ORCID Profile
0000-0002-3951-9016
Current Organisation
Curtin University
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In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Atomic, Molecular, Nuclear, Particle and Plasma Physics | Atomic and Molecular Physics | Plasma Physics; Fusion Plasmas; Electrical Discharges | Atomic And Molecular Physics | Radiation Therapy | Numerical Analysis | Plasmas And Electrical Discharges
Expanding Knowledge in the Physical Sciences | Physical sciences | Cancer and Related Disorders | Energy not elsewhere classified |
Publisher: AIP
Date: 2011
DOI: 10.1063/1.3585814
Publisher: American Physical Society (APS)
Date: 31-01-2005
Publisher: American Physical Society (APS)
Date: 10-02-2020
Publisher: CSIRO Publishing
Date: 1999
DOI: 10.1071/PH98085
Abstract: We have used the nonrelativistic convergent close-coupling (CCC) method to investigate electron scattering from the ground (6s2)1S state and excited (6s6p)1 Po1 and (6s5d)1,3De2 states of barium. For the scattering from the barium ground state, we have found very good agreement with measurements of (6s6p)1 Po1 apparent cross sections at all energies. Similarly, good agreement is found for differential cross sections for elastic scattering and (6s6p)1 Po and (6s5d)1 De2 excitations and with the (6s6p)1 Po1 state electron{photon angular correlations. For the scattering from excited states of barium we have found good agreement with elastic (6s6p)1 Po1 scattering and the (6s5d)1De2 → (6s6p)1 Po1 transition for both differential cross sections and electron–photon angular correlations.
Publisher: American Physical Society (APS)
Date: 11-10-2010
Publisher: American Physical Society (APS)
Date: 24-10-2019
Publisher: American Physical Society (APS)
Date: 08-1995
Publisher: American Physical Society (APS)
Date: 30-01-2002
Publisher: IOP Publishing
Date: 11-2009
Publisher: IOP Publishing
Date: 02-2011
Publisher: American Physical Society (APS)
Date: 08-10-2019
Publisher: American Physical Society (APS)
Date: 31-10-2012
Publisher: IOP Publishing
Date: 03-2012
Publisher: American Physical Society (APS)
Date: 23-08-2011
Publisher: IOP Publishing
Date: 05-11-2012
Publisher: American Physical Society (APS)
Date: 09-01-2013
Publisher: American Physical Society (APS)
Date: 07-12-2009
Publisher: American Physical Society (APS)
Date: 08-04-1996
Publisher: American Physical Society (APS)
Date: 05-1998
Publisher: American Physical Society (APS)
Date: 11-1994
Publisher: American Physical Society (APS)
Date: 08-06-2010
Publisher: American Physical Society (APS)
Date: 13-06-2014
Publisher: American Physical Society (APS)
Date: 1995
Publisher: IOP Publishing
Date: 12-06-2004
Publisher: American Physical Society (APS)
Date: 25-06-2012
Publisher: American Physical Society (APS)
Date: 21-06-2011
Publisher: IOP Publishing
Date: 04-12-2019
Publisher: IOP Publishing
Date: 28-12-1997
Publisher: American Physical Society (APS)
Date: 29-12-2008
Publisher: American Physical Society (APS)
Date: 03-08-2010
Publisher: American Physical Society (APS)
Date: 04-2009
Publisher: IOP Publishing
Date: 11-2009
Publisher: American Physical Society (APS)
Date: 05-1998
Publisher: IOP Publishing
Date: 14-08-1997
Publisher: American Physical Society (APS)
Date: 07-09-2011
Publisher: IOP Publishing
Date: 16-08-2001
Publisher: MDPI AG
Date: 06-08-2019
DOI: 10.3390/ATOMS7030075
Abstract: We present convergent close-coupling (CCC) calculations of electron-impact dissociation of vibrationally-excited molecular hydrogen into neutral fragments. This work follows from our previous results for dissociation of molecular hydrogen in the ground vibrational level [Scarlett et al., Eur. Phys. J. D 72, 34 (2018)], which were obtained from calculations performed in a spherical coordinate system. The present calculations, performed utilizing a spheroidal formulation of the molecular CCC method, reproduce the previous dissociation cross sections for the ground vibrational level, while allowing the extension to scattering on excited levels.
