| 1. |
- 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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| 2. |
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- 2019
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Tidskriftsartikel (refereegranskat)
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| 3. |
- Wu, X. Y., et al.
(författare)
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1.142 mu m GaAsBi/GaAs Quantum Well Lasers Grown by Molecular Beam Epitaxy
- 2017
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Ingår i: ACS Photonics. - : American Chemical Society (ACS). - 2330-4022. ; 4:6, s. 1322-1326
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Tidskriftsartikel (refereegranskat)abstract
- As a promising new class of near-infrared light emitters, GaAsBi laser diodes (LDs) are considered to have a high energy efficiency and an insensitive temperature dependence of the band gap. In this paper, we realize the longest ever reported lasing wavelength up to 1.142 mu m at room temperature in GaAsBi0.058/GaAs quantum well LDs grown by molecular beam epitaxy. The output power is up to 127 mW at 300 K under pulsed mode. We also demonstrate continuous wave mode operation up to 273 K for the first time. The temperature coefficient of the GaAsBi/GaAs LD is 0.26 nm/K in the temperature range of 77-350 K, lower than that of both InGaAsP/InP and InGaAs/GaAs LDs. The characteristic temperature is extracted to be 139 K in the temperature range of 77-225 K and decreases to 79 K at 225-350 K.
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| 4. |
- Zhang, Fengling, et al.
(författare)
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Ordered mesoporous Ag-TiO2-KIT-6 heterostructure: synthesis, characterization and photocatalysis
- 2009
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Ingår i: Journal of Materials Chemistry. - : Royal Society of Chemistry (RSC). - 1364-5501 .- 0959-9428. ; 19:18, s. 2771-2777
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Tidskriftsartikel (refereegranskat)abstract
- Ordered mesoporous Ag-TiO2-KIT-6 heterostructured nanocrystals were successfully synthesized by a template-based method, where a layer of TiO2 and Ag2O nanoparticles were deposited on cubic (Ia3d) silica (KIT-6) in an orderly manner; at the same time, the formed Ag2O nanoparticles were photolyzed to metallic Ag nanoparticles. Our results show that Ag-TiO2-KIT-6 is an ordered mesoporous composite material, which is composed of Ag-TiO2 heterostructures and the amorphous KIT-6 template. In addition, Ag-TiO2-KIT-6 possesses the highest photocatalytic activity among the as-synthesized photocatalysts, which can be attributed to the Ag-TiO2 heterojunctions and the excellent texture: (1) Ag-TiO2 heterojunctions improve the separation of photogenerated electron-hole pairs due to the potential energy differences between Ag and TiO2 nanocrystals, thus enhancing the photocatalytic activity; (2) the Ag-TiO2-KIT-6 sample possesses a high BET surface area and a large number of ordered pore channels, which facilitate adsorption and transportation of dye molecules, also leading to higher photocatalytic activity. It was also found that the Ag-TiO2 heterostructure plays a more important role in enhancing the photocatalytic activity than high BET surface area.
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| 5. |
- Dong, B., et al.
(författare)
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Local surface plasmon resonance of single silver nanorice particles in the near-infrared
- 2014
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Ingår i: Mikrochimica Acta. - : Springer Science and Business Media LLC. - 1436-5073 .- 0026-3672. ; 181:7-8, s. 791-795
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Tidskriftsartikel (refereegranskat)abstract
- We report on the synthesis and optical spectra of silver nanorice particles. Two strong absorption bands are resolved in the near UV and near-IR region, and the dark field scattering spectra are consistent with the absorption spectra. Finite-difference time-domain simulations reveal that the peak in the IR region can be attributed to the E field that is parallel to the long axis, while the peak in the UV can be attributed to the E field perpendicular to the short axis of the silver nanorice particles.
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| 6. |
- Wang, Shu Min, 1963, et al.
(författare)
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A novel semiconductor compatible path for nano-graphene synthesis using CBr4 precursor and Ga catalyst
- 2014
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- We propose a novel semiconductor compatible path for nano-graphene synthesis using precursors containing C-Br bonding and liquid catalyst. The unique combination of CBr4 as precursor and Ga as catalyst leads to efficient C precipitation at a synthesis temperature of 200 degrees C or lower. The non-wetting nature of liquid Ga on tested substrates limits nano-scale graphene to form on Ga droplets and substrate surfaces at low synthesis temperatures of T = 400 degrees C. Good quality interface nano-graphene is demonstrated and the quality can be further improved by optimization of synthesis conditions and proper selection of substrate type and orientation. The proposed method provides a scalable and transfer-free route to synthesize graphene/semiconductor heterostructures, graphene quantum dots as well as patterned graphene nano-structures at a medium temperature range of 400-700 degrees C suitable for most important elementary and compound semiconductors.
