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  • 1
    Online Resource
    Online Resource
    Simulation and real-time replacement of missing plasma signals for disruption prediction: an implementation with APODIS
    IOP Publishing ; 2014
    In:  Plasma Physics and Controlled Fusion Vol. 56, No. 11 ( 2014-11-01), p. 114004-
    Details
    In: Plasma Physics and Controlled Fusion, IOP Publishing, Vol. 56, No. 11 ( 2014-11-01), p. 114004-
    Type of Medium: Online Resource
    ISSN: 0741-3335 , 1361-6587
    URL: Article
    DOI: 10.1088/0741-3335/56/11/114004
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2014
    detail.hit.zdb_id: 1473144-7
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  • 2
    Online Resource
    Online Resource
    Overview of the JET preparation for deuterium–tritium operation with the ITER like-wall
    IOP Publishing ; 2019
    In:  Nuclear Fusion Vol. 59, No. 11 ( 2019-11-01), p. 112021-
    Details
    In: Nuclear Fusion, IOP Publishing, Vol. 59, No. 11 ( 2019-11-01), p. 112021-
    Abstract: For the past several years, the JET scientific programme (Pamela et al 2007 Fusion Eng. Des . 82 590) has been engaged in a multi-campaign effort, including experiments in D, H and T, leading up to 2020 and the first experiments with 50%/50% D–T mixtures since 1997 and the first ever D–T plasmas with the ITER mix of plasma-facing component materials. For this purpose, a concerted physics and technology programme was launched with a view to prepare the D–T campaign (DTE2). This paper addresses the key elements developed by the JET programme directly contributing to the D–T preparation. This intense preparation includes the review of the physics basis for the D–T operational scenarios, including the fusion power predictions through first principle and integrated modelling, and the impact of isotopes in the operation and physics of D–T plasmas (thermal and particle transport, high confinement mode (H-mode) access, Be and W erosion, fuel recovery, etc). This effort also requires improving several aspects of plasma operation for DTE2, such as real time control schemes, heat load control, disruption avoidance and a mitigation system (including the installation of a new shattered pellet injector), novel ion cyclotron resonance heating schemes (such as the three-ions scheme), new diagnostics (neutron camera and spectrometer, active Alfvèn eigenmode antennas, neutral gauges, radiation hard imaging systems…) and the calibration of the JET neutron diagnostics at 14 MeV for accurate fusion power measurement. The active preparation of JET for the 2020 D–T campaign provides an incomparable source of information and a basis for the future D–T operation of ITER, and it is also foreseen that a large number of key physics issues will be addressed in support of burning plasmas.
    Type of Medium: Online Resource
    ISSN: 0029-5515 , 1741-4326
    URL: Article
    DOI: 10.1088/1741-4326/ab2276
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2019
    detail.hit.zdb_id: 2037980-8
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  • 3
    Online Resource
    Online Resource
    Overview of the JET results in support to ITER
    IOP Publishing ; 2017
    In:  Nuclear Fusion Vol. 57, No. 10 ( 2017-10-01), p. 102001-
    Details
    In: Nuclear Fusion, IOP Publishing, Vol. 57, No. 10 ( 2017-10-01), p. 102001-
    Type of Medium: Online Resource
    ISSN: 0029-5515 , 1741-4326
    URL: Article
    DOI: 10.1088/1741-4326/aa5e28
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2017
    detail.hit.zdb_id: 2037980-8
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  • 4
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    Overview of progress in European medium sized tokamaks towards an integrated plasma-edge/wall solution a
    IOP Publishing ; 2017
    In:  Nuclear Fusion Vol. 57, No. 10 ( 2017-10-01), p. 102014-
    Details
    In: Nuclear Fusion, IOP Publishing, Vol. 57, No. 10 ( 2017-10-01), p. 102014-
    Type of Medium: Online Resource
    ISSN: 0029-5515 , 1741-4326
    URL: Article
    DOI: 10.1088/1741-4326/aa6084
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2017
