Electron emission at very low electron impact energy: experimental and Monte-Carlo results

The behaviour of electron emission under electron impact at very low energy is of great importance in many applications such as high energy physics, satellites, nuclear reactors, etc. However the question of the total electron reflectivity is still in discussion. Our experimental and theoretical studies show that the total reflectivity at very low energy is far from being an obvious fact. Moreover, our results show that the yield is close to zero and not equal to one for low energy incident electron.Comment: 3 pages, contribution to the Joint INFN-CERN-EuCARD-AccNet Workshop on Electron-Cloud Effects: ECLOUD'12; 5-9 Jun 2012, La Biodola, Isola d'Elba, Italy; CERN Yellow Report CERN-2013-002, pp.137-13

HIGH RESOLUTION FAR INFRARED FOURIER TRANSFORM SPECTROSCOPY OF THE NH2_2 RADICAL.

Author Institution: SOLEIL Synchrotron, AILES beamline, Saint-Aubin, France and Institut des Sciences Moleculaires d'Orsay, ISMO, CNRS, Universite Paris XI, Orsay, France; SOLEIL Synchrotron, AILES beamline, Saint-Aubin, FranceFirst identified toward Sgr B2}, the NH$_2$ radical has recently been detected in the interstellar medium by the HIFI instrument on board of Herschel}. Despite the fact that this radical has not been detected in brown dwarfs and exoplanets yet, it is already included in physical and chemical models of those environments} (temperature higher than 2000 K expected in several objects). Its detection in those objects will depend on the existence of a reliable high temperature and high resolution spectroscopic database on the NH$_2$ radical.The absorption spectrum of NH$_2$ has been recorded between 15 and 700 cm$^{-1}$ at the highest resolution available using the Bruker IFS125HR Fourier transform interferometer connected to the far infrared AILES beamline at SOLEIL (R=0.001~cm$^{-1}$). The radical was produced by an electrical discharge (DC) through a continuous flow of NH$_3$ and He using the White-type discharge cell developped on the beamline (optical path: 24m). Thanks to the brilliance of the synchrotron radiation, more than 700 pure rotational transitions of NH$_2$ have been identified with high N values (N$_{max}$=25) in its fundamental and first excited vibrational modes. By comparison to the previous FT spectroscopic study on that radical in the FIR spectral range}, asymmetric splitting as well as fine and hyperfine structure have been resolved for several transitions

Pranolium

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72226/1/j.1527-3466.1983.tb00447.x.pd

Wall fluxes of reactive oxygen species of an rf atmospheric-pressure plasma and their dependence on sheath dynamics

This article was published in the serial, Journal of Physics D: Applied Physics [© IOP Publishing Ltd]. The definitive version is available at: http://dx.doi.org/10.1088/0022-3727/45/30/305205A radio-frequency (rf) atmospheric-pressure discharge in He–O2 mixture is studied using a fluid model for its wall fluxes and their dependence on electron and chemical kinetics in the sheath region. It is shown that ground-state O, O+2 and O− are the dominant wall fluxes of neutral species, cations and anions, respectively. Detailed analysis of particle transport shows that wall fluxes are supplied from a boundary layer of 3–300μm immediately next to an electrode, a fraction of the thickness of the sheath region. The width of the boundary layer mirrors the effective excursion distance during lifetime of plasma species, and is a result of much reduced length scale of particle transport at elevated gas pressures. As a result, plasma species supplying their wall fluxes are produced locally within the boundary layer and the chemical composition of the overall wall flux depends critically on spatio-temporal characteristics of electron temperature and density within the sheath. Wall fluxes of cations and ions are found to consist of a train of nanosecond pulses, whereas wall fluxes of neutral species are largely time-invariant

Influence of the injected charge polarity on the electrical behavior of CMX 100-AR cover glass submitted to electron irradiation

International audienceUnder electron irradiation, insulating materials may charge either negatively or positively depending on their electron emission properties and characteristics of the incident electrons. The electrical behavior of these materials is linked to the sign of the injected charge. Some spacecraft materials may be subject is some situations to negative charging and in other situations to positive charging. The aim of this work is to investigate the effect of the sign of the injected charge on the electric characteristics of CMX 100 AR coverglass. It was shown that the positive charging leads to about 4 times higher surface conductivity than negative charging. The practical consequences of these results are then discussed