The modeling of atom – neutral collisions for beam emission spectroscopy applications

Asztalos, Ö.; Szondy, B.; Tőkési, K.; Pokol, Gergö

doi:10.1140/epjd/e2019-90690-2

Cited by 3 publications

(5 citation statements)

References 27 publications

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“…The CTMC model, as a classical approach, uses the planetary motion of electron under a central force. The CTMC method is a nonperturbative method, where classical equations of motions are solved numerically [66][67][68][69][70][71][72][73]. It is based on the calculation of a large number of individual particle trajectories where the initial atomic states are chosen randomly.…”

Section: Classical Trajectory Monte-carlo Modelsmentioning

confidence: 99%

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Atomic collisional data for neutral beam modeling in fusion plasmas

Hill,

Dipti,

Heinola

et al. 2023

Nucl. Fusion

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The injection of energetic neutral particles into the plasma of magnetic confinement fusion reactors is a widely-accepted method for heating such plasmas; various types of neutral beam are also used for diagnostic purposes. Accurate atomic data are required to properly model beam penetration into the plasma and to interpret photoemission spectra from both the beam particles themselves and from plasma impurities with which they interact. This paper reviews and compares theoretical methods for calculating ionization, excitation and charge exchange cross sections applied to several important processes relevant to neutral hydrogen beams, including H + Be4+ and H + H+. In particular, a new cross section for the proton-impact ionization of H (1s) is recommended which is significantly larger than that previously accepted at fusion-relevant energies. Coefficients for an empirical fit function to this cross section and to that of the first excited states of H are provided and uncertainties estimated. The propagation of uncertainties in this cross section in modeling codes under JET-like conditions has been studied and the newly-recommended values determined to have a significant effect on the predicted beam attenuation. In addition to accurate calculations of collisional atomic data, the use of these data in codes modeling beam penetration and photoemission for fusion-relevant plasma density and temperature profiles is discussed. In particular, the discrepancies in the modelling of impurities are reported.The present paper originates from a Coordinated Research Project (CRP) on the topic of fundamental atomic data for neutral beam modeling that the International Atomic Energy Agency (IAEA) ran from 2017 – 2022; this project brought together 10 research groups in the fields of fusion plasma modeling and collisional cross section calculations. Data calculated during the CRP is summarized in an Appendix and is available online in the IAEA's atomic database, CollisionDB.

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Section: Classical Trajectory Monte-carlo Modelsmentioning

confidence: 99%

“…The participating codes apply different levels of detail and methodology to solve the governing rate equations: RENATE [127], RENATE-OD [128],…”

Section: Code Comparison Of the Beam Penetration And Photoemissionmentioning

confidence: 99%

Atomic collisional data for neutral beam modeling in fusion plasmas

Hill,

Dipti,

Heinola

et al. 2023

Nucl. Fusion

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“…For the case of heavy projectiles, calculations were presented for targets of helium [ 32 ] and lithium atoms [ 33 ], as well as for water molecules [ 34 ], and neutral atoms and hydrogen molecules [ 35 ] collisions. Differential cross sections for charge-exchange and single and double electronic emission in collisions of protons with He-atoms at intermediate impact energies were theoretically evaluated by the classical trajectory Monte Carlo methods [ 32 ].…”

Section: Theoretical Advancesmentioning

confidence: 99%

“…The collisional radiative models used in the modelling of beam emission spectroscopy diagnostics neglect atom–atom collisions because of a lack of sufficiently detailed atomic data. Filling this scantiness, Asztalos and co-workers presented 4-body classical trajectory Monte Carlo simulations to calculate the cross sections for various channels in collisions between and for a wide range of projectile energies [ 35 ]. Based on the calculated cross sections, a simplified version of the collisional radiative model has been derived.…”

Section: Theoretical Advancesmentioning

confidence: 99%

Topical Issue on many particle spectroscopy of atoms, molecules, clusters and surfaces editorial

et al. 2021

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Many particle spectroscopy is a subject of continued interest to many experimental and theoretical groups worldwide. It is based on the coincidence spectroscopy of minimum two particles coming from the same elementary process. It is a very powerful tool for studying not just atoms and molecules but also more extended electronic systems such as clusters and surfaces. Due to the large variety of its applications, it is really an interdisciplinary research field. This Topical Issue presents a state-of-the-art description of current research activities in the field of many particle spectroscopy. The contributions to this Issue represent original research results on both experimental and theoretical studies, involving the interaction of various projectiles, like photons, electrons, ions with atoms, molecules, clusters and surfaces.

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“…and an effective core charge (Z eff = 1.165). This approximation was shown to be successful in calculating cross-section studies in collisions between Li and H projectiles and H 2 [ 33 ]. A similar approximation was also successfully used by several groups in the investigation of H 2 O, leading to a good agreement between theoretical predictions and experimental data [ 34 , 35 , 36 , 37 ].…”

Section: Introductionmentioning

confidence: 99%

Ionization Cross Sections of Hydrogen Molecule by Electron and Positron Impact

Tőkési,

DuBois

2024

IJMS

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We present ionization cross sections of hydrogen molecules by electron and positron impact for impact energies between 20 and 1000 eV. A three-body Classical Trajectory Monte Carlo approximation is applied to mimic the collision system. In this approach, the H2 molecule is modeled by a hydrogen-type atom with one active electron bound to a central core of effective charge with an effective binding energy. Although this model is crude for describing a hydrogen molecule, we found that the total cross sections for positron impact agree reasonably well with the experimental data. For the electron impact, our calculated cross sections are in good agreement with the experimental data in impact energies between 80 eV and 400 eV but are smaller at higher impact energies and larger at lower impact energies. Our calculated cross sections are compared with the scaled cross sections obtained experimentally for an atomic hydrogen target. We also present single differential cross sections as a function of the energy and angle of the ejected electron and scattered projectiles for a 250 eV impact. These are shown to agree well with available data. Impact parameter distributions are also compared for several impact energies.

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The modeling of atom – neutral collisions for beam emission spectroscopy applications

Cited by 3 publications

References 27 publications

Atomic collisional data for neutral beam modeling in fusion plasmas

Atomic collisional data for neutral beam modeling in fusion plasmas

Topical Issue on many particle spectroscopy of atoms, molecules, clusters and surfaces editorial

Ionization Cross Sections of Hydrogen Molecule by Electron and Positron Impact

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