Recent Publications

Concept of a megawatt power-level G-band planar gyrotron with transverse energy extraction

V. Yu. Zaslavsky, I. V. Zheleznov, M. N. Vilkov, A. S. Sergeev, A. N. Kuftin, N. S. Ginzburg

At present, the novel compact fusion reactors with strong magnetic fields, including the DEMO project, require the development of 220–240 GHz megawatt continuous-wave heating sources. In this paper, gyrotrons of planar geometry of interaction space with a sheet polyhelical electron beam and transverse energy extraction are considered as such sources. An advantage of this design in comparison with the conventional cylindrical gyrotron configuration is the possibility to ensure effective mode selection over the open transverse coordinate in combination with radiation outcoupling. The theoretical analysis and numerical 3D PIC simulations of a 230 GHz megawatt power planar gyrotron operating at the first harmonic of the cyclotron frequency are performed. The paper considers the feasibility of single-mode generation with output power exceeding 1 MW, efficiency of 30%, and Ohmic loads less than 1.5 kW/cm2, which is compatible with the continuous-wave operation regime.

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.

Diagnostic of magnetically confined plasmas with superconducting transition edge sensors

Luciano Gottardi, Filipe Ventura Grilo, Liyi Gu, M Botz, M De Wit, Jonas Werner Danisch, José R. R Crespo López-Urrutia

High-resolution X-ray spectroscopy is a key diagnostic tool for the hot plasma core of fusion reactors, since it delivers crucial information on temperature, density and concentrations of heavy element impurities. Originally developed for astrophysical applications, cryogenic X-ray instruments based on superconducting transition-edge sensor (TES) microcalorimeters are non-dispersive spectrometers with high resolving power over a broad energy range of 100 eV to 12 keV. They reach over 90% quantum efficiency and offer extremely low background counts. In this study, we explore the advantages of our TES microcalorimeter for a specific burning plasma scenario of the International Thermonuclear Experimental Reactor (ITER) using a realistic end-to-end simulator developed for future X-ray space instrumentation. We compare the performance of existing diagnostic instruments with that of our TES microcalorimeter, which can simultaneously register spectra from the soft to the hard X-ray range at a fast rate, resolving closely spaced lines from heavy ions such as iron (Fe) and tungsten (W). This provides detailed diagnostics of ionisation balance and impurity content for ITER and other tokamaks as well as stellarators and reversed-field pinches. The TES spectrometer is capable of passively detecting X-ray emissions without interfering with the plasma. It can function from a considerable distance, minimizing neutron hazards, which makes it ideal for future fusion reactor such as DEMO, where diagnostic access is limited.

Tuning of generalized k-omega turbulence model for prediction of heat transfer and pressure drop for helium cooled demo FW

Christine Klein, Frederik Arbeiter

Integrated workflow for DEMO divertor design using Reduced Order Models

D. Valente, C. Poloni, G. Degrassi, R. Ambrosino, F. Subba, D. Marzullo

Activation analysis on diagnostic windows and coating materials for HCPB and WCLL blankets in EU DEMO

Sabahattin Akbas, Barbara Bieńkowska, Ewa Łaszyńska, Jakub Piotr Włodarczyk, Matthew Lukacs, Sandrine Rosanvallon, Joelle Elbez-Uzan

Plasma diagnostics and reactor control systems in future fusion power plants, such as DEMO, will rely on optical windows to monitor key plasma characteristics under intense irradiation conditions. Selecting suitable window and coating materials such as quartz, fused silica, sapphire, HfO₂, and MgF₂ is therefore critical to ensuring component reliability and safety. This study investigates these candidate materials’ activation calculations in the DEMO environment. Using the MCNP code, neutron spectra have been calculated at window-relevant locations in the outboard equatorial port and upper port limiters, considering both Helium-Cooled Pebble Bed and Water-Cooled Lithium Lead breeding blankets. Activation analyses have been subsequently performed with the FISPACT-II inventory code to evaluate the activity, decay heat, contact dose rates, and dominant contributing nuclides under the initial DEMO irradiation scenario. The results provide insights into neutron irradiation effects relevant to the activation performance of window materials and coatings, and contribute valuable input to component design and safety evaluations within the EUROfusion Safety & Environment Work Package framework.

Tritium balance in fuel cycle system for a fusion DEMO with water cooled ceramic breeder blanket

Fumiya Nakamura, Kazunari Katayama, Kentaro Masuta, Akito Ipponsugi, Ryoji Hiwatari, Yuki Edao, Youji Someya

Multibody dynamics with joint modeling and trajectory optimization for the breeding blanket vertical transporter robot

Hjalte Durocher, Christian Bachmann, Rocco Mozzillo, Günter Janeschitz, Xuping Zhang

Effect of neutron irradiation swelling on monoblock fracture in the DEMO reactor

M. Bruno, G. Cricrì, N. Mantel, J.H. You, R. Citarella

Comparison between OTSG and UTSG for DEMO nuclear fusion facility under pump trip scenarios

Jaime Valverde-Hernández, César Queral, Francisco Martín-Fuertes, Kevin Fernández-Cosials

Features of fusion power measurements in next-generation magnetic plasma confinement experiments

V. Krasilnikov, T. Kormilitsyn, D. Fridrikhsen, E. Afanasenko, A. Kovalev, Y. Kashchuk, L. Bertalot, A. Dzhurik, S. Obudovsky, B. Coriton, et al.

Fusion power measurements provide one of the key benchmarks for any successful reactor-scale magnetic confinement fusion facility. In a deuterium–tritium fuel mix, neutrons carry about 4/5 of the produced fusion power outside the plasma volume. Thus, the 14 MeV neutron yield provides the primary direct measurement of the fusion power of a machine. The challenge of determining uncertainty in total neutron yield measurements is solved using several strategies: detailed detector assessment in a metrological neutron laboratory, in situ calibration using a mobile neutron source (typically 252 Cf), and cross-calibration using a well-characterized detector in a well-known discharge. Transition to reactor-scale devices, such as BEST, ITER, and DEMO, will require the use of neutron sources with yields of 10 10 –10 11 s −1 and above. Multiple diagnostics systems fall within this scope: neutron counters, neutron activation systems, and multi-collimator systems. Together, they provide fusion power measurements with up to 10% accuracy and 1 ms time resolution for the case of ITER, across a broad dynamic range of fusion power. Two methods for in situ calibration are considered: (1) using multiple neutron generator (NG) positions to emulate a circular or ‘ring’ source of fusion neutrons for calibrating the permanent detector set, and (2) making use of multiple temporary detectors at various locations inside the vacuum vessel during calibration, thereby allowing us to obtain more reference points for further Monte Carlo model validation with the same (or less) irradiation duration. This study details the results of neutron detector characterization under laboratory conditions using compact NGs, showing that the use of powerful (up to 10 11 s −1 D–T and 10 9 s −1 D–D) yet compact NGs with sealed tubes raises the challenge of steady-source metrological assurance, especially when considering said sources for in situ calibration.

Manufacturing of a representative DEMO divertor shielding liner mock-up by hot isostatic pressing

Emma Piozin, Mathieu Monteremand, Julien Cigna, Paolo Rossi, Jeong-Ha You