Free Electron Laser
Mostrando 1-12 de 21 artigos, teses e dissertações.
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1. Efeitos de distribuição de carga na instabilidade de estados com partículas aprisionadas em Free-Electron Lasers
O free-electron laser (FEL) surgiu como uma nova fonte de radiação eletromagnética. O presente trabalho trata do efeito de carga em um FEL específico: de passagem única; e, sendo que as interações relevantes são entre o feixe e o campo magnético e entre os elétrons (não são estudados os campos auto consistentes do laser). Encontram-se as equaçõ
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 2011
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2. Collective effects on the operation of free-eletron lasers with an axial guide field
The collective interaction in a free-electroii laser with combined helical wiggler and uniform axial guide fields is presented in the linearized regime. The analysis involves a perturbation of the Vlasov-Maxwell equations about the constant-velocity helical trajectories, and the general driving currents are derived for this configuration. The complete disper
Publicado em: 2011
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3. Coherent and incoherent radiation from free-electron lasers with an axial guide field
The spontaneous and induced emission from a free-electron laser is treated for the case in which an axial magnetic field is imposed in addition to the helical, axially periodic wiggler magnetic field. The classes of possible single-particle trajectories in this configuration are discussed, and the results are applied to a calculation of the incoherent radiat
Publicado em: 2011
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4. SYNTHESIS AND CERAMIC PROCESSING OF ALUMINA AND ZIRCONIA BASED COMPOSITES INFILTRATED WITH GLASS PHASE FOR DENTAL APPLICATIONS / Síntese e processamento de compósitos á base de alumina e zircônia com infiltração de fase vítrea para aplicações odontológicas
The interest for the use of ceramic materials for dental applications started due to the good aesthetic appearance promoted by the similarity to natural teeth. However, the fragility of traditional ceramics was a limitation for their use in stress conditions. The development of alumina and zirconia based materials, that associate aesthetic results, biocompat
Publicado em: 2009
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5. Fabricação de multicamadas de Quantum Dots de PbTe por laser ablation
This thesis was dedicated to the fabrication of thin films, quantum dots and multilayer ofIV-VI semi conducting materiaIs by pulsed-Iaser deposition (PLD). In the first part we report on the construction of a "home made" facility for pulsed laser deposition. The basic experimental set-up fabricated for PLD consists of a vacuum chamber pumped to a base pressu
Publicado em: 2004
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6. Electron trajectories in a helical free-electron laser
A description is made of electron trajectories in a magnetic field consisting of helical wiggler and a uniform axial guide field. The explicit motion of particles for which the quadratic approximation to the Hamiltonian was carried out in some previous publications is now presented. The transverse position as a function of time is essentially the superpositi
Brazilian Journal of Physics. Publicado em: 2002-09
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7. Normal modes propagation in a helical free-electron laser with an axial guide field
Following up the detailed three-dimensional analysis of the particle dynamics in a free electron laser with a helical wiggler and a uniform axial guide magnetic field, achieved by Rhimi et al. [1], we study the motion of the electrons in the neighborhood of the ideal trajectory. The normal modes ± of the quadrat
Braz. J. Phys.. Publicado em: 2001-09
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8. Free electron laser irradiation at 200 microns affects DNA synthesis in living cells.
We describe the effect of a 200-microns wavelength free electron laser beam on the ability of asynchronized and synchronized mammalian tissue culture cells to incorporate tritiated thymidine. Compared to controls (unexposed cells), a significant proportion of exposed cells exhibited a reduction in isotope incorporation. The results suggest that this waveleng
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9. Primary charge separation in bacterial photosynthesis: oxidized chlorophylls and reduced pheophytin.
Bacteriopheophytin, the magnesium-free base of bacteriochlorophyll, undergoes reversible one-electron reduction in organic solvents to yield an anionic free radical with characteristic optical and electron spin resonance spectra. The reduction potential of bacteriopheophytin, E1/2 approximately --0.55 V against a normal hydrogen electrode, compared to E1/2 a
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10. Design, synthesis, and characterization of a photoactivatable flavocytochrome molecular maquette
We report the construction of a synthetic flavo-heme protein that incorporates two major physiological activities of flavoproteins: light activation of flavin analogous to DNA photolyase and rapid intramolecular electron transfer between the flavin and heme cofactors as in several oxidoreductases. The functional tetra-α-helix protein comprises two 62-aa hel
The National Academy of Sciences.
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11. Laser flash photolysis studies of electron transfer between semiquinone and fully reduced free flavins and horse heart cytochrome c.
Laser flash photolysis has been used to determine the second-order rate constants for the reduction of horse heart cytochrome c by the semiquinone and fully reduced forms of various flavin analogs. We find that substitution in the dimethylbenzene ring of the flavin causes appreciable changes in the rate constants, whereas substitutions at the N-10 position d
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12. An approach to three-dimensional structures of biomolecules by using single-molecule diffraction images
We describe an approach to the high-resolution three-dimensional structural determination of macromolecules that utilizes ultrashort, intense x-ray pulses to record diffraction data in combination with direct phase retrieval by the oversampling technique. It is shown that a simulated molecular diffraction pattern at 2.5-Å resolution accumulated from m
The National Academy of Sciences.