Browsing by Author "Groth, M."

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  • 1D kinetic modelling of the JET SOL with tungsten divertor
    (2013-07) Tskhakaya, D.; Groth, M.; Contributors, JET EFDA
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    In this work a fully kinetic model of the JET SOL with tungsten divertor plates has been developed. It includes the dynamics of main-ions (D+) and electrons, the neutrals (D, C, W) and the impurity particles (C+m, W+n). Our simulations show extremely low concentration of W impurity. We identify two reasons which are responsible for this effect: (1) for low temperature divertor plasma the energy of most of the main-ions and the impurities in a low-ionization state impinging the divertor plates is below the W-sputtering threshold energy; (2) with increasing temperature the W-sputtering increases, but the potential drop across the divertor plasma increases too, so that most of the W ions are reabsorbed at the divertors.
  • Addressing the impact of Lyman opacity in inference of divertor plasma conditions with 2D spectroscopic camera analysis of Balmer emission during detachment in JET L-mode plasmas
    (2025-03) Karhunen, J.; Lomanowski, B.; Aleiferis, S.; Carvalho, P.; Groth, M.; Holm, A.; Lawson, K. D.; Meigs, A. G.; Shaw, A.; Solokha, V.; , JET Contributors; , EUROfusion Tokamak Exploitation Team
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The impact of re-absorption of the deuterium Lyman series emission was addressed in inferring divertor plasma conditions from Balmer series emission with 2D spectroscopic camera analysis during detachment in JET L-mode plasmas. The previously presented methodology was amended by modifying the standard photon emission coefficients and ionization and recombination rate coefficients of the ADAS database to consider the re-population of excited states due to Lyman opacity. This resulted in the estimate for the atomic density near the outer strike point to decrease by up to 75% at the onset of detachment at strike point temperatures of Te,osp≈ 1.0–3.0 eV with respect to the strongly overestimated previously obtained values, whereas the estimated electron temperature and density were unaffected by the opacity correction within the scatter of the data and only a moderate reduction by up to 20% was observed in the estimate for the molecularly induced fraction of the Balmer emission. No noticeable change was seen in the ionization rate, calculated from the estimated outer strike point conditions, due to the decrease in the atomic density estimate compensating for the increased values of the opacity-corrected ADAS rate coefficients for ionization. In detached conditions at Te,osp≈ 0.5–1.0 eV, 25%–35% lower recombination rates were provided by the opacity-corrected model. The observed effects on the experimental analysis were supported by a corresponding synthetic analysis based on EDGE2D-EIRENE simulations.
  • Application of spatially hybrid fluid–kinetic neutral model on JET L-mode plasmas
    (2021-06) Horsten, N.; Groth, M.; Blommaert, M.; Dekeyser, W.; Pérez, I. Paradela; Wiesen, S.; , JET Contributors
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    We present a spatially hybrid fluid–kinetic neutral model that consists of a fluid model for the hydrogen atoms in the plasma grid region coupled to a kinetic model for atoms sampled at the plasma–void interfaces and a fully kinetic model for the hydrogen molecules. The atoms resulting from molecular dissociation are either treated kinetically (approach 1) or are incorporated in the fluid model (approach 2). For a low-density JET L-mode case, the hybrid method reduces the maximum fluid–kinetic discrepancies for the divertor strike-point electron densities and electron temperatures from approximately 150% to approximately 20% for approach 1 and to approximately 40% for approach 2. Although the simulations with purely fluid neutral model become more accurate for increasing upstream plasma density, we still observe a significant improvement by using the hybrid approach. When consuming the same CPU time in averaging the electron strike-point densities and temperatures over multiple iterations as for the simulations with fully kinetic neutrals, hybrid approach 1 reduces the statistical error with on average a factor 2.5. Hybrid approach 2 further increases this factor to approximately 3.3, at the expense of accuracy.
  • Assessment of filtered cameras for quantitative 2D analysis of divertor conditions during detachment in JET L-mode plasmas
    (2021-08) Karhunen, J.; Lomanowski, B.; Solokha, V.; Aleiferis, S.; Carvalho, P.; Groth, M.; Lawson, K. D.; Meigs, A. G.; Shaw, A.; , JET Contributors
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Estimates for 2D distributions of electron temperature, Te, electron density, ne, and atomic deuterium density, n0, in the JET divertor volume have been inferred from deuterium Balmer line intensity ratios obtained from tomographic reconstructions of divertor camera measurements. This enables also investigation of ionization, Sion, and recombination, Srec, rates. The analysis shows a decrease of Te to 0.5-1.0 eV throughout the outer divertor during detachment in low-confinement (L-mode) plasmas. Simultaneously, the high-ne region and the n0 distribution in the outer divertor are observed to elongate and shift from the outer strike point towards the X-point. The observations are in qualitative agreement and follow the same sequence with modelling predictions of EDGE2D-EIRENE simulations of a density scan. While the method was found to provide good representation of the evolution of volumetric recombination during detachment, in agreement with the simulations, the movement of the ionization front upstream could not be followed due to lack of spatial overlap between the ionization region and the necessary emission distributions. Consequently, the representation of the ionization conditions and the particle balance in the detached outer divertor are compromised.
  • Assessment of particle and heat loads to the upper open divertor in ASDEX Upgrade in favourable and unfavourable toroidal magnetic field directions
    (2019-05-01) Paradela Pérez, I.; Groth, M.; Wischmeier, M.; Scarabosio, A.; Brida, D.; David, P.; Silvagni, D.; Coster, D.; Lunt, T.; Faitsch, M.; , ASDEX Upgrade Team
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Pairs of ASDEX Upgrade L-mode discharges with the toroidal magnetic field, B T , in the forward and reverse directions have been used to study the impact of neoclassical drifts on the divertor plasma conditions and detachment. The evolution of the peak heat flux and the total power loads onto both the outer and the inner targets depends significantly on the toroidal field direction: increasing the core plasma density affects mainly the heat loads in the B T < 0 (unfavourable) direction, whereas increasing the plasma current has a larger impact on the heat loads for B T > 0 (favourable). Ion saturation current measurements show similar trends to those of the IR heat flux data. These discrepancies are not only caused by drifts but also by different levels of radiated power in the core, thus the power across the separatrix, P sep . Tomographic reconstructions show that P sep is not constant within the entire dataset. Finally, at I p =0.8MA, a significant reduction of the peak heat flux is observed at both targets for both field directions. On the other hand, at I p =0.6MA, a reduction of the peak heat flux is only observed for B T < 0 at the outer target. Additionally, the onset of particle detachment is only observed at the outer target for B T < 0 with I p =0.8MA.
  • Beryllium global erosion and deposition at JET-ILW simulated with ERO2.0
    (2019-01-01) Romazanov, J.; Brezinsek, S.; Borodin, D.; Groth, M.; Wiesen, S.; Kirschner, A.; Huber, A.; Widdowson, A.; Airila, M.; Eksaeva, A.; Borodkina, I.; Linsmeier, Ch; , JET Contributors
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The recently developed Monte-Carlo code ERO2.0 is applied to the modelling of limited and diverted discharges at JET with the ITER-like wall (ILW). The global beryllium (Be) erosion and deposition is simulated and compared to experimental results from passive spectroscopy. For the limiter configuration, it is demonstrated that Be self-sputtering is an important contributor (at least 35%) to the Be erosion. Taking this contribution into account, the ERO2.0 modelling confirms previous evidence that high deuterium (D) surface concentrations of up to ∼ 50% atomic fraction provide a reasonable estimate of Be erosion in plasma-wetted areas. For the divertor configuration, it is shown that drifts can have a high impact on the scrape-off layer plasma flows, which in turn affect global Be transport by entrainment and lead to increased migration into the inner divertor. The modelling of the effective erosion yield for different operational phases (ohmic, L- and H-mode) agrees with experimental values within a factor of two, and confirms that the effective erosion yield decreases with increasing heating power and confinement.
