Article
Physics, Fluids & Plasmas
A. Mathews, N. Mandell, M. Francisquez, J. W. Hughes, A. Hakim
Summary: The study compared turbulent field fluctuations between electrostatic two-fluid theory and electromagnetic gyrokinetic modeling using a novel physics-informed deep learning framework, finding good overall agreement in magnetized helical plasmas at low normalized pressure. This technique presents a new approach for the numerical validation and discovery of reduced global plasma turbulence models.
PHYSICS OF PLASMAS
(2021)
Article
Physics, Fluids & Plasmas
G. M. Staebler, E. A. Belli, J. Candy, J. E. Kinsey, H. Dudding, B. Patel
Summary: This paper verifies and calibrates a new quasi-linear transport model based on a large database of gyrokinetic turbulence simulations. The modification of a key parameter in the model is found to be necessary for better fitting temperature and density gradients. The new model shows significantly improved fit in electron and ion energy fluxes compared to previous saturation models, leading to revisions in related models.
Article
Physics, Fluids & Plasmas
D. Kouprienko, A. D. Gurchenko, E. Z. Gusakov, A. B. Altukhov, L. G. Askinazi, A. A. Belokurov, V. V. Dyachenko, L. A. Esipov, V. A. Ivanov, O. A. Kaledina, S. Lashkul, S. Shatalin, A. Sidorov, N. Tropin, S. Janhunen
Summary: A detailed study of the FT-2 tokamak reveals significant differences in the behavior of deuterium and hydrogen plasmas in high density regimes. It indicates the stability of improved energy confinement in deuterium plasma.
Article
Physics, Fluids & Plasmas
A. Mariani, N. Bonanomi, P. Mantica, C. Angioni, T. Gorler, O. Sauter, G. M. Staebler
Summary: This study collects and compares the results of dedicated plasma discharges performed at TCV, AUG, and JET tokamaks in Europe, analyzing the electron heat transport related to electron temperature gradient instability. The experimental results suggest that a proper balance of electron and ion heating, with similar electron and ion temperatures and sufficiently large ETG, could have a significant impact on electron heat transport.
Article
Physics, Fluids & Plasmas
Dragos Iustin Palade, Madalina Vlad, Florin Spineanu
Summary: A detailed analysis of a special type of turbulent pinch mechanism for tungsten (W) ions is presented, which is based on numerical simulations. The mechanism involves a special type of order generated by an average poloidal velocity V (p) superposed on the E x B stochastic drift, leading to a pair of radial symmetric drifts that exactly compensate. The study concludes that this turbulent mechanism can be experimentally relevant for a large domain of parameters and can be responsible for an important amount of the W ion accumulation.
Article
Physics, Fluids & Plasmas
N. R. Mandell, G. W. Hammett, A. Hakim, M. Francisquez
Summary: This study demonstrates that electromagnetic effects can moderately increase cross field transport in the scrape-off layer (SOL) in high-beta regimes, leading to broadening of the electron heat-flux width on the endplates.
PHYSICS OF PLASMAS
(2022)
Article
Physics, Fluids & Plasmas
E. Narita, M. Honda, M. Nakata, M. Yoshida, N. Hayashi
Summary: The novel quasilinear turbulent transport model DeKANIS is based on the gyrokinetic analysis of JT-60U plasmas, predicting particle and heat fluxes fast with a neural network (NN) approach and distinguishing diffusive and non-diffusive transport processes. Originally focusing only on particle transport, the model has been extended to cover multi-channel turbulent transport. With the new saturation model, DeKANIS can now be applied independently of the device.
Article
Physics, Fluids & Plasmas
T. Stoltzfus-Dueck, W. A. Hornsby, S. R. Grosshauser
Summary: The study investigates the interaction between ion Landau damping and E X B drift, as well as their impact on momentum flux in turbulence. Nonlinear simulations provide insights into the fraction of fluctuation free energy through ion Landau damping and the variability of symmetry-breaking momentum flux.
