Spectroscopic study of Kr+ plasma through a detailed collisional radiative plasma model with extended ground, metastable and quasi-metastable electron impact excitation cross-section calculations
Ayushi Agrawal, S.P. Gupta, Lalita Sharma, Rajesh Srivastava
Abstract
An extensive spectroscopic investigation of Kr + plasma has been carried out through a comprehensive collisional-radiative plasma model along with the calculations of electron impact excitation cross-sections. The fully relativistic distorted wave method has been employed to calculate the detailed electron impact cross-sections for the transitions from the ground state , four metastable states of 4 p 4 4 d and a quasi-metastable state of 4 p 4 5 s to the fine structure levels of 4 p 4 n 1 s 7 ≤ n 1 ≤ 9 , 4 p 4 n 1 p , 4 p 4 n 2 d 6 ≤ n 2 ≤ 9 and 4 p 4 n 3 f 4 ≤ n 3 ≤ 9 excited states. For this purpose, the relativistic multi-configuration Dirac-Fock method is applied to compute the Kr + ionic structure, Kr + ion bound-state wave functions, excitation energies , oscillator strengths and transition probabilities . These results are compared with the previously reported values. Further, the complete set of electron impact excitation cross-sections has been incorporated in the collisional-radiative model along with the other relevant kinetic processes, viz. electron impact ionization , de-excitation, three-body recombination, and radiative decay. To validate the reliability of the electron collision data and the present collision radiative model, the measurements of Mar et al [J. Phys. B: At. Mol. Opt. Phys. 39 3,709 (2006)] at 40 μs and 90 μ s instants of plasma lifetime have been utilized for the diagnosis of experimentally measured pulsed discharge Kr + plasma at 3.3 × 10 3 Pa. The measured line emissions from Kr + in the wavelength range of 457–485 nm are compared with the intensities obtained from the present theoretical collision radiative model to obtain the plasma parameters such as electron temperature ( T e ) and electron density ( n e ). The electron temperature results at 40 μs and 90 μ s reported by Mar et al obtained through the Boltzmann plots, have been compared with the values obtained from the present collision radiative model.