Article
Chemistry, Physical
Stjepko Fazinic, Georgios Provatas, Iva Bozicevic Mihalic, Tonci Tadic, Marek Rubel, Justyna Grzonka, Per Petersson, Anna Widdowson, Sunwoo Moon, Elzbieta Fortuna-Zalesna
Summary: Silicon plates were installed above the inner and outer divertor of the JET with the ITER-like wall (ILW) to monitor dust generation and deposition. The study found different categories of Be-rich particles, including co-deposits peeled off from plasma-facing components (PFC), complex multi-element spherical objects, and solid metal splashes and regular spherical droplets. Tungsten droplets were not detected, and the only W-containing particles were fragments of tungsten coatings from the divertor tiles.
Article
Nuclear Science & Technology
C. Ruset, E. Grigore, M. Mayer, F. Baiasu, C. Porosnicu, S. Krat, A. Widdowson, J. Likonen, M. Analytis, R. Meihsner, Jet Contributors
Summary: The JET divertor tiles were analyzed using GDOES technique, and it was found that the Be layer can protect the tile surface from erosion. Two mechanisms of D retention were identified based on the concentration of Be.
NUCLEAR MATERIALS AND ENERGY
(2022)
Article
Nuclear Science & Technology
S. Krat, M. Mayer, J. P. Coad, C. P. Lungu, K. Heinola, A. Baron-Wiechec, I Jepu, A. Widdowson
Summary: The study focused on the net erosion of material from recessed areas of the JET main chamber inner wall during the first three ITER-like wall (JET-ILW) campaigns. Both Be and W erosion rates showed changes between campaigns, with potential explanations including testing of power handling capability, changes in incident particle energy distribution, and limiter to divertor discharge time ratio. The net erosion rate of W remained relatively stable through the first two campaigns but increased significantly in the third, possibly due to changes in the energy spectrum of eroding particles and the addition of Kr and Xe to fueling.
NUCLEAR MATERIALS AND ENERGY
(2021)
Article
Physics, Fluids & Plasmas
S. Lee, Y. Hatano, S. Masuzaki, Y. Oya, M. Tokitani, M. Yajima, T. Otsuka, N. Ashikawa, Y. Torikai, N. Asakura, H. Nakamura, H. Kurotaki, T. Hayashi, T. Nozawa, A. M. Ito, J. Likonen, A. Widdowson, M. Rubel
Summary: In this study, the tritium retention in the castellated structure of beryllium limiters used in JET with the ITER-like wall was evaluated. Tritium was found to be deposited inside the grooves along with other elements. The tritium content was higher after the ILW1 campaign compared to the ILW3 campaign, which is attributed to a decrease in carbon impurities. The majority of tritium was retained in shallow regions in the grooves, and the retention patterns differed on plasma-facing surfaces.
Article
Physics, Multidisciplinary
E. Fortuna-Zalesna, T. Plocinski, S. W. Moon, P. Petersson, M. Rubel, A. Widdowson
Summary: This study analyzed dust particles and co-deposits sampled from beryllium limiters, bulk tungsten divertor, and test mirrors using various microscopy methods, revealing different morphologies and structures.
Article
Physics, Multidisciplinary
Maciej Spychalski, E. Fortuna-Zalesna, Joanna Zdunek, Marek Rubel, Anna Widdowson, Spyridon Aleiferis, Beth Thomas
Summary: Tungsten Langmuir probes retrieved from the JET tokamak with the ITER-Like Wall (JET-ILW) after the second ILW campaign were examined by nano-indentation, microscopy and x-ray diffraction to determine changes in mechanical properties and phase composition. The probes showed significant differences in hardness between the tip and support structure, while the Young's modulus values were similar. The material in the tip has a smaller range of elastic deformations compared to that of the support structure.
Article
Nuclear Science & Technology
H. A. Kumpulainen, M. Groth, S. Brezinsek, G. Corrigan, L. Frassinetti, D. Harting, F. Koechl, J. Karhunen, A. G. Meigs, M. O'Mulane, J. Romazanov, J. E. T. Contributors JET Contributors
Summary: Simulations of JET ITER-like wall high-confinement mode plasmas predict almost perfect screening of primary tungsten erosion sources at the divertor targets, with the largest influx of tungsten to the main plasma coming from the outer vertical divertor. However, the predictions for tungsten II emission underestimate the actual measurements by a factor of 10. The discrepancies may be due to uncertainties in atomic data, assumptions on sheath properties and sputtering angles distribution, and the influence of metastable states.
