Investigation the energy influence and excitation wavelength on spectral characteristics of laser induced MgZn plasma

Abstract

In the current study, we have diagnostic the laser-induced MgZn plasma parameter created in the air by the two harmonics of a Q-switched Nd: YAG pulsed laser at fundamental (1064nm) and second (532 nm) harmonics generation. The basic plasma parameters (i.e., electron temperature and density) have been assessed by using the spectral line intensity ratio method and Stark broadening line profile, respectively. Te was assessed by utilized the spectral line intensity at 602.1 nm of the transitions (3d105p 2P3/2 → 3d104d 2D5/2) and 636.2 nm (4s4p 3P2 → 4s4d 3D3) upon excitation by FHG, in the contract, the transitions 334.5 nm (3s4p 1P1 → 3s4d 1D2) and 407.8 nm (3d105p 2P1/2 → 3d107s 2S1/2) upon excitation by SHG. The electrons temperature values were ranging from 16893-18693 K for 1064 nm and 14890-16574 K for 532 nm, and the electron density in the range of 1.13×1018-4.5×1018 cm-3 and 1.88 × 1018-4.9×1018 cm-3 for 1064 nm and 532 nm, respectively, in the range of the studied laser energy from 300 to 700 mJ. The results were compared with the available reported experiment and theory and were found to be following the Local Thermodynamic Equilibrium theory (LTE). On the other hand, the other fundamental plasma parameters were investigated, such as Debye length (λD), Debye sphere (ND) and plasma frequency (ωp). We observed that all plasma parameters are influenced by laser energy and the wavelength. Besides that, the estimated values of the absorption coefficients of the inverse bremsstrahlung (α1B) at both laser wavelengths showed that the α1B a mechanism is dominant for the infrared (1064 nm) laser.