Measurement of electron number density and temperature of laser-induced Silver plasma

Abstract

Silver (Ag) plasma generated by second harmonics (532 nm) using Nd:YAG laser has been investigated at 17.6 mJ and 88.6 mJ energy level. The excitation temperature was determined from the Boltzmann plot method of the transition (3D3  ® 3P2) at 243.779 nm, (2S1/2  ® 2P3/2) at 328.068 nm, (2S1/2  ®  2P1/2) at 338.289 nm, (2P1/2   ®  2D3/2) at 520.907 nm and (2P3/2   ®  2D5/2) at 546.550 nm, while the Stark Broadening (SB) method was used to measure the Electron Number Density (END) of 2P3/2 ®  2S1/2 at 827.351 nm transition. The spatial behavior of the END and Electron Temperature (ET) was measured at ambient air pressures at different energy level and distance ranging from 0-4.5 mm form the target metal. The ET’s were found to be varies from 17895 K to 10593 K, while END was found to be 2.229 ´ 1015 to 6.44 ´ 1014 cm-3 and 1.76 ´ 1016 to 1.893 ´ 1015 cm-3 for 17.6 mJ and 88.6 mJ energy, respectively. The relationship of END and ET found directly related to laser irradiance, while they were inverse to the distance from the target material surface to laser beam source.