Relativistic Electron-Atom Collisions: Recent Progress and Applications

Detailed electron-impact excitation cross-section results for xenon in the wide range of incident energy from threshold to 1000 eV are calculated using relativistic distorted wave theory. Various transitions from the ground 5p 6 state to the excited 5p 5 6s, 5p 5 6p, 5p 5 5d, 5p 5 7s and 5p 5 7p as well as among these excited states are considered. The relativistic Dirac-Fock multi-configuration wave functions for the ground and excited states of Xe are obtained and used in the calculations. Where available, our cross-section results are compared with previously reported measurements and calculations. We have also fitted the calculated cross-sections through analytical formulae for plasma modeling purposes. As an application, using the obtained cross-sections, a collisional-radiative (C-R) model coupled with an optical emission measurement from the inductively coupled Xe plasma is developed and the extracted plasma parameters are reported.

Section: Rdw Theorymentioning

confidence: 99%

“…Once the distortion potential is obtained, the projectile electron distorted wave functions are obtained by solving the coupled Dirac equations numerically. Detailed description of the RDW method can be seen in [18,30,39].…”

Section: Rdw Theorymentioning

confidence: 99%

Collisional-radiative model of xenon plasma with calculated electron-impact fine-structure excitation cross-sections

Priti

Gangwar

Srivastava

2019

“…Previously, the approach has been successfully applied to various atoms and ions. Therefore, we shall only provide a summarized overview, and for further details, readers are referred to earlier publications [20,21,23]. In the RDW approach, the scattering amplitude 'f' is described as,…”

Section: Rdw Theorymentioning

confidence: 99%

“…spin-orbit interactions and j-j coupling [8,9,20]. Therefore, in our CR models, the required electron-impact excitation (EIE) cross-sections were obtained using a fully relativistic distorted wave (RDW) approximation approach [8,[20][21][22][23]. The detailed fine-structure-resolved EIE crosssections for Ar, Kr and Xe inert atoms were calculated and reported, as well as being made available through the LXCat database [17,24].…”

Section: Introductionmentioning

confidence: 99%

Diagnostics of low-temperature neon plasma through a fine-structure resolved collisional–radiative model

Baghel

Gupta

Gangwar

et al. 2019

A collisional-radiative (CR) model for low-temperature Ne plasma is developed. Various radiative and collisional processes involving the ground 2p 6 and the excited 2p 5 3s, 2p 5 3p, 2p 5 3d, 2p 5 4s and 2p 5 4p states are considered in the plasma. First, we calculate a complete set of required electron-impact excitation cross-sections of Ne, which is an important process in such low-temperature plasma. We used the relativistic distorted wave (RDW) theory and calculated electron excitation cross-sections for the transitions from the ground 2p 6 state to the excited 2p 5 3s, 2p 5 3p, 2p 5 3d, 2p 5 4s and 2p 5 4p states, as well as from the excited state 2p 5 3s to the 2p 5 3p and 2p 5 4p excited states of the Ne atom in a wide range of incident electron energies from the threshold to 500 eV. The ground and different excited states of the Ne are represented through the multiconfiguration Dirac-Fock wave functions, which are obtained using the GRASP2K code. To ascertain the reliability of the obtained wave functions, we calculated the oscillator strengths for different dipole allowed transitions, and compared them with the available experimental and theoretical results. Further, the calculated detailed RDW cross-sections are presented and compared with the available experimental and other theoretically calculated values. The cross-sections for 2p 5 3s to 2p 5 4p and 2p 5 3s (J=1 only) to 2p 5 3p are reported for the first time. The complete set of calculated electron excitation cross-sections of different transitions of Ne along with other processes are used to develop the CR model. The model has been applied to the diagnostics of low-temperature Ne plasma by coupling it to the optical emission and absorption measurements of Boffard et al (2012 J. Phys. D: Appl. Phys. 45 382001, and 2009 Plasma Sources Sci. Technol. 18 035017). The extracted values of electron density, electron temperature and the calculated 1s i level populations have been compared with the corresponding measurements available in the pressure range of 5-25 mTorr and are found to be in excellent agreement.

“…The general theory for EIE of atomic ions in the RDW approximation is quite well known [24][25][26]. Typically, all the characteristics of the excitation process can be described using the transition matrix.…”

Section: Relativistic Distorted Wave Theorymentioning

confidence: 99%

Fine structure resolved excitation cross sections of singly ionized Ga for the modeling and diagnostics of Ga plasmas

Suresh,

Priti,

Srivastava

et al. 2024

Calculation of electron impact excitation cross sections for singly charged Ga ions plays a crucial role in plasma modeling, facilitating the comprehension of plasma behavior, characteristics, and dynamics in diverse domains, such as astrophysics, fusion research, the semiconductor industry, etc. In the available literature, there is a notable scarcity of, or even a complete absence of, these cross sections. Hence, in the present work, electron impact excitation cross sections are calculated for the transitions from the fine structure resolved energy levels of the configurations 4s2 and 4s4p to the fine structure resolved energy levels of the configurations 4s4p, 4s5s, 4p2 and 4s4d of the singly charged Ga ion (Ga+) using the relativistic distorted wave approximation theory with the target states represented by multi configurational Dirac Fock wavefunctions. The cross sections are calculated for projectile electron energy varying from threshold to 500 eV. Furthermore, the electron impact excitation rate coefficients for all the transitions under investigation are also calculated for electron temperatures ranging from 0.5 to 5 eV. In addition, analytic fitting of the rate coefficients is also performed, providing a practical resource for directly utilizing in plasma modeling applications.