چكيده به لاتين
In this thesis, we studied laser induced breakdown via the interaction of high power Nd:YAG laser operating at fundamental wavelength of 1064 nm and pulse duration ~10 ns with solid copper and Aluminum target in ambient air. Electron temperature and density of laser induced copper and Aluminum plasma experiment were measured using Optical Emission Spectroscopy by Boltzmann plot method and stark broadening, respectively. The electron temperature and density was determined for the condition of laser intensity varying from 5.21-18.23 GW/cm2. The results showed that by changing the laser pulse energy, electron temperature in the copper plasma varies from 9210-10310 K for recording the spectrum with delay time 1μs and 9115-9850 K for delay time 2μs. According to our results within the applied laser pulse energy ranges, the estimated electron density increases from 5.4×1017 cm-3 to 9.85×1017 cm-3 for recording spectrum with delay time 1μs and 2.48×1017 cm-3 to 7.44×1017 cm-3 with delay time 2μs. Calculation of the electron temperature and density in the Aluminum sample, such as the copper sample was performed at the same intensity range.
The consequences indicated electron temperature in the delay time 1 and 2 μs varies from 9955 to 10440 K and 9815 to 10275 k, respectively. Also, the estimated electron density increases from 3.62×1017 cm-3 to 4.44×1017 cm-3 for recording spectrum with delay time 1μs and 3.33×1017 cm-3 to 4.09×1017 cm-3 with delay time 2μs.
In order to verify the validation of the results for the electron density, hydrogen-alpha line was inspected.
Also, the validity of the assumption of local thermodynamic equilibrium and the optically thin plasma (effect of self-absorption) were discussed.
Keywords: Electron temperature and density; Optical Emission Spectroscopy; Optical Breakdown; plasma emission; Copper and Aluminum.
