advanced electric propulsion diagnostic tools at iom

Abstract Recently, we have set up an Advanced Electric Propulsion Diagnostic (AEPD) platform [1] , which allows for the in-situ measurement of a comprehensive set of thruster performance parameters. The platform utilizes a five-axis-movement system for precise positioning of the thruster with respect to the diagnostic heads. In the first setup (AEPD1) an energy-selective mass spectrometer (ESMS) and a miniaturized Faraday probe for ion beam characterization, a telemicroscope and a triangular laser head for measuring the erosion of mechanical parts, and a pyrometer for surface temperature measurements were integrated. The capabilities of the AEPD1 platform were demonstrated with two electric propulsion thrusters, a gridded ion thruster RIT 22 (Airbus Defence & Space, Germany, [13]) and a Hall effect thruster SPT 100D EM1 (EDB Fakel, Russia, [1] , [4] ), in two different vacuum facilities

Mechanisms of enhancement of light emission in nanostructures of II–VI compounds doped with manganese

Intra-shell transitions of transition metal and rare earth ions are parity forbidden processes. For Mn²⁺ ions this is also a spin forbidden process, i.e., light emission should be inefficient. Surprisingly, it was reported that in nanostructures of ZnMnS the ⁴T₁ to ⁶A₁ intra-shell transition of Mn²⁺ results in a bright photoluminescence characterized by a short PL decay time. The model of a quantum confined atom was introduced to explain the observed experimental results. It was later claimed that this model is incorrect. Based on the results of our photoluminescence, photoluminescence kinetics, time-resolved photoluminescence, electron spin resonance and optically detected magnetic resonance investigations we confirm photoluminescence enhancement and decrease of photoluminescence lifetime and relate these effects to spin dependent magnetic interactions between localized spins of Mn²⁺ ions and spins/magnetic moments of free carriers. This mechanism is active in both bulk and in low-dimensional structures, but is significantly enhanced in nanostructure samples

Growth of pea plants (Pisum sativum L.) subjected to different soil water potentials : physiological indexes

A ervilha é cultivada no Brasil Central, durante o inverno seco, exigindo para o pleno êxito da cultura o uso da irrigação. Assim, o presente trabalho se propõe a avaliar os efeitos do potencial da água no solo nos índices fisiológicos da análise quantitativa de crescimento de plantas de ervilha (Pisum sativum L.). O experimento foi montado em casa de vegetação, em solos de textura argilosa, com delineamento experimental inteiramente casualizado, com quatro tratamentos decorrentes de potenciais mínimos da água no solo (-33, -100, -200 e -1500 kPa) em três repetições, cada qual contendo duas plantas de ervilha, cultivar Caprice. Os resultados obtidos evidenciaram que a redução do potencial água no solo, induziu o decréscimo na área foliar, sem interferir no comportamento da razão de massa foliar, razão de área foliar, taxa assimilatória líquida e taxa de crescimento relativo. _________________________________________________________________________________________ ABSTRACT: Peas are cultivated in the central region of Brazil, during the dry winter, demanding for the complete success the use of irrigation. Therefore, the present work has the aim of evaluating soil water potential effects on the indexes of physiological growth analysis of peas (Pisum sativum L.). The experiment was carried out in a greenhouse using soils of clayey texture, in a fully randomized design, with four treatments, based on minimum soil water potentials (-33, -100, -200 and -1500 kPa) in three replicates, each one containing two pea plants Caprice cultivar. The results obtained indicate that the reduction of soil water potential induced the decrease of leaf area, but did not interfer on the behaviour of leaf weight ratio, leaf area ratio, net assimilation rate and relative growth rate

Magneto-optical studies of wide-gap dilute magnetic semiconductor heterostructures and quantum dots

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN010497 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Investigation of Compositional Disorder in GaAsN:H

Proceedings della 28ma "International Conference on the Physics of Semiconductors", Vienna, Austria (2006)

Carrier relaxation dynamics in annealed and hydrogenated (GaIn)(NAs) quantum wells

We measured time-resolved photoluminescence on as-grown, annealed, as well as annealed and hydrogenated (Ga0.7In0.3)(N0.006As0.994)∕GaAs quantum-well structures. The postgrowth treatment changes not only the photoluminescence decay time but also the intensity of photoluminescence directly after excitation. This initial luminescence intensity is determined by a competition between relaxation of electrons into nitrogen related potential fluctuations in the conduction band and their capture by deep traps. In contrast, the decay of the photoluminescence is mainly determined by the competition between radiative and nonradiative recombination, which are both influenced by localization. Annealing decreases localization effects and nonradiative recombination. Hydrogenation also reduces localization effects but increases nonradiative recombination