We have successfully demonstrated a great advantage of plasmonic Au nanoparticles for efficient enhancement of Cu(In,Ga)Se2(CIGS) flexible photovoltaic devices. The incorporation of Au NPs can ...eliminate obstacles in the way of developing ink-printing CIGS flexible thin film photovoltaics (TFPV), such as poor absorption at wavelengths in the high intensity region of solar spectrum, and that occurs significantly at large incident angle of solar irradiation. The enhancement of external quantum efficiency and photocurrent have been systematically analyzed via the calculated electromagnetic field distribution. Finally, the major benefits of the localized surface plasmon resonances (LSPR) in visible wavelength have been investigated by ultrabroadband pump–probe spectroscopy, providing a solid evidence on the strong absorption and reduction of surface recombination that increases electron–hole generation and improves the carrier transportation in the vicinity of pn-juction.
Electrothermal instability plays an important role in applications of current-driven metal, creating striations (which seed the magneto-Rayleigh-Taylor instability) and filaments (which provide a ...more rapid path to plasma formation). However, the initial formation of both structures is not well understood. Simulations show for the first time how a commonly occurring isolated defect transforms into the larger striation and filament, through a feedback loop connecting current and electrical conductivity. Simulations have been experimentally validated using defect-driven self-emission patterns.
We address the methodology of a complex study of phase equilibria and thermodynamic properties in ternary metal and semiconductor systems using the emf method. A focus is on the behavior of partial ...molar functions in heterogeneous phase fields in the context of Voronin’s concept of partial heterogeneous functions (PHFs). The applicability criteria of emf measurements in heterogeneous phase fields for thermodynamic calculations have been determined. The scheme for calculating the integral thermodynamic functions (ITFs) of ternary phases from the partial molar functions of one component and the phase diagram using the integration of the Gibbs–Duhem equation has been described. Numerous thermodynamic data for ternary chalcogenide and chalcohalide systems gained by various variants of the emf method are cited.
Collisionless space plasma turbulence can generate reconnecting thin current sheets as suggested by recent results of numerical magnetohydrodynamic simulations. The Magnetospheric Multiscale (MMS) ...mission provides the first serious opportunity to verify whether small ion-electron-scale reconnection, generated by turbulence, resembles the reconnection events frequently observed in the magnetotail or at the magnetopause. Here we investigate field and particle observations obtained by the MMS fleet in the turbulent terrestrial magnetosheath behind quasi-parallel bow shock geometry. We observe multiple small-scale current sheets during the event and present a detailed look of one of the detected structures. The emergence of thin current sheets can lead to electron scale structures. Within these structures, we see signatures of ion demagnetization, electron jets, electron heating, and agyrotropy suggesting that MMS spacecraft observe reconnection at these scales.
Plasmas in Earth's outer magnetosphere, magnetosheath, and solar wind are essentially collisionless. This means particle distributions are not typically in thermodynamic equilibrium and deviate ...significantly from Maxwellian distributions. The deviations of these distributions can be further enhanced by plasma processes, such as shocks, turbulence, and magnetic reconnection. Such distributions can be unstable to a wide variety of kinetic plasma instabilities, which in turn modify the electron distributions. In this paper, the deviation of the observed electron distributions from a bi‐Maxwellian distribution function is calculated and quantified using data from the Magnetospheric Multiscale spacecraft. A statistical study from tens of millions of electron distributions shows that the primary source of the observed non‐Maxwellianity is electron distributions consisting of distinct hot and cold components in Earth's low‐density magnetosphere. This results in large non‐Maxwellianities at low densities. However, after performing a statistical study we find regions where large non‐Maxwellianities are observed for a given density. Highly non‐Maxwellian distributions are routinely found at Earth's bowshock, in Earth's outer magnetosphere and in the electron diffusion regions of magnetic reconnection. Enhanced non‐Maxwellianities are observed in the turbulent magnetosheath, but are intermittent and are typically not correlated with local processes. The causes of enhanced non‐Maxwellianities are investigated.
