The Research On Time-resolved Spectroscopy Of Pulsed-laser Plasmas Of Aluminum

Since the inception of the laser, the interaction of laser and matter has been much concerned by scholars of both domestic and foreign. In the industrial, military defense, medicine and other aspects, the laser has been widely applied, while there are some problems, we need to know more about the laser interaction with matter for better application of the laser.From the study and analysis on plasma, we found some deficiencies, for this we make some efforts like these. The time-resolved spectroscopy of aluminum laser plasma was measured from the moment of production of plasma till its turn off of the whole process, propose a new method to measure the electron temperature during the initial evolution of the plasma and verify its correctness.In this thesis, we obtain time resolved spectroscopy of aluminum plasma under different in injecting energy by ablating aluminum thin films with variational energy of pulse from Nd: YAG laser, which has an output of 1064 nm in wavelength and 10 ns in pulse duration. After analyze the change of plasma spectroscopy with time and the influence of injecting laser energy on the shape of spectroscopy, we find that the plasma spectroscopy change from continuous spectrum (or added with broadened line spectrum) to line spectrum, and the duration of continuous spectrum added with broadened line spectrum increase with the increased injecting energy.As there is a continuous background in the plasma's line spectrum, which is caused by electron bremsstrahlung and recombination radiation, we believe that electron temperature can be calculated from Planck formula by treating the background as a continuous background. Therefore, we compare the plasma electron temperature calculated by common Stark effect to the result calculated from blackbody radiation formula, and validate that electron temperature can be calculate from blackbody radiation formula by treating the background as a continuous background. In this thesis, we analyze the merit and demerit and the application foreground of the method above, and we also discuss the solution to shortage of thismethod. There are various mechanism of the shape and broadening of plasma spectroscopy, and each of them results in different effect. A comparatively comprehensive introduction is shown to the causation of these broadening effects as well as the calculation of the broadened magnitude is shown. We get that Stark broadening and equipment broadening dominate in high density plasma, and we also discuss the methods to eliminate the broadening caused by equipments. Using Stark effect we calculate electron density at different time under different injected laser energy, and after fitting the electron density magnitudes we finally obtain that electron density binomially changes with time.