Publisher: American Physical Society (APS)
Date: 09-08-2018
Publisher: IOP Publishing
Date: 08-01-2021
Abstract: Collisional radiative (CR) models for molecular hydrogen are of high relevance for performing qualitative and quantitative analysis of excited-state population densities measured in plasmas or predicting the dependence of plasma emission on parameter variations. Although the development of such models for H 2 started decades ago, major uncertainties still exist regarding the most important set of input parameters, namely the cross sections for electron-impact excitation. The deviations between cross sections from different datasets are particularly pronounced in the energy region close to the threshold energy, strongly increasing the uncertainty of CR models applied to low-temperature plasmas. This paper presents experimental validation of a set of newly calculated non ro-vibrationally resolved electron-impact cross sections calculated for the triplet system of H 2 using the molecular convergent close-coupling method in the adiabatic-nuclei formulation. These cross sections are implemented into a CR model based on the flexible solver Yacora. A first comparison of CR calculations with the different datasets to experimentally-determined population densities is performed at a planar ICP discharge for varying pressure (between 1 and 10 Pa) and RF power (between 700 and 1100 W). For the experimentally-accessible electron temperature and density range (2.5–10 eV and 1.8–3.3 × 10 16 m −3 , respectively), very good agreement between the model and experiment is obtained using the new data set, in contrast to previously used cross sections.
Publisher: American Physical Society (APS)
Date: 08-09-2023
Publisher: American Physical Society (APS)
Date: 20-03-2008
Publisher: American Physical Society (APS)
Date: 25-09-2008
Publisher: American Physical Society (APS)
Date: 16-11-2015
Publisher: American Physical Society (APS)
Date: 24-05-2018
Publisher: American Physical Society (APS)
Date: 05-02-2020
Publisher: IOP Publishing
Date: 02-03-2004
Publisher: IOP Publishing
Date: 16-01-2013
Publisher: Springer Science and Business Media LLC
Date: 06-2023
DOI: 10.1140/EPJD/S10053-023-00705-6
Abstract: The relativistic convergent close-coupling method is applied to calculate integrated cross sections for the electron-impact excitation of Sn $$^{2+}$$ 2 + . Cross sections have been calculated for excitations to all states in the 5 s 5 p , $$5p^2$$ 5 p 2 , 5 s 6 s and 5 s 5 d manifolds from the ground state for projectile electron energies ranging from 24 eV to 500 eV. The total discrete inelastic scattering cross section is also presented.
Publisher: IOP Publishing
Date: 04-07-2008
Publisher: Elsevier BV
Date: 06-2016
Publisher: American Physical Society (APS)
Date: 18-08-2014
Publisher: American Physical Society (APS)
Date: 15-08-2014
Publisher: Elsevier BV
Date: 04-2012
Publisher: Elsevier BV
Date: 03-2017
Publisher: IOP Publishing
Date: 06-12-2012
Publisher: American Physical Society (APS)
Date: 09-02-2001
Publisher: EDP Sciences
Date: 07-2019
DOI: 10.1051/0004-6361/201935156
Abstract: Context. Older models of Galactic chemical evolution (GCE) predict [K/Fe] ratios as much as 1 dex lower than those inferred from stellar observations. Abundances of potassium are mainly based on analyses of the 7698 Å resonance line, and the discrepancy between GCE models and observations is in part caused by the assumption of local thermodynamic equilibrium (LTE) in spectroscopic analyses. Aims. We study the statistical equilibrium of K I , focusing on the non-LTE effects on the 7698 Å line. We aim to determine how non-LTE abundances of potassium can improve the analysis of its chemical evolution, and help to constrain the yields of GCE models. Methods. We construct a new model K I atom that employs the most up-to-date atomic data. In particular, we calculate and present inelastic e+K collisional excitation cross-sections from the convergent close-coupling (CCC) and the B -Spline R -matrix (BSR) methods, and H+K collisions from the two-electron model (LCAO). We constructed a fine, extended grid of non-LTE abundance corrections based on 1D MARCS models that span 4000 T eff ∕K 8000, 0.50 log g 5.00, − 5.00 [Fe/H] + 0.50, and applied the corrections to potassium abundances extracted from the literature. Results. In concordance with previous studies, we find severe non-LTE effects in the 7698 Å line. The line is stronger in non-LTE and the abundance corrections can reach approximately − 0.7 dex for solar-metallicity stars such as Procyon. We determine potassium abundances in six benchmark stars, and obtain consistent results from different optical lines. We explore the effects of atmospheric inhomogeneity by computing for the first time a full 3D non-LTE stellar spectrum of K I lines for a test star. We find that 3D modeling is necessary to predict a correct shape of the resonance 7698 Å line, but the line strength is similar to that found in 1D non-LTE. Conclusions. Our non-LTE abundance corrections reduce the scatter and change the cosmic trends of literature potassium abundances. In the regime [Fe/H] ≲−1.0 the non-LTE abundances show a good agreement with the GCE model with yields from rotating massive stars. The reduced scatter of the non-LTE corrected abundances of a s le of solar twins shows that line-by-line differential analysis techniques cannot fully compensate for systematic LTE modelling errors the scatter introduced by such errors introduces a spurious dispersion to K evolution.