NUCLEAR MATERIALS AND ENERGY
(2022)
Article
Nuclear Science & Technology
E. Pajuste, G. Kizane, L. Avotina, A. Vitins, A. S. Teimane
Summary: The ITER-Like Wall (ILW) project at Joint European Torus (JET) aims to test plasma-facing materials relevant to the ITER. Beryllium and tungsten tiles were used in different parts of the vacuum vessel, with tritium measurements showing varying concentrations across different positions and ILW campaigns. Tritium content was highest in samples from the outer wall of the vacuum vessel, particularly in the central part of tiles where plasma erosion had occurred.
NUCLEAR MATERIALS AND ENERGY
(2021)
Article
Nuclear Science & Technology
S. E. Lee, Y. Hatano, M. Tokitani, S. Masuzaki, Y. Oya, T. Otsuka, N. Ashikawa, Y. Torikai, N. Asakura, H. Nakamura, K. Isobe, H. Kurotaki, D. Hamaguchi, T. Hayashi, A. Widdowson, S. Jachmich, J. Likonen, M. Rubel
Summary: Nondestructive analysis of tritium distribution was conducted on specimens from the JET tokamak, revealing different levels of tritium retention after different experimental campaigns. The correlation between tritium distributions, surface morphology, and discharge conditions was discussed.
NUCLEAR MATERIALS AND ENERGY
(2021)
Article
Physics, Fluids & Plasmas
G. Birkenmeier, E. R. Solano, E. Lerche, D. Taylor, D. Gallart, M. J. Mantsinen, E. Delabie, I. S. Carvalho, P. Carvalho, E. Pawelec, J. C. Hillesheim, F. Parra Diaz, C. Silva, S. Aleiferis, J. Bernardo, A. Boboc, D. Douai, E. Litherland-Smith, R. Henriques, K. K. Kirov, C. F. Maggi, J. Mailloux, M. Maslov, F. G. Rimini, S. A. Silburn, P. Siren, H. Weisen
Summary: Experimental results at the JET tokamak facility suggest that the heating power threshold in tritium plasmas with metallic walls is inversely proportional to the isotope mass of the main ion species. Tritium showed the lowest power threshold in Ohmically heated plasmas at low density, while ion cyclotron heated plasmas of pure tritium or tritium-hydrogen mixtures had significantly higher power thresholds due to increased radiation levels. However, when considering radiated power, ion cyclotron heating showed similar power thresholds to neutral beam heating, approaching the expected scaling.
Article
Physics, Fluids & Plasmas
D. Brunetti, C. J. Ham, J. P. Graves, E. Lazzaro, S. Nowak, A. Mariani, C. Wahlberg, W. A. Cooper, E. R. Solano, S. Saarelma, L. Frassinetti, M. Fontana, A. Kleiner, G. Bustos Ramirez, E. Viezzer
Summary: This paper presents an analysis of edge localised mode-free (quiescent) H-mode discharges with edge harmonic magnetohydrodynamic activity in the JET-carbon wall machine. It is observed that quiescent pulses with multiple-n harmonic oscillations are sustained until a threshold in pedestal electron density and collisionality is crossed. The macroscopic pedestal parameters associated with the quiescent phase are compared with a database of JET-ELMy discharges to identify the relevant regions for edge harmonic oscillations in JET plasmas. The study suggests that ILW operation with JET-carbon quiescent-like parameters could be achieved and improved pedestal performance could be observed in more recent JET-ILW pulses.
PLASMA PHYSICS AND CONTROLLED FUSION
(2022)
Article
Physics, Fluids & Plasmas
M. Faitsch, I. Balboa, P. Lomas, S. A. Silburn, A. Tookey, D. Kos, A. Huber, E. de la Luna, D. Keeling, A. Kappatou, JET Contributors
Summary: This article presents the first results of a divertor power load characterization in tritium plasmas during the JET deuterium-tritium campaign in 2021. The study shows that the transient loads and power fall-off length in tritium plasmas are not explicitly dependent on ion mass, with similar values to deuterium plasma experiments. This supports the credibility of scaling law predictions based on deuterium plasma experiments. Additionally, the impact of type-I ELMs on the inner divertor target in deuterium discharges is studied.
