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| 2. |
- Fenstermacher, M.E., et al.
(författare)
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DIII-D research advancing the physics basis for optimizing the tokamak approach to fusion energy
- 2022
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 62:4
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
- Girard-Alcindor, V., et al.
(författare)
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New narrow resonances observed in the unbound nucleus F 15
- 2022
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Ingår i: Physical Review C. - : American Physical Society (APS). - 2469-9985 .- 2469-9993. ; 105:5
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Tidskriftsartikel (refereegranskat)abstract
- The structure of the unbound F15 nucleus is investigated using the inverse kinematics resonant scattering of a radioactive O14 beam impinging on a CH2 target. The analysis of H1(O14,p)O14 and H1(O14,2p)N13 reactions allowed the confirmation of the previously observed narrow 1/2- resonance, near the two-proton decay threshold, and the identification of two new narrow 5/2- and 3/2- resonances. The newly observed levels decay by 1p emission to the ground of O14, and by sequential 2p emission to the ground state of N13 via the 1- resonance of O14. Gamow shell model (GSM) analysis of the experimental data suggests that the wave functions of the 5/2- and 3/2- resonances may be collectivized by the continuum coupling to nearby 2p- and 1p-decay channels. The observed excitation function H1(O14,p)O14 and resonance spectrum in F15 are well reproduced in the unified framework of the GSM.
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| 4. |
- Tokitani, M., et al.
(författare)
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Surface morphology of the bulk tungsten divertor tiles from JET ITER-like wall
- 2020
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Ingår i: Physica Scripta. - : IOP PUBLISHING LTD. - 0031-8949 .- 1402-4896. ; T171:1
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Tidskriftsartikel (refereegranskat)abstract
- Surface characterization of bulk tungsten tiles (W lamellae) used during the first campaign of JET with the ITER-Like Wall (JET-ILW) was performed by means of microscopy and tritium imaging techniques. This is the first report regarding very detailed structural studies of W lamellae from the JET-ILW divertor. A special feature of the W lamellae installed in JET is the intrinsic network of micro-cracks detected on surfaces of the as-manufactured material. Analyses of different W lamellae samples on the plasma-facing surface reveal two types of surface structures caused by plasma impact: areas with strong erosion and regions of mild plasma interaction. In regions of strong erosion, a thin modified layer (thickness of similar to 20 nm) with a high density of defects including bubble-like structures has been formed. In addition, features indicating melting along edges of micro-cracks with the micro-scale plastic deformation have been identified.
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| 5. |
- Kourtit, Karima, et al.
(författare)
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Comparative urban performance assessment of safe cities through data envelopment analysis
- 2020
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Ingår i: Regional Science Policy & Practice. - : Blackwell Publishing Ltd. - 1757-7802.
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Tidskriftsartikel (refereegranskat)abstract
- Sustainable urban development calls for a balanced package of conditions that induce a high quality of life (including safety and security) in cities. We argue that modern cities have to develop knowledge- based strategies for smart, safe and sound (3-S) city development, supported by urban performance assessment (UPA) as a framework for sustainable urban planning. The present study builds on these strategic notions and articulates the message that smart urban policy should look into input resources in relation to output performance. Particular attention will be paid to the constituents and the role of multiple safety indicators in urban performance analysis. Next, an appropriate method from the industrial management literature, namely, super-efficient data envelopment analysis (SE-DEA) will be utilized in order to undertake a comparative performance assessment of safety conditions in 57 world cities, followed by a similar analysis for 14 large European cities. Both world-wide and Europe-wide, there appear to be significant differences in safety performance of cities, which means that there is much scope for strategic and effective safety policy in many cities.
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