PHYSICS OF PLASMAS
(2022)
Article
Physics, Fluids & Plasmas
P. A. Schneider, N. Bonanomi, C. Angioni, M. Weiland, M. Cavedon, P. David, R. Fischer, P. Hennequin, J. Hobirk, A. Kappatou, B. Kurzan, R. M. McDermott, U. Plank, T. Puetterich, F. Ryter, M. Willensdorfer
Summary: The study reveals that there is little isotopic dependence in core heat transport between H and D plasmas at low fast-ion content, but an isotope dependence is observed at high fast-ion fractions. The fast-ion pressure in H and D plasmas differs for comparable NBI heating powers in AUG. Gyrokinetic analysis shows that linear growth rates of ITG modes follow the experimentally observed mass dependence when considering collisions, EM-effects, and fast ions. Non-linear gyrokinetic simulations reproduce the experimental heat fluxes for different isotopes when fast ions are included, indicating the key role of fast-ion pressure in explaining differences in the core of H and D plasmas.
Article
Physics, Multidisciplinary
V Solokha, M. Groth, G. Corrigan, S. Wiesen
Summary: Experiments in JET show that the density limit in pure hydrogen plasmas is approximately 20% higher than in deuterium plasmas, primarily due to the lower density of hydrogen atoms at the separatrix. Additionally, more efficient dissociation and ionization of hydrogen molecules and atoms occur at the high-field X-point region, leading to a higher density limit in hydrogen plasmas compared to deuterium plasmas under certain conditions.
Article
Physics, Fluids & Plasmas
P. A. Schneider, C. Angioni, L. Frassinetti, L. Horvath, M. Maslov, F. Auriemma, M. Cavedon, C. D. Challis, E. Delabie, M. G. Dunne, J. M. Fontdecaba Climent, J. Hobirk, A. Kappatou, D. L. Keeling, B. Kurzan, M. Lennholm, B. Lomanowski, C. F. Maggi, R. M. McDermott, T. Puetterich, A. Thorman, M. Willensdorfer
Summary: Experiments in ASDEX Upgrade and JET with the ITER-like wall were conducted to investigate the pedestal and core contributions to confinement in H-mode plasmas with different main ion masses. The results show a strong dependence of the pedestal on isotope mass, which is enhanced at high gas puffing. The matched pedestals in H and D plasmas were obtained by varying only the triangularity while keeping the engineering parameters relevant for core transport the same. The core transport simulations predict the experimental profiles equally well, indicating a negligible mass dependence and no gyro-Bohm scaling. However, considering fast-ion dilution and rotation is necessary to match the experimental observations at medium beta, and the quasilinear modeling with TGLF overestimates the transport in the core of H and D plasmas.
Article
Physics, Fluids & Plasmas
A. Ho, J. Citrin, C. D. Challis, C. Bourdelle, F. J. Casson, J. Garcia, J. Hobirk, A. Kappatou, D. L. Keeling, D. B. King, F. Koechl, E. Lerche, C. F. Maggi, J. Mailloux
Summary: This study applies the coupled JINTRAC and QuaLiKiz-neural-network (QLKNN) model to investigate the ohmic current ramp-up phase of a JET D discharge. It reveals the role of transport on the Te hollowing, which is caused by the isotope effect on the electron-ion energy exchange. The study demonstrates the potential of neural network surrogates for fast routine analysis and discharge design, but discrepancies between QuaLiKiz and QLKNN impurity transport behavior were found, suggesting further investigation into the turbulent component of heavy impurity transport.
Article
Physics, Fluids & Plasmas
S. Mazzi, J. Garcia, D. Zarzoso, Ye O. Kazakov, J. Ongena, M. Dreval, M. Nocente, Z. Stancar, G. Szepesi
Summary: The impact of fast ions on turbulence properties in JET plasmas is presented through complex numerical simulations. The suppression of ion-scale turbulent transport is achieved through the presence of toroidal Alfven eigenmodes destabilized by highly energetic ions. The nonlinear mechanism triggered by fast ions is the main cause of turbulence suppression and improvement of ion thermal confinement, as validated by experimental studies.
