196,729 research outputs found
Slow light with interleaved p-n junction to enhance performance of integrated Mach-Zehnder silicon modulators
No full textSlow light is a very important concept in nanophotonics, especially in the context of photonic crystals. In this work, we apply our previous design of band-edge slow light in silicon waveguide gratings [M. Passoni et al, Opt. Express 26, 8470 (2018)] to Mach-Zehnder modulators based on the plasma dispersion effect. The key idea is to employ an interleaved p-n junction with the same periodicity as the grating, in order to achieve optimal matching between the electromagnetic field profile and the depletion regions of the p-n junction. The resulting modulation efficiency is strongly improved as compared to common modulators based on normal rib waveguides, even in a bandwidth of 20–30 nm near the band edge, while the total insertion loss due to free carriers is not increased. The present concept is promising in view of realizing slow-light modulators for silicon photonics with reduced energy dissipation
Target normal sheath acceleration analytical modeling, comparative study and developments
No full textUltra-intense laser interaction with solid targets appears to be an extremely promising technique to accelerate ions up to several MeV, producing beams that exhibit interesting properties for many foreseen applications. Nowadays, most of all the published experimental results can be theoretically explained in the framework of the target normal sheath acceleration (TNSA) mechanism proposed by Wilks [Phys. Plasmas 8(2), 542 (2001)10.1063/1.1333697]. As an alternative to numerical simulation various analytical or semi-analytical TNSA models have been published in the latest years, each of them trying to provide predictions for some of the ion beam features, given the initial laser and target parameters. However, the problem of developing a reliable model for the TNSA process is still open, which is why the purpose of this work is to enlighten the present situation of TNSA modeling and experimental results, by means of a quantitative comparison between measurements and theoretical predictions of the maximum ion energy. Moreover, in the light of such an analysis, some indications for the future development of the model proposed by Passoni and Lontano [Phys. Plasmas 13(4), 042102 (2006)10.1063/1.2184067] are then presented. © 2012 American Institute of Physics
Target normal sheath acceleration analytical modeling, comparative study and developments
No full textUltra-intense laser interaction with solid targets appears to be an extremely promising technique to accelerate ions up to several MeV, producing beams that exhibit interesting properties for many foreseen applications. Nowadays, most of all the published experimental results can be theoretically
explained in the framework of the target normal sheath acceleration (TNSA) mechanism proposed by Wilks et al. [Phys. Plasmas 8(2), 542 (2001)]. As an alternative to numerical simulation various analytical or semi-analytical TNSA models have been published in the latest years, each of them trying to provide predictions for some of the ion beam features, given the initial laser and target parameters. However, the problem of developing a reliable model for the TNSA process is still open, which is why the purpose of this work is to enlighten the present situation of TNSA modeling and experimental results, by means of a quantitative comparison between measurements and theoretical predictions of the maximum ion energy. Moreover, in the light of such an analysis, some indications
for the future development of the model proposed by Passoni and Lontano [Phys. Plasmas 13(4), 042102 (2006)] are then presented
Efficacy of narrow buffer strips in removing agricultural pollutants in the shallow subsurface water flux from a cultivated field in north-east Italy
No full textCompost utilization as nitrogen source on wheat (Triticum aestivum L.,) and sunflower (Helianthus annuus L.)
No full textUse of compost source for maze (Zea Mays): total biomass, grain yield and N efficiency evaluation.
No full textDe Neve S., Salomez J., Van Den Bosshe A., Haneklaus S., Van Cleemput O., Hofman G. and Schung E. (Eds.
One-dimensional model of the electrostatic ion acceleration in the ultraintense laser-solid interaction
No full textEffects of different composts on soil nitrogen balance and dynamics in a biennial crop succession.
No full textWith the one exception of compost derived from food processing industry residues and municipal waste immediately after the first application, differences in N soil concentrations between compost treatments and control were always low, suggesting that, in general, composts released scarce amounts of nitrogen. In addition, no differences were detected among compost types even though they derived from materials of very different origin.
The rhythm of nitrogen release from compost appears to be of less importance given the weak rate of compost mineralization.
Crop response and N uptake were scarcely affected by compost fertilization, with little difference with respect to the unfertilized treatment. These data are in accordance with the literature, which reports values of available N, in the first year, of less than one fifth of the total N applied with compost. Hence, looking at the short-term, compost does not fulfil the N needs of crops under the pedo-climatic conditions of the experimental environment, so its use as unique source of N for crops is not recommendable. Nevertheless, these indications have to be considered transient, because they are relative to the first years of compost application. Indeed, according to the literature, an increment of both compost mineralization rate and crop recovery efficiency might be expected in the medium-long term. Moreover, the data highlighted the importance of compost in the integration of original N content of soil, with the purpose of maintaining the apparent N balance in equilibrium and avoiding a progressive depletion of the soil N
Theory of light-ion acceleration driven by a strong charge separation
No full textA theoretical model of the quasistatic electric field, formed at the rear surface of a thin solid target irradiated by a ultraintense subpicosecond laser pulse, due to the appearance of a cloud of ultrarelativistic bound electrons, is developed. It allows one to correctly describe the spatial profile of the accelerating field and to predict the maximum energies and the energy spectra of the accelerated ions. The agreement of the theoretical expectations with the experimental data looks satisfactory in a wide range of conditions. Previsions of regimes achievable in the future are given
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