  • Calibration improvements expand filterscope diagnostic use
    (2024-02-01) Herfindal, J. L.; Unterberg, E. A.; Davda, K. M.; Garren, E. W.; Groth, M.; Scotti, F.; Sontag, Aaron C.; Truong, D. D.; Wilcox, R. S.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The filterscope diagnostic on DIII-D utilizes photomultiplier tubes to measure visible light emission from the plasma. The system has undergone a substantial upgrade since previous attempts to cross-calibrate the filterscope with other spectroscopic diagnostics were unsuccessful. The optics now utilize a dichroic mirror to initially split the light at nearly 99% transmission or reflectance for light below or above 550 nm. This allows the system to measure Dα emission without degrading visible light emission from the plasma for wavelengths below 550 nm (to measure Dβ, Dγ, W-I, C-III, etc.). Additional optimization of the optical components and calibration techniques reduce the error in the signal up to 10% in some channels compared to previous methods. Cross-calibration measurements with two other high resolution spectroscopic diagnostics now show excellent agreement for the first time. This expands the capabilities of the filterscope system allowing measurement of divertor detachment, emission profiles, edge-localized mode behavior, and plasma-wall interactions. It also enables direct comparisons against calculations from boundary plasma simulations. These were not possible before.
  • Characterisation of divertor detachment onset in JET-ILW hydrogen, deuterium, tritium and deuterium–tritium low-confinement mode plasmas
    (2023-03) Groth, M.; Solokha, V.; Aleiferis, S.; Brezinsek, S.; Brix, M.; Carvalho, I. S.; Carvalho, P.; Corrigan, G.; Harting, D.; Horsten, N.; Jepu, I.; Karhunen, J.; Kirov, K.; Lomanowski, B.; Lawson, K. D.; Lowry, C.; Meigs, A. G.; Menmuir, S.; Pawelec, E.; Pereira, T.; Shaw, A.; Silburn, S.; Thomas, B.; Wiesen, S.; Börner, P.; Borodin, D.; Jachmich, S.; Reiter, D.; Sergienko, G.; Stancar, Z.; Viola, B.; Beaumont, P.; Bernardo, J.; Coffey, I.; Conway, N. J.; de la Luna, E.; Douai, D.; Giroud, C.; Hillesheim, J.; Horvath, L.; Huber, A.; Lomas, P.; Maggi, C. F.; Maslov, M.; Perez von Thun, C.; Scully, S.; Vianello, N.; Wischmeier, M.; , JET Contributors
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Measurements of the ion currents to and plasma conditions at the low-field side (LFS) divertor target plate in low-confinement mode plasmas in the JET ITER-like wall materials configuration show that the core plasma density required to detach the LFS divertor plasma is independent of the hydrogenic species protium, deuterium and tritium, and a 40 %/60 % deuterium–tritium mixture. This observation applies to a divertor plasma configuration with the LFS strike line connected to the horizontal part of the LFS divertor chosen because of its superior diagnostic coverage. The finding is independent of the operational status of the JET cryogenic pump. The electron temperature (Te) at the LFS strike line was markedly reduced from 25 eV to 5 eV over a narrow range of increasing core plasma density, and observed to be between 2 eV and 3 eV at the onset of detachment. The electron density (ne) peaks across the LFS plasma when Te at the target plate is 1 eV, and spatially moves to the X-point for higher core densities. The density limit was found approximately 20 % higher in protium than in tritium and deuterium–tritium plasmas.
  • Characterisation of the scrape-off layer in JET-ILW deuterium and helium low-confinement mode plasmas
    (2024-06) Rees, D.; Groth, M.; Aleiferis, S.; Brezinsek, S.; Brix, M.; Jepu, I.; Lawson, K. D.; Meigs, A. G.; Menmuir, S.; Kirov, K.; Lomas, P.; Lowry, C.; Thomas, B.; Widdowson, A.; Carvalho, P.; Delabie, E.; , JET Contributors
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Langmuir probe measurements in neutral beam injection (NBI) heated, low-confinement mode plasmas in JET ITER-like wall showed that the current to the divertor targets, Idiv, in helium (He) plasmas was up to 70% lower on the low-field side (LFS) than in otherwise identical deuterium (D) plasmas. The edge plasma density at which the rollover of Idiv occurred i.e. the onset of detachment, was 10% higher in He plasmas on both the LFS and high-field side (HFS). The density of Idiv rollover increases by 25% for He when the NBI power increases 1MW to 5MW. The total radiated power was similar in He and D plasmas for densities below the Idiv rollover. At densities above the Idiv rollover density, the total radiated power and power from within the separatrix are higher in He, reducing the power across the separatrix and subsequently Idiv,LFS. In He plasmas, the peak radiated power was observed within the confined region above the X-point in tomographic reconstructions from bolometry.
  • Characterization of detachment inferred from the Balmer line ratios in JET-ILW low-confinement mode plasmas
    (2025-03) Rikala, Vesa Pekka; Groth, M.; Meigs, A. G.; Reiter, D.; Lomanowski, B.; Shaw, A.; Aleiferis, S.; Corrigan, G.; Carvalho, I. S.; Harting, D.; Horsten, N.; Jepu, I.; Karhunen, J.; Lawson, K. D.; Lowry, C.; Menmuir, S.; Thomas, B.; Borodin, D.; Douai, D.; Huber, A.; , JET Contributors
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Spectroscopic measurements of the hydrogenic Balmer-α and Balmer-γ line emission in JET-ILW low-confinement mode (L-mode) deuterium plasmas are used to assess the onset of volume recombination in the low-field side (LFS) divertor. The evolution of the EDGE2D-EIRENE predicted Balmer-γ to Balmer-α emission ratio from low-recycling to detached conditions is in qualitative agreement with the measured ratio. In low-recycling conditions the EDGE2D-EIRENE predicted line-emission is within 30% of measured emission, in high-recycling within 20%t, and in detached conditions lower by a factor of 2.5.