PLASMA PHYSICS AND CONTROLLED FUSION
(2022)
Article
Physics, Fluids & Plasmas
A. Di Siena, R. Bilato, T. Goerier, E. Poli, A. Banon Navarro, D. Jarema, F. Jenko
Summary: A novel type of internal transport barrier called F-ATB has been observed in global gyrokinetic simulations, which is triggered by a resonant interaction between supra-thermal particles and ion scale plasma turbulence. The shape of the fast ion temperature and density profiles plays a crucial role in this resonant mechanism. By performing systematic studies with global simulations, the parameter space and physical conditions for the generation of F-ATB are explored, with particular emphasis on the width and localization of the transport barrier.
PLASMA PHYSICS AND CONTROLLED FUSION
(2022)
Article
Physics, Fluids & Plasmas
A. Mariani, P. Mantica, I. Casiraghi, J. Citrin, T. Gorler, G. M. Staebler
Summary: A benchmark study was conducted to compare the reduced quasi-linear models QuaLiKiz and TGLF with GENE gyrokinetic simulations for a high performance hybrid pulse in deuterium on JET. Results showed that TGLF agrees better with GENE on the linear spectra and flux levels, while only QuaLiKiz can reproduce the GENE radial trend of a gyro-Bohm (gB) scaling at inner radii and anti-gB scaling at outer radii in deuterium plasma.
Article
Physics, Fluids & Plasmas
I Casiraghi, P. Mantica, R. Ambrosino, L. Aucone, B. Baiocchi, L. Balbinot, T. Barberis, A. Castaldo, M. Cavedon, L. Frassinetti, P. Innocente, F. Koechl, S. Nowak, P. Agostinetti, S. Ceccuzzi, L. Figini, G. Granucci, P. Vincenzi
Summary: Deuterium plasma discharges of the DTT in different scenarios were predicted through a comprehensive first-principle based integrated modelling activity using state-of-art quasi-linear transport models. The focus was on core modelling, while ensuring consistency with scrape-off layer parameters necessary for divertor plasma detachment. The compatibility of these predicted scenarios with the electromagnetic coil system capabilities was verified, and initial estimates of DTT sawteeth and edge localised modes were obtained.
PLASMA PHYSICS AND CONTROLLED FUSION
(2023)
Article
Engineering, Multidisciplinary
A. Dal Molin, M. Nocente, M. Dalla Rosa, E. Panontin, D. Rigamonti, M. Tardocchi, A. Shevelev, E. Khilkevitch, M. Iliasova, L. Giacomelli, G. Gorini, E. Perelli Cippo, F. D'Isa, G. Pautasso, G. Papp, G. Tardini, E. Macusova, J. Cerovsky, O. Ficker, M. Salewski, V Kiptily
Summary: A novel hard x-ray (HXR) spectrometer, called runaway electron gamma-ray detection system, has been developed for measuring bremsstrahlung radiation from runaway electrons in fusion plasmas. The system consists of a 1'x1' LaBr3:Ce scintillator crystal and a photomultiplier tube, providing an energy dynamic range exceeding 20 MeV and an energy resolution of 3% at 661.7 keV. The detector gain remains stable even under severe loads, with a gain shift below 3% at HXR counting rates over 1 MCps. The system's outstanding performance allows unprecedented studies of the time-dependent runaway electron energy distribution function in recent experiments.
MEASUREMENT SCIENCE AND TECHNOLOGY
(2023)
Article
Physics, Fluids & Plasmas
T. Wauters, J. Buermans, J. Cavalier, E. Huett, R. Ragona, J. Svoboda, V. Bobkov, M. Griener, A. S. Jacobsen, A. Kallenbach, J. Likonen, T. Loarer, T. Lunt, S. K. Nielsen, R. A. Pitts, D. Ricci, V. Rohde, J. Stober, P. Schneider, M. Usoltseva
Summary: ASDEX Upgrade characterises Electron Cyclotron Wall Condition (ECWC) discharges with full tungsten plasma facing components and X2 polarised waves launched from the equatorial ports, relevant to ECWC conditions in ITER Pre-Fusion Power Operation phase 1. The characterisation is based on experimental inputs such as electron density measurements, in-vessel pressure measurements, poloidal field maps obtained from the measured coil currents, as well as advanced tomographic methods on camera images filtered at the hydrogen Balmer lines. TOMATOR-1D simulations and collective Thomson scattering radiometer spectra complement the findings. By optimizing the poloidal field pattern and the location of the electron cyclotron heating (ECH) resonance, the strongest surface interaction regions for the charged particles can be controlled.