    detail.hit.zdb_id: 2037980-8
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  • 5
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    Online Resource
    Dependence on plasma shape and plasma fueling for small edge-localized mode regimes in TCV and ASDEX Upgrade
    IOP Publishing ; 2019
    In:  Nuclear Fusion Vol. 59, No. 8 ( 2019-08-01), p. 086020-
    Details
    In: Nuclear Fusion, IOP Publishing, Vol. 59, No. 8 ( 2019-08-01), p. 086020-
    Type of Medium: Online Resource
    ISSN: 0029-5515 , 1741-4326
    URL: Article
    DOI: 10.1088/1741-4326/ab2211
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2019
    detail.hit.zdb_id: 2037980-8
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  • 6
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    Online Resource
    Overview of physics studies on ASDEX Upgrade
    IOP Publishing ; 2019
    In:  Nuclear Fusion Vol. 59, No. 11 ( 2019-11-01), p. 112014-
    Details
    In: Nuclear Fusion, IOP Publishing, Vol. 59, No. 11 ( 2019-11-01), p. 112014-
    Abstract: The ASDEX Upgrade (AUG) programme, jointly run with the EUROfusion MST1 task force, continues to significantly enhance the physics base of ITER and DEMO. Here, the full tungsten wall is a key asset for extrapolating to future devices. The high overall heating power, flexible heating mix and comprehensive diagnostic set allows studies ranging from mimicking the scrape-off-layer and divertor conditions of ITER and DEMO at high density to fully non-inductive operation ( q 95   =  5.5, ) at low density. Higher installed electron cyclotron resonance heating power   6 MW, new diagnostics and improved analysis techniques have further enhanced the capabilities of AUG. Stable high-density H-modes with MW m −1 with fully detached strike-points have been demonstrated. The ballooning instability close to the separatrix has been identified as a potential cause leading to the H-mode density limit and is also found to play an important role for the access to small edge-localized modes (ELMs). Density limit disruptions have been successfully avoided using a path-oriented approach to disruption handling and progress has been made in understanding the dissipation and avoidance of runaway electron beams. ELM suppression with resonant magnetic perturbations is now routinely achieved reaching transiently . This gives new insight into the field penetration physics, in particular with respect to plasma flows. Modelling agrees well with plasma response measurements and a helically localised ballooning structure observed prior to the ELM is evidence for the changed edge stability due to the magnetic perturbations. The impact of 3D perturbations on heat load patterns and fast-ion losses have been further elaborated. Progress has also been made in understanding the ELM cycle itself. Here, new fast measurements of and E r allow for inter ELM transport analysis confirming that E r is dominated by the diamagnetic term even for fast timescales. New analysis techniques allow detailed comparison of the ELM crash and are in good agreement with nonlinear MHD modelling. The observation of accelerated ions during the ELM crash can be seen as evidence for the reconnection during the ELM. As type-I ELMs (even mitigated) are likely not a viable operational regime in DEMO studies of ‘natural’ no ELM regimes have been extended. Stable I-modes up to have been characterised using -feedback. Core physics has been advanced by more detailed characterisation of the turbulence with new measurements such as the eddy tilt angle—measured for the first time—or the cross-phase angle of and fluctuations. These new data put strong constraints on gyro-kinetic turbulence modelling. In addition, carefully executed studies in different main species (H, D and He) and with different heating mixes highlight the importance of the collisional energy exchange for interpreting energy confinement. A new regime with a hollow profile now gives access to regimes mimicking aspects of burning plasma conditions and lead to nonlinear interactions of energetic particle modes despite the sub-Alfvénic beam energy. This will help to validate the fast-ion codes for predicting ITER and DEMO.