  • Comparative H-mode density limit studies in JET and AUG
    (2017-08-01) Huber, A.; Bernert, M.; Brezinsek, S.; Chankin, A. V.; Sergienko, G.; Huber, V.; Wiesen, S.; Abreu, P.; Beurskens, M. N.A.; Boboc, A.; Brix, M.; Calabrò, G.; Carralero, D.; Delabie, E.; Eich, T.; Esser, H. G.; Groth, M.; Guillemaut, C.; Jachmich, S.; Järvinen, A.; Joffrin, E.; Kallenbach, A.; Kruezi, U.; Lang, P.; Linsmeier, Ch; Lowry, C. G.; Maggi, C. F.; Matthews, G. F.; Meigs, A. G.; Mertens, Ph; Reimold, F.; Schweinzer, J.; Sips, G.; Stamp, M.; Viezzer, E.; Wischmeier, M.; Zohm, H.; , JET Contributors
     A2 Katsausartikkeli tieteellisessä aikakauslehdessä
    Identification of the mechanisms for the H-mode density limit in machines with fully metallic walls, and their scaling to future devices is essential to find for these machines the optimal operational boundaries with the highest attainable density and confinement. Systematic investigations of H-mode density limit plasmas in experiments with deuterium external gas fuelling have been performed on machines with fully metallic walls, JET and AUG and results have been compared with one another. Basically, the operation phases are identical for both tokamaks: the stable H-mode phase, degrading H-mode phase, breakdown of the H-mode with energy confinement deterioration usually accompanied by a dithering cycling phase, followed by the L-mode phase. The observed H-mode density limit on both machines is found close to the Greenwald limit (n/nGW = 0.8–1.1 in the observed magnetic configurations). The similar behavior of the radiation on both tokamaks demonstrates that the density limit (DL) is neither related to additional energy losses from the confined region by radiation, nor to an inward collapse of the hot discharge core induced by overcooling of the plasma periphery by radiation. It was observed on both machines that detachment, as well as the X-point MARFE itself, does not trigger a transition in the confinement regime and thus does not present a limit on the plasma density. It is the plasma confinement, most likely determined by edge parameters, which is ultimately responsible for the transition from H- to L-mode. The measured Greenwald fractions are found to be consistent with the predictions from different theoretical models [16,30] based on MHD instability theory in the near-SOL.
  • Comparison of 2D simulations of detached divertor plasmas with divertor Thomson measurements in the DIII-D tokamak
    (2017) Rognlien, T. D.; McLean, A. G.; Fenstermacher, M. E.; Groth, M.; Jaervinen, A. E.; Joseph, I.; Lasnier, C. J.; Meyer, W.; Moser, A.; Porter, G. D.; Umansky, M. V.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    A modeling study is reported using new 2D data from DIII-D tokamak divertor plasmas and improved 2D transport model that includes large cross-field drifts for the numerically difficult low anomalous transport regime associated with the H-mode. The data set, which spans a range of plasma densities for both forward and reverse toroidal magnetic field (Bt ), is provided by divertor Thomson scattering (DTS). Measurements utilizing X-point sweeping give corresponding 2D profiles of electron temperature (Te ) and density (ne ) across both divertor legs for individual discharges. The simulations focus on the open magnetic field-line regions, though they also include a small region of closed field lines. The calculations show the same features of in/out divertor plasma asymmetries as measured in the experiment, with the normal Bt direction (ion ∇. B drift toward the X-point) having higher ne and lower Te in the inner divertor leg than outer. Corresponding emission data for total radiated power shows a strong inner-divertor/outer-divertor asymmetry that is reproduced by the simulations. These 2D UEDGE transport simulations are enabled for steep-gradient H-mode conditions by newly implemented algorithms to control isolated grid-scale irregularities.
  • Comparison of a collisional-radiative fluid model of H2 in UEDGE to the kinetic neutral code EIRENE
    (2021-06) Holm, A.; Börner, P.; Rognlien, T. D.; Meyer, W. H.; Groth, M.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    A fluid collisional-radiative model for H2 has been implemented in the edge-fluid code UEDGE and compared to the kinetic neutral code EIRENE on a simple, 2D, orthogonal domain with a constant, static plasma distribution. The novel CRUMPET Python tool was used to implement dissociation and energy rate coefficients that consider molecular-assisted processes, binding energy, and radiation due to molecular processes into the UEDGE fluid molecular model. The agreement between the fluid and kinetic molecular models was found to be within 20% when corresponding rates were used in UEDGE and EIRENE for a domain with absorbing boundaries. When wall recycling was considered, EIRENE predicted up to a factor of 2.2 higher molecular densities than UEDGE at T < 5 eV. The difference is due to the absence of radial gradients driving diffusive wall fluxes and, thus, recycling in UEDGE and molecular self-scattering in EIRENE, and is likely dependent on plasma profiles and domain geometry. Comparison of the molecular energy sources in EIRENE and UEDGE suggest the constant elastic scattering rate coefficient used in UEDGE needs to be updated to a temperature-dependent coefficient and that atom-molecule equipartition should be considered in the EIRENE model for background plasma density in excess of 1×1019m-3. Finally, collisional-radiative CRUMPET simulations indicate that the vibrational molecular populations become comparable to the ground-state molecular population when the plasma temperature decrease below 6 eV and, thus, require time-dependent evaluation.
  • Comparison of DIVIMP and EDGE2D-EIRENE tungsten transport predictions in JET edge plasmas
    (2020-12) Kumpulainen, H. A.; Groth, M.; Fontell, M.; Jaervinen, A. E.; Corrigan, G.; Harting, D.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The average tungsten concentrations in the pedestal region (cW) predicted by the Monte Carlo code DIVIMP and the coupled multi-fluid plasma/kinetic neutral code EDGE2D-EIRENE are found to agree within a factor of 2 for a range of JET-ILW L-mode and H-mode plasma conditions. Under attached divertor conditions with cW exceeding 10−6, the cW predicted by DIVIMP is consistently ~50% higher than by EDGE2D-EIRENE. In colder plasma scenarios with cW <10-6, stochastic variations exceed the systematic disagreement between the two codes. The average tungsten charge predicted by EDGE2D-EIRENE in the upstream scrape-off layer is lower by 40–50% due to the bundling of the 74 tungsten ion charge states into 6 fluid species, which explains the reduced tungsten accumulation in the main plasma compared to the DIVIMP predictions.
  • A control oriented strategy of disruption prediction to avoid the configuration collapse of tokamak reactors
    (2024-12) Aho-Mantila, L.; Airila, M.; Akhtar, M.; Ali, M.; Chang, C. S.; Chone, L.; Collins, J.; Collins, S.; Dawson, K.; Eriksson, J.; Eriksson, L. G.; Fagan, D.; Gao, Y.; Gonçalves, B.; Groth, M.; Hakola, A.; Horsten, N.; Horton, A.; Hu, Z.; Kilpeläinen, J.; Kim, C.; Kim, S. H.; King, D. B.; Kirjasuo, A.; Kiviniemi, T.; Kumpulainen, H.; Kurki-Suonio, T.; Lee, S. E.; Leerink, S.; Leppänen, J.; Li, L.; Li, Y.; Liu, F.; Lomanowski, B.; López, J. M.; Machielsen, M.; Mäenpää, R.; Marin, M.; Martin, A.; Miyamoto, M.; Moon, S.; Moradi, S.; Moulton, D.; Na, Yong Su; Nordman, H.; Rossi, R.; Rubel, M.; Salmi, A.; Särkimäki, K.; Schneider, P. A.; Silva, C.; Silva, J.; Simpson, J.; Sipilä, S. K.; Solokha, V.; Sun, H. J.; Tan, H.; Varje, J.; Virtanen, A. J.; de Vries, P.; Wang, N.; West, A.; Wood, R.; Xu, T.; Yang, Y.; Zhang, W.; Zhou, Y.; , JET Contributors
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The objective of thermonuclear fusion consists of producing electricity from the coalescence of light nuclei in high temperature plasmas. The most promising route to fusion envisages the confinement of such plasmas with magnetic fields, whose most studied configuration is the tokamak. Disruptions are catastrophic collapses affecting all tokamak devices and one of the main potential showstoppers on the route to a commercial reactor. In this work we report how, deploying innovative analysis methods on thousands of JET experiments covering the isotopic compositions from hydrogen to full tritium and including the major D-T campaign, the nature of the various forms of collapse is investigated in all phases of the discharges. An original approach to proximity detection has been developed, which allows determining both the probability of and the time interval remaining before an incoming disruption, with adaptive, from scratch, real time compatible techniques. The results indicate that physics based prediction and control tools can be developed, to deploy realistic strategies of disruption avoidance and prevention, meeting the requirements of the next generation of devices.
