摘要
Optical emission spectra of the plasma generated by a 532 nm Nd：YAG laser irra- diation onto a standard aluminum alloy （E414d） was recorded and analyzed. The electron tem- perature was determined using the Boltzmann plot method with three aluminum spectral lines at 236.71 nm, 257.509 nm and 308.215 nm, whereas the electron density was inferred by measuring the Stark broadening line profile of Al（II） 281.619 nm. The experimental results confirmed that the local thermodynamic equilibrium was valid and the plasma was optically thin. The spectral line intensity increased initially with the increase in laser irradiance and saturated at higher Jr- radiance levels. Results showed that the energy losses due to the reflection of laser beam from the plasma itself were insignificant. The absorption in the plasma through inverse bremsstrahlung and two-photon ionization were studied. At the same timer the variation of transition probability ratio of Al（I） 309.28 nm to Al（I） 308.21 nm with laser power density was also studied.
Optical emission spectra of the plasma generated by a 532 nm Nd：YAG laser irra- diation onto a standard aluminum alloy （E414d） was recorded and analyzed. The electron tem- perature was determined using the Boltzmann plot method with three aluminum spectral lines at 236.71 nm, 257.509 nm and 308.215 nm, whereas the electron density was inferred by measuring the Stark broadening line profile of Al（II） 281.619 nm. The experimental results confirmed that the local thermodynamic equilibrium was valid and the plasma was optically thin. The spectral line intensity increased initially with the increase in laser irradiance and saturated at higher Jr- radiance levels. Results showed that the energy losses due to the reflection of laser beam from the plasma itself were insignificant. The absorption in the plasma through inverse bremsstrahlung and two-photon ionization were studied. At the same timer the variation of transition probability ratio of Al（I） 309.28 nm to Al（I） 308.21 nm with laser power density was also studied.
基金
supported by the Chinese Academy of Sciences/State Administration of Foreign Experts Affairs (CAS/SAFEA) International Partnership Program for Creative Research Teams