Article
Instruments & Instrumentation
B. Eriksson, S. Conroy, G. Ericsson, J. Eriksson, A. Hjalmarsson, M. Weiszflog, Z. Ghani, M. Maslov, JET Contributors
Summary: TOFOR is a TOF neutron spectrometer at JET with a vertical sightline. It consists of 5 start and 32 stop detectors for generating TOF spectra. The neutron TOF spectra produced by the JET plasma are analyzed to determine fuel ion ratio and the presence of fast ion species. The upgraded TOFOR system, TOFu, utilizes a new digital data acquisition system with improved offline analysis capabilities.
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT
(2023)
Article
Physics, Fluids & Plasmas
Daniel Suarez, Eduardo Iraola, Joaquim Serrat, Elisabet Mas de les Valls, Shimpei Futatani, Lluis Batet
Summary: This study investigates the flow of liquid metals in breeding blankets of tokamak fusion reactors with an externally applied transverse magnetic field. The effect of magnetohydrodynamics (MHD) under the tokamak magnetic field enhances the laminarization of the flow. Under certain conditions, the combination of Lorentz forces, momentum, and buoyant forces can trigger the formation of vortical structures. A quasi-two-dimensional (Q2D) model is used to study this phenomenon, assuming electrically insulating walls and a high Hartmann number. The application of the bi-dimensional fast Fourier transform (FFT2) is proposed as a suitable method to detect the presence of eddies in the flow domain.
PLASMA PHYSICS AND CONTROLLED FUSION
(2023)
Article
Microscopy
Helene Waldl, Marcus Hans, Maximilian Schiester, Daniel Primetzhofer, Michael Burtscher, Nina Schalk, Michael Tkadletz
Summary: It has been found that the elemental composition determined by atom probe tomography (APT) can be significantly influenced by measurement parameters, especially in laser-assisted APT. This study performed laser-assisted APT experiments on Cr0.51N0.49 and thermally more stable (Cr0.47Al0.53)0.49N0.51, comparing different base temperatures, laser wavelengths, and laser pulse energies. The results showed that the laser pulse energy had a strong effect on the apparent elemental composition, and the thermal stability of the material also played a role.
Article
Physics, Fluids & Plasmas
M. J. Mantsinen, P. Jacquet, E. Lerche, D. Gallart, K. Kirov, P. Mantica, D. Taylor, D. Van Eester, M. Baruzzo, I. Carvalho, C. D. Challis, A. Dal Molin, E. Delabie, E. de la Luna, R. Dumont, P. Dumortier, J. Eriksson, D. Frigione, J. Garcia, L. Garzotti, C. Giroud, R. Henriques, J. Hobirk, A. Kappatou, Y. Kazakov, D. Keeling, D. King, V. Kiptily, M. Lennholm, P. Lomas, C. Lowry, C. F. Maggi, J. Mailloux, M. Maslov, S. Menmuir, I. Monakhov, R. B. Morales, C. Noble, M. Nocente, A. Patel, G. Pucella, C. Reux, D. Rigamonti, F. Rimini, A. Sheikh, S. Silburn, P. Siren, E. R. Solano, Z. Stancar, M. Tardocchi
Summary: Experiments were conducted to study the ICRF heating schemes for ITER D-T plasmas, and the results showed that second harmonic heating of T can achieve higher fusion power and ion temperature, which is important for future fusion reactors.
Article
Physics, Fluids & Plasmas
H. J. C. Oliver, S. E. Sharapov, Z. Stancar, M. Fitzgerald, E. Tholerus, B. N. Breizman, M. Dreval, J. Ferreira, A. Figueiredo, J. Garcia, N. Hawkes, D. L. Keeling, P. G. Puglia, P. Rodrigues, R. A. Tinguely
Summary: The Joint European Torus conducted an experimental campaign using a mixture of deuterium (D) and tritium (T) plasma and observed a high-frequency mode known as the toroidal Alfven eigenmode (TAE). Through simulations and calculations, it was found that the TAE can be driven by beam ions with high toroidal mode numbers, while alpha particles contribute less to the driving force. Radiative damping was identified as the dominant damping mechanism. The observed TAE matched the calculated results.