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| 7. |
- Amanullah, Rahman, et al.
(författare)
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Diversity in extinction laws of Type Ia supernovae measured between 0.2 and 2 μm
- 2015
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 453:3, s. 3300-3328
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Tidskriftsartikel (refereegranskat)abstract
- We present ultraviolet (UV) observations of six nearby Type Ia supernovae (SNe Ia) obtained with the Hubble Space Telescope, three of which were also observed in the near-IR (NIR) with Wide-Field Camera 3. UV observations with the Swift satellite, as well as ground-based optical and NIR data provide complementary information. The combined data set covers the wavelength range 0.2-2 mu m. By also including archival data of SN 2014J, we analyse a sample spanning observed colour excesses up to E(B - V) = 1.4 mag. We study the wavelength-dependent extinction of each individual SN and find a diversity of reddening laws when characterized by the total-to-selective extinction R-V. In particular, we note that for the two SNe with E(B - V) greater than or similar to 1 mag, for which the colour excess is dominated by dust extinction, we find R-V = 1.4 +/- 0.1 and R-V = 2.8 +/- 0.1. Adding UV photometry reduces the uncertainty of fitted R-V by similar to 50 per cent allowing us to also measure R-V of individual low-extinction objects which point to a similar diversity, currently not accounted for in the analyses when SNe Ia are used for studying the expansion history of the Universe.
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| 8. |
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| 9. |
- Chen, Xiangrong, 1982, et al.
(författare)
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Study on conducting characteristics of electrical trees in cross-linked polyethylene cable insulation
- 2012
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Ingår i: Wuli Xuebao/Acta Physica Sinica. - : Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences. - 1000-3290. ; 61:8, s. Art. no. 087701-
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Tidskriftsartikel (refereegranskat)abstract
- The conducting characteristics of two typical electrical trees in cross-linked polyethylene (XLPE) cable insulation are studied by a combination of optical microscopy observation, partial discharge measurement and con-focal Raman spectroscopy analysis. Although they are grown under similar conditions, these two trees display very different shapes. One is a typical branch-pine tree grown at 9 kV, and the other is a branch tree grown at 11 kV. The growth and the partial discharge regularities show obvious differences. The disordered graphitic carbon is condensed in the main tree channels of the branch-pine tree. From the relative intensity of the graphitic carbon G band to D band, the graphitic domain is estimated to be about 8 nm in size. The tree channel resistance per unit length is less than 10 Ω· μm-1, which is sufficient to prevent the partial discharge from developing within the tree structure. The branch-pine tree shows the features of the conducting tree. The fluorescence background is observed in the channels of branch tree, which shows the existence of the products of the material degradation, but no disordered graphitic carbon is observed in these tree channels. These tree channels display obvious non-conducting characteristics, which is not sufficient to prevent the continuous effect of the partial discharges. Finally, a single channel growth model is proposed for the conducting and non-conducting trees grown in XLPE cable insulation. Based on the equivalent circuit theory, the growth mechanisms of the two trees with different conducting characteristics in XLPE cable insulation are discussed.
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| 10. |
- Feng, S. Z., et al.
(författare)
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Siloxane-Terminated Side Chain Engineering of Acceptor Polymers Leading to Over 7% Power Conversion Efficiencies in All-Polymer Solar Cells
- 2017
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Ingår i: ACS Macro Letters. - : American Chemical Society (ACS). - 2161-1653. ; 6:11, s. 1310-1314
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Tidskriftsartikel (refereegranskat)abstract
- To investigate the influence of functional pendent groups on acceptor polymers and photovoltaic properties of all-polymer solar cells (all-PSCs), two novel acceptor polymers containing siloxane-terminated side chains are synthesized and characterized. Increasing the content of siloxane-terminated side chains can reduce pi-pi stacking distance and improve crystalline behavior, yet lead to poorer solubility of the acceptor polymers. By modulating the proper loadings of siloxane-terminated side chains on the acceptor polymers, the PBDB-T:PNDI-Si25 all-PSC attains a maximal power conversion efficiency (PCE) of 7.4% with an outstanding fill factor of 0.68. The results provide, new insights for developing high-performance all-PSCs through functional group engineering on the acceptor polymers, to achieve good solubility, polymer miscibility, and blend morphology.
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