  • Dependence on plasma shape and plasma fueling for small edge-localized mode regimes in TCV and ASDEX Upgrade
    (2019-06-26) Labit, B.; Eich, T.; Harrer, G. F.; Wolfrum, E.; Bernert, M.; Dunne, M. G.; Frassinetti, L.; Hennequin, P.; Maurizio, R.; Merle, A.; Meyer, H.; Saarelma, S.; Sheikh, U.; Adamek, J.; Agostini, M.; Aguiam, D.; Akers, R.; Albanese, Raffaele; Albert, C.; Alessi, E.; Ambrosino, R.; Andr be, Y.; Angioni, C.; Apruzzese, G.; Aradi, M.; Arnichand, H.; Auriemma, F.; Avdeeva, G.; Ayllon-Guerola, J. M.; Bagnato, F.; Bandaru, V. K.; Barnes, M.; Barrera-Orte, L.; Bettini, P.; Bilato, R.; Biletskyi, O.; Bilkova, P.; Bin, William; Blanchard, P.; Blanken, T.; Bobkov, V.; Bock, A.; Boeyaert, D.; Bogar, K.; Bogar, O.; Bohm, P.; Bolzonella, T.; Bombarda, F.; Boncagni, L.; Bouquey, F.; Bowman, C.; Brezinsek, S.; Brida, D.; Brunetti, D.; Bucalossi, J.; Buchanan, J.; Buermans, J.; Bufferand, H.; Buller, S.; Buratti, P.; Burckhart, A.; Calabr, G.; Calacci, L.; Camenen, Y.; Cannas, B.; Cano Megías, P.; Carnevale, D.; Carpanese, F.; Carr, M.; Carralero, D.; Carraro, L.; Casolari, A.; Cathey, A.; Causa, F.; Cavedon, M.; Cecconello, M.; Ceccuzzi, S.; Cerovsky, J.; Chapman, S.; Chmielewski, P.; Choi, D.; Cianfarani, C.; Ciraolo, G.; Coda, S.; Coelho, R.; Colas, L.; Colette, D.; Cordaro, L.; Cordella, F.; Costea, S.; Coster, D.; Cruz Zabala, D. J.; Cseh, G.; Czarnecka, A.; Cziegler, I.; D'Arcangelo, O.; Dal Molin, A.; David, P.; De Carolis, G.; De Oliveira, H.; Decker, J.; Dejarnac, R.; Delogu, R.; Den Harder, N.; Dimitrova, M.; Dolizy, F.; Domínguez-Palacios Durán, J. J.; Douai, D.; Drenik, A.; Dreval, M.; Dudson, B.; Dunai, D.; Duval, B. P.; Dux, R.; Elmore, S.; Embréus, O.; Erds, B.; Fable, E.; Faitsch, M.; Fanni, A.; Farnik, M.; Faust, I.; Faustin, J.; Fedorczak, N.; Felici, F.; Feng, S.; Feng, X.; Ferreira, J.; Ferr, G.; Février, O.; Ficker, O.; Figini, L.; Figueiredo, A.; Fil, A.; Fontana, M.; Francesco, M.; Fuchs, C.; Futatani, S.; Gabellieri, L.; Gadariya, D.; Gahle, D.; Galassi, D.; Gałązka, K.; Galdon-Quiroga, J.; Galeani, S.; Gallart, D.; Gallo, A.; Galperti, C.; Garavaglia, S.; Garcia, J.; Garcia-Lopez, Javier; Garcia-Mu oz, M.; Garzotti, L.; Gath, J.; Geiger, B.; Giacomelli, L.; Giannone, L.; Gibson, S.; Gil, L.; Giovannozzi, E.; Giruzzi, G.; Gobbin, M.; Gonzalez-Martin, J.; Goodman, T. P.; Gorini, G.; Gospodarczyk, M.; Granucci, G.; Grekov, D.; Grenfell, G.; Griener, M.; Groth, M.; Grover, O.; Gruca, M.; Gude, A.; Guimarais, L.; Gyergyek, T.; Hacek, P.; Hakola, A.; Ham, C.; Happel, T.; Harrison, J.; Havranek, A.; Hawke, J.; Henderson, S.; Hesslow, L.; Hitzler, F.; Hnat, B.; Hobirk, J.; Hoelzl, M.; Hogeweij, D.; Hopf, C.; Hoppe, M.; Horacek, J.; Hron, M.; Huang, Z.; Iantchenko, A.; Iglesias, D.; Igochine, V.; Innocente, P.; Ionita-Schrittwieser, C.; Isliker, H.; Ivanova-Stanik, I.; Jacobsen, A.; Jakubowski, M.; Janky, F.; Jardin, A.; Jaulmes, F.; Jensen, T.; Jonsson, T.; Kallenbach, A.; Kappatou, A.; Karpushov, A.; Kasilov, S.; Kazakov, Y.; Kazantzidis, P. V.; Keeling, D.; Kelemen, M.; Kendl, A.; Kernbichler, W.; Kirk, A.; Kocsis, G.; Komm, M.; Kong, M.; Korovin, V.; Koubiti, M.; Kovacic, J.; Krawczyk, N.; Krieger, K.; Kripner, L.; Křivská, A.; Kudlacek, O.; Kulyk, Y.; Kurki-Suonio, T.; Kwiatkowski, R.; Laggner, F.; Laguardia, L.; Lahtinen, A.; Lang, P.; Likonen, J.; Lipschultz, B.; Liu, Fukun; Lombroni, R.; Lorenzini, R.; Loschiavo, V. P.; Lunt, T.; MacUsova, E.; Madsen, J.; Maggiora, R.; Maljaars, B.; Manas, P.; Mantica, P.; Mantsinen, M. J.; Manz, P.; Maraschek, M.; Marchenko, V.; Marchetto, C.; Mariani, A.; Marini, C.; Markovic, T.; Marrelli, L.; Martin, P.; Martín Solís, J. R.; Martitsch, A.; Mastrostefano, S.; Matos, F.; Matthews, G.; Mayoral, M. L.; Mazon, D.; Mazzotta, C.; Mc Carthy, P.; McClements, K.; McDermott, R.; McMillan, B.; Meineri, C.; Menkovski, V.; Meshcheriakov, D.; Messmer, M.; Micheletti, D.; Milanesio, D.; Militello, F.; Miron, I. G.; Mlynar, J.; Moiseenko, V.; Molina Cabrera, P. A.; Morales, J.; Moret, J. M.; Moro, A.; Moulton, D.; Nabais, F.; Naulin, V.; Naydenkova, D.; Nem, R. D.; Nespoli, F.; Newton, S.; Nielsen, A. H.; Nielsen, S. K.; Nikolaeva, V.; Nocente, M.; Nowak, S.; Oberkofler, M.; Ochoukov, R.; Ollus, P.; Olsen, J.; Omotani, J.; Ongena, J.; Orain, F.; Orsitto, F. P.; Paccagnella, R.; Palha, A.; Panaccione, L.; Panek, R.; Panjan, M.; Papp, G.; Paradela Perez, I.; Parra, F.; Passeri, M.; Pau, A.; Pautasso, G.; Pavlichenko, R.; Perek, A.; Pericoli Radolfini, V.; Pesamosca, F.; Peterka, M.; Petrzilka, V.; Piergotti, V.; Pigatto, L.; Piovesan, P.; Piron, C.; Piron, L.; Plyusnin, V.; Pokol, G.; Poli, E.; Pölöskei, P.; Popov, T.; Popovic, Z.; Pór, G.; Porte, L.; Pucella, G.; Puiatti, M. E.; Pütterich, T.; Rabinski, M.; Juul Rasmussen, J.; Rasmussen, J.; Rattá, G. A.; Ratynskaia, S.; Ravensbergen, T.; Réfy, D.; Reich, M.; Reimerdes, H.; Reimold, F.; Reiser, D.; Reux, C.; Reznik, S.; Ricci, D.; Rispoli, N.; Rivero-Rodriguez, J. F.; Rocchi, G.; Rodriguez-Ramos, M.; Romano, A.; Rosato, J.; Rubinacci, G.; Rubino, G.; Ryan, D. A.; Salewski, M.; Salmi, A.; Samaddar, D.; Sanchis-Sanchez, L.; Santos, J.; Särkimäki, K.; Sassano, M.; Sauter, O.; Scannell, R.; Scheffer, M.; Schneider, B. S.; Schneider, P.; Schrittwieser, R.; Schubert, M.; Seidl, J.; Seliunin, E.; Sharapov, S.; Sheeba, R. R.; Sias, G.; Sieglin, B.; Silva, C.; Sipilä, S.; Smith, S.; Snicker, A.; Solano, E. R.; Hansen, S. K.; Soria-Hoyo, C.; Sorokovoy, E.; Sozzi, C.; Sperduti, A.; Spizzo, G.; Spolaore, M.; Stejner, M.; Stipani, L.; Stober, J.; Strand, P.; Sun, H.; Suttrop, W.; Sytnykov, D.; Szepesi, T.; Tál, B.; Tala, T.; Tardini, G.; Tardocchi, M.; Teplukhina, A.; Terranova, D.; Testa, D.; Theiler, C.; Thorén, E.; Thornton, A.; Tilia, B.; Tolias, P.; Tomes, M.; Toscano-Jimenez, M.; Tsironis, C.; Tsui, C.; Tudisco, O.; Urban, J.; Valisa, M.; Vallar, M.; Vallejos Olivares, P.; Valovic, M.; Van Vugt, D.; Vanovac, B.; Varje, J.; Varju, J.; Varoutis, S.; Vartanian, S.; Vasilovici, O.; Vega, J.; Verdoolaege, G.; Verhaegh, K.; Vermare, L.; Vianello, Nicola; Vicente, J.; Viezzer, E.; Villone, F.; Voitsekhovitch, I.; Voltolina, D.; Vondracek, P.; Vu, N. M.T.; Walkden, N.; Wauters, T.; Weiland, M.; Weinzettl, V.; Wensing, M.; Wiesen, S.; Wiesenberger, M.; Wilkie, G.; Willensdorfer, M.; Wischmeier, M.; Wu, K.; Xiang, L.; Zagorski, R.; Zaloga, D.; Zanca, P.; Zaplotnik, R.; Zebrowski, J.; Zhang, Wei; Zisis, A.; Zoletnik, S.; Zuin, M.; Wu, Kai
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Within the EUROfusion MST1 work package, a series of experiments has been conducted on AUG and TCV devices to disentangle the role of plasma fueling and plasma shape for the onset of small ELM regimes. On both devices, small ELM regimes with high confinement are achieved if and only if two conditions are fulfilled at the same time. Firstly, the plasma density at the separatrix must be large enough (ne,sep/nG ∼ 0.3), leading to a pressure profile flattening at the separatrix, which stabilizes type-I ELMs. Secondly, the magnetic configuration has to be close to a double null (DN), leading to a reduction of the magnetic shear in the extreme vicinity of the separatrix. As a consequence, its stabilizing effect on ballooning modes is weakened.
  • DIII-D research advancing the physics basis for optimizing the tokamak approach to fusion energy
    (2022-04-01) Fenstermacher, M. E.; Abbate, J.; Abe, S.; Abrams, T.; Adams, M.; Adamson, B.; Aiba, N.; Akiyama, T.; Aleynikov, P.; Allen, E.; Allen, S.; Anand, H.; Anderson, J.; Andrew, Y.; Andrews, T.; Appelt, D.; Arbon, R.; Ashikawa, N.; Ashourvan, A.; Aslin, M.; Asnis, Y.; Austin, M.; Ayala, D.; Bak, J.; Bandyopadhyay, I.; Banerjee, S.; Barada, K.; Bardoczi, L.; Barr, J.; Bass, E.; Battaglia, D.; Battey, A.; Baumgartner, W.; Baylor, L.; Beckers, J.; Beidler, M.; Belli, E.; Berkery, J.; Bernard, T.; Bertelli, N.; Beurskens, M.; Bielajew, R.; Bilgili, S.; Biswas, B.; Blondel, S.; Boedo, J.; Bogatu, I.; Boivin, R.; Bolzonella, T.; Bongard, M.; Bonnin, X.; Bonoli, P.; Bonotto, M.; Bortolon, A.; Bose, S.; Bosviel, N.; Bouwmans, S.; Boyer, M.; Boyes, W.; Bradley, L.; Brambila, R.; Brennan, D.; Bringuier, S.; Brodsky, L.; Brookman, M.; Brooks, J.; Brower, D.; Brown, G.; Brown, W.; Burke, M.; Burrell, K.; Butler, K.; Buttery, R.; Bykov, I.; Byrne, P.; Cacheris, A.; Callahan, K.; Callen, J.; Campbell, G.; Candy, J.; Canik, J.; Cano-Megias, P.; Cao, N.; Carayannopoulos, L.; Carlstrom, T.; Carrig, W.; Carter, T.; Cary, W.; Casali, L.; Cengher, M.; Cespedes Paz, G.; Chaban, R.; Chan, V.; Chapman, B.; Char, I.; Chattopadhyay, A.; Chen, R.; Chen, J.; Chen, X.; Chen, M.; Chen, Z.; Choi, M.; Choi, W.; Choi, G.; Chousal, L.; Chrobak, C.; Chrystal, C.; Chung, Y.; Churchill, R.; Cianciosa, M.; Clark, J.; Clement, M.; Coda, S.; Cole, A.; Collins, C.; Conlin, W.; Cooper, A.; Cordell, J.; Coriton, B.; Cote, T.; Cothran, J.; Creely, A.; Crocker, N.; Crowe, C.; Crowley, B.; Crowley, T.; Cruz-Zabala, D.; Cummings, D.; Curie, M.; Curreli, D.; Dal Molin, A.; Dannels, B.; Dautt-Silva, A.; Davda, K.; De Tommasi, G.; De Vries, P.; Degrandchamp, G.; Degrassie, J.; Demers, D.; Denk, S.; Depasquale, S.; Deshazer, E.; Diallo, A.; Diem, S.; Dimits, A.; Ding, R.; Ding, S.; Ding, W.; Do, T.; Doane, J.; Dong, G.; Donovan, D.; Drake, J.; Drews, W.; Drobny, J.; Du, X.; Du, H.; Duarte, V.; Dudt, D.; Dunn, C.; Duran, J.; Dvorak, A.; Effenberg, F.; Eidietis, N.; Elder, D.; Eldon, D.; Ellis, R.; Elwasif, W.; Ennis, D.; Erickson, K.; Ernst, D.; Fasciana, M.; Fedorov, D.; Feibush, E.; Ferraro, N.; Ferreira, J.; Ferron, J.; Fimognari, P.; Finkenthal, D.; Fitzpatrick, R.; Fox, P.; Fox, W.; Frassinetti, L.; Frerichs, H.; Frye, H.; Fu, Y.; Gage, K.; Galdon Quiroga, J.; Gallo, A.; Gao, Q.; Garcia, A.; Garcia Munoz, M.; Garnier, D.; Garofalo, A.; Gattuso, A.; Geng, D.; Gentle, K.; Ghosh, D.; Giacomelli, L.; Gibson, S.; Gilson, E.; Giroud, C.; Glass, F.; Glasser, A.; Glibert, D.; Gohil, P.; Gomez, R.; Gomez, S.; Gong, X.; Gonzales, E.; Goodman, A.; Gorelov, Y.; Graber, V.; Granetz, R.; Gray, T.; Green, D.; Greenfield, C.; Greenwald, M.; Grierson, B.; Groebner, R.; Grosnickle, W.; Groth, M.; Grunloh, H.; Gu, S.; Guo, W.; Guo, H.; Gupta, P.; Guterl, J.; Guttenfelder, W.; Guzman, T.; Haar, S.; Hager, R.; Hahn, S.; Halfmoon, M.; Hall, T.; Hallatschek, K.; Halpern, F.; Hammett, G.; Han, H.; Hansen, E.; Hansen, C.; Hansink, M.; Hanson, J.; Hanson, M.; Hao, G.; Harris, A.; Harvey, R.; Haskey, S.; Hassan, E.; Hassanein, A.; Hatch, D.; Hawryluk, R.; Hayashi, W.; Heidbrink, W.; Herfindal, J.; Hicok, J.; Hill, D.; Hinson, E.; Holcomb, C.; Holland, L.; Holland, C.; Hollmann, E.; Hollocombe, J.; Holm, A.; Holmes, I.; Holtrop, K.; Honda, M.; Hong, R.; Hood, R.; Horton, A.; Horvath, L.; Hosokawa, M.; Houshmandyar, S.; Howard, N.; Howell, E.; Hoyt, D.; Hu, W.; Hu, Y.; Hu, Q.; Huang, J.; Huang, Y.; Hughes, J.; Human, T.; Humphreys, D.; Huynh, P.; Hyatt, A.; Ibanez, C.; Ibarra, L.; Icasas, R.; Ida, K.; Igochine, V.; In, Y.; Inoue, S.; Isayama, A.; Izacard, O.; Izzo, V.; Jackson, A.; Jacobsen, G.; Jaervinen, A.; Jalalvand, A.; Janhunen, J.; Jardin, S.; Jarleblad, H.; Jeon, Y.; Ji, H.; Jian, X.; Joffrin, E.; Johansen, A.; Johnson, C.; Johnson, T.; Jones, C.; Joseph, I.; Jubas, D.; Junge, B.; Kalb, W.; Kalling, R.; Kamath, C.; Kang, J.; Kaplan, D.; Kaptanoglu, A.; Kasdorf, S.; Kates-Harbeck, J.; Kazantzidis, P.; Kellman, A.; Kellman, D.; Kessel, C.; Khumthong, K.; Kim, E.; Kim, H.; Kim, J.; Kim, S.; Kim, K.; Kim, C.; Kimura, W.; King, M.; King, J.; Kinsey, J.; Kirk, A.; Kiyan, B.; Kleiner, A.; Klevarova, V.; Knapp, R.; Knolker, M.; Ko, W.; Kobayashi, T.; Koch, E.; Kochan, M.; Koel, B.; Koepke, M.; Kohn, A.; Kolasinski, R.; Kolemen, E.; Kostadinova, E.; Kostuk, M.; Kramer, G.; Kriete, D.; Kripner, L.; Kubota, S.; Kulchar, J.; Kwon, K.; La Haye, R.; Laggner, F.; Lan, H.; Lantsov, R.; Lao, L.; Lasa Esquisabel, A.; Lasnier, C.; Lau, C.; Leard, B.; Lee, J.; Lee, R.; Lee, M.; Lee, Y.; Lee, C.; Lee, S.; Lehnen, M.; Leonard, A.; Leppink, E.; Lesher, M.; Lestz, J.; Leuer, J.; Leuthold, N.; Li, X.; Li, K.; Li, E.; Li, G.; Li, L.; Li, Z.; Li, J.; Li, Y.; Lin, Z.; Lin, D.; Liu, X.; Liu, J.; Liu, Y.; Liu, T.; Liu, C.; Liu, Z.; Liu, A.; Liu, D.; Loarte-Prieto, A.; Lodestro, L.; Logan, N.; Lohr, J.; Lombardo, B.; Lore, J.; Luan, Q.; Luce, T.; Luda Di Cortemiglia, T.; Luhmann, N.; Lunsford, R.; Luo, Z.; Lvovskiy, A.; Lyons, B.; Ma, X.; Madruga, M.; Madsen, B.; Maggi, C.; Maheshwari, K.; Mail, A.; Mailloux, J.; Maingi, R.; Major, M.; Makowski, M.; Manchanda, R.; Marini, C.; Marinoni, A.; Maris, A.; Markovic, T.; Marrelli, L.; Martin, E.; Mateja, J.; Matsunaga, G.; Maurizio, R.; Mauzey, P.; Mauzey, D.; McArdle, G.; McClenaghan, J.; McCollam, K.; McDevitt, C.; McKay, K.; McKee, G.; McLean, A.; Mehta, V.; Meier, E.; Menard, J.; Meneghini, O.; Merlo, G.; Messer, S.; Meyer, W.; Michael, C.; Michoski, C.; Milne, P.; Minet, G.; Misleh, A.; Mitrishkin, Y.; Moeller, C.; Montes, K.; Morales, M.; Mordijck, S.; Moreau, D.; Morosohk, S.; Morris, P.; Morton, L.; Moser, A.; Moyer, R.; Moynihan, C.; Mrazkova, T.; Mueller, D.; Munaretto, S.; Munoz Burgos, J.; Murphy, C.; Murphy, K.; Muscatello, C.; Myers, C.; Nagy, A.; Nandipati, G.; Navarro, M.; Nave, F.; Navratil, G.; Nazikian, R.; Neff, A.; Neilson, G.; Neiser, T.; Neiswanger, W.; Nelson, D.; Nelson, A.; Nespoli, F.; Nguyen, R.; Nguyen, L.; Nguyen, X.; Nichols, J.; Nocente, M.; Nogami, S.; Noraky, S.; Norausky, N.; Nornberg, M.; Nygren, R.; Odstrcil, T.; Ogas, D.; Ogorman, T.; Ohdachi, S.; Ohtani, Y.; Okabayashi, M.; Okamoto, M.; Olavson, L.; Olofsson, E.; Omullane, M.; Oneill, R.; Orlov, D.; Orvis, W.; Osborne, T.; Pace, D.; Paganini Canal, G.; Pajares Martinez, A.; Palacios, L.; Pan, C.; Pan, Q.; Pandit, R.; Pandya, M.; Pankin, A.; Park, Y.; Park, J.; Parker, S.; Parks, P.; Parsons, M.; Patel, B.; Pawley, C.; Paz-Soldan, C.; Peebles, W.; Pelton, S.; Perillo, R.; Petty, C.; Peysson, Y.; Pierce, D.; Pigarov, A.; Pigatto, L.; Piglowski, D.; Pinches, S.; Pinsker, R.; Piovesan, P.; Piper, N.; Pironti, A.; Pitts, R.; Pizzo, J.; Plank, U.; Podesta, M.; Poli, E.; Poli, F.; Ponce, D.; Popovic, Z.; Porkolab, M.; Porter, G.; Powers, C.; Powers, S.; Prater, R.; Pratt, Q.; Pusztai, I.; Qian, J.; Qin, X.; Ra, O.; Rafiq, T.; Raines, T.; Raman, R.; Rauch, J.; Raymond, A.; Rea, C.; Reich, M.; Reiman, A.; Reinhold, S.; Reinke, M.; Reksoatmodjo, R.; Ren, Q.; Ren, Y.; Ren, J.; Rensink, M.; Renteria, J.; Rhodes, T.; Rice, J.; Roberts, R.; Robinson, J.; Rodriguez Fernandez, P.; Rognlien, T.; Rosenthal, A.; Rosiello, S.; Rost, J.; Roveto, J.; Rowan, W.; Rozenblat, R.; Ruane, J.; Rudakov, D.; Ruiz