    Type of Medium: Online Resource
    ISSN: 0029-5515 , 1741-4326
    URL: Article
    DOI: 10.1088/1741-4326/ab18b8
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2019
    detail.hit.zdb_id: 2037980-8
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  • 7
    Online Resource
    Online Resource
    Overview of JET results for optimising ITER operation
    IOP Publishing ; 2022
    In:  Nuclear Fusion Vol. 62, No. 4 ( 2022-04-01), p. 042026-
    Details
    In: Nuclear Fusion, IOP Publishing, Vol. 62, No. 4 ( 2022-04-01), p. 042026-
    Abstract: The JET 2019–2020 scientific and technological programme exploited the results of years of concerted scientific and engineering work, including the ITER-like wall (ILW: Be wall and W divertor) installed in 2010, improved diagnostic capabilities now fully available, a major neutral beam injection upgrade providing record power in 2019–2020, and tested the technical and procedural preparation for safe operation with tritium. Research along three complementary axes yielded a wealth of new results. Firstly, the JET plasma programme delivered scenarios suitable for high fusion power and alpha particle ( α ) physics in the coming D–T campaign (DTE2), with record sustained neutron rates, as well as plasmas for clarifying the impact of isotope mass on plasma core, edge and plasma-wall interactions, and for ITER pre-fusion power operation. The efficacy of the newly installed shattered pellet injector for mitigating disruption forces and runaway electrons was demonstrated. Secondly, research on the consequences of long-term exposure to JET-ILW plasma was completed, with emphasis on wall damage and fuel retention, and with analyses of wall materials and dust particles that will help validate assumptions and codes for design and operation of ITER and DEMO. Thirdly, the nuclear technology programme aiming to deliver maximum technological return from operations in D, T and D–T benefited from the highest D–D neutron yield in years, securing results for validating radiation transport and activation codes, and nuclear data for ITER.
    Type of Medium: Online Resource
    ISSN: 0029-5515 , 1741-4326
    URL: Article
    DOI: 10.1088/1741-4326/ac47b4
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2022
    detail.hit.zdb_id: 2037980-8
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  • 8
    Online Resource
    Online Resource
    Progress from ASDEX Upgrade experiments in preparing the physics basis of ITER operation and DEMO scenario development
    IOP Publishing ; 2022
    In:  Nuclear Fusion Vol. 62, No. 4 ( 2022-04-01), p. 042006-
    Details
    In: Nuclear Fusion, IOP Publishing, Vol. 62, No. 4 ( 2022-04-01), p. 042006-
    Abstract: An overview of recent results obtained at the tokamak ASDEX Upgrade (AUG) is given. A work flow for predictive profile modelling of AUG discharges was established which is able to reproduce experimental H-mode plasma profiles based on engineering parameters only. In the plasma center, theoretical predictions on plasma current redistribution by a dynamo effect were confirmed experimentally. For core transport, the stabilizing effect of fast ion distributions on turbulent transport is shown to be important to explain the core isotope effect and improves the description of hollow low- Z impurity profiles. The L–H power threshold of hydrogen plasmas is not affected by small helium admixtures and it increases continuously from the deuterium to the hydrogen level when the hydrogen concentration is raised from 0 to 100%. One focus of recent campaigns was the search for a fusion relevant integrated plasma scenario without large edge localised modes (ELMs). Results from six different ELM-free confinement regimes are compared with respect to reactor relevance: ELM suppression by magnetic perturbation coils could be attributed to toroidally asymmetric turbulent fluctuations in the vicinity of the separatrix. Stable improved confinement mode plasma phases with a detached inner divertor were obtained using a feedback control of the plasma β . The enhanced D α H-mode regime was extended to higher heating power by feedback controlled radiative cooling with argon. The quasi-coherent exhaust regime was developed into an integrated scenario at high heating power and energy confinement, with a detached divertor and without large ELMs. Small ELMs close to the separatrix lead to peeling-ballooning stability and quasi continuous power exhaust. Helium beam density fluctuation measurements confirm that transport close to the separatrix is important to achieve the different ELM-free regimes. Based on separatrix plasma parameters and interchange-drift-Alfvén turbulence, an analytic model was derived that reproduces the experimentally found important operational boundaries of the density limit and between L- and H-mode confinement. Feedback control for the X-point radiator (XPR) position was established as an important element for divertor detachment control. Stable and detached ELM-free phases with H-mode confinement quality were obtained when the XPR was moved 10 cm above the X-point. Investigations of the plasma in the future flexible snow-flake divertor of AUG by means of first SOLPS-ITER simulations with drifts activated predict beneficial detachment properties and the activation of an additional strike point by the drifts.