Article
Physics, Fluids & Plasmas
D. Wendler, G. Birkenmeier, M. Griener, R. Dux, R. Fischer, D. Stieglitz, E. Wolfrum, U. Stroth, ASDEX Upgrade Team
Summary: In the scrape-off layer (SOL) of fusion plasmas, the parameters of plasma filaments, which transport radial particle and energy, can be measured by the thermal helium beam diagnostic (THB). This study focuses on the light intensity response of neutral helium transitions from filaments, which is influenced by filament and background parameters. The dominant parameter affecting line intensities is found to be the electron density of the filament. Using a numerical reconstruction algorithm based on a collisional radiative model (CRM), the electron temperatures, densities, and sizes of measured filaments are obtained, enabling the measurement of temporal decay rates of filament density and temperature in the co-moving frame and radial propagation velocity.
PHYSICS OF PLASMAS
(2023)
Article
Microbiology
Giulia Bernabe, Paola Brun, Giuseppe Di Pietra, Veronica Zatta, Shirin Asad, Silvia Meneghello, Giampaolo Cordioli, Enrico Lavezzo, Elisabetta Valente, Sofia Mietto, Valeria Besutti, Ignazio Castagliuolo
Summary: Aeromonas spp. are emerging human pathogens causing intestinal and extra-intestinal infections. The relevance of these pathogens in Western Europe is not well established. This study investigated the prevalence of Aeromonas spp. in diarrheal fecal samples in an Italian University Hospital and characterized the virulence mechanisms of the isolates. The findings showed that Aeromonas spp. were the second most common enteropathogens, with high resistance to amikacin and a diverse range of virulence factors.
MICROBIOLOGY SPECTRUM
(2023)
Article
Instruments & Instrumentation
M. Dibon, P. de Marne, G. Papp, I. Vinyar, A. Lukin, S. Jachmich, U. Kruezi, A. Muir, V. Rohde, M. Lehnen, P. Heinrich, T. Peherstorfer, D. Podymskii
Summary: A new shattered pellet injection system has been developed for disruption mitigation experiments on ASDEX Upgrade. The system is capable of injecting pellets with variable dimensions and can accelerate them to high speeds using helium or deuterium as propellant gas. The system allows for simultaneous preparation of multiple pellets and features flight tubes with varying diameters and shatter heads with different characteristics. The gas preparation and control systems ensure precision and reproducibility of shattered pellet experiments.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2023)
Article
Materials Science, Multidisciplinary
Julia Lumetzberger, Verena Ney, Anna Zakharova, Nieli Daffe, Daniel Primetzhofer, F. Wilhelm, A. Rogalev, Andreas Ney
Summary: Zinc ferrite (ZnFe2O4) epitaxial thin films were grown on MgAl2O4 and Al2O3 substrates using reactive magnetron sputtering. The study investigated the structural and magnetic properties of the films, confirming epitaxial growth of ZnFe2O4 with nominal stoichiometric composition and long-range magnetic order. The growth rate of the films was found to be the main parameter influencing the temperature Tf, while growth temperature or Ar:O2 ratio did not have a systematic effect on Tf. The highest Tf, indicating magnetic glassiness, was observed in ZnFe2O4 epitaxial films.
Article
Nuclear Science & Technology
L. Piron, M. Baruzzo, L. Baylor, C. D. Challis, M. P. Gryaznevich, T. C. Hender, R. B. Henriques, N. Hawkes, S. Jachmich, E. Joffrin, M. Lehnen, M. Lennholm, Y. Q. Liu, J. Mailloux, L. Moreira, D. Valcarcel
Summary: This paper describes the usage of Error Field Correction Coil (EFCC) system in introducing magnetic field perturbations, probing plasma stability, studying radiation asymmetry, and controlling edge localized modes in various plasma experiments.
FUSION ENGINEERING AND DESIGN
(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.