Article
Physics, Fluids & Plasmas
M. Rubel, Sunwoo Moon, P. Petersson, A. Widdowson, R. A. Pitts, S. Aleiferis, E. Fortuna-Zalesna, G. De Temmerman, R. Reichle
Summary: Mirror tests for ITER were conducted in JET for over 15 years, with a recent experiment during the third JET campaign showing no degradation in total reflectivity but an increase in diffuse reflectivity at shorter wavelengths. The mirrors were coated with a thin layer containing various elements, providing valuable input for ITER's erosion/deposition modeling and mirror cleaning methods consideration.
Article
Physics, Multidisciplinary
E. Pajuste, A. S. Teimane, G. Kizane, L. Avotina, M. Halitovs, A. Lescinskis, A. Vitins, P. Kalnina, E. Lagzdina, R. J. Zabolockis
Summary: The ITER-Like-Wall project at JET examines plasma facing materials for ITER, including bulk metals and coatings, analyzing tritium retention and behavior through various methods to understand its distribution and accumulation in the vacuum vessel.
Article
Nuclear Science & Technology
Laura Dittrich, Per Petersson, Sunwoo Moon, Marek Rubel, Tuan Thien Tran, Anna Widdowson
Summary: The aim of this work was to determine the lateral and depth distribution of various gases in plasma-facing components and compare their retention with deuterium in the studied areas.
FUSION ENGINEERING AND DESIGN
(2023)
Article
Nuclear Science & Technology
Loris Zanotto, Marco Boldrin, Giuseppe Chitarin, Mattia Dan, Tommaso Patton, Francesco Santoro, Vanni Toigo, Hiroyuki Tobari, Atsushi Kojima, Hans Decamps
Summary: This paper describes the commissioning and integration tests of the Acceleration Grid Power Supply of the MITICA test facility in Padova, Italy. Stable operation at 700 kV was achieved for the first time, but breakdowns occurred in the HV part and DC generator. A test campaign was conducted to identify the breakdown locations and collect measurement patterns for different cases.
FUSION ENGINEERING AND DESIGN
(2023)
Article
Physics, Fluids & Plasmas
M. Vallar, M. Dreval, M. Garcia-Munoz, S. Sharapov, J. Poley, A. N. Karpushov, P. Lauber, S. Mazzi, L. Porte, TCV Team
Summary: In Tokamak Configuration Variable (TCV), unstable modes excited by the resonant interaction between shear Alfven waves and energetic particles have been observed during scenarios with neutral beam injection (NBI). The Alfvenic nature of the modes has been confirmed by studying their sensitivity to plasma parameters and comparing with linear kinetic stability code predictions. The mode's radial profile has been estimated using electron cyclotron emission measurement and agrees well with modeling results. Additionally, the fast particle distribution function has been modeled using TRANSP/NUBEAM code.
Article
Physics, Fluids & Plasmas
S. O. Makarov, D. P. Coster, E. G. Kaveeva, V. A. Rozhansky, I. Y. Senichenkov, I. Y. Veselova, S. P. Voskoboynikov, A. A. Stepanenko, X. Bonnin, R. A. Pitts
Summary: A new Grad-Zhdanov module is implemented into the SOLPS-ITER code to calculate parallel kinetic coefficients. A complete multi-ion generalization is performed, relaxing the assumption of heavy impurities. A JET-like test simulation is conducted to demonstrate the ability to model a 50/50 deuterium (D) and tritium (T) mixture in SOLPS-ITER.