Publisher: American Physical Society (APS)
Date: 31-05-2005
Publisher: IOP Publishing
Date: 25-05-2001
Publisher: IOP Publishing
Date: 28-07-1998
Publisher: IOP Publishing
Date: 03-2023
Publisher: MDPI AG
Date: 11-02-2022
Abstract: The convergent close-coupling (CCC) method was initially developed to describe electron scattering on atomic hydrogen and the hydrogenic ions such as He+. The latter allows implementation of double photoionization (DPI) of the helium atom. For more complex single valence-electron atomic and ionic targets, the direct and exchange interaction with the inner electron core needs to be taken into account. For this purpose, the Hartree-Fock (HF) computer codes developed in the group of Miron Amusia have been adapted. In this brief review article, we demonstrate the utility of the HF technique by ex les of electron scattering on Li and the DPI of the H− and Li− ions. We also discuss that modern-day computer infrastructure allows the associated CCC code, and others, to be readily run directly via the Atomic, Molecular and Optical Science Gateway.
Publisher: American Physical Society (APS)
Date: 12-09-2006
Publisher: American Physical Society (APS)
Date: 03-03-2011
Publisher: American Physical Society (APS)
Date: 02-06-2023
Publisher: IOP Publishing
Date: 12-08-2009
Publisher: American Physical Society (APS)
Date: 10-12-2018
Publisher: American Astronomical Society
Date: 12-12-2017
Publisher: American Physical Society (APS)
Date: 15-08-2002
Publisher: IOP Publishing
Date: 07-09-2012
Publisher: IOP Publishing
Date: 14-07-1995
Publisher: American Physical Society (APS)
Date: 1999
Publisher: American Physical Society (APS)
Date: 19-01-2023
Publisher: American Physical Society (APS)
Date: 16-11-2010
Publisher: American Physical Society (APS)
Date: 07-11-2011
Publisher: MDPI AG
Date: 07-09-2020
DOI: 10.3390/ATOMS8030057
Abstract: Two computational methods developed recently [McNamara, Fursa, and Bray, Phys. Rev. A 98, 043435 (2018)] for calculating Rayleigh and Raman scattering cross sections for atomic hydrogen have been extended to quasi one-electron systems. A comprehensive set of cross sections have been obtained for the alkali atoms: lithium, sodium, potassium, rubidium, and cesium. These cross sections are accurate for incident photon energies above and below the ionization threshold, but they are limited to energies below the excitation threshold of core electrons. The effect of spin-orbit interaction, importance of accounting for core polarization, and convergence of the cross sections have been investigated.
Publisher: IOP Publishing
Date: 14-02-1997
Publisher: Elsevier BV
Date: 10-2001
Publisher: Elsevier BV
Date: 07-2008
Publisher: IOP Publishing
Date: 12-01-2009
Publisher: American Physical Society (APS)
Date: 10-1996
Publisher: IOP Publishing
Date: 10-04-2014
Publisher: American Physical Society (APS)
Date: 12-02-2008
Publisher: American Physical Society (APS)
Date: 22-09-2009
Publisher: AIP Publishing
Date: 16-05-2023
DOI: 10.1063/5.0145933
Abstract: Results from the application of optical potential, relativistic optical potential, relativistic convergent close-coupling, and binary encounter Bethe models to electron scattering from gas-phase cadmium are presented. In particular, integral cross sections for elastic scattering, summed discrete electronic-state excitation, and ionization scattering processes are reported over an extended incident electron-energy range. Total cross sections are constructed by taking their sum. Measurements are presented for elastic scattering and for excitation to the 51P1 state. The theoretical and experimental results are compared to previous calculations and measurements. Recommended electron cross-section datasets are constructed over an incident electron energy range of 0.01–10 000 eV.
Publisher: American Physical Society (APS)
Date: 12-1991
Publisher: IOP Publishing
Date: 14-10-2008
Publisher: American Physical Society (APS)
Date: 21-12-2017
Publisher: IOP Publishing
Date: 2020
DOI: 10.1088/1742-6596/1412/14/142009
Abstract: We investigate the possible effect of cascade transitions from the (4s5p) 3 P 0,1,2 states to the (4s5s) 3 S 1 state of Zn. Our calculations suggest that the excitation cross sections and the polarization of the cascade radiation cannot explain the serious controversy between two existing experimental datasets below the cascade threshold and raise additional questions regarding the measurements at higher energies.