Key Points
Electron non‐Maxwellianity is computed for 6 months of data (85 million electron distributions)
Electron non‐Maxwellianity is typically large in the magnetosphere due to hot and cold electron populations
Enhanced non‐Maxwellianity is found in reconnection regions, the bowshock, and magnetosheath turbulence
Kink‐like flapping motions of current sheets are commonly observed in the magnetotail. Such oscillations have periods of a few minutes down to a few seconds and they propagate toward the flanks of ...the plasma sheet. Here, we report a short‐period (T≈25 s) flapping event of a thin current sheet observed by the Magnetospheric Multiscale spacecraft in the dusk‐side plasma sheet following a fast Earthward plasma flow. We characterize the flapping structure using the multi‐spacecraft spatiotemporal derivative and timing methods, and we find that the wave‐like structure is propagating along the average current direction with a phase velocity comparable to the ion velocity. We show that the wavelength of the oscillating current sheet scales with its thickness as expected for a drift‐kink mode. The decoupling of the ion bulk motion from the electron bulk motion suggests that the current sheet is thin. We discuss the presence of the lower hybrid waves associated with gradients of density as a broadening process of the thin current sheet.
Key Points
Kink‐like flapping ion‐scale current sheet (CS) propagating along the current direction is observed in the dusk‐side plasma sheet
The wavenumber k of the flapping oscillations scales with CS thickness h as kh ∼ 1.15, consistent with a drift‐kink instability
Lower hybrid drift waves are observed when the CS is the thinnest. Growth of the waves can be one of the factors limiting CS thinning
We present observations of asymmetric magnetic reconnection showing evidence of electron demagnetization in the electron outflow. The observations were made at the magnetopause by the four ...Magnetospheric Multiscale (MMS) spacecraft, separated by approximately 15 km. The reconnecting current sheet has negligible guide field, and all four spacecraft likely pass close to the electron diffusion region just south of the X line. In the electron outflow near the X line, all four spacecraft observe highly structured electron distributions in a region comparable to a few electron gyroradii. The distributions consist of a core with T(sub parallel) greater than T(sub perpendicular) and a nongyrotropic crescent perpendicular to the magnetic field. The crescents are associated with finite gyroradius effects of partly demagnetized electrons. These observations clearly demonstrate the manifestation of finite gyroradius effects in an electron-scale reconnection current sheet.
Electrostatic solitary waves (ESWs) have been reported inside reconnection jets, but their source and role remain unclear hitherto. Here we present the first observational evidence of ESWs generation ...by cold ion beams inside the jet, by using high‐cadence measurements from the Magnetospheric Multiscale spacecraft in the Earth's magnetotail. Inside the jet, intense ESWs with amplitude up to 30 mV m−1 and potential up to ~7% of the electron temperature are observed in association with accelerated cold ion beams. Instability analysis shows that the ion beams are unstable, providing free energy for the ESWs. The waves are observed to thermalize the beams, thus providing a new channel for ion heating inside the jet. Our study suggests that electrostatic turbulence can play an important role in the jet dynamics.
Key Points
Source and role of intense ESWs in a reconnection jet are investigated with MMS data
Accelerated cold ion beams in the jet are found to be the source of the waves
Wave‐beam interaction can provide a new channel for particle heating in the jet
When analyzing plasma waves, a key parameter to determine is the phase velocity. It enables us to, for example, compute wavelengths, wave potentials, and determine the energy of resonant particles. ...The phase velocity of a wave, observed by a single spacecraft equipped with electric field probes, can be determined using interferometry techniques. While several methods have been developed to do this, they have not been documented in detail. In this study, we use an analytical model to analyze and compare three interferometry methods applied on the probe geometry of the Magnetospheric Multiscale spacecraft. One method relies on measured probe potentials, whereas the other two use different E‐field measurements: one by reconstructing the E‐field between two probes and the spacecraft, the other by constructing four pairwise parallel E‐field components in the spacecraft spin‐plane. We find that the potential method is sensitive both to how planar the wave is, and to spacecraft potential changes due to the wave. The E‐field methods are less affected by the spacecraft potential, and while the reconstructed E‐field method is applicable in some cases, the second E‐field method is almost always preferable. We conclude that the potential based interferometry method is useful when spacecraft potential effects are negligible and the signals of the different probes are very well correlated. The method using two pairs of parallel E‐fields is practically always preferable to the reconstructed E‐field method and produces the correct velocity in the spin‐plane, but it requires knowledge of the propagation direction to provide the full velocity.
Key Points
We analyze the applicability and accuracy of three single‐spacecraft interferometry methods
Interferometry based on probe potentials should be used only in dense plasmas and for planar waves
Electric field‐based interferometry in the spin‐plane is accurate in all plasma conditions and for both planar and non‐planar waves
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