Review
Physics, Fluids & Plasmas
Luis L. Alves, Markus M. Becker, Jan van Dijk, Timo Gans, David B. Go, Katharina Stapelmann, Jonathan Tennyson, Miles M. Turner, Mark J. Kushner
Summary: The field of low-temperature plasmas (LTPs) excels by its intellectual diversity, interdisciplinarity, and range of applications. Communication challenges arise due to diverse reporting practices and expectations. This paper addresses these challenges by discussing standards for measurements, diagnostics, computations, reporting, and plasma sources to improve communication and transparency within the LTP field.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2023)
Article
Physics, Fluids & Plasmas
S. Lee, Y. Hatano, S. Masuzaki, Y. Oya, M. Tokitani, M. Yajima, T. Otsuka, N. Ashikawa, Y. Torikai, N. Asakura, H. Nakamura, H. Kurotaki, T. Hayashi, T. Nozawa, A. M. Ito, J. Likonen, A. Widdowson, M. Rubel
Summary: In this study, the tritium retention in the castellated structure of beryllium limiters used in JET with the ITER-like wall was evaluated. Tritium was found to be deposited inside the grooves along with other elements. The tritium content was higher after the ILW1 campaign compared to the ILW3 campaign, which is attributed to a decrease in carbon impurities. The majority of tritium was retained in shallow regions in the grooves, and the retention patterns differed on plasma-facing surfaces.
Article
Physics, Fluids & Plasmas
O. Myatra, D. Moulton, B. Dudson, B. Lipschultz, S. Newton, K. Verhaegh, A. Fil
Summary: This study investigated the role of ion-molecule (D+ - D-2) elastic collisions in strongly detached divertor conditions. Two steady state solutions were compared: one obtained through a main-ion fuelling scan and the other through a nitrogen seeding scan. The results showed significant differences in electron-ion recombination levels between the two solutions.
Article
Physics, Fluids & Plasmas
Cheng Ye, You-Wen Sun, Hui-Hui Wang, Yue-Qiang Liu, Tong-Hui Shi, Qing Zang, Tian-Qi Jia, Qun Ma, Shuai Gu, Nan Chu, Kai-Yang He, Man-Ni Jia, Xue-Min Wu, Peng-Cheng Xie, Hui Sheng, Hua Yang, Lian-Sheng Huang, Biao Shen, Miao-Hui Li, Jin-Ping Qian, EAST Team
Summary: The plasma-beta effect on the n=1 resonant magnetic perturbation (RMP) field penetration in purely radio-frequency (RF) wave heated discharges has been investigated. The experimental results show that the error-field tolerance is improved with increasing RF power, benefiting from the increased electron perpendicular flow dominated by a counter-current electron diamagnetic flow. However, the theoretical scaling overestimates the power index, and the degradation effect of plasma beta is observed.
Article
Physics, Fluids & Plasmas
F. Nespoli, K. Tanaka, S. Masuzaki, N. Ashikawa, M. Shoji, E. P. Gilson, R. Lunsford, T. Oishi, K. Ida, M. Yoshinuma, Y. Takemura, T. Kinoshita, G. Motojima, M. Osakabe, N. Kenmochi, G. Kawamura, C. Suzuki, A. Nagy, A. Bortolon, N. A. Pablant, A. Mollen, N. Tamura, D. A. Gates, T. Morisaki
Summary: An improvement in the confinement regime of the Large Helical Device has been observed, characterized by reduced turbulent fluctuations, upon the injection of boron powder into the plasma. This article presents the experimental observations of increased plasma temperature and decreased turbulent fluctuations across the plasma cross section, using a larger database. Powder penetration modeling and analysis of neoclassical electric field and fluxes support the interpretation of the experimental results. The article also reports evidence of the temperature improvement depending on powder injection rates, density, and heating power, while the plasma turbulence response varies depending on the initial conditions.
Article
Public, Environmental & Occupational Health
Cristiano Franchi, Riccardo Rossi, Andrea Malizia, Pasqualino Gaudio, Daniele Di Giovanni
Summary: Through analysis, it was found that there is a strong correlation between the infection trends in Italian prisons and the external community. The infection prevalence is higher in prisons, but the reproduction number and hospitalization rate are lower. There is a lag of 1-2 weeks in prison, which can provide a useful time-window for strengthening countermeasures.
OCCUPATIONAL AND ENVIRONMENTAL MEDICINE
(2023)
Review
Chemistry, Analytical
Bruno Goncalves, Paulo Varela, Antonio Silva, Filipe Silva, Jorge Santos, Emanuel Ricardo, Alberto Vale, Raul Luis, Yohanes Nietiadi, Artur Malaquias, Jorge Belo, Jose Dias, Jorge Ferreira, Thomas Franke, Wolfgang Biel, Stephane Heuraux, Tiago Ribeiro, Gianluca De Masi, Onofrio Tudisco, Roberto Cavazzana, Giuseppe Marchiori, Ocleto D'Arcangelo
Summary: Providing energy from fusion and scaling up the process efficiently and economically is a major challenge in engineering. Plasma Position Reflectometry (PPR) plays an important role in future fusion machines by monitoring plasma position and shape. It uses radar methods in microwave and millimetre wave frequency ranges to measure density profile for plasma control.
