Search results for "Plasmas"
showing 10 items of 1475 documents
Ultrarelativistic bound states in the spherical well
2016
We address an eigenvalue problem for the ultrarelativistic (Cauchy) operator $(-\Delta )^{1/2}$, whose action is restricted to functions that vanish beyond the interior of a unit sphere in three spatial dimensions. We provide high accuracy spectral datafor lowest eigenvalues and eigenfunctions of this infinite spherical well problem. Our focus is on radial and orbital shapes of eigenfunctions. The spectrum consists of an ordered set of strictly positive eigenvalues which naturally splits into non-overlapping, orbitally labelled $E_{(k,l)}$ series. For each orbital label $l=0,1,2,...$ the label $k =1,2,...$ enumerates consecutive $l$-th series eigenvalues. Each of them is $2l+1$-degenerate. …
Status of new 18 GHz ECRIS HIISI
2018
A new 18 GHz ECR ion source HIISI is under commissioning at the Accelerator Laboratory at the University of Jyvaskyla (JYFL). The main purpose of HIISI is to produce high-energy beam cocktails, e.g. Xe44+, for radiation effects testing of electronics with the K130 cyclotron. The initial commissioning results in 18+14 GHz operation with oxygen, argon and xenon are reported. The beam currents are compared to those produced by reference ion sources (JYFL 14 GHz ECRIS, GTS and SuSI). At the moment (October 2017) 560 µA of O6+ and 310 µA of Ar13+, for example, have been reached with HIISI at 2.3 kW total power.A new 18 GHz ECR ion source HIISI is under commissioning at the Accelerator Laboratory…
Fractional-order theory of thermoelasticicty. I: Generalization of the Fourier equation
2018
The paper deals with the generalization of Fourier-type relations in the context of fractional-order calculus. The instantaneous temperature-flux equation of the Fourier-type diffusion is generalized, introducing a self-similar, fractal-type mass clustering at the micro scale. In this setting, the resulting conduction equation at the macro scale yields a Caputo's fractional derivative with order [0,1] of temperature gradient that generalizes the Fourier conduction equation. The order of the fractional-derivative has been related to the fractal assembly of the microstructure and some preliminary observations about the thermodynamical restrictions of the coefficients and the state functions r…
Thermal conductivity measurement of insulating innovative building materials by hot plate and heat flow meter devices: A Round Robin Test
2019
Abstract The characterization of thermal insulation properties of construction materials represents a fundamental step on the building insulation assessment. In recent years innovative materials have been introduced in the market to fulfill the continuously growing requirements of energy saving and sustainability, and their performance is not so reliable and mature as it happens for traditional insulators. The work presents a Round Robin Test realised among six European laboratories hosting hot plates devices to measure the thermal conductivity of four different materials: aerogel, vacuum insulation panels, polystyrene and birch wood fibre insulation boards. After the definition of the comm…
Draining and drying process development of the Tokamak Cooling Water System of ITER
2016
Abstract The ITER Organization (IO) developed a thermal-hydraulic (TH) model of the complex first wall and blanket (FW/BLK) cooling channels to determine gas flow rate and pressure required to effectively blow out the water in the FW/BLK. In addition, US ITER conducted experiments for selected geometries of FW/BLK flow channels to predict the blowout parameters. The analysis indicates that as low as 2 MPa of pressure difference over the blanket modules will ensure substantial evacuation of the water in blankets with just a few percent remaining in the blanket flow channels. A limited validation study indicates that the analysis yields less conservative results to compare against data collec…
A comparison of the efficacy of commercial and experimental vaccines for contagious agalactia in sheep
2013
Abstract An effective vaccine that improves the control of contagious agalactia in Mediterranean regions would be beneficial for poorer farmers who use traditional husbandry methods for sheep and goat production. However while there is little published data on the efficacy of commercially available vaccines for contagious agalactia, evidence from the field suggests that some provide inadequate protection. This paper compares four different vaccine formulations, including a widely used commercial vaccine, using clinical signs and mycoplasma excretion as measures of protection in sheep. Results showed that protection afforded by the vaccines, following contact challenge with experimentally in…
INFLUENCE OF CITRATE NANOPARTICLES ON PHOTOCHEMICAL ACTIVITY, RESISTANCE TO PATHOGENS AND PRODUCTIVITY OF WHEAT
2021
In field experiments, increase the quantum efficiency of PSII (Fv/Fp), the Rfd-values (the chlorophyll fluorescence vitality indices) and the content of photosynthetic pigments in wheat leaves at pretreatment of wheat seeds with solutions of citrate nanoparticles has been shown. The green weight of plants at bacterial and phytoplasmas infecting at pretreatment with solutions of citrate nanoparticles, was increase, than without pre-treatment, in order: GeNPs>I-Se>SeNPs>VNPs as it has been shown. The Fv/Fp-values in leaves infected with phytoplasmas of plants at pretreatment of VNPs or I-Se solutions were more, than without pretreatment. The Fv/Fp-value in leafs with bacterial infecting at pr…
Caractérisation des tôles Fer-Silicium en régime dynamique pulsant
1992
Using a characterization method based on the Epstein's frame principle, we study the evolution of the magnetic and losses characteristics of NO Fe-Si sheets with respect to the fundamental frequency, the temperature and the wave front under time-variable sinusoidal or constant wave front trapezoidal magnetic flux density. At last, we modelise the evolution of the iron losses with respect to these parameters, except the temperature
Propagation failure in discrete bistable reaction-diffusion systems: Theory and experiments
2001
International audience; Wave front propagation failure is investigated in discrete bistable reaction-diffusion systems. We present a theoretical approach including dissipative effects and leading to an analytical expression of the critical coupling beyond which front propagation can occur as a function of the nonlinearity threshold parameter. Our theoretical predictions are confirmed by numerical simulations and experimental results on an equivalent electrical diffusive lattice.
Experimental investigation of the relation between H− negative ion density and Lyman-α emission intensity in a microwave discharge
2016
International audience; A new mechanism for producing negative ions in low density and low power hydrogen plasmas was proposed recently. It refers to anion formation due to collisions between hydrogen atoms being in the first excited state. The proposed mechanism was indirectly supported by the quadratic relation observed between the extracted negative ion current and Lyman-α radiation of a filament-driven arc discharge, when borrowed data from the literature were combined. The present work provides experimental data comparing directly the absolute negative ion density and Lyman-α radiation in an ECR-driven hydrogen plasma source. The previously mentioned quadratic relation is not observed …