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Garching bei München, Germany

Lux H.,Culham Center for Fusion Energy | Kemp R.,Culham Center for Fusion Energy | Fable E.,Max Planck Institute for Plasma Physics (Garching) | Wenninger R.,Max Planck Institute for Plasma Physics (Garching) | Wenninger R.,EUROfusion Programme Management Unit
Plasma Physics and Controlled Fusion | Year: 2016

In systems modelling for fusion power plants, it is essential to robustly predict the performance of a given machine design (including its respective operating scenario). One measure of machine performance is the energy confinement time τE that is typically predicted from experimentally derived confinement scaling laws (e.g. IPB98(y,2)). However, the conventionally used scaling laws have been derived for ITER which-unlike a fusion power plant-will not have significant radiation inside the separatrix. In the absence of a new high core radiation relevant confinement scaling, we propose an ad hoc correction to the loss power PL used in the ITER confinement scaling and the calculation of the stored energy Wth by the radiation losses from the core of the plasma Prad,core. Using detailed ASTRA / TGLF simulations, we find that an appropriate definition of Prad,core is given by 60% of all radiative losses inside a normalised minor radius ρcore = 0.75. We consider this an improvement for current design predictions, but it is far from an ideal solution. Wetherefore encourage more detailed experimental and theoretical work on this issue. © 2016 IOP Publishing Ltd Printed in the UK.

Murari A.,Culham Center for Fusion Energy | Murari A.,EUROfusion Programme Management Unit | Craciunescu T.,Consorzio RFX | Peluso E.,National Institute for Laser, Plasma and Radiation Physics | And 6 more authors.
Nuclear Fusion | Year: 2016

Control of instabilities such as ELMs and sawteeth is considered an important ingredient in the development of reactor-relevant scenarios. Various forms of ELM pacing have been tried in the past to influence their behavior using external perturbations. One of the main problems with these synchronization experiments resides in the fact that ELMs are periodic or quasi-periodic in nature. Therefore, after any pulsed perturbation, if one waits long enough, an ELM is always bound to occur. To evaluate the effectiveness of ELM pacing techniques, it is crucial to determine an appropriate interval over which they can have a real influence and an effective triggering capability. In this paper, three independent statistical methods are described to address this issue: Granger causality, transfer entropy and recurrence plots. The obtained results for JET with the ITER-like wall (ILW) indicate that the proposed techniques agree very well and provide much better estimates than the traditional heuristic criteria reported in the literature. Moreover, their combined use allows for the improvement of the time resolution of the assessment and determination of the efficiency of the pellet triggering in different phases of the same discharge. Therefore, the developed methods can be used to provide a quantitative and statistically robust estimate of the triggering efficiency of ELM pacing under realistic experimental conditions. © 2016 EURATOM.

Pereslavtsev P.,Karlsruhe Institute of Technology | Bachmann C.,EUROfusion Programme Management Unit | Fischer U.,Karlsruhe Institute of Technology
Fusion Engineering and Design | Year: 2015

Neutronic analyses were performed to assess systematically the tritium breeding ratio (TBR) variations in the DEMO for the different blanket concepts HCPB, HCLL, WCLL and DCLL DEMOs due to modifications of the blanket configurations. A dedicated automated procedure was developed to fill the breeding modules in the common generic model in correspondence to the different concepts. The TBR calculations were carried out using the MCNP5 Monte Carlo code. The following parameters affecting the global TBR were investigated: TBR poloidal distribution, radial breeder zone depth, 6Li enrichment, steel content in the breeder modules, poloidal segmentation of the breeder blanket volume, size of gaps between blankets, thickness of the first wall and of the tungsten armour. Based on the results a set of practical guidelines was prepared for the designers developing the individual breeding blanket concepts with the goal to achieve the required tritium breeding performance in DEMO. © 2016 Elsevier B.V.

Stan-Sion C.,Horia Hulubei National Institute of Physics and Nuclear Engineering | Bekris N.,EUROfusion Programme Management Unit | Bekris N.,Karlsruhe Institute of Technology | Kizane G.,University of Latvia | And 4 more authors.
Nuclear Fusion | Year: 2016

Accelerator mass spectrometry (AMS) and the full combustion method (FCM) followed by liquid scintillation counting were applied to quantitatively determine the tritium retention in the tungsten-coated carbon fibre composites (CFC), in comparison to uncoated CFC tiles from the JET divertor. The tiles were adjacent and exposed to plasma operations between 2007 and 2009. The tritium depth profiles are showing that the tritium retention on the W-coated tile was reduced by a factor of 13.5 in comparison to the uncoated tile whereas the bulk tritium concentration is approximately the same for both tiles. © 2016 EURATOM.

Fischer U.,Karlsruhe Institute of Technology | Bachmann C.,EUROfusion Programme Management Unit | Jaboulay J.-C.,CEA Saclay Nuclear Research Center | Moro F.,ENEA | And 3 more authors.
Fusion Engineering and Design | Year: 2016

This paper presents nuclear performance issues of the HCPB, HCLL, DCLL and WCLL breeder blankets, which are under development within the PPPT (Power Plant Physics and Technology) programme of EUROfusion, with the objective to assess the potential and suitability of the blankets for the application to DEMO. The assessment is based on the initial design versions of the blankets developed in 2014. The Tritium breeding potential is considered sufficient for all breeder blankets although the initial design versions of the HCPB, HCLL and DCLL blankets were shown to require further design improvements. Suitable measures have been proposed and proven to be sufficient to achieve the required Tritium Breeding Ratio (TBR). ≥. 1.10. The shielding performance was shown to be sufficient to protect the super-conducting toroidal field coil provided that efficient shielding material mixtures including WC or borated water are utilized. The WCLL blanket does not require the use of such shielding materials due to a very compact blanket support structure/manifold configuration which yet requires design verification. The vacuum vessel can be safely operated over the full anticipated DEMO lifetime of 6 full power years for all blanket concepts considered. © 2015.

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