The plasma generated in a two-target closed field unbalanced magnetron sputtering system for thin film deposition is characterized by means of Hall probes and cylindrical Langmuir probes as a ...function of the position inside the vacuum system. The plasma potential, electron density and temperature profiles in different locations are measured by two diagnostic systems equipped with cylindrical Langmuir probes. The plasma non-homogeneity due to the presence of magnetic field gradients is evaluated. In order to test the effects of measured plasma non-homogeneity on the physical properties of sputter-deposited coatings, several substrates are put inside the chamber in regions characterized by different plasma density and plasma potential. The composition, microstructure and morphology of TiN sub x films grown onto these substrates are then studied by means of nuclear techniques (RBS, n-RBS, NRA, ERDA), X-ray diffraction (XRD) and secondary electron microscopy (SEM). The mechanical properties are determined by micro-scratch test and nanoindentation and correlated to the local plasma parameters. Materials used as substrates: M42 steel.
It has been proved that the co-deposition of a proper amount of titanium can significantly improve the properties of sputter-deposited MoS sub 2 coatings, leading to the deposition of coatings, which ...are harder, much more wear resistant and also less sensitive to atmospheric water vapour during tribological testing. The MoS sub 2 /Ti coatings, studied here by the authors, also give excellent industrial results in a wide range of applications. In this paper the mechanical and micro-structural properties of MoS sub 2 coatings containing titanium with molar fractions up to 0.44 are studied. The mechanical properties are tested with pin-on-disk and reciprocating wear tests (multipass) in different experimental conditions. Frictional force and friction coefficient against a number of cycles are recorded. Coatings composition is determined by Rutherford and non-Rutherford backscattering (RBS) and coating thickness is measured by cross-section scanning electron microscopy (SEM). Structural analysis is carried out using X-ray diffraction (XRD). The mechanical properties are presented as a function of the Ti content and the optimal titanium concentration is determined. Other metals like Cr, W, Zr and Mo are also investigated. The composition of MoS sub 2 /metal composite coatings of the same quality of the MoS sub 2 /Ti films ('optimized' coatings) is studied by RBS. Substrates include M42 tool steel.
The goal of nuclear astrophysics is to measure cross sections of nuclear physics reactions of interest in astrophysics. At stars temperatures, these cross sections are very low due to the suppression ...of the Coulomb barrier. Cosmic ray induced background can seriously limit the determination of reaction cross sections at energies relevant to astrophysical processes and experimental setups should be arranged in order to improve the signal-to-noise ratio. Placing experiments in underground sites, however, reduces this background opening the way towards ultra low cross section determination. LUNA (Laboratory for Underground Nuclear Astrophysics) was pioneer in this sense. Two accelerators were mounted at the INFN National Laboratories of Gran Sasso (LNGS) allowing to study nuclear reactions close to stellar energies. A summary of the relevant technology used, including accelerators, target production and characterisation, and background treatment is given.
The first wall and the vessel of the Reversed Field Pinch RFX has been in situ coated with a B/C:H film by glow discharge cleaning with a mixture of 12.5% of trimethylboron ((CH
3)
3B) in He. The ...film has been analysed and the effects on the plasma discharges of the boronized wall are reported for a plasma current of 520 kA. The main effects on the plasma are a reduction in the oxygen content by a factor of 5 to 10 and a decrease in the carbon content by a factor of two. The
Z
eff has been reduced from 2–2.5 to 1.4–1.5. A slight reduction of the loop voltage is observed. The radiation power decreases by a factor of 2, enhancing the high density operation limit with a consequent increase of the poloidal beta
β
ϑ
and of the energy confinement time
τ
E.
