Modification of argon impurity transport by electron cyclotron heating in KSTAR H-mode plasmas

Experiments with a small amount of Ar gas injection as a trace impurity were conducted in the Korea Superconducting Tokamak Advanced Research (KSTAR) H-mode plasma (BT  = 2.8 T, IP = 0.6 MA, and PNBI = 4.0 MW). 170 GHz electron cyclotron resonance heating (ECH) at 600 and 800 kW was focused along the mid-plane with a fixed major radial position of R  =  1.66 m. The emissivity of the Ar16+ (3.949 Å) and Ar15+ (353.860 Å) spectral lines were measured by x-ray imaging crystal spectroscopy (XICS) and a vacuum UV (VUV) spectrometer, respectively. ECH reduces the peak Ar15+ emission and increases the Ar16+ emission, an effect largest with 800 kW. The ADAS-SANCO impurity transport code was used to evaluate the Ar transport coefficients. It was found that the inward convective velocity found in the plasma core without ECH was decreased with ECH, while diffusion remained approximately constant resulting in a less-peaked Ar density profile. Theoretical results from the NEO code suggest that neoclassical transport is not responsible for the change in transport, while the microstability analysis using GKW predicts a dominant ITG mode during both ECH and non-ECH plasmas

Chemical compatibility between a hole conductor and organic dye enhances the photovoltaic performance of solid-state dye-sensitized solar cells

A series of organic dyes having an unsymmetrical geometry, 3-(5'-{4-[(4-tert-butyl-phenyl)-(4-fluoro-phenyl)-amino]-phenyl}-[2,2']bithio-phenyl-5-yl)-2-cyano-acrylic acid (D-F), 3-(5'-{4-[(4-tert-butyl-phenyl)-p-tolyl-amino]-phenyl}-[2,2']bithiophenyl-5-yl)-2-cyano-acrylic acid (D-CH3), and 3-(5'-{4-[(4-tert-butyl-phenyl)-(4-methoxy-phenyl)-amino]-phenyl}-[2,2']bithiophenyl-5-yl)-2-cyano-acrylic acid (D-OCH3), were designed and synthesized for use in solid-state dye-sensitized solar cells (sDSCs). The dye regeneration energy levels and surface properties were characterized to determine the hole transfer yield from the oxidized dye to the hole conductor (spiro-OMeTAD) by measuring the degree of pore-filling by the spiro-OMeTAD and the transient absorption spectra (TAS). An electrode sensitized with D-OCH3 exhibited the highest spiro-OMeTAD filling fraction and hole transfer quantum yield (F) to spiro-OMeTAD, resulting in an enhanced photocurrent and a power conversion efficiency of 3.56% in the sDSC, despite a lower energy driving force for hole transfer compared to those of D-F, or D-CH3. This result illustrates the importance of the chemical compatibility between the hole conductor and the dye on the surface of TiO2.open112826sciescopu

Exploring the Heterogeneous Interfaces in Organic or Ruthenium Dye-Sensitized Liquid- and Solid-State Solar Cells

The interfacial properties were systematically investigated using an organic sensitizer (3-(5'-{4-[(4-tert-butyl-phenyl)-p-tolyl-amino]-phenyl)-[2,2']bithiophenyl-5-yl)-2-cyano-acrylic acid (D)) and inorganic sensitizer (bis(tetrabutylammonium) cis-bis(thiocyanato)bis(2,2'-bipyridine-4,4'-dicarboxylato) ruthenium(II) (N719)) in a liquid-state and a solid-state dye-sensitized solar cell (DSC). For liquid-DSCs, the faster charge recombination for the surface of D-sensitized TiO2 resulted in shorter diffusion length (L-D) of similar to 3.9 mu m than that of N719 (similar to 7.5 mu m), limiting the solar cell performance at thicker films used in liquid-DSCs. On the other hand, for solid-DSCs using thin TiO2 films 2 pm), D-sensitized device outperforms the N719-sensitized device in an identical fabrication condition, mainly due to less perfect wetting ability of solid hole conductor into the porous TiO2 network, inducing the dye monolayer act as an insulation layer, while liquid electrolyte is able to fully wet the surface of TiO2. Such insulation effect was attributed to the fact that the significant increase in recombination resistance (from 865 to 4,400 Cl/cm(2)) but shorter electron lifetime (from 10.8 to 0.8 ms) when compared to liquid-DSCs. Higher recombination resistance for solid-DSCs induced the electron transport-limited situation, showing poor performance of N719-sensitized device which has shorter electron transport time and similar LD (2.9 mu m) with D-sensitized device (3.0 mu m).X111212sciescopu

