Spectroscopic studies of Ca plasma generated by the fundamental, second, and third harmonics of a Nd:YAG laser

Abstract

The ablation of calcium sample has been studied by the optical emission spectroscopy of the evolving plasma using the fundamental, second, and third harmonic of a Nd:YAG laser, which reveals numerous transitions due to neutral and singly ionized calcium. The measurements have been performed to determine the electron temperature and electron number density and their spatial behavior. In addition, the behavior of the electron temperature and number density as a function of laser irradiance and ambient gas pressure has been studied. The processes of laser photon absorption in the plasma through inverse bremsstrahlung and photoionization have also been discussed.

Characteristics of the aluminum alloy plasma produced by a 1064 nm Nd:YAG laser with different irradiances

“…On the trailing edge of the laser pulse, the electron recombination cannot be compensated by the production of free electrons because of the decrease of the laser irradiance. This is consistent with previous conclusions [26,31].…”

“…However, at higher irradiance, the saturation of N e and T e occurs. This is because the increase in the electron number density and temperature with the increase in the laser power density is due to the absorption and/or reflection of the laser photon by the plasma [31]. The plasma frequency is given as ν p = 8.9 × 10 3 N 1/2 e [32].…”

“…The other is that the thermal energy is rapidly converted into kinetic energy causing the temperature to drop off rapidly as the plasma expands. The spatial dependence of the electron temperature has been studied by many other researchers also [18,26,31]. Their studies showed that the temperature was decreased with distance.…”

On the use of laser induced breakdown spectroscopy to characterize the naturally existing crystal in Pakistan and its optical emission spectrum

“…The LIBS apparatus used in the present study is the same as described in our earlier papers [22][23][24][25]. In brief, it consists of a Q switched Nd:YAG laser (Brilliant, Quantel France), 5 ns pulse duration and 10 Hz repetition rate.…”

Influence of pulse width on the laser ablation of zinc in nitrogen ambient

“…Ablation yield, material removal, ionization, and plume expansion to the surroundings depend on parameters such as fluence [7][8][9], pulse width [10,11], wavelength [12][13][14], spot size [15], and material properties, along with the nature and pressure of the ambient gas [16,17]. Unlike femtosecond (fs) laser ablation, nanosecond (ns) laser ablation is a fairly complex phenomenon, as the ablated species can interact with the trailing edge of the relatively longer laser pulse, leading to further excitation and ionization.…”