young Ahn, Paritosh Chaudhuri, Seungyon Cho, Takanori Hirose, Paul Humrickhouse, Yoshinori Kawamura, Francesca Fantini, Italo Ricapito, Rossella Rotella, et al.

Adapting the D1S methodology for high-fluence fusion environments with tungsten: application to ITER

Alberto Bittesnich, Marco Fabbri, Patrick Sauvan, Antonio Jesus Lopez-Revelles, Aljaž Kolšek, Neil Taylor, Alfredo Portone

Application of the TUD-W benchmark for nuclear data and code assessment

Marta Campos Fornés, Marco Fabbri, Luigino Petrizzi, Aljaž Kolšek, Davide Laghi