Experimental Investigation on the Electron Temperature of Laser-Induced Ti Plasmas

Laser pulse which was produced by Nd : YAG pulse laser, with a wavelength of 1 064 nm and pulse width of 12 ns, was used to shock the Ti target under the condition of room temperature and atmospheric pressure. By changing the laser energy (180, 230 and 280 mJ) and adjusting the delay time through a digital delay generator of DG645, a series of plasma characteristic spectral lines of Ti alloy were obtained by a mechelle grating spectrometer in the time range of 0 similar to 500 ns. By analyzing the spectrum, 9 different Ti I and Ti 11 plasma lines can be found. It was shown that under the experimental conditions, the Ti target can fully absorb the energy to ionization and the ion spectral line has different evolution rate. The Saha-Boltzmann method was used to calculate and analyze the electron temperature of Ti plasma. The experimental results showed that at the same delay time, the greater of laser energy was used, the stronger of relative intensity of the line was obtained, and the higher of electron temperature could be induced. When the variable quantity of laser energy increased, the variable quantity of spectral line relative intensity will increase. In the delay time of 0 similar to 150 ns, the plasma electron temperature and the spectrum line relative intensity of the three kinds of laser energy decrease rapidly with the increase of the delay time, of which the electron temperature and spectrum line intensity decrease faster under laser energy of 280 mJ. During 150 to 250 ns, the electron temperature and spectrum line intensity have a slow rise with the increase of delay time, and the rising rate of the plasma electron temperature and the spectral line intensity were faster when laser energy is 180 mJ. In the range of 250 to 500 ns, the electron temperature and the spectrum line intensity of the three kinds of laser energy decrease slowly with the increase of the delay time.