Publisher: IOP Publishing
Date: 05-11-2012
Publisher: IOP Publishing
Date: 1999
Publisher: IOP Publishing
Date: 12-05-2003
Publisher: IOP Publishing
Date: 15-09-2004
Publisher: American Physical Society (APS)
Date: 12-03-2001
Publisher: American Physical Society (APS)
Date: 09-1997
Publisher: IOP Publishing
Date: 28-04-1998
Publisher: American Physical Society (APS)
Date: 18-08-2017
Publisher: American Physical Society (APS)
Date: 31-10-2022
Publisher: IOP Publishing
Date: 06-2010
Publisher: American Physical Society (APS)
Date: 22-02-2010
Publisher: IOP Publishing
Date: 06-2010
Publisher: AIP
Date: 2010
DOI: 10.1063/1.3517588
Publisher: IOP Publishing
Date: 10-04-2014
Publisher: Elsevier BV
Date: 2003
Publisher: American Physical Society (APS)
Date: 03-2021
Publisher: IOP Publishing
Date: 27-06-2018
Publisher: IOP Publishing
Date: 11-2017
Publisher: IOP Publishing
Date: 05-11-2012
Publisher: IOP Publishing
Date: 04-04-2018
Publisher: American Physical Society (APS)
Date: 21-07-2014
Publisher: American Physical Society (APS)
Date: 30-10-2018
Publisher: IOP Publishing
Date: 23-08-2016
Publisher: American Physical Society (APS)
Date: 28-04-2014
Publisher: American Physical Society (APS)
Date: 08-1999
Publisher: Elsevier BV
Date: 11-2015
Publisher: IOP Publishing
Date: 09-12-2012
Publisher: IOP Publishing
Date: 03-04-2003
Publisher: IOP Publishing
Date: 28-05-1996
Publisher: Elsevier BV
Date: 2000
Publisher: MDPI AG
Date: 06-02-2023
Abstract: Electron collision physics covers a broad range of processes in atoms and molecules [...]
Publisher: American Physical Society (APS)
Date: 23-08-2019
Publisher: American Physical Society (APS)
Date: 27-06-2005
Publisher: IOP Publishing
Date: 02-11-2005
Publisher: IOP Publishing
Date: 1999
Publisher: IOP Publishing
Date: 28-07-1994
Publisher: Elsevier BV
Date: 2023
Publisher: American Physical Society (APS)
Date: 13-08-2007
Publisher: EDP Sciences
Date: 11-2000
DOI: 10.1051/AAS:2000277
Publisher: MDPI AG
Date: 27-07-2022
Abstract: The relativistic convergent close-coupling method is applied to calculate cross sections for electron scattering from atomic tin. We present integrated and momentum-transfer cross sections for elastic scattering from the ground and the first four excited states of tin for projectile energies ranging from 0.1 to 500 eV. Integrated and selected differential cross sections are presented for excitation to the 5p2, 5p6s, 5p5d and 5p6p manifolds from the ground state. The total ionisation cross sections are calculated from the ground and the first four excited states, accounting for the direct ionisation of the 5p valence shell and the closed 5s shell and the indirect contributions from the excitation–autoionisation. The presented results are compared with previous theoretical predictions and an experiment where available. For the total ionisation cross sections, we find good agreement with the experiment and other theories, while for excitation cross sections, the agreement is mixed.
Publisher: IOP Publishing
Date: 05-05-2021
Abstract: Positron scattering on atomic and molecular targets is a two-centre problem due to the possibility of rearrangement (Ps-formation) processes. In certain kinematic regions, single-centre expansion methods can be applied to two-centre scattering problems. In such approaches, however, information about Ps-formation and direct ionization processes are combined into excitation litudes of positive-energy pseudostates. In this report we show that Ps-formation litudes can be extracted using the total scattering wave function, which we reconstruct from single-centre convergent close-coupling calculations. The method is applied to positron scattering from hydrogen and lithium atomic targets. Excellent agreement with the two-centre theoretical benchmark results show the validity of the proposed technique.
Publisher: EDP Sciences
Date: 02-2022
DOI: 10.1051/0004-6361/202142560
Abstract: Context. Low-energy cosmic rays ( TeV) play a fundamental role in the chemical and dynamical evolution of molecular clouds, as they control the ionisation, dissociation, and excitation of H 2 . Their characterisation is therefore important both for the interpretation of observations and for the development of theoretical models. However, the methods used so far for estimating the cosmic-ray ionisation rate in molecular clouds have several limitations due to uncertainties in the adopted chemical networks. Aims. We refine and extend a previously proposed method to estimate the cosmic-ray ionisation rate in molecular clouds by observing rovibrational transitions of H 2 at near-infrared wavelengths, which are mainly excited by secondary cosmic-ray electrons. Methods. Combining models of interstellar cosmic-ray propagation and attenuation in molecular clouds with the rigorous calculation of the expected secondary electron spectrum and updated electron-H 2 excitation cross sections, we derive the intensity of the four H 2 rovibrational transitions observable in cold dense gas: (1−0)O(2), (1−0)Q(2), (1−0)S(0), and (1−0)O(4). Results. The proposed method allows the estimation of the cosmic-ray ionisation rate for a given observed line intensity and H 2 column density. We are also able to deduce the shape of the low-energy cosmic-ray proton spectrum impinging upon the molecular cloud. In addition, we present a look-up plot and a web-based application that can be used to constrain the low-energy spectral slope of the interstellar cosmic-ray proton spectrum. We finally comment on the capability of the James Webb Space Telescope to detect these near-infrared H 2 lines, which will make it possible to derive, for the first time, spatial variation in the cosmic-ray ionisation rate in dense gas. Besides the implications for the interpretation of the chemical-dynamic evolution of a molecular cloud, it will finally be possible to test competing models of cosmic-ray propagation and attenuation in the interstellar medium, as well as compare cosmic-ray spectra in different Galactic regions.