The Mediating Effect of Presenteeism on the Relationship between Emotional Labor and Work Engagement of Coaches for Disability Sports

The aim of present study was to examine the mediating effect of presenteeism on the relationship between emotional labor and work engagement of coaches for disability sports. A total of 198 coaches in Korea participated in this study. Participants responded a survey measuring emotional labor, presenteeism, and work engagement. After analyzing the correlation between each variable, the mediation model was verified through structural equation model analysis. The results reveal that emotional labor of coaches for disability sports positively predicted their work engagement, but negatively predicted presenteeism. In addition, the participants’ presenteeism can have a negative effect on their work engagement. Moreover, completing work in presenteeism was found to mediate the relationship between the deep acting and surface acting in emotional labor and work engagement of disability sports coaches

Prevention of Carbon Corrosion by TiC Formation on Ti Current Collector in Seawater Batteries

Seawater batteries (SWBs) are a type of sodium-air batteries that use abundant seawater as the source of the catholyte. A cathode current collector in traditional SWBs is composed of titanium (Ti) and carbon-based current collectors. The high contact resistance between Ti and carbon-based current collectors as well as the slow kinetics of oxygen evolution and reduction reactions increase the overpotential, resulting in side reactions such as carbon corrosion. To enhance the performance of SWBs, previous studies have focused on carbon current collectors, catalysts, and polymer binders, while ignoring the importance of Ti. In this study, a facile carbon diffusion technique is employed to successfully form titanium carbide (TiC) on the surface of Ti. SWBs with engineered Ti demonstrate considerably improved performance (four times higher cycling stability, 30% increased power performance, 40% reduced voltage gap) in relation to those with pristine Ti. This significantly improved electrochemical performance is found to be attributable to the prevention of carbon corrosion due to i) the reduction of contact resistance (owing to rough TiC surface) and ii) the electrocatalytic effect of TiC. Finally, engineered Ti is applied to large-area SWBs and its potential applicability in energy storage systems is confirmed

Design of ITER divertor VUV spectrometer and prototype test at KSTAR tokamak

Design and development of the ITER divertor VUV spectrometer have been performed from the year 1998, and it is planned to be installed in the year 2027. Currently, the design of the ITER divertor VUV spectrometer is in the phase of detail design. It is optimized for monitoring of chord-integrated VUV signals from divertor plasmas, chosen to contain representative lines emission from the tungsten as the divertor material, and other impurities. Impurity emission from overall divertor plasmas is collimated through the relay optics onto the entrance slit of a VUV spectrometer with working wavelength range of 14.6–32 nm. To validate the design of the ITER divertor VUV spectrometer, two sets of VUV spectrometers have been developed and tested at KSTAR tokamak. One set of spectrometer without the field mirror employs a survey spectrometer with the wavelength ranging from 14.6 nm to 32 nm, and it provides the same optical specification as the spectrometer part of the ITER divertor VUV spectrometer system. The other spectrometer with the wavelength range of 5–25 nm consists of a commercial spectrometer with a concave grating, and the relay mirrors with the same geometry as the relay mirrors of the ITER divertor VUV spectrometer. From test of these prototypes, alignment method using backward laser illumination could be verified. To validate the feasibility of tungsten emission measurement, furthermore, the tungsten powder was injected in KSTAR plasmas, and the preliminary result could be obtained successfully with regard to the evaluation of photon throughpu