    Type of Medium: Online Resource
    ISSN: 0029-5515 , 1741-4326
    URL: Article
    DOI: 10.1088/1741-4326/ac207f
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2022
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  • 9
    Online Resource
    Online Resource
    Overview of the TCV tokamak experimental programme
    IOP Publishing ; 2022
    In:  Nuclear Fusion Vol. 62, No. 4 ( 2022-04-01), p. 042018-
    Details
    In: Nuclear Fusion, IOP Publishing, Vol. 62, No. 4 ( 2022-04-01), p. 042018-
    Abstract: The tokamak à configuration variable (TCV) continues to leverage its unique shaping capabilities, flexible heating systems and modern control system to address critical issues in preparation for ITER and a fusion power plant. For the 2019–20 campaign its configurational flexibility has been enhanced with the installation of removable divertor gas baffles, its diagnostic capabilities with an extensive set of upgrades and its heating systems with new dual frequency gyrotrons. The gas baffles reduce coupling between the divertor and the main chamber and allow for detailed investigations on the role of fuelling in general and, together with upgraded boundary diagnostics, test divertor and edge models in particular. The increased heating capabilities broaden the operational regime to include T e / T i ∼ 1 and have stimulated refocussing studies from L-mode to H-mode across a range of research topics. ITER baseline parameters were reached in type-I ELMy H-modes and alternative regimes with ‘small’ (or no) ELMs explored. Most prominently, negative triangularity was investigated in detail and confirmed as an attractive scenario with H-mode level core confinement but an L-mode edge. Emphasis was also placed on control, where an increased number of observers, actuators and control solutions became available and are now integrated into a generic control framework as will be needed in future devices. The quantity and quality of results of the 2019–20 TCV campaign are a testament to its successful integration within the European research effort alongside a vibrant domestic programme and international collaborations.
    Type of Medium: Online Resource
    ISSN: 0029-5515 , 1741-4326
    URL: Article
    DOI: 10.1088/1741-4326/ac369b
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2022
    detail.hit.zdb_id: 2037980-8
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  • 10
    Online Resource
    Online Resource
    Confinement transitions in TJ-II under Li-coated wall conditions
    IOP Publishing ; 2009
    In:  Nuclear Fusion Vol. 49, No. 10 ( 2009-10-01), p. 104018-
    Details
    In: Nuclear Fusion, IOP Publishing, Vol. 49, No. 10 ( 2009-10-01), p. 104018-
    Abstract: This paper presents the latest results on confinement studies in the TJ-II stellarator. The inherently strong plasma–wall interaction of TJ-II has been successfully reduced after lithium coating by vacuum evaporation. Besides H retention and low Z , Li was chosen because there exists a reactor-oriented interest in this element, thus giving special relevance to the investigation of its properties. The Li-coating has led to important changes in plasma performance. Particularly, the effective density limit in NBI plasmas has been extended reaching central values of 8 × 10 19  m −3 and T e ≈ 250–300 eV, with peaked density, rather flat T e profiles and higher ion temperatures. Due to the achieved density control, a second type of transition has been added to the low density ones previously observed in ECRH plasmas: higher density transitions characterized by the fall in Hα emission, the onset of steep density gradient and the reduction in the turbulence; which are characteristics of transition to the H mode. Confinement studies in ECH plasmas indicate that lowest order magnetic resonances, even in a low shear environment, locally reduce the effective electron heat diffusivities, while Alfven eigenmodes destabilized in NBI plasmas can influence fast ion confinement.
    Type of Medium: Online Resource
    ISSN: 0029-5515 , 1741-4326
    URL: Article
    DOI: 10.1088/0029-5515/49/10/104018
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2009
    detail.hit.zdb_id: 2037980-8
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