Bulletin of the American Physical Society
75th Annual Gaseous Electronics Conference
Volume 67, Number 9
Monday–Friday, October 3–7, 2022;
Sendai International Center, Sendai, Japan
The session times in this program are intended for Japan Standard Time zone in Tokyo, Japan (GMT+9)
Session GR2: Atomic and Molecular Physics |
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Chair: Alisher Kadyrov, Curtin University, Australia Room: Sendai International Center Shirakashi 2 |
Thursday, October 6, 2022 10:00AM - 10:30AM |
GR2.00001: Atomic and Molecular data activities at the IAEA in support of nuclear fusion energy research Invited Speaker: Christian Hill The Atomic and Molecular Data (AMD) Unit of the International Atomic Energy Agency (IAEA) is dedicated to the provision of databases for atomic, molecular and plasma-material interaction data that are relevant for nuclear fusion research. The modelling of plasma in experimental fusion energy reactors requires large amounts of collisional and spectroscopic data on species in a wide variety of ionization states; the projects that the AMD Unit undertakes in support of the provision of these data will be described in this presentation, including those relating to the use of neutral beams for plasma heating and diagnostics, impurity species injected into fusion plasmas to enhance confinement and mitigate instabilities, and the vapour shielding phenomenon.
The AMD Unit maintains several databases of relevant data that result from these activities, