| 1. |
- Kazakov, Ye O., et al.
(författare)
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Physics and applications of three-ion ICRF scenarios for fusion research
- 2021
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Ingår i: Physics of Plasmas. - : American Institute of Physics (AIP). - 1070-664X .- 1089-7674. ; 28:2
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Forskningsöversikt (refereegranskat)abstract
- This paper summarizes the physical principles behind the novel three-ion scenarios using radio frequency waves in the ion cyclotron range of frequencies (ICRF). We discuss how to transform mode conversion electron heating into a new flexible ICRF technique for ion cyclotron heating and fast-ion generation in multi-ion species plasmas. The theoretical section provides practical recipes for selecting the plasma composition to realize three-ion ICRF scenarios, including two equivalent possibilities for the choice of resonant absorbers that have been identified. The theoretical findings have been convincingly confirmed by the proof-of-principle experiments in mixed H–D plasmas on the Alcator C-Mod and JET tokamaks, using thermal 3He and fast D ions from neutral beam injection as resonant absorbers. Since 2018, significant progress has been made on the ASDEX Upgrade and JET tokamaks in H–4He and H–D plasmas, guided by the ITER needs. Furthermore, the scenario was also successfully applied in JET D–3He plasmas as a technique to generate fusion-born alpha particles and study effects of fast ions on plasma confinement under ITER-relevant plasma heating conditions. Tuned for the central deposition of ICRF power in a small region in the plasma core of large devices such as JET, three-ion ICRF scenarios are efficient in generating large populations of passing fast ions and modifying the q-profile. Recent experimental and modeling developments have expanded the use of three-ion scenarios from dedicated ICRF studies to a flexible tool with a broad range of different applications in fusion research.
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| 2. |
- Na, Yong-Su, et al.
(författare)
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On benchmarking of simulations of particle transport in ITER
- 2019
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 59:7
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Tidskriftsartikel (refereegranskat)abstract
- We report results of benchmarking of core particle transport simulations by a collection of codes widely used in transport modelling of tokamak plasmas. Our analysis includes formulation of transport equations, difference between electron and ion solvers, comparison of modules of the pellet and edge gas fuelling on the ITER baseline scenario. During the first phase of benchmarking we address the particle transport effects in the stationary phase. Firstly, simulations are performed with identical sources, sinks, transport coefficients, and boundary conditions prescribed in the flattop H-mode phase. The transformation of ion particle transport equations is introduced so to directly compare their results to electron transport solvers. Secondly, the pellet fuelling models are benchmarked in various conditions to evaluate the dependency of the pellet deposition on the pellet volume, injection side, pedestal, and separatrix parameters. Thirdly, edge gas fuelling is benchmarked to assess sensitivities of source profile predictions to uncertainties in plasma conditions and detailed model assumptions. At the second phase, we address particle transport effects in the time- evolving plasma including the current ramp-up to the ramp-down phase. The ion and the electron solvers are benchmarked together. Differences between the simulation results of the solvers are investigated in terms of equilibrium, grid resolution, radial coordinate, radial grid distribution, and plasma volume evolution term. We found that the selection of the radial coordinate can yield prominent differences between the solvers mainly due to differences in the edge grid distribution. The simulations reveal that electron and ion solvers predict noticeably different density peaking for the same diffusion and pinch velocity while with the peaked profile of helium, expected in fusion reactors. The fuelling benchmarking shows that gas puffing is not efficient for core fuelling in H-modes and density control should be done by the high field side pellet injection in contrast to present machines.
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| 3. |
- Loarte, A., et al.
(författare)
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H-mode plasmas in the pre-fusion power operation 1 phase of the ITER research plan
- 2021
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 61:7
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Tidskriftsartikel (refereegranskat)abstract
- The optimum conditions for access to and sustainment of H-mode plasmas and their expected plasma parameters in the pre-fusion power operation 1 (PFPO-1) phase of the ITER research plan, where the additional plasma heating will be provided by 20 MW of electron cyclotron heating, are assessed in order to identify key open R&D issues. The assessment is performed on the basis of empirical and physics-based scalings derived from present experiments and integrated modelling of these plasmas including a range of first-principle transport models for the core plasma. The predictions of the integrated modelling of ITER H-mode plasmas are compared with ITER-relevant experiments carried out at JET (low-collisionality high-current H modes) and ASDEX Upgrade (significant electron heating) for both global H-mode properties and scale lengths of density and temperature profiles finding reasonable agreement. Specific integration issues of the PFPO-1 H-mode plasma scenarios are discussed taking into account the impact of the specificities of the ITER tokamak design (level of ripple, etc).
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| 4. |
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| 5. |
- Yavorskij, V., et al.
