Classical description of the electron-impact ionization of carbon

N. BACHI; S. OTRANTO; K. TOKESI

Conferencia; Virtual International Conference on Photonic, Electronic and Atomic Collisions 2021; 2021

The ITER project aims to demonstrate thefeasibility of fusion as a large-scale energy source.It is currently under construction in Cadarache,France, and relies on the efforts of 35 countries tobuild the world's largest tokamak. Since the reactorhas carbon components in their divertors, accuratedata on collisions of electrons with carbon atomsare needed for plasma diagnostics, such as impurityinflux studies.Despite the potential interest in this topic, thenumber of experimental reports is quite limited [1].From a theoretical point of view, during the lastdecade efforts have been devoted to calculate thetotal ionization cross sections for the presentcollision system, either from the ground state orfrom excited states, by means of highly numericallyintensive methods, such us the time dependent closecoupling and time independent distorted wavemethods[2]ortheB-splineR-matrix-with-pseudostates [3]. These studies haveconsidered impact energies up to 60 eV and 100 eVrespectively, range which encompasses the peakregion.In the present work, we show the performance ofthe 3-body classical trajectory Monte Carlo methodfor the calculation of ionization cross sections forcollisions of electrons with carbon atoms.Ionization cross sections obtained by differenteffective potentials, such as effective charges andpotential models derived from Hartree-Fockcalculations, are presented and analyzed.Moreover, predictions based on the simple additionrule 2σ 2p + 2σ 2s are compared to those obtained bymeans of the independent electron (IEL) and theindependent event (IEV) models.In Figure 1, we show the total ionization crosssections (TCS) in collision between electron andCarbon atom up to an impact energy of 1 keV. We observe that in the low energy range our resultstend to overestimate the experimental data.Furthermore, the maxima of the different modelsexhibit a clear shift towards lower impact energiescompared to the experimental data. In contrast, ourcalculations tend to agree with each other and withthe experimental trends at the larger impact energiesconsidered.This work has been carried out within theframework of the EUROfusion Consortium and hasreceived funding from the Euratom research andtraining programme 2014-2018 and 2019-2020under grant agreement No 633053. The views andopinions expressed herein do not necessarily reflectthose of the European Commission.References[1]E Brook et al 1978 J. Phys. B: Atom. Mol. Phys.11 3115[2] Sh. A. Abdel-Naby et al 2013 Phys. Rev. A 87022708[3] Y Wang et al 2013 Phys. Rev. A 87 012704