Search results for "electron emission"
showing 10 items of 36 documents
Photoelectron Emission from Metal Surfaces Induced by Radiation Emitted by a 14 GHz Electron Cyclotron Resonance Ion Source
2015
Photoelectron emission measurements have been performed using a room-temperature 14 GHz ECR ion source. It is shown that the photoelectron emission from Al, Cu, and stainless steel (SAE 304) surfaces, which are common plasma chamber materials, is predominantly caused by radiation emitted from plasma with energies between 8 eV and 1 keV. Characteristic X-ray emission and bremsstrahlung from plasma have a negligible contribution to the photoelectron emission. It is estimated from the measured data that the maximum conceivable photoelectron flux from plasma chamber walls is on the order of 10% of the estimated total electron losses from the plasma. peerReviewed
ZnO/ZnS heterostructures for hydrogen production by photoelectrochemical water splitting
2016
This work studies the photoelectrochemical behavior of novel ZnO/ZnS heterostructures obtained by means of anodization in water and glycerol/water/NH4F electrolytes with different Na2S additions under controlled hydrodynamic conditions. For this purpose different techniques such as Field Emission Scanning Electronic Microscopy (FE-SEM) with EDX, Raman spectroscopy and photoelectrochemical water splitting tests under standard AM 1.5 conditions have been carried out. The obtained results showed that the hydrodynamic conditions promoted an ordered nanotubular morphology which facilitates electron-hole separation and consequently, the photoelectrochemical activity for water splitting is enhance…
Structural transformations in amorphous selenium as studied by the differential thermal analysis and exoelectron emission technique
2007
The parameters (temperature, activation energy) of the surface and volume glass transition (retrification process) in amorphous selenium produced by rapid quenching of the liquid phase have been determined using the EEE and DTA techniques. EEE is a surface effect connected with structural transformations in the surface layer whereas the DTA measurements give the information about the transformations occurring in the volume of the sample. It has been found that the surface retrification of selenium occurs with activation energy smaller than the volume retrification, both observed in the first heating run. The value of activation energy for the volume retrification measured in the second DTA …
Electron Emission of Pt: Experimental Study and Comparison With Models in the Multipactor Energy Range
2016
Experimental data of secondary emission yield (SEY) and electron emission spectra of Pt under electron irradiation for normal incidence and primary energies lower than 1 keV are presented. Several relevant magnitudes, as total SEY, elastic backscattering probability, secondary emission spectrum, and backscattering coefficient, are given for different primary energies. These magnitudes are compared with theoretical or semiempirical formulas commonly used in the related literature.
Study of the Secondary Electron Yield in Dielectrics Using Equivalent Circuital Models
2018
[EN] Secondary electron emission has an important role on the triggering of the multipactor effect; therefore, its study and characterization are essential in radio-frequency waveguide applications. In this paper, we propose a theoretical model, based on equivalent circuit models, to properly understand charging and discharging processes that occur in dielectric samples under electron irradiation for secondary electron emission characterization. Experimental results obtained for Pt, Si, GaS, and Teflon samples are presented to verify the accuracy of the proposed model. Good agreement between theory and experiments has been found.
Electron beam induced optical and electronical properties of SiO 2
2000
Abstract Ionizing radiation in dielectric and optically transparent silica as well as thin SiO 2 layers produces defect luminescence as well as charge storage. A comparison of different excitation–relaxation processes like cathodoluminescence, charge injection and trapping, secondary electron field emission, and exoelectron emission leads to a generally similar excitation dose behaviour described by an electron beam saturation dose of 0.01–0.1 C/cm 2 . This suggests a correlation of these four electron excitation mechanisms likely related to the same kind of defect in glassy SiO 2 , the 2-fold-coordinated silicon Si: centre with typical electronic singlet–singlet and singlet–triplet transit…
Carbon nanotube bags: catalytic formation, physical properties, two-dimensional alignment and geometric structuring of densely filled carbon tubes.
2001
The catalytic CVD synthesis, using propyne as carbon precursor and Fe(NO3)3 as catalyst precursor inside porous alumina, gives carbon nanotube (CNT) bags in a well-arranged two-dimensional order. The tubes have the morphology of bags or fibers, since they are completely filled with smaller helicoidal CNTs. This morphology has so far not been reported for CNTs. Owing to the dense filling of the outer mother CNTs with small helicoidal CNTs, the resulting CNT fibers appear to be stiff and show no sign of inflation, as sometimes observed with hollow CNTs. The fiber morphology was observed by raster electron microscopy (REM), transmission electron microscopy (TEM), and atomic force microscopy (A…
The positioning system of the ANTARES Neutrino Telescope
2012
The ANTARES neutrino telescope, located 40km off the coast of Toulon in the Mediterranean Sea at a mooring depth of about 2475m, consists of twelve detection lines equipped typically with 25 storeys. Every storey carries three optical modules that detect Cherenkov light induced by charged secondary particles (typically muons) coming from neutrino interactions. As these lines are flexible structures fixed to the sea bed and held taut by a buoy, sea currents cause the lines to move and the storeys to rotate. The knowledge of the position of the optical modules with a precision better than 10cm is essential for a good reconstruction of particle tracks. In this paper the ANTARES positioning sys…
Highly-parallelized simulation of a pixelated LArTPC on a GPU
2023
The rapid development of general-purpose computing on graphics processing units (GPGPU) is allowing the implementation of highly-parallelized Monte Carlo simulation chains for particle physics experiments. This technique is particularly suitable for the simulation of a pixelated charge readout for time projection chambers, given the large number of channels that this technology employs. Here we present the first implementation of a full microphysical simulator of a liquid argon time projection chamber (LArTPC) equipped with light readout and pixelated charge readout, developed for the DUNE Near Detector. The software is implemented with an end-to-end set of GPU-optimized algorithms. The alg…
Cathodoluminescence characterization of ZnO/ZnS nanostructures anodized under hydrodynamic conditions
2018
[EN] ZnO/ZnS nanostructures were successfully synthesized by a simple electrochemical anodization of zinc in a glycerol based electrolyte containing sulfide-ammonium fluoride. The influence of different hydrodynamic conditions and anodization potentials during anodization on the morphological and electronic properties of the obtained ZnO/ZnS nanostructures was studied. The anodized samples were characterized using confocal Raman microscopy, X-Ray Diffraction (XRD), Field Emission Scanning Electronic Microscopy (FE-SEM), cathodoluminescence (CL), and photoelectrochemical water splitting tests under standard AM 1.5 conditions. The results showed that hydrodynamic conditions and higher potenti…