Time-and-space Evolution Of Laser-induced Zinc Plasma Spectrum

Neutral zinc spectral lines are present in stellar and solar spectra. Consequently, stark broadening parameters of Zn I lines are of interest for a number of astrophysical problem, e.g. for abundance determinations, as well as for stellar plasma analysis, modeling and diagnostics. The main conclusions of this thesis as follow:(1) The space-and-time evolution of the plasma spectrum intensity for zinc atom induced by laser is studied. In the experiment, we choose four different positions of plasma, A, B, C and D. The distance between any two positions is1.5millimeter. At the initial time, the intensity of plasma spectrum is the most strongest. And then, due to the electron recombination with ion, the intensity of plasma spectrum decreases gradually.(2) The space-and-time evolution of the temperature of laser-induced plasma is studied. Near the sample surface, due to the energy absorption from laser for plasma, the temperature of electron is becoming higher. After the laser pulse cuts off, the thermal energy of electron translates into the kinetic energy, which diffuses rapidly along the opposite direction of laser. At the same time, the temperature of electron reduces gradually.(3) The space-and-time evolution of electron density of laser-induced plasma is studied. By means of laser ablation, the zinc atom steam is formed. Subsequently the zinc atom is ionized by laser and then becomes plasma. During the time of laser pulse, the electron density beside sample surface should be the most highest. With the increase of the distance, the electron density drops rapidly. After the laser pulse cuts off, the electron density no longer increases. Meanwhile, the electron diffuses rapidly along the opposite direction of laser. This leads to the decrease of the electron density.