Laboratoire Of Physique Des Plasmas

Brussels, Belgium

Laboratoire Of Physique Des Plasmas

Brussels, Belgium
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Huang S.Y.,Wuhan University | Huang S.Y.,Chinese Academy of Sciences | Zhou M.,Chinese Academy of Sciences | Zhou M.,Nanchang University | And 10 more authors.
Geophysical Research Letters | Year: 2012

We present the first comprehensive observations of turbulence properties within high speed reconnection jet in the plasma sheet with moderate guide field. The power spectral density index is about-1.73 in the inertial range, and follows the value of-2.86 in the ion dissipation range. The turbulence is strongly anisotropic in the wave-vector space with the major power having its wave-vector highly oblique to the ambient magnetic field, suggesting that the turbulence is quasi-2D. The measured "dispersion relations" obtained using the k-filtering technique are compared with theory and are found to be consistent with the Alfvén-Whistler mode. In addition, both Probability Distribution Functions and flatness results show that the turbulence in the reconnection jet is intermittent (multifractal) at scales less than the proton gyroradius/inertial lengths. The estimated electric field provided by anomalous resistivity caused by turbulence is about 3mV/m, which is close to the typical reconnection electric field in the magnetotail. © 2012. American Geophysical Union. All Rights Reserved.

Kiyani K.H.,Imperial College London | Kiyani K.H.,University of Warwick | Chapman S.C.,University of Warwick | Sahraoui F.,Laboratoire Of Physique Des Plasmas | And 4 more authors.
Astrophysical Journal | Year: 2013

The anisotropic nature of solar wind magnetic turbulence fluctuations is investigated scale by scale using high cadence in situ magnetic field measurements from the Cluster and ACE spacecraft missions. The data span five decades in scales from the inertial range to the electron Larmor radius. In contrast to the inertial range, there is a successive increase toward isotropy between parallel and transverse power at scales below the ion Larmor radius, with isotropy being achieved at the electron Larmor radius. In the context of wave-mediated theories of turbulence, we show that this enhancement in magnetic fluctuations parallel to the local mean background field is qualitatively consistent with the magnetic compressibility signature of kinetic Alfvén wave solutions of the linearized Vlasov equation. More generally, we discuss how these results may arise naturally due to the prominent role of the Hall term at sub-ion Larmor scales. Furthermore, computing higher-order statistics, we show that the full statistical signature of the fluctuations at scales below the ion Larmor radius is that of a single isotropic globally scale-invariant process distinct from the anisotropic statistics of the inertial range. © 2013. The American Astronomical Society. All rights reserved.

Liang J.,University of Calgary | Uritsky V.,University of Calgary | Donovan E.,University of Calgary | Ni B.,University of California at Los Angeles | And 6 more authors.
Journal of Geophysical Research: Space Physics | Year: 2010

We present multiprobe, multi-instrument observations of the electron cyclotron harmonic (ECH) emissions and ultralow-frequency (ULF) waves from Time History of Events and Macroscale Interactions during Substorms (THEMIS) and explore their potential linkage to the concurrent ground-observed pulsating auroras (PsA) on 4 January 2009. The ECH emissions were observed as discrete packets modulated by the ULF flapping motion of the neutral sheet around the probes. Combining different data sets of the ECH observations, we infer that the ECH emission intensities were strongly fluctuating and contained multi-time scale fine structures. The distribution of PsA patches featured longitudinal "wavelength" in concert with the in situ ULF wave characteristics inferred from a cross-phase analysis. The overall activeness of the PsA correlated with the in situ-measured energetic electron fluxes and ECH wave intensities. We suggest that ECH waves played the key role in the pitch angle diffusion of the plasma sheet electrons that led to the PsA, while the ULF waves structured the plasma sheet and imposed a macroscopic effect over the spatial distribution of the PsA. Copyright 2010 by the American Geophysical Union.

Agapitov O.,University of Orléans | Agapitov O.,Taras Shevchenko National University | Krasnoselskikh V.,University of Orléans | Zaliznyak Y.,University of Orléans | And 4 more authors.
Annales Geophysicae | Year: 2010

Discrete ELF/VLF chorus emissions, the most intense electromagnetic plasma waves observed in the Earth's radiation belts and outer magnetosphere, are thought to propagate roughly along magnetic field lines from a localized source region near the magnetic equator towards the magnetic poles. THEMIS project Electric Field Instrument (EFI) and Search Coil Magnetometer (SCM) measurements were used to determine the spatial scale of the chorus source localization region on the day side of the Earth's outer magnetosphere. We present simultaneous observations of the same chorus elements registered onboard several THEMIS spacecraft in 2007 when all the spacecraft were in the same orbit. Discrete chorus elements were observed at 0.15-0.25 of the local electron gyrofrequency, which is typical for the outer magnetosphere. We evaluated the Poynting flux and wave vector distribution and obtained chorus wave packet quasi-parallel propagation to the local magnetic field. Amplitude and phase correlation data analysis allowed us to estimate the characteristic spatial correlation scale transverse to the local magnetic field to be in the 2800-3200 km range. © 2010 Author(s).