Article
Physics, Fluids & Plasmas
J. Garcia, F. J. Casson, L. Frassinetti, D. Gallart, L. Garzotti, H. -t. Kim, M. Nocente, S. Saarelma, F. Auriemma, J. Ferreira, S. Gabriellini, A. Ho, P. Huynh, K. K. Kirov, E. Lerche, M. J. Mantsinen, V. K. Zotta, Z. Stancar, D. M. A. Taylor, D. Van Eester, C. D. Challis, JET Contributors
Summary: For more than a decade, an unprecedented predict-first activity has been carried out to predict fusion power and provide guidance to the DTE2 campaign. It is shown that detailed physics-based predictions are necessary and a combination of different modeling complexities and an extended interplay between modeling and experiment are essential for reliable predictions of D-T plasmas.
Article
Physics, Fluids & Plasmas
J. Cazabonne, P. Donnel, S. Coda, J. Decker, G. Di Giannatale, A. Iantchenko, U. Kumar, Y. Peysson, L. Porte, S. Rienacker, A. Tema-Biwole, L. Villard, TCV Team
Summary: Energy transfer from electron-cyclotron waves to the plasma is used in tokamaks for heating and current drive. However, observations show a broader distribution of suprathermal electrons than predicted. This study investigates the wave-induced increase in electron turbulent transport using power-modulated electron-cyclotron waves, and confirms the power dependency of electron transport through experimental data and simulations.
PLASMA PHYSICS AND CONTROLLED FUSION
(2023)
Article
Chemistry, Physical
Simona Breidokaite, Gediminas Stankunas
Summary: EU DEMO is the first demonstrative fusion power plant that aims to demonstrate the production of net electric energy that can be supplied to the grid. It is expected to have a comparable lifespan and availability as a commercial fusion power plant. One of DEMO's objectives is to safely and continuously provide considerable net electric power to the grid (ranging from 100 MW to 500 MW). This study assesses the DPA and helium production in the divertor, focusing on the structural material EUROFER. The helium production rates peak at around 117 appm/fpy, while the DPA values reach a maximum of about 4 dpa/fpy.
RADIATION PHYSICS AND CHEMISTRY
(2023)
Article
Chemistry, Physical
Vibhuti Vashi, Rajnikant Makwana, B. Quintana, M. H. Mehta, R. K. Singh, B. K. Soni, R. Chauhan, S. Mukherjee, M. Abhangi, S. Vala, N. L. Singh, G. B. Patel, S. V. Suryanarayana, B. K. Nayak, S. C. Sharma, T. N. Nag, Y. Kavun
Summary: The standard activation analysis technique with gamma ray spectroscopy was used to estimate reaction cross sections. Proton beams generated by the BARC-TIFR accelerator were directed at a Cd-nat target. The study estimated the activation cross sections for the Cd-110(p, n) and Cd-110(p, 2n)In-109 reactions at specific proton energies. The results provide valuable information for improving theoretical nuclear model codes and have significance in Positron Emission Tomography (PET) studies.
RADIATION PHYSICS AND CHEMISTRY
(2023)
Article
Materials Science, Multidisciplinary
Thomas Bierschenk, Werner Wesch, Boshra Afra, Matias D. Rodriguez, Flyura Djurabekova, Levi Keller, Olli H. Pakarinen, Kai Nordlund, Mark C. Ridgway, Patrick Kluth
Summary: Swift heavy ion irradiation leads to the self-organization of nano-porosity in amorphous Ge, with pores segregating into layers parallel to the sample surface. The self-organization mechanism depends on ion energy, thickness of the amorphous Ge layer, and ion incidence angle, with a characteristic length determined by ion energy and irradiation angle. Molecular dynamics simulations show that voids form due to the transition from low-density amorphous to high-density liquid phase, resulting in a flow away from large pores and surfaces and supporting void formation at the amorphous/crystalline interface.