Modeling of laser produced Zn plasma with detailed electron impact fine structure excitation cross-sections

Abstract

An intricate collisional radiative (CR) model is developed including all the important processes for the laser induced zinc plasma. The electron impact excitation (EIE) and de-excitation of several fine structure levels of Zn play a dominant role in the laser induced plasma and their cross-sections are needed. In view of this, an extensive calculation is performed to obtain the EIE cross-sections of the large number of fine structure transitions of zinc atom. The cross-sections of Zn are calculated and presented for the excitations from its ground state 4s 2 (J=0) as well as from the 4s4p excited state to the various fine structure levels of different excited states using fully relativistic distorted wave (RDW) theory. In the calculation, relativistic multi-configuration bound target atomic wave functions are obtained through GRASP2K program using 4s 2 , 4s4p, 4s5s, 4s5p, 4s4d, 4s6s, 4s6p, 4s5d, 4s7s and 4s7p configuration state functions while the projectile incident and scattered electron distorted wave functions are obtained by solving the relativistic Dirac equations. Further, the calculated cross-sections are incorporated in the CR model for the plasma characterization as the various rate coefficients are linked through their corresponding cross-sections. The model gives the state population distribution of the fine structure energy levels of the neutral Zn atom considered in the model and from which the intensities of the line emissions are obtained. The calculated intensities from the CR model for the four emission lines (334.5, 468, 472, and 481 nm) are matched with the spectroscopic measurements (Smijesh et al 2013 J. Appl. Phys. 114 093301) and the plasma parameters viz electron density n e ( ) and electron temperature T e ( ) are evaluated. The plasma parameters are presented at different ambient pressures in the range of 0.05-10 Torr.

Non-invasive optical characterization and estimation of Zn porosity in gas tungsten arc welding of Fe–Al joints using CR model and OES measurements

“…The electron impact cross-sections are used from previous calculations using a fully relativistic distorted wave (RDW) approximation. The RDW cross-sections are consistent and in good agreement with previously reported values for the relevant transitions and employed successfully in various plasma modeling and diagnostic applications [21][22][23][24]. It is worth noting that to develop CR models, one needs cross sections for a significantly large number of transitions in a wide projectile energy range.…”

“…It solves the Dirac equations to calculate the bound wave functions of both the initial and final and also for the scattered electron. More information on the cross-section calculation using the RDW approach can be found in our previous study on the laser-induced Zn plasma [23].…”

Diagnostics of laser-produced Mg plasma through a detailed collisional radiative model with reliable electron impact fine structure excitation cross-sections and self-absorption intensity correction

“…However, in the light of such requirements, our research group has been making continuous effort to produce a consistent dataset of electron impact excitation cross-sections for various atoms and ions for different plasma studies. Also, our work extends to demonstrate the application of these cross-sections in developing CR models for the plasma diagnostics [41,59,60,79].…”

“…So far, only few such CR models are reported in the literature [17,29,39,40]. Very recently, our group has reported the elegant diagnostic study on laser-induced Zn plasma using a detailed CR model [41]. In this CR model, first, a complete set of consistent calculated electron impact excitation (EIE) cross-section data was obtained for Zn by using a fully relativistic distorted wave (RDW) approach [42,43] and then these were incorporated in the CR model.…”

Electron impact excitation of Ge-like to Cu-like xenon ions in the extreme ultraviolet

“…However, there are only few experimental studies on electron excitation cross sections of ions due to the inherent difficulty to perform such experiments. Thus, accurate theoretical calculations of electron-ion excitation cross sections [3][4][5][6] are needed to fulfill this requirement.…”