Publisher: IOP Publishing
Date: 30-07-2010
Publisher: American Physical Society (APS)
Date: 09-04-2012
Publisher: IOP Publishing
Date: 28-02-1997
Publisher: IOP Publishing
Date: 11-2021
Abstract: A Monte Carlo simulation of electron energy deposition in a gas of molecular hydrogen has been conducted with the aim of producing an ab initio estimate of energy deposition parameters such as the mean energy per ion pair. A set of cross sections obtained using the molecular convergent close-coupling method were used as input. At high incident electron energies the mean energy per ion pair was calculated to be 36.3 eV, agreeing with the recommended value of 36.5 ± 0.3 eV. This represents the first fully ab initio calculation of the mean energy per ion pair using a self consistent data set.
Publisher: IOP Publishing
Date: 07-09-2015
Publisher: American Physical Society (APS)
Date: 14-06-2000
Publisher: American Physical Society (APS)
Date: 11-07-2005
Publisher: IOP Publishing
Date: 15-01-2015
Publisher: American Physical Society (APS)
Date: 19-03-2008
Publisher: American Physical Society (APS)
Date: 12-1997
Publisher: IOP Publishing
Date: 22-05-2017
Publisher: American Physical Society (APS)
Date: 22-02-2016
Publisher: Canadian Science Publishing
Date: 05-2011
DOI: 10.1139/P11-012
Abstract: We present a review of the relativistic convergent close-coupling (RCCC) method and describe how it has been used to resolve the discrepancy between theory and experiment for the polarization of the Lyman-α 1 X-ray line emitted by hydrogen-like Ti 21+ , Ar 17+ , and Fe 25+ ions excited by electron impact. We find that taking account of Breit relativistic corrections is important to resolve the discrepancy between experiment and theoretical calculations.
Publisher: American Physical Society (APS)
Date: 23-08-2010
Publisher: American Physical Society (APS)
Date: 12-10-2021
Publisher: American Physical Society (APS)
Date: 06-02-2017
Publisher: American Physical Society (APS)
Date: 12-1999
Publisher: American Physical Society (APS)
Date: 03-1999
Publisher: IOP Publishing
Date: 11-2009
Publisher: IOP Publishing
Date: 10-04-2014
Publisher: IOP Publishing
Date: 29-03-2018
Publisher: Elsevier BV
Date: 05-2019
Publisher: IOP Publishing
Date: 18-11-2016
Publisher: American Physical Society (APS)
Date: 23-11-2015
Publisher: IOP Publishing
Date: 21-12-2021
Abstract: A technique has been developed for calculating the electron-impact ionization single differential cross section directly from the integrated cross sections of positive-energy pseudostates occuring in close-coupling methods. Using the cross sections arising in the convergent close-coupling method, the approach is first tested against the existing benchmark theoretical and experimental data for electron scattering on hydrogen and helium. It is then applied to electron scattering on molecular hydrogen yielding excellent agreement with experimental data when normalized to the total ionization cross section.
Publisher: American Physical Society (APS)
Date: 11-09-2015
Publisher: IOP Publishing
Date: 09-2009
Publisher: IOP Publishing
Date: 02-10-2006
Publisher: American Physical Society (APS)
Date: 26-02-2018
Publisher: IOP Publishing
Date: 05-11-2012
Publisher: American Physical Society (APS)
Date: 03-08-2020
Publisher: American Physical Society (APS)
Date: 04-1994
Publisher: IOP Publishing
Date: 28-04-1997
Publisher: IOP Publishing
Date: 23-07-2003
Publisher: IOP Publishing
Date: 05-2014
Publisher: American Physical Society (APS)
Date: 07-02-2211
Publisher: American Physical Society (APS)
Date: 28-08-2009
Publisher: American Physical Society (APS)
Date: 10-12-2013
Publisher: IOP Publishing
Date: 16-06-2009
Publisher: EDP Sciences
Date: 26-09-2017
Publisher: IOP Publishing
Date: 10-10-2006
Publisher: IOP Publishing
Date: 09-2009
Publisher: American Physical Society (APS)
Date: 21-02-2014
Publisher: MDPI AG
Date: 08-07-2021
DOI: 10.3390/ATOMS9030042
Abstract: A fully relativistic approach to calculating photoionization and photon-atom scattering cross sections for quasi one-electron atoms is presented. An extensive set of photoionization cross sections have been calculated for alkali atoms: lithium, sodium, potassium, rubidium and cesium. The importance of relativistic effects and core polarization on the depth and position of the Cooper minimum in the photoionization cross section is investigated. Good agreement was found with previous Dirac-based B-spline R-matrix calculations of Zatsarinny and Tayal and recent experimental results.
