RESUMO
In the present paper, the time evolution study on slip soils treated by different proportions of ionic soil stabilizer (ISS) water solution was conducted by the LIBS system and the relationship between the cation exchange and such engineering properties of reinforcing soil as plasticity index, cohesive force and coefficient of compressibility were analyzed. The results showed that the cation exchange velocity of the proportion of 1:200 ISS reinforcing soil is the fastest among the three proportions (1:100, 1:200 and 1:300) and the modification effect of engineering performance index is quite obvious. These studies provide an experimental basis for the ISS applied to curing project, and monitoring geotechnical engineering performance by LIBS technology also provides a new way of thinking for the curing project monitoring.
RESUMO
An 1. 06 microm Nd : YAG laser beam (energy: -500 mJ/pulse, pulse width: 10 ns, repetition rate: 30 Hz) was focused by a conical lens, and a column of laser-induced air plasmas (LIAP) came into being. The LIAP column, about 8 cm of long and 5 cm in maximal diameter, was studied by spectra measurement. The spectra of the LIAP column at different position were measured in the directions both perpendicular and parallel to the laser propagation respectively. From these data, the electron densities of the LIAP were evaluated. The experimental results indicate that the LIAP formed in an olivary shape, i. e. , symmetrical in the vertical direction but unsymmetrical in the horizontal direction, and the maximal electron density is about 10(18) cm(-3). The spatial distributions of atoms, molecules and ions in different states in the LIAP were also discussed, and provide clues for discovering the microstructure of LIAP.
RESUMO
The present paper reports the results of spectroscopic study on the oxygen plasma induced by a pulsed laser with a wavelength of 1.06 microm. The gas samples were pure oxygen (99.9999%) and the spectral range was from 300 to 900 nm. The temporal behavior of the spectra was measured. The experiment results showed that the spectra could be divided into continuous spectra and line spectra. Each component of the spectra attenuated according to the disparate mode along temporal development. The microcosmic physical processes and mechanisms were analyzed. The reason for the longer plasma spectral lifetime was discussed. These works were helpful to better understanding of the microscopic mechanisms during the decay of the laser-induced air plasmas, and also provide more experimental evidences for prolonging the decay time of plasmas in some technical applications.