Teste A.,University of California at Berkeley | Fontaine D.,Laboratoire Of Physique Des Plasmas | Canu P.,Laboratoire Of Physique Des Plasmas | Belmont G.,Laboratoire Of Physique Des Plasmas
Geophysical Research Letters | Year: 2010

We investigate the excellent correlation between ionospheric upgoing electron beams and broadband electrostatic emissions (0-6 kHz) observed by Cluster, at ∼5 to 9 Earth's radii above the polar cap. In the absence of detailed, high time resolution waveform data in that region, we precisely analyzed several electron beams to obtain information concerning wave-particle interactions. Our results indicate that these beams are extremely variable and occasionally show multiple components. The processes involved might then occur on very short time scales, of the order of or shorter than sampling rates, typically 100 ms. We suggest that non linearities are at the origin of the spread of the frequency range of the waves simultaneously observed, as well as of the beam variability. We conclude that these electron beams are likely to destabilize Langmuir waves and, by the non-linear evolution of the electron bump-on-tail instability, could be responsible for the appearance of electrostatic solitary waves above the polar cap. Copyright © 2010 by the American Geophysical Union.

Benstali W.,Laboratoire Of Physique Des Plasmas | Belasri A.,Laboratoire Of Physique Des Plasmas
Advanced Materials Research | Year: 2011

In this paper, we present Plasma Display Panel (PDP) cell discharge using a 1D Particle in Cell with Monte Carlo Collisions model. The effect of gas pressure on the PDP characteristics including current density, voltage margins and energy balance is then studied in order to show the optimized conditions to obtain more energy dissipated in xenon excitation. The results show, at first, the spatiotemporal variation of the electric field and charges densities. It is also seen that for more important gas pressure, there is an increase of the current density, voltage margins and the energy deposited into xenon excitation and ionization. © (2011) Trans Tech Publications.

Khodja K.,Laboratoire Of Physique Des Plasmas | Sisabeur H.,Laboratoire Of Physique Des Plasmas | Belasri A.,Laboratoire Of Physique Des Plasmas
Advanced Materials Research | Year: 2011

The dielectric barriers discharges or silent discharges had knew these last years a great progress, particularly in the area of ultraviolet light production, which produced by Xe2* excimer molecules. This new application led to the realization of the nonpolluting excimer lamps. In this work we develop a one-dimensional model of sheath coupled to a kinetic model in NeXe mixture. Calculations were done for sixteen chemicals species in xenon concentration of 10% and under pressure of 400 torr. The results illustrate the spatiotemporal evolution of the charged particles and neutral species as well as the variations of the electric parameters of the lamp during the first pulse discharge. © (2011) Trans Tech Publications.

Ghaleb F.,Laboratoire Of Physique Des Plasmas | Belasri A.,Laboratoire Of Physique Des Plasmas
EPJ Web of Conferences | Year: 2013

In this work a two-dimensional numerical study of dielectric barrier discharge has been proposed in order to understand the breakdown process in rare gases. We used a fluid model which is based on the numerical solution of the two Boltzmann equations (continuity and momentum); these equations are coupled to the Poisson's equation. This model allowed us to plot the Paschen curve, which represents the breakdown voltage as a function of pressure-distance product. The aim of the study is to optimize the applied voltage and to understand how the discharge geometry and other physical parameters such as the secondary emission coefficient affected the breakdown voltage. © 2013 Owned by the authors, published by EDP Sciences.

Khodja K.,Laboratoire Of Physique Des Plasmas | Belasri A.,Laboratoire Of Physique Des Plasmas
Radiation Effects and Defects in Solids | Year: 2012

The sheath is formed near the cathode immediately after applying the voltage across the electrodes. This formation is mainly due to the depopulation of this region by electrons. Using the one-dimensional model of the sheath region and the kinetic model coupled to the dielectric barrier discharge discharge electric circuit, we studied the formation of the cathode sheath and its evolution during the first pulse in Ne-Xe mixture for 10% and 20% of xenon at a total gas pressure of 400 Torr and for an applied voltage of 3kV. The results illustrate the discharge behaviors as well as the evolution of the electric field and the charged particles in the cathode region. The effect of the xenon concentration is also studied and discussed. © 2012 Taylor & Francis Group, LLC.

A solar cell (indium tin oxide (ITO)/p-doped amorphous silicon (p-a-Si:H)/intrinsic polymorphous silicon (i-pm-Si:H)/n-doped crystalline silicon (n-c-Si)) simulation, focused on p-layer doping density NA and surface band bending Esbb at the interface ITO/p-layer has been performed. Despite the deterioration of p-layer material quality with doping density, the reduced bulk recombination was found to compensate for the increased loss in the p-layer. An increase of p-layer doping density NA and contact barrier height φb0 (variation of the surface band bending Esbb) leads to an increase of the efficiency of heterojunction with intrinsic thin layer solar cells. © 2015, Polish Academy of Sciences. All rights reserved.

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