Publisher: IOP Publishing
Date: 05-11-2012
Publisher: IOP Publishing
Date: 07-09-2015
Publisher: IOP Publishing
Date: 05-11-2012
Publisher: IOP Publishing
Date: 10-04-2014
Publisher: American Physical Society (APS)
Date: 05-1993
Publisher: IOP Publishing
Date: 2011
Publisher: American Physical Society (APS)
Date: 09-12-2011
Publisher: American Physical Society (APS)
Date: 05-06-2015
Publisher: American Physical Society (APS)
Date: 12-12-2013
Publisher: IOP Publishing
Date: 14-10-1998
Publisher: American Physical Society (APS)
Date: 19-06-2008
Publisher: Elsevier BV
Date: 11-2012
Publisher: IOP Publishing
Date: 30-07-2002
Publisher: IOP Publishing
Date: 19-03-2010
Publisher: IOP Publishing
Date: 16-03-2011
Publisher: IOP Publishing
Date: 06-2022
Abstract: Many laboratory and industrial plasma applications require accurate modeling techniques to understand the interplay between microscopic and macroscopic processes. A prime ex le of this interplay is how particle and Monte Carlo (MC) simulation codes describe angular scattering of electrons following elastic scattering events. The forward peaked nature of high energy electron elastic scattering is relatively trivial to accurately describe in plasma simulations. However, for lower energy collisions, which produce near isotropic or backward peaked differential cross sections, there is not a strong consensus among the plasma modeling community on how to best describe these angular scattering trends. In this study, we propose a systematic method to approximate the aforementioned non-trivial angular scattering behavior with a formula that can be readily implemented in particle-in-cell (PIC) and/or MC plasma simulation codes. The present approach is specifically applied to fusion relevant atomic hydrogen and helium, as well as for molecular hydrogen, and results are also applicable to the atomic isotopes and homonuclear molecular isotopologues of these species. Comparisons between the present angular distribution function and benchmark scattering data were used to validate the proposed models. In addition, two-term Boltzmann calculations and PIC direct simulation MC simulations revealed that the proposed angular distribution function is accurate, agreeing very well with benchmark convergent close-coupling scattering calculations, and electron transport measurements. These studies confirmed that the present angular distribution function model can be utilized without the need of renormalization to the momentum transfer cross section (as opposed to using the elastic scattering integrated cross section), which has been suggested by several studies in order to correct for deficient angular scattering models, and to agree with transport measurements. Hence, the present anisotropic angular scattering model can be utilized to accurately model the momentum transfer as well as the electron trajectories of elastic collisions.
Publisher: IOP Publishing
Date: 02-2010
Publisher: American Physical Society (APS)
Date: 24-05-2011
Publisher: IOP Publishing
Date: 28-10-1999
Publisher: IOP Publishing
Date: 05-11-2012
Publisher: IOP Publishing
Date: 14-06-1996
Publisher: American Physical Society (APS)
Date: 24-05-2011
Publisher: IOP Publishing
Date: 18-05-2012
Publisher: American Physical Society (APS)
Date: 02-1993
Publisher: IOP Publishing
Date: 11-2009
Publisher: American Physical Society (APS)
Date: 24-03-2014
Publisher: IOP Publishing
Date: 11-2009
Publisher: American Physical Society (APS)
Date: 18-11-2009
Publisher: IOP Publishing
Date: 07-09-2015
Publisher: American Physical Society (APS)
Date: 19-02-2021
Publisher: AIP
Date: 2006
DOI: 10.1063/1.2165617
Publisher: AIP Publishing
Date: 29-01-2021
DOI: 10.1063/5.0035218
Abstract: We report, over an extended energy range, recommended angle-integrated cross sections for elastic scattering, discrete inelastic scattering processes, and the total ionization cross section for electron scattering from atomic indium. In addition, from those angle-integrated cross sections, a grand total cross section is subsequently derived. To construct those recommended cross-section databases, results from original B-spline R-matrix, relativistic convergent close-coupling, and relativistic optical-potential computations are also presented here. Electron transport coefficients are subsequently calculated, using our recommended database, for reduced electric fields ranging from 0.01 Td to 10 000 Td using a multiterm solution of Boltzmann’s equation. To facilitate those simulations, a recommended elastic momentum transfer cross-section set is also constructed and presented here.