Ruiz, J.; Rupani, R.; Saarelma, S.; Sabbagh, S.; Sachdev, J.; Saenz, J.; Saib, S.; Salewski, M.; Salmi, A.; Sammuli, B.; Samuell, C.; Sandorfi, A.; Sang, C.; Sarff, J.; Sauter, O.; Schaubel, K.; Schmitz, L.; Schmitz, O.; Schneider, J.; Schroeder, P.; Schultz, K.; Schuster, E.; Schwartz, J.; Sciortino, F.; Scotti, F.; Scoville, J.; Seltzman, A.; Seol, S.; Sfiligoi, I.; Shafer, M.; Sharapov, S.; Shen, H.; Shepard, T.; Shi, S.; Shibata, Y.; Shin, G.; Shiraki, D.; Shousha, R.; Si, H.; Simmerling, P.; Sinclair, G.; Sinha, J.; Sinha, P.; Sips, G.; Sizyuk, T.; Skinner, C.; Sladkomedova, A.; Slendebroek, T.; Slief, J.; Smirnov, R.; Smith, J.; Smith, S.; Smith, D.; Snipes, J.; Snoep, G.; Snyder, A.; Snyder, P.; Solano, E.; Solomon, W.; Song, J.; Sontag, A.; Soukhanovskii, V.; Spendlove, J.; Spong, D.; Squire, J.; Srinivasan, C.; Stacey, W.; Staebler, G.; Stagner, L.; Stange, T.; Stangeby, P.; Stefan, R.; Stemprok, R.; Stephan, D.; Stillerman, J.; Stoltzfus-Dueck, T.; Stonecipher, W.; Storment, S.; Strait, E.; Su, D.; Sugiyama, L.; Sun, Y.; Sun, P.; Sun, Z.; Sun, A.; Sundstrom, D.; Sung, C.; Sungcoco, J.; Suttrop, W.; Suzuki, Y.; Suzuki, T.; Svyatkovskiy, A.; Swee, C.; Sweeney, R.; Sweetnam, C.; Szepesi, G.; Takechi, M.; Tala, T.; Tanaka, K.; Tang, X.; Tang, S.; Tao, Y.; Tao, R.; Taussig, D.; Taylor, T.; Teixeira, K.; Teo, K.; Theodorsen, A.; Thomas, D.; Thome, K.; Thorman, A.; Thornton, A.; Ti, A.; Tillack, M.; Timchenko, N.; Tinguely, R.; Tompkins, R.; Tooker, J.; Torrezan De Sousa, A.; Trevisan, G.; Tripathi, S.; Trujillo Ochoa, A.; Truong, D.; Tsui, C.; Turco, F.; Turnbull, A.; Umansky, M.; Unterberg, E.; Vaezi, P.; Vail, P.; Valdez, J.; Valkis, W.; Van Compernolle, B.; Van Galen, J.; Van Kampen, R.; Van Zeeland, M.; Verdoolaege, G.; Vianello, N.; Victor, B.; Viezzer, E.; Vincena, S.; Wade, M.; Waelbroeck, F.; Wai, J.; Wakatsuki, T.; Walker, M.; Wallace, G.; Waltz, R.; Wampler, W.; Wang, L.; Wang, H.; Wang, Y.; Wang, Z.; Wang, G.; Ward, S.; Watkins, M.; Watkins, J.; Wehner, W.; Wei, Y.; Weiland, M.; Weisberg, D.; Welander, A.; White, A.; White, R.; Wiesen, S.; Wilcox, R.; Wilks, T.; Willensdorfer, M.; Wilson, H.; Wingen, A.; Wolde, M.; Wolff, M.; Woller, K.; Wolz, A.; Wong, H.; Woodruff, S.; Wu, Y.; Wukitch, S.; Wurden, G.; Xiao, W.; Xie, R.; Xing, Z.; Xu, X.; Xu, C.; Xu, G.; Yan, Z.; Yang, X.; Yang, Seongmoo; Yokoyama, T.; Yoneda, R.; Yoshida, M.; You, K.; Younkin, T.; Yu, J.; Yu, M.; Yu, G.; Yuan, Q.; Zaidenberg, L.; Zakharov, L.; Zamengo, A.; Zamperini, S.; Zarnstorff, M.; Zeger, E.; Zeller, K.; Zeng, L.; Zerbini, M.; Zhang, L.; Zhang, X.; Zhang, R.; Zhang, B.; Zhang, J.; Zhao, L.; Zhao, B.; Zheng, Y.; Zheng, L.; Zhu, B.; Zhu, J.; Zhu, Y.; Zsutty, M.; Zuin, M.; Wu, Mingfu; Sheng, Zhicai
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    DIII-D physics research addresses critical challenges for the operation of ITER and the next generation of fusion energy devices. This is done through a focus on innovations to provide solutions for high performance long pulse operation, coupled with fundamental plasma physics understanding and model validation, to drive scenario development by integrating high performance core and boundary plasmas. Substantial increases in off-axis current drive efficiency from an innovative top launch system for EC power, and in pressure broadening for Alfven eigenmode control from a co-/counter-I p steerable off-axis neutral beam, all improve the prospects for optimization of future long pulse/steady state high performance tokamak operation. Fundamental studies into the modes that drive the evolution of the pedestal pressure profile and electron vs ion heat flux validate predictive models of pedestal recovery after ELMs. Understanding the physics mechanisms of ELM control and density pumpout by 3D magnetic perturbation fields leads to confident predictions for ITER and future devices. Validated modeling of high-Z shattered pellet injection for disruption mitigation, runaway electron dissipation, and techniques for disruption prediction and avoidance including machine learning, give confidence in handling disruptivity for future devices. For the non-nuclear phase of ITER, two actuators are identified to lower the L-H threshold power in hydrogen plasmas. With this physics understanding and suite of capabilities, a high poloidal beta optimized-core scenario with an internal transport barrier that projects nearly to Q = 10 in ITER at ∼8 MA was coupled to a detached divertor, and a near super H-mode optimized-pedestal scenario with co-I p beam injection was coupled to a radiative divertor. The hybrid core scenario was achieved directly, without the need for anomalous current diffusion, using off-axis current drive actuators. Also, a controller to assess proximity to stability limits and regulate β N in the ITER baseline scenario, based on plasma response to probing 3D fields, was demonstrated. Finally, innovative tokamak operation using a negative triangularity shape showed many attractive features for future pilot plant operation.
