| 1. |
- Baruzzo, M., et al.
(författare)
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3D effects on RWM physics in RFX-mod
- 2011
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Ingår i: Nuclear Fusion. - 1741-4326 .- 0029-5515. ; 51, s. 083037-
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Tidskriftsartikel (refereegranskat)abstract
- n this paper insights into the behaviour of resistive wall modes (RWMs) in the RFX-mod reversed field pinch device are given, with a focus on 3D issues in the characterization of the m spectrum of the mode and on the study of multi-harmonic coupling.In the first part of the paper the interaction between multiple unstable RWMs is studied and the presence of a coupling between different poloidal components of the most unstable RWM is demonstrated, taking advantage of the flexibility of the RFX-mod control system.In the second part of the work, the dependence of the growth rates of RWMs on a complete set of plasma parameters is studied in order to create a complete and homogeneous database, which permits a careful validation of stability codes.Finally, the experimental data are compared with the code predictions which take into account the 3D structure of conductors around the plasma. The different effects that modify the simple description, where unstable modes can be identified with single Fourier harmonics, appear to be explained by a mixture of toroidicity-induced and 3D eddy current effects.
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| 2. |
- Hao, G. Z., et al.
(författare)
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Effect of Trapped Energetic Particles on the Resistive Wall Mode
- 2011
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Ingår i: Physical Review Letters. ; 107, s. 015001-
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Tidskriftsartikel (refereegranskat)abstract
- A stability analysis for the resistive wall mode is studied in the presence of trapped energetic particles (EPs). When the EPs’ beta exceeds a critical value, a fishbonelike bursting mode (FLM) with an external kink eigenstructure can exist. This offers the first analytic interpretation of the experimental observations [ Phys. Rev. Lett. 103 045001 (2009)]. The mode-particle resonances for the FLM and the q=1 fishbone occur in different regimes of the precession frequency of EPs. In certain ranges of the plasma rotation speed and the EPs’ beta, a mode conversion can occur between the resistive wall mode and FLM.
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| 3. |
- Hao, G. Z, et al.
(författare)
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Stabilization of the Resistive Wall Mode Instability by Trapped Energetic Particles
- 2011
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Ingår i: Physics of Plasmas. - 1089-7674 .- 1070-664X. ; 18, s. 032513-
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Tidskriftsartikel (refereegranskat)abstract
- A theoretical model for investigating the effect of the trapped energetic particles (EPs) on the resistive wall mode (RWM) instability is proposed. The results demonstrate that the trapped EPs have a dramatic stabilizing effect on the RWM because of resonant interaction between the mode and the magnetic precession drift motion of the trapped EPs. The results also show that the effect of the trapped EPs depends on the wall position. In addition, the stabilizing effect becomes stronger when the plasma rotation is taken into account. For sufficiently fast plasma rotation, the trapped EPs can lead to the complete stabilization of the RWM. Furthermore, the trapped EPs can induce a finite real frequency of the RWM in the absence of plasma rotation.
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| 4. |
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| 5. |
- Wang, Yueqiang, et al.
(författare)
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2-Diphenylaminothiophene as the donor of porphyrin sensitizers for dye-sensitized solar cells
- 2014
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Ingår i: New Journal of Chemistry. - : Royal Society of Chemistry (RSC). - 1144-0546 .- 1369-9261. ; 38:7, s. 3227-3235
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Tidskriftsartikel (refereegranskat)abstract
- Four novel D-pi-A porphyrin dyes (YQ1 YQ4) with 2-diphenylaminothiophene attached at the mesoposition as the electron donor have been synthesized and used as the sensitizers for dye sensitized solar cells (DSSCs). 4-Ethynylbenzoic acid and 2-cyanoacrylic acid were incorporated as the anchoring moieties in YQ1, and YQ2 YQ4, respectively. Due to the extended conjugation size, the absorption spectra of YQ2 YQ4 showed Soret band maxima in the range of 447-468 nm, which is red shifted as compared to that of 446 nm for Y01. Furthermore, in comparison with most reported porphyrin dyes with similar structures, YQ1-YQ4 demonstrate obviously red-shifted absorption maxima and broadened Soret bands, indicating that these porphyrin dyes may be developed as promising DSSC sensitizers. The electrochemical studies and DFT calculations indicated that all the four dyes were capable of serving as DSSC sensitizers. Thus, DSSCs were fabricated based on these dyes. The cells based on YQ4 showed the power conversion efficiency of 5.00%, which is higher than those of 4.23% and 4.38% for YQ2 and YQ3, respectively. This observation may be attributed to the suppression of the dye aggregation by the hexyl group attached to the thienyl ring of YQ4. On the other hand, YQ2 YQ4 demonstrated lower efficiencies compared with Y01, which may be ascribed to the floppy structures of the cyanoacrylic acid-based porphyrins that provide free space for charge recombination. As a result, the DSSCs based on Y01 exhibited the highest efficiency of 6.01%. This work demonstrates that the introduction of 2-diphenylaminothiophene into a porphyrin framework can obviously red-shift and broaden the absorption bands of the porphyrin dyes, resulting in high solar cell efficiencies. Hence, the introduction of 2-diphenylaminothiophene as the electron donor may be promising for the design of efficient porphyrin-based DSSC sensitizers.
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| 6. |
- Wang, Yueqiang, et al.
(författare)
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Porphyrins bearing long alkoxyl chains and carbazole for dye-sensitized solar cells : tuning cell performance through an ethynylene bridge
- 2013
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 3:34, s. 14780-14790
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Tidskriftsartikel (refereegranskat)abstract
- Two novel porphyrin dyes (Q1 and Q2) bearing alkoxyl chains with a carbazole moiety as the electron donor have been synthesized and utilized as sensitizers for dye-sensitized solar cells (DSSCs). Compared with Q2, the molecule of Q1 has an additional ethynylene bridge between the carbazole moiety and the porphyrin framework. Photophysical and electrochemical properties of the two dyes were investigated by UV-vis, fluorescence spectroscopy and cyclic voltammetry. DFT calculations indicated that Q2 has a more twisted non-planar conformation associated with a smaller p conjugation size because of the absence of ethynylene bridge, which resulted in its better solubility and larger amount of adsorption on TiO2. Compared with Q1, Q2 showed better photovoltaic performance, with a short-circuit photocurrent density (J(sc)) of 11.3 mA cm(-2), an open-circuit photovoltage (V-oc) of 0.68 V, and a fill factor (ff) of 0.71, corresponding to an overall conversion efficiency of 5.51% under standard global AM 1.5 solar light conditions. The additional ethynylene bridge in Q1 extends the absorption bands to a longer wavelength region with the absorption threshold of 743 nm on the TiO2 film compared with that of 681 nm for Q2, but the cell efficiency is decreased to 2.22%, which may be ascribed to the worse solubility and stronger aggregation tendency resulting from the better molecule planarity. These results indicate that the extension of the absorption bands to a longer wavelength region by the introduction of an additional ethynylene bridge may result in worse solubility and more severe aggregation, and thus decrease the cell efficiency. For the design of efficient DSSC sensitizers, these contradictory effects must be fully considered and well balanced.
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