Publisher: Elsevier BV
Date: 2021
Publisher: SPIE
Date: 10-12-2001
DOI: 10.1117/12.450057
Publisher: MDPI AG
Date: 23-06-2014
DOI: 10.3390/ATOMS2020277
Publisher: American Physical Society (APS)
Date: 24-11-2021
Publisher: IOP Publishing
Date: 16-12-2010
Publisher: American Physical Society (APS)
Date: 09-07-2014
Publisher: Springer Science and Business Media LLC
Date: 10-2011
Publisher: American Physical Society (APS)
Date: 19-11-2012
Publisher: American Physical Society (APS)
Date: 27-09-2010
Publisher: American Physical Society (APS)
Date: 29-04-2019
Publisher: American Physical Society (APS)
Date: 09-11-2012
Publisher: IOP Publishing
Date: 18-06-2020
Abstract: We present benchmark integrated and differential cross-sections for electron collisions with H 2 using two different theoretical approaches, namely, the R-matrix and molecular convergent close-coupling. This is similar to comparative studies conducted on electron–atom collisions for H, He and Mg. Electron impact excitation to the b 3 Σ u + , a 3 Σ g + , B 1 Σ u + , c 3 Π u , E F 1 Σ g + , C 1 Π u , e 3 Σ u + , h 3 Σ g + , B ′ 1 Σ u + and d 3 Π u excited electronic states are considered. Calculations are presented in both the fixed nuclei and adiabatic nuclei approximations, where the latter is shown only for the b 3 Σ u + state. Good agreement is found for all transitions presented. Where available, we compare with existing experimental and recommended data.
Publisher: Canadian Science Publishing
Date: 11-1996
DOI: 10.1139/P96-807
Abstract: Convergent close-coupling (CCC) calculations are used to obtain electron–photon coincidence parameters for 2 1 P,3 1,3 P, and 3 1,3 D states of helium in the intermediate energy region. Results of the CCC calculations are compared with experiment and other calculations. Consistent agreement of the CCC calculations with experiment has been achieved for these states at all scattering angles.
Publisher: American Physical Society (APS)
Date: 1999
Publisher: IOP Publishing
Date: 2010
Publisher: IOP Publishing
Date: 19-01-2010
Publisher: IOP Publishing
Date: 05-11-2012
Publisher: IOP Publishing
Date: 11-2009
Publisher: Elsevier BV
Date: 11-2022
Publisher: IOP Publishing
Date: 14-03-1997
Publisher: IOP Publishing
Date: 11-2009
Publisher: Springer Science and Business Media LLC
Date: 10-2023
Publisher: Elsevier BV
Date: 2022
Publisher: American Physical Society (APS)
Date: 03-07-2019
Publisher: American Physical Society (APS)
Date: 02-1999
Publisher: IOP Publishing
Date: 22-06-2000
Publisher: American Physical Society (APS)
Date: 17-07-2019
Publisher: IOP Publishing
Date: 11-2021
Abstract: We study the transport of electrons and propagation of the negative ionisation fronts in indium vapour. Electron swarm transport properties are calculated using a Monte Carlo simulation technique over a wide range of reduced electric fields E / N (where E is the electric field and N is the gas number density) and indium vapour temperatures in hydrodynamic conditions, and under non-hydrodynamic conditions in an idealised steady-state Townsend (SST) setup. As many indium atoms are in the first ( 5 s 2 5 p ) 2 P 3 / 2 metastable state at vapour temperatures of a few thousand Kelvin, the initial Monte Carlo code was extended and generalized to consider the spatial relaxation and the transport of electrons in an idealised SST experiment, in the presence of thermal motion of the host-gas atoms and superelastic collisions. We observe a significant sensitivity of the spatial relaxation of the electrons on the indium vapour temperature and the initial conditions used to release electrons from the cathode into the space between the electrodes. The calculated electron transport coefficients are used as input for the classical fluid model, to investigate the inception and propagation of negative ionisation fronts in indium vapour at various E / N and vapour temperatures. We calculate the electron density, electric field, and velocity of ionisation fronts as a function of E / N and indium vapour temperature. The presence of indium atoms in the first ( 5 s 2 5 p ) 2 P 3 / 2 metastable state significantly affects the characteristics of the negative ionisation fronts. The transition from an avalanche into a negative ionisation front occurs faster with increasing indium vapour temperature, due to enhanced ionisation and more efficient production of electrons at higher vapour temperatures. For lower values of E / N , the electron density behind the streamer front, where the electric field is screened, does not decay as one might expect for atomic gases, but it could be increased due to the accumulation of low-energy electrons that are capable of initiating ionisation in the streamer interior.
Publisher: Springer Science and Business Media LLC
Date: 02-2020
Publisher: American Physical Society (APS)
Date: 22-07-2013
Publisher: IOP Publishing
Date: 08-01-2008
Publisher: IOP Publishing
Date: 07-09-2015
Publisher: American Physical Society (APS)
Date: 16-11-2018
Publisher: IOP Publishing
Date: 14-06-1998
Publisher: IOP Publishing
Date: 02-05-2006
Publisher: American Physical Society (APS)
Date: 12-09-2011
Publisher: American Physical Society (APS)
Date: 27-12-2005
Publisher: IOP Publishing
Date: 28-03-1995
Publisher: American Physical Society (APS)
Date: 06-02-2017
Publisher: IOP Publishing
Date: 28-12-1994
Publisher: IOP Publishing
Date: 2020
DOI: 10.1088/1742-6596/1412/22/222004
Abstract: A new method based on partial-wave expansion of the Ps radial wave functions has been developed for calculating the Ps-formation matrix elements. The method utilises the Euler-Wijngaarden tansformation to accelerate slowly converging series. The integrals in the method are free of the Coulomb singularity that appears in previously used momentum-space methods and therefore more straightforward to apply to complex and charged targets. The results are compared with the existing benchmark calculations for positron scattering on H and He + targets.