(författare)
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Results of Predictive Fokker-Planck Modelling of NBI Deuterons in ITER
- 2011
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Ingår i: Journal of fusion energy. - : Springer Science and Business Media LLC. - 0164-0313 .- 1572-9591. ; 30:4, s. 307-322
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Tidskriftsartikel (refereegranskat)abstract
- First an analytical formalism is presented for calculating the source distribution of ions generated by neutral beam injection (NBI) in tokamak plasmas. A general NBI ion source term, applicable to studies in the phase space up to 6 dimensions, is provided for neutral beams with finite thickness and divergence. Further, using this source term for the envisaged NBI in ITER, we carry out 3D Fokker-Planck modelling of the steady-state deuteron distribution function of NBI produced fast deuterons relaxing on bulk plasma components. For two basic ITER scenarios we demonstrate the poloidal profiles of the beam deuteron density, of the NBI generated current as well as of the NBI power deposition to bulk electrons and ions. Further, we evaluate the capability of gamma and NPA diagnostics of NBI ions in ITER and demonstrate the sensitivity of the distributions of NBI generated ions to different ITER operation scenarios.
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| 6. |
- Kjaerandsen, Jostein, et al.
(författare)
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Annotated checklist of fungus gnats from Sweden (Diptera: Bolitophilidae, Diadocidiidae, Ditomyiidae, Keroplatidae and Mycetophilidae).
- 2007
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Ingår i: Insect Systematics & Evolution. - 1399-560X. ; 65, s. 1-128
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Forskningsöversikt (refereegranskat)abstract
- The first modern Swedish checklist of fungus gnats of the families Bolitophilidae, Diadocidiidae, Ditomyiidae, Keroplatidae and Mycetophilidae is presented. The checklist results from a comprehensive literature research as well as treatment of a considerable determined and undetermined material from Swedish museum collections and recent material from several sources. To get better grounds for judging many old and doubtful records from Sweden, a nearly complete review of fungus gnats from the J. W. Zetterstedt collection at the Museum of Zoology in Lund has been undertaken and identifications corrected where needed. In order to preserve nomenclatural stability three species names are reinstated, all with priority over junior synonyms, viz. Orfelia lugubris (Zetterstedt, 1851) comb. n. = Orfelia tristis (Lundström, 1911) syn. n., Ectrepesthoneura ovata Ostroverkhova, 1977 = Ectrepesthoneura bucera Plassmann, 1980 syn. n., and Dynatosoma thoracicum (Zetterstedt, 1838) sens. auct. nec Zaitzev = Dynatosoma norwegiense Zaitzev & Økland, 1994 syn. n. We further find the holotype of Mycetophila grisea Zetterstedt, 1852 to be identical to Mycetophila perpallida Chandler, 1993, but retain Mycetophila perpallida pending a review of other possible synonyms with precedence. Ectrepesthoneura pubescens (Zetterstedt, 1860) is found to be a synonym of Ectrepesthoneura unifurcata (Zetterstedt, 1860) comb. n. syn. n. where the first name is retained as valid due to page priority. Four names described by Zetterstedt remain nom. dub., viz.: Mycomya diluta (Zetterstedt, 1860), Mycomya (Mycomya) notata (Zetterstedt, 1860), Brevicornu fusculum (Zetterstedt, 1838), and Brevicornu obscurellum (Zetterstedt, 1838) comb. n. Stigmatomeria obscura (Winnertz, 1863) sp. restit. is found to be a distinct species separate from Stigmatomeria crassicornis (Stannius, 1831). New combinations are suggested for Exechia praedita Plassmann, 1976 = Exechiopsis (Xenexechia) praedita (Plassmann, 1976) comb. n., and for Rhymosia pectinacea Ostroverkhova, 1979 = Pseudexechia pectinacea (Ostroverkhova, 1979) comb. n. Having removed 17 published species names with doubtful or wrong records (listed at the end) we find that the published sources comprise altogether 585 species. 137 species are reported for the first time in Sweden, bringing the total up to 722. Additional 36 species considered to be new to science are mentioned for completeness, but will be further presented and described elsewhere. Hence, at present the known fauna (including claimed undescribed species) comprises 758 species in 83 genera; 25 species of the family Bolitophilidae, 5 of the family Diadocidiidae, 3 of the family Ditomyiidae, 45 of the family Keroplatidae, 679 of the family Mycetophilidae and 1 in the unplaced genus Sciarosoma Chandler. For each species a full account of published Swedish sources with pagination, all synonyms used in Sweden, and the currently known distribution in the Swedish provinces as well as the known world distribution is given. The Swedish species of fungus gnats are generally very widespread: 47% being widespread in Europe, 43% being distributed in the Eastern Palaearctic Region, and 25% having a Holarctic distribution. We find significantly higher species richness in the boreal forests of northern Sweden, but only 3% of the species so far described are known only from the Nordic biogeographical region.
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| 7. |
- Kurina, Olavi, et al.