  • DIII-D research to provide solutions for ITER and fusion energy
    (2024-11) Ahmed, S.; Anderson, J.; Chen, J.; Chen, R.; Chen, X.; Chen, Y.; Choi, W.; Chowdhury, S.; Ding, R.; Du, X.; Groth, M.; Guo, H.; Han, X.; Holm, A.; Hu, Y.; Hu, Q.; Huang, Y.; Huang, J.; Huang, A.; Jarvinen, A.; Jiang, Y.; Johnson, J.; Jones, M.; Kim, J.; Kim, H.; Kim, S.; Kim, K.; Kim, C.; Kim, T.; Kumar, N.; Lee, S.; Lee, K.; Li, G.; Li, X.; Li, Y.; Li, L.; Li, Z.; Lin, Z.; Lin, Y.; Liu, J.; Liu, D.; Liu, C.; Liu, Z.; Liu, Y.; Ma, X.; Mohamed, M.; Nguyen, P.; Nguyen, D.; Pan, C.; Park, J.; Qian, J.; Qin, X.; Ross, M.; Salmi, A.; Shen, H.; Smith, S.; Smith, D.; Song, X.; Su, D.; Sun, P.; Sun, Y.; Suzuki, Y.; Tang, S.; Truong, D.; Wang, L.; Wang, Y.; Wang, H.; Wang, Z.; Wang, A.; Wei, X.; Xie, R.; Xu, G.; Xu, X.; Yan, Z.; Yang, X.; Yang, L.; Yang, S.; Yang, J.; Yu, J.; Zhang, X.; Zhang, J.; Zhang, B.; Zhao, B.; Zheng, Y.; Zhu, Y.; Zhu, J.; , DIII-D Team
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The DIII-D tokamak has elucidated crucial physics and developed projectable solutions for ITER and fusion power plants in the key areas of core performance, boundary heat and particle transport, and integrated scenario operation, with closing the core-edge integration knowledge gap being the overarching mission. New experimental validation of high-fidelity, multi-channel, non-linear gyrokinetic turbulent transport models for ITER provides strong confidence it will achieve Q ≥ 10 operation. Experiments identify options for easing H-mode access in hydrogen, and give new insight into the isotopic dependence of transport and confinement. Analysis of 2,1 islands in unoptimized low-torque IBS demonstration discharges suggests their onset time occurs randomly in the constant β phase, most often triggered by non-linear 3-wave coupling, thus identifying an NTM seeding mechanism to avoid. Pure deuterium SPI for disruption mitigation is shown to provide favorable slow cooling, but poor core assimilation, suggesting paths for improved SPI on ITER. At the boundary, measured neutral density and ionization source fluxes are strongly poloidally asymmetric, implying a 2D treatment is needed to model pedestal fuelling. Detailed measurements of pedestal and SOL quantities and impurity charge state radiation in detached divertors has validated edge fluid modelling and new self-consistent ‘pedestal-to-divertor’ integrated modeling that can be used to optimize reactors. New feedback adaptive ELM control minimizes confinement reduction, and RMP ELM suppression with sustained high core performance was obtained for the first time with the outer strike point in a W-coated, compact and unpumped small-angle slot divertor. Advances have been made in integrated operational scenarios for ITER and power plants. Wide pedestal intrinsically ELM-free QH-modes are produced with more reactor-relevant conditions, Low torque IBS with W-equivalent radiators can exhibit predator-prey oscillations in Te and radiation which need control. High-βP scenarios with qmin > 2, q95–7.9, βN > 4, βT–3.3% and H98y2 > 1.5 are sustained with high density (n̄ = 7E19 m−3, fG–1) for 6 τE, improving confidence in steady-state tokamak reactors. Diverted NT plasmas achieve high core performance with a non-ELMing edge, offering a possible highly attractive core-edge integration solution for reactors.
  • Disruption prediction with artificial intelligence techniques in tokamak plasmas
    (2022-07) Aho-Mantila, L.; Airila, M.; Akhtar, M.; Ali, M.; Chang, C. S.; Chone, L.; Collins, J.; Collins, S.; Eriksson, J.; Eriksson, L. G.; Fagan, D.; Gao, Y.; Gonçalves, B.; Groth, M.; Hakola, A.; Horsten, N.; Horton, A.; Hu, Z.; Karhunen, J.; Kilpeläinen, J.; Kim, C.; Kim, S. H.; Kirjasuo, A.; kiviniemi, T.; Kumpulainen, H.; Kurki-Suonio, T.; Lee, S. E.; Leerink, S.; Li, L.; Li, Y.; Liu, F.; Lomanowski, B.; López, J. M.; Machielsen, M.; Mäenpää, R.; Marin, M.; Moradi, S.; Moulton, D.; Na, Yong Su; Nordman, H.; Salmi, A.; Sarkimaki, K.; Silva, C.; Simpson, J.; Sipilä, S. K.; Sirén, P.; Solokha, V.; Sun, H. J.; Tan, H.; Varje, J.; Virtanen, A. J.; Wang, N.; Wood, R.; Xu, T.; Yang, Y.; Zhang, Wei; Zhou, Y.; , JET Contributors
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    In nuclear fusion reactors, plasmas are heated to very high temperatures of more than 100 million kelvin and, in so-called tokamaks, they are confined by magnetic fields in the shape of a torus. Light nuclei, such as deuterium and tritium, undergo a fusion reaction that releases energy, making fusion a promising option for a sustainable and clean energy source. Tokamak plasmas, however, are prone to disruptions as a result of a sudden collapse of the system terminating the fusion reactions. As disruptions lead to an abrupt loss of confinement, they can cause irreversible damage to present-day fusion devices and are expected to have a more devastating effect in future devices. Disruptions expected in the next-generation tokamak, ITER, for example, could cause electromagnetic forces larger than the weight of an Airbus A380. Furthermore, the thermal loads in such an event could exceed the melting threshold of the most resistant state-of-the-art materials by more than an order of magnitude. To prevent disruptions or at least mitigate their detrimental effects, empirical models obtained with artificial intelligence methods, of which an overview is given here, are commonly employed to predict their occurrence—and ideally give enough time to introduce counteracting measures.
  • EDGE2D-EIRENE predictions of molecular emission in DIII-D high-recycling divertor plasmas
    (2019-05-01) Groth, M.; Lomanowski, B.; , the DIII-D team
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The contributions of deuterium molecular emission to the total deuterium radiation was assessed in DIII-D ohmically-confined plasmas in high-recycling divertor conditions. Radial profiles of the deuterium Ly-α line intensity across the low-field side divertor leg were obtained with the recently installed divertor Survey Poor Resolution, Extended Spectrometer [1]. A high-resolution spectrometer was used to measure the poloidal profiles of the deuterium Balmer-α and the deuterium Fulcher-α band intensity in the visible wavelength range. The scrape-off layer plasma and neutral distributions were simulated using the edge fluid EDGE2D-EIRENE [2], and the numerical solutions constrained utilizing Thomson scattering and Langmuir probe measurements at the low-field side midplane and the divertor target plate. The studies show that for these conditions molecular emission plays a negligible role in the total radiative power balance of the low-field side divertor, but molecular processes are important when evaluating deuterium Balmer-α line intensity for code-experiment validation.