Publisher: American Physical Society (APS)
Date: 08-06-2001
Publisher: American Physical Society (APS)
Date: 25-10-2013
Publisher: IOP Publishing
Date: 14-10-2003
Publisher: IOP Publishing
Date: 08-12-2004
Publisher: IOP Publishing
Date: 04-03-2011
Publisher: IOP Publishing
Date: 2020
DOI: 10.1088/1742-6596/1412/22/222005
Abstract: Convergent close-coupling method has been applied to positron scattering by the hydrogen negative ion. Internal consistency of the method and convergence of the cross sections are achieved with use of both the single- and two-centre approaches. Calculations were performed using accurate target wave functions obtained with the multi-core approach.
Publisher: American Physical Society (APS)
Date: 26-02-2002
Publisher: American Physical Society (APS)
Date: 07-12-2012
Publisher: American Physical Society (APS)
Date: 08-06-2016
Publisher: IOP Publishing
Date: 20-10-2006
Publisher: American Physical Society (APS)
Date: 07-12-2012
Publisher: Elsevier BV
Date: 06-2019
Publisher: IOP Publishing
Date: 11-1993
Publisher: IOP Publishing
Date: 04-2011
Publisher: American Physical Society (APS)
Date: 06-12-2021
Publisher: IOP Publishing
Date: 05-11-2012
Publisher: IOP Publishing
Date: 03-12-2020
Publisher: IOP Publishing
Date: 02-2010
Publisher: Canadian Science Publishing
Date: 05-2011
DOI: 10.1139/P11-033
Abstract: The population of magnetic sublevels in hydrogen-like uranium ions has been investigated in relativistic ion–atom collisions by observing the subsequent X-ray emission. Using the gas target at the experimental storage ring facility we observed the angular emission of Lyman-α radiation from hydrogen-like uranium ions. The alignment parameter for three different interaction energies was measured and found to agree well with theory. In addition, the use of different gas targets allowed for the electron-impact excitation process to be observed.
Publisher: American Physical Society (APS)
Date: 17-03-2023
Publisher: IOP Publishing
Date: 07-09-2015
Publisher: IOP Publishing
Date: 28-01-1996
Publisher: IOP Publishing
Date: 10-04-2014
Publisher: American Physical Society (APS)
Date: 17-08-2015
Publisher: Canadian Science Publishing
Date: 05-2011
DOI: 10.1139/P11-029
Abstract: We have obtained expressions for the creation, destruction, and transfer of atomic multipole moments by electron scattering under relativistic conditions. More specifically, we have obtained separate expressions for different-level processes (inelastic scattering) and for same-level processes (elastic and inelastic scattering). The cross sections for different-level processes are expressed in terms of inelastic magnetic sublevel cross sections, except for the coherence transfer cross section, which is expressed in terms of an angular integral of a product of inelastic magnetic sublevel litudes. The same-level cross sections are expressed in terms of the imaginary part of the elastic forward scattering litude and in terms of elastic scattering magnetic sublevel cross sections, except for the coherence transfer cross section, which is expressed in terms of the (complex) forward elastic scattering litudes and an angular integral of a product of elastic scattering magnetic sublevel litudes. If the collisional model supports the optical theorem, then the same-level cross sections can be rewritten in such a form that they are broken up into two parts: an elastic scattering part and an inelastic scattering part. In carrying out this work, we have used the density matrix formalism of Fano and Blum in combination with the electron scattering formalism of Gell-Mann and Goldberger.
Publisher: American Physical Society (APS)
Date: 24-09-2012
Publisher: Springer Science and Business Media LLC
Date: 02-2018
Publisher: American Physical Society (APS)
Date: 04-09-2018
Publisher: IOP Publishing
Date: 25-02-2019
Start Date: 2011
End Date: 11-2014
Amount: $769,832.00
Funder: Australian Research Council
View Funded ActivityStart Date: 09-2005
End Date: 12-2008
Amount: $120,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 03-2019
End Date: 12-2024
Amount: $420,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2018
End Date: 08-2023
Amount: $431,435.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2004
End Date: 12-2008
Amount: $390,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2016
End Date: 05-2019
Amount: $415,300.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2004
End Date: 12-2006
Amount: $34,800.00
Funder: Australian Research Council
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