Search results for "physics.plasm-ph"
showing 8 items of 48 documents
Caractérisation du plasma LIBS : réflexions, bonnes pratiques et conséquences analytiques
2022
International audience; La matrice d'un échantillon est définie par l'IUPAC (International Union of Pure and Applied Chemistry) comme les composants de l'échantillon autres que l'analyte. Et l'effet de matrice d'une technique analytique désignent alors l'effet combiné de tous les composants autres que l'analyte sur la mesure de sa quantité. Chose que l'on peut visualiser, par exemple, sur des droites d'étalonnage de pente différente pour différentes matrices. En LIBS, ces effets se traduisent physiquement par une interaction laser-surface et laser-plasma dépendant de la nature du matériau analysé, et induisant des variations de masse ablatée, de température et de densité électroniques d'un …
Hyperfine structure of some near-infrared Xe I and Xe II lines
2011
International audience; This work reports on the experimental determination of the hyperfine splitting of the Xe I lines at 828.01 nm and 834.68 nm and the Xe II line at 834.72 nm. Measurements were performed by means of Doppler-free saturation spectroscopy in a low-pressure radio-frequency discharge. The absolute wavelength of all hyperfine components is obtained by way of a high-precision wavemeter backed-up with the absorption spectrum of the NO 2 molecule. We provide an accurate estimate of hyperfine constants for the lower level of the Xe II transition at 834.72 nm. The two Xe I transition outcomes of our experimental study are compared with data available in the literature.
Nitric oxide production rate of pulsed nanosecond and microsecond discharge in atmospheric pressure air
2016
International audience
Nonlinear electrostatic oscillations in a cold magnetized electron-positron plasma
2017
We study the spatio-temporal evolution of the nonlinear electrostatic oscillations in a cold magnetized electron-positron (e-p) plasma using both analytics and simulations. Using a perturbative method we demonstrate that the nonlinear solutions change significantly when a pure electrostatic mode is excited at the linear level instead of a mixed upper-hybrid and zero-frequency mode that is considered in a recent study. The pure electrostatic oscillations undergo phase mixing nonlinearly. However, the presence of the magnetic field significantly delays the phase-mixing compared to that observed in the corresponding unmagnetized plasma. Using 1D PIC simulations we then analyze the damping of t…
Three-Dimensional Simulations of Solar Wind Preconditioning and the 23 July 2012 Interplanetary Coronal Mass Ejection
2020
Predicting the large-scale eruptions from the solar corona and their propagation through interplanetary space remains an outstanding challenge in solar- and helio-physics research. In this article, we describe three dimensional magnetohydrodynamic simulations of the inner heliosphere leading up to and including the extreme interplanetary coronal mass ejection (ICME) of 23 July 2012, developed using the code PLUTO. The simulations are driven using the output of coronal models for Carrington rotations 2125 and 2126 and, given the uncertainties in the initial conditions, are able to reproduce an event of comparable magnitude to the 23 July ICME, with similar velocity and density profiles at 1 …
A comparative study of the behaviour of silver, copper and nickel submitted to a constant high power flux density
2005
In this paper, we present a numerical simulation of three metal cathode (silver, copper and nickel) submitted to a constant flux power flux density ranging between and . The goal is to compare the interface evolution (vaporization and liquefaction rate, appearance time of liquid and vapour, energetic repartition) to predict the behaviour of the cathodes during an electric arc.
Measurement of the energy distribution of electrons escaping minimum-B ECR plasmas
2017
The measurement of the electron energy distribution (EED) of electrons escaping axially from a minimum-B electron cyclotron resonance ion source (ECRIS) is reported. The experimental data were recorded with a room-temperature 14 GHz ECRIS at the JYFL accelerator laboratory. The electrons escaping through the extraction mirror of the ion source were detected with a secondary electron amplifier placed downstream from a dipole magnet serving as an electron spectrometer with 500 eV resolution. It was discovered that the EED in the range of 5–250 keV is strongly non-Maxwellian and exhibits several local maxima below 20 keV energy. It was observed that the most influential ion source operating pa…
VUV emission spectroscopy combined with H- density measurements in the ion source Prometheus I
2016
“Prometheus I” is a volume H− negative ion source, driven by a network of dipolar electron cyclotron resonance (ECR; 2.45 GHz) modules. The vacuum-ultraviolet (VUV) emission spectrum of low-temperature hydrogen plasmas may be related to molecular and atomic processes involved directly or indirectly in the production of negative ions. In this work, VUV spectroscopy has been performed in the above source, Prometheus I, both in the ECR zones and the bulk (far from ECR zones and surfaces) plasma. The acquired VUV spectra are correlated with the negative ion densities, as measured by means of laser photodetachment, and the possible mechanisms of negative ion production are considered. The well-e…