Se estudió la multiplicación de plántulas de papa empleando técnicas de micropropagación en un sistema semejante a los utilizados en hidroponía. Se utilizaron segmentos uninodales de plántulas ...obtenidas por micropropagación, los que se cultivaron autotróficamente, sin agregar sacarosa ni reguladores del crecimiento; para ello fue necesario evaluar contenedores descartables, substratos y soluciones nutritivas. Además, se buscó un método que permitiera la propagación de las plántulas obtenidas autotróficamente, para lo cual se evaluaron microesquejes de distinta ubicación en la planta madre según su capacidad de regeneración y adaptabilidad al trasplante. Los segmentos, plantados en vermiculita en cajas de polipropileno y regados con solución nutritiva hidropónica, enraizaron a los 7 días y a los 15 días desarrollaron una plántula de varios nudos, con buen tamaño y vigor como para ser trasplantados en invernadero. Este crecimiento se comprobó en 10 variedades comerciales de papa. Los esquejes de los cortes sucesivos se plantaron en substrato a base de turba (Sphagnum). Tanto los esquejes apicales como los esquejes medios enraizaron sin la necesidad de aplicar reguladores del crecimiento; además las plántulas cortadas rebrotaron, optimizándose el uso del material utilizado. Las plántulas obtenidas autotróficamente presentaron un aspecto morfológico distinto a las obtenidas comúnmente in vitro, siendo aquéllas de baja altura, pero de tallos robustos y hojas anchas. Los envases descartables, el substrato económico y el uso de bajas cantidades de una simple solución de hidroponía, sumado a la disminución de posibles pérdidas por contaminación y trasplante, contribuyeron a que el sistema resultara una alternativa muy práctica y de bajo costo para la producción de plántulas de papa. Se presentan evidencias estadísticas del crecimiento en los diferentes sistemas.
Studies on potato plantlet multiplication were conducted by combining micropropagation and hydroponic techniques. Nodal cuttings from micropropagated plantlets were excided and cultivated in a photoautotrophic hydroponic system, without sacarose and in absence of growth regulators. It was necessary to evaluate different disposable containers, root media and nutrient solutions. A method to continue propagation of the plants obtained by the new system was also developed. The regeneration ability of the cuttings from different parts of the photoautotrofic obtained plants was also evaluated. Nodal cuttings growing on vermiculite with hydroponic nutrient solution in polypropylene boxes rooted after 7 days. A vigorous plant with several nodes, of enough size to be transplanted to the greenhouse, were obtained after 15 days. This type of growth was observed with 10 commercial potato varieties. Successive cuttings were planted in a sphagnum moss rooting media. The apical cuttings as well as node cuttings from the rest of the plants rooted easily without growth regulating substances. These photoautotrophic produced plantlets showed short but vigorous stems and wider leaves than the conventional in vitro plants. The use of disposable containers, low cost media and low quantities of a very simple hydroponic solution plus a reduction on the material lost due to contamination and to transplant, made this system a very easy to use and a low cost alternative to produce potato plantlets.
In order to evaluate the charge collection efficiency (CCE) profile of single-crystal diamond devices based on a p type/intrinsic/metal configuration, a lateral Ion Beam Induced Charge (IBIC) ...analysis was performed over their cleaved cross sections using a 2 MeV proton microbeam. CCE profiles in the depth direction were extracted from the cross-sectional maps at variable bias voltage. IBIC spectra relevant to the depletion region extending beneath the frontal Schottky electrode show a 100% CCE, with a spectral resolution of about 1.5%. The dependence of the width of the high efficiency region from applied bias voltage allows the constant residual doping concentration of the active region to be evaluated. The region where the electric field is absent shows an exponentially decreasing CCE profile, from which it is possible to estimate the diffusion length of the minority carriers by means of a drift-diffusion model.
The \(^{10}\)B(p,\(\alpha\))\(^{7}\)Be reaction is of great interest since it has many applications in different fields of research such as nuclear astrophysics, nuclear physics, and models of new ...reactors for clean energy generation. This reaction has been studied at the AN2000 accelerator of the INFN National Laboratories of Legnaro (LNL). The total cross section has been measured in a wide energy range (250 \(-\) 1182 keV) by using the activation method. The decays of the \(^7\)Be nuclei produced by the reaction were measured at the low counting facility of LNL by using two fully shielded high-purity germanium detectors. The present dataset shows a large discrepancy with respect to one of the previous data at the same energies and reduces the total uncertainty to the level of 6\%. An R-matrix calculation has been performed on the present data using the parameters from previous Trojan Horse measurements for the 10 and 500 keV resonances. The present data do not lay on the R-matrix fit in one point suggesting the existence of a \(^{11}\)C level not observed yet. Further nuclear investigations are needed to confirm this hypothesis.
Thin films were deposited onto fused SiO sub 2 slides and annealed at up to 400 degrees C. Films were single-phase solid solutions. Films had a low density, and H and C were still present in the ...coatings after heat treatment.
