46 research outputs found

    Overview of ASDEX Upgrade Results

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    Overview of ASDEX Upgrade results

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    Recent results from the ASDEX Upgrade experimental campaigns 2001 and 2002 are presented. An improved understanding of energy and particle transport emerges in terms of a 'critical gradient' model for the temperature gradients. Coupling this to particle diffusion explains most of the observed behaviour of the density profiles, in particular, the finding that strong central heating reduces the tendency for density profile peaking. Internal transport barriers (ITBs) with electron and ion temperatures in excess of 20 keV (but not simultaneously) have been achieved. By shaping the plasma, a regime with small type II edge localized modes (ELMs) has been established. Here, the maximum power deposited on the target plates was greatly reduced at constant average power. Also, an increase of the ELM frequency by injection of shallow pellets was demonstrated. ELM free operation is possible in the quiescent H-mode regime previously found in DIII-D which has also been established on ASDEX Upgrade. Regarding stability, a regime with benign neoclassical tearing modes (NTMs) was found. During electron cyclotron current drive (ECCD) stabilization of NTMs, βN could be increased well above the usual onset level without a reappearance of the NTM. Electron cyclotron resonance heating and ECCD have also been used to control the sawtooth repetition frequency at a moderate fraction of the total heating power. The inner wall of the ASDEX Upgrade vessel has increasingly been covered with tungsten without causing detrimental effects on the plasma performance. Regarding scenario integration, a scenario with a large fraction of noninductively driven current (≥50%), but without ITB has been established. It combines improved confinement (τE/τITER98 ≈ 1.2) and stability (βN ≤ 3.5) at high Greenwald fraction (ne/nGW ≈ 0.85) in steady state and with type II ELMy edge and would offer the possibility for long pulses with high fusion power at reduced current in ITER

    The implementation of Natura 2000 in forests: A trans- and interdisciplinary assessment of challenges and choices.

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    Natura 2000 is the core of the EU's biodiversity conservation policy. 50% of the overall protected area under Natura 2000 is forest. Yet, comparatively little is known about the implementation of the policy in forests. Building on a rich set of social and natural science data, and an inter- and transdisciplinary discussion process involving scientists from different disciplines as well as EU, national and local stakeholders, this paper identifies five important challenges related to the implementation of Natura 2000 in forests: (1) the balancing of biodiversity conservation and timber production, (2) the integration of conservation (science) and local stakeholders’ demands, (3) climate change, (4) lacking and less effective funding, and (5) conflicts related to other sectoral policies. Subsequently, five possible pathways to tackle these challenges are proposed: (1) a learning approach through better communication and transparency, (2) a pathway emphasizing the role of conservation science in developing management strategies and responding to climate change, (3) an approach of better integrating Europe's citizens in the design and implementation of the policy, (4) an approach highlighting the necessity of an effective funding strategy, and (5) the vision to work towards an integrated European land use and conservation policy. In conclusion, we emphasize, on one hand, the distinct character of the five pathways but, on the other hand, underline that probably all of them need to be followed in order to make the implementation of Natura 2000 in Europe's forests a success story
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