Positron induced scattering cross sections for hydrocarbons relevant to plasma

Abstract

This article explores positron scattering cross sections by simple hydrocarbons such as ethane, ethene, ethyne, propane, and propyne. Chemical erosion processes occurring on the surface due to plasma–wall interactions are an abundant source of hydrocarbon molecules which contaminate the hydrogenic plasma. These hydrocarbons play an important role in the edge plasma region of Tokamak and ITER. In addition to this, they are also one of the major components in the planetary atmospheres and astrophysical mediums. The present work focuses on calculation of different positron impact interactions with simple hydrocarbons in terms of the total cross section (Qtot), elastic cross section (Qel), direct ionization cross section (Qion), positronium formation cross section (Qps), and total ionization cross section (Qtion). Knowing that the positron-plasma study is one of the trending fields, the calculated data have diverse plasma and astrophysical modeling applications. A comprehensive study of Qtot has been provided where the inelastic cross sections have been reported for the first time. Comparisons are made with those available from the literature, and a good agreement is obtained with the measurements.

Scattering of e± by C2H6 Molecule over a Wide Range of Energy: A Theoretical Investigation

“…As shown in Figure 13 c, the IAMS, Chiari et al [ 28 ], Occhigrossi and Gianturco [ 50 ], and Dapor and Miotello [ 34 ] produce similar cross-sections, while the IAM result overestimates the IECS, especially at lower incident energies. Although the calculated MTCS using the IAM and IAMS and the TICS, using the IAMS, are consistent in pattern with the result of Singh and Antony [ 49 ], but different in magnitude. Figure 13 e,f show that both the IAM and IAMS results for the MTCS and VCS agree with the calculations of Dapor and Miotello [ 34 ].…”

“…The IAM and IAMS generated TCS, TICS, IECS, INCS, MTCS, and VCS for the scattering of positrons by are compared in Figure 13 with the measurements of Chiari et al [ 28 ], Sueoka and Mori [ 21 ], and Floeder et al [ 19 ]; and theoretical studies of Singh and Antony [ 49 ], Raizada and Baluja [ 47 ], Raj and Tomar [ 48 ], Chiari et al [ 28 ], Occhigrossi and Gianturco [ 50 ], and Dapor and Miotello [ 34 ]. Here, again, the IAM overestimates the experimental TCS, while the IAMS generated cross-sections fairly agree with the experimental data [ 19 , 21 , 28 ] and the theoretical calculations of [ 47 , 48 , 49 ] ( Figure 13 a). As shown in Figure 13 c, the IAMS, Chiari et al [ 28 ], Occhigrossi and Gianturco [ 50 ], and Dapor and Miotello [ 34 ] produce similar cross-sections, while the IAM result overestimates the IECS, especially at lower incident energies.…”

“…The TCS for – scattering in the energy range 100–1000 eV was also calculated by Raj and Tomar [ 48 ] using the independent atom model (IAM). Recently, Singh and Antony [ 49 ], in 2018, used the modified SCOP and CSP-ic methods, respectively, to calculate the positron TCS and TICS for at collision energies from the positronium threshold to 5000 eV. Occhigrossi and Gianturco [ 50 ] theoretically calculated the low-energy positron IECS at impact energies up to 6 eV.…”

Low-energy positron scattering from C2H2

“…On the theoretical side, we find the works of da Silva et al [5], de Carvalho et al [6,7], Occhigrossi and Gianturco [8], Franz et al [9] and Zhang et al [10] for the elastic process, and the works of Baluja and Jain [11], Raizada and Baluja [12] and Singh and Antony [13] which considered the inelastic processes through absorption potential formulations. It is noteworthy that the works of the SMC group ( [5][6][7]), Franz and scaled R-matrix) employed correlation polarization models in order to obtain the scattering potential.…”

“…However, the inclusion of the inelastic processes as positronium formation, direct ionization and electronic excitation from a coupled channel formalism may produce relevant effects over the elastic scattering cross sections, which in principle could not be well evaluated from a model approach that disregards coupling effects close to the inelastic thresholds. Even that the inelastic cross sections obtained via model approaches are relevant and give valuable insight to the analysis of the scattering dynamics as we can observe in the work of Singh and Antony [13] for C 2 H 2 and other small hydrocarbons, the coupling between scattering channels should be considered carefully, which may lead to improvements on the calculated cross sections lowering even more the presented D values. Nevertheless, such effects may be superseded by the use of an incomplete expansion of the scattering wave function or Present results de Carvalho [7] Occhigrossi [8] Sueoka [1] Zecca [3] Fig.…”