2001
Autores
Desai, T; Daido, H; Suzuk, M; Sakaya, N; Guerreiro, AR; Mima, K;
Publicação
Atoms, Solids, and Plasmas in Super-Intense Laser Fields
Abstract
2001
Autores
Desai, T; Daido, H; Suzuki, M; Sakaya, N; Guerreiro, AP; Mima, K;
Publicação
LASER AND PARTICLE BEAMS
Abstract
X-ray emission spectra in the 5-22 nm range were recorded from planar and structured (meshlike groove surface) gold targets at 45 degrees and 90 degrees to the laser axis. A laser beam of 10-ns duration with E-L less than or equal to 700 mJ and 1.06-mum wavelength was used for the experiment. Experimental results indicate an enhanced X-ray yield from a structured target as compared to a planar target under identical experimental conditions. Increased X-ray emission is attributed to plasma confinement and the possibility of conversion of kinetic energy into localized thermal energy of the plasma. Results are analyzed explicitly on the incident laser energy.
2001
Autores
Mendonca, JT; Rao, NN; Guerreiro, A;
Publicação
EUROPHYSICS LETTERS
Abstract
The quantization procedure for low-frequency modes in a plasma has been generalized to include dust-Coulomb waves (DCWs) which are driven by the grain charge oscillations in a dusty plasma. We thus introduce the concept of "chargeon", the elementary excitation of the ultra low-frequency electrostatic fields in a dusty plasma, which are mainly supported by the grain charge oscillations. Their characteristic features are similar to the usual phonons, but they correspond to very different physical properties of the medium.
2000
Autores
Baptista, JM; Santos, JL; Lage, AS;
Publicação
OPTICAL ENGINEERING
Abstract
A theoretical and experimental study of self-referencing fiber optic intensity sensors based on Michelson and on Mach-Zehnder configurations is conducted. Via the definition of the measurement parameter R, sensor linearity and sensitivity are analyzed. Theoretical and experimental results are compared, considering the problem of sensor design and optimization. The choice between the hive configurations is addressed; the Michelson one is recommended for practical reasons. (C) 2000 Society of Photo-Optical instrumentation Engineers. [S0091-3286(00)03406-1].
2000
Autores
Baptista, JM; Santos, JL; Lage, AS;
Publicação
OPTICS COMMUNICATIONS
Abstract
A theoretical and experimental characterisation of a self-referenced fibre optic intensity sensor based on a multiple beam Sagnac configuration is conducted. Via the definition of the measurement parameter (R parameter) sensor linearity and sensitivity are analysed. Theoretical and experimental results are compared, being considered the problem of sensor design and optimisation.
2000
Autores
Jorge, PAS; Ferreira, LA; Santos, JL;
Publicação
OPTICAL ENGINEERING
Abstract
An analysis is performed of the degradation of the signal readout of fiber optic Bragg grating sensors demodulated using the serrodyne interferometric technique. Experimental results are presented that validate the analysis. It is also shown that synchronous detection of the interferometric signal referenced to the serrodyne waveform that modulates the phase of the readout interferometer allows the elimination of the system do offset introduced by the serrodyne flyback, (C) 2000 Society of Photo-Optical Instrumentation Engineers.
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