Occurrence Rates and Heating Effects of Tangential and Rotational Discontinuities as Obtained from Three-dimensional Simulation of Magnetohydrodynamic Turbulence

In solar wind, magnetohydrodynamic (MHD) discontinuities are ubiquitous and often found to be at the origin of turbulence intermittency. They may also play a key role in the turbulence dissipation and heating of the solar wind. The tangential (TD) and rotational (RD) discontinuities are the two most important types of discontinuities. Recently, the connection between turbulence intermittency and proton thermodynamics has been being investigated observationally. Here we present numerical results from three-dimensional MHD simulation with pressure anisotropy and define new methods to identify and to distinguish TDs and RDs. Three statistical results obtained about the relative occurrence rates and heating effects are highlighted: (1) RDs tend to take up the majority of the discontinuities along with time; (2) the thermal states embedding TDs tend to be associated with extreme plasma parameters or instabilities, while RDs do not; (3) TDs have a higher average T as well as perpendicular temperature $T_\perp$. The simulation shows that TDs and RDs evolve and contribute to solar wind heating differently. These results will inspire our understanding of the mechanisms that generate discontinuities and cause plasma heating.Comment: 5 Figures, Submitted to Astrophys. J. Lett., in the process of refereein

Photoelectrochemical properties of mesoporous NiOx deposited on technical FTO via nanopowder sintering in conventional and plasma atmospheres

Nanoporous nickel oxide (NiO x ) has been deposited with two different procedures of sintering (CS and RDS). Both samples display solid state oxidation at about 3.1 V vs Li+/Li. Upon sensitization of CS/RDS NiO x with erythrosine b (ERY), nickel oxide oxidation occurs at the same potential. Impedance spectroscopy revealed a higher charge transfer resistance for ERY-sensitized RDS NiO x with respect to sensitized CS NiO x . This was due to the chemisorption of a larger amount of ERY on RDS with respect to CS NiO x . Upon illumination the photoinduced charge transfer between ERY layer and NiO x could be observed only with oxidized CS. Photoelectrochemical effects of sensitized RDS NiO x were evidenced upon oxide reduction. With the addition of iodine RDS NiOx electrodes could give the reduction iodine → iodide in addition to the reduction of RDS NiO x . p-type dye sensitized solar cells were assembled with RDS NiO x photocathodes sensitized either by ERY or Fast Green. Resulting overall efficiencies ranged between 0.02 and 0.04 % upon irradiation with solar spectrum simulator (Iin : 0.1 W cm −2 )