(författare)
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Fungus gnats (Diptera: Sciaroidea excl. Sciaridae) in the Swedish boreonemoral forests
- 2004
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Ingår i: Studia dipterologica. ; 11:2, s. 471-488
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Tidskriftsartikel (refereegranskat)abstract
- Fungus gnats in boreonemoral forests of south Sweden are studied using material collected with Malaise and window traps from 17 localities in the years 2001 and 2002. 250 species are recorded including 76 species new to Sweden. 14 of these are found in Fennoscandia for the first time: Docosia setosa Landrock, D. spec. (indet. sensu Hutson et al. 1980), Brevicornu cognatum Ostroverkhova, Mycetophila eppingensis Chandler, M. lobulata A. Zaitzev, M. pyrenaica Matile, M. subsigillata A. Zaitzev, Sceptonia cryptocauda Chandler, S. flavipuncta Edwards, S. longisetosa Ševcik, S. pilosa Bukowski, S. pughi Chandler, Sciophila interrupta (Winnertz) and S. plurisetosa Edwards. One new synonym is proposed: Dynatosoma dihaeta Polevoi, 1995 = Dynatosoma schachti Plassmann, 1999 syn. nov.
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| 8. |
- Liu, Yueqiang, 1971, et al.
(författare)
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Stabilization of Resistive Wall Modes in ITER by Active Feedback and Toroidal Rotation
- 2004
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Ingår i: Nuclear Fusion. - 1741-4326 .- 0029-5515. ; 44, s. 232-
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Tidskriftsartikel (refereegranskat)abstract
- Two approaches are examined for stabilization of the resistive wall mode (RWM) of toroidal mode number n = 1 in an advanced ITER scenario. Active feedback control, with the present coil design and poloidal sensors placed just inside the inner wall, can be very efficient in stabilizing the RWM. Within the voltage limit of the present design for the feedback coils and conservative constraints on performance, the plasma pressure can be increased up to at least 70% between the no-wall and ideal-wall beta limits. Stabilization of the RWM by toroidal plasma rotation depends on the rotation profile as well as on the model for ion Landau damping. Feedback control of rotating plasmas for the advanced scenario is considered. The effect of the blanket is also studied using a simplified model.
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| 9. |
- Pinches, S. D., et al.
(författare)
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Implementation of plasma simulators and plasma reconstruction workflows in ITER’s Integrated Modelling & Analysis Suite (IMAS)
- 2017
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Ingår i: 44th EPS Conference on Plasma Physics, EPS 2017. - : European Physical Society (EPS).
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Konferensbidrag (refereegranskat)abstract
- IMAS has been installed within the majority of the ITER Members and is being used to support ITPA activities including code benchmarking and validation. Sophisticated workflows, such as Plasma Simulators and those describing H&CD systems, have been adapted to IMAS and applied to ITER scenarios. The framework is considered sufficiently flexible to handle all foreseen approaches to the integrated (probabilistic) determination of measurement parameters (and their errors). The inclusion of UDA within the IMAS data Access Layer has allowed the fetching of IDSs directly from experimental databases and the demonstration of the first plasma reconstruction chain. An interactive Live Display in which signals are selected through a web interface has also been demonstrated.
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| 10. |
- Schneider, Mireille, et al.
(författare)
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Simulation of heating and current drive sources for scenarios of the ITER research plan
- 2021
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Ingår i: Nuclear Fusion. - : IOP Publishing Ltd. - 0029-5515 .- 1741-4326. ; 61:12
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Tidskriftsartikel (refereegranskat)abstract
- Predicting the impact of heating and current drive (H&CD) sources is essential to evaluate the performance of ITER plasmas and to subsequently optimise the scenarios for the four stages of the ITER research plan. This should be done in the context of global transport calculations of complete plasma discharges. For this purpose, a dedicated workflow has been developed in the ITER integrated modelling and analysis suite as a modular component to be used together with transport solvers to quantify the dynamics of H&CD sources for the different phases of a plasma discharge, including possible synergetic effects between the heating sources. This paper presents the results of the combined modelling of H&CD sources for the ITER DT baseline 15 MA/5.3 T scenario including the synergy between neutral beam injection (NBI) of deuterium, fusion-born alpha particles and ion cyclotron resonance heating (ICRH) at the fundamental frequency of deuterium, showing modest synergetic effects. The results of the combined H&CD sources for an ITER 7.5 MA/2.65 T helium plasma of the second pre-fusion power operation phase (PFPO-2) are also shown, exhibiting more significant synergetic effects between the fundamental ICRH minority hydrogen heating and NBI hydrogen beams. Finally, a study of electron cyclotron heating absorption for an ITER helium PFPO scenario at 7.5 MA/2.65 T is also presented with a discussion on the edge parasitic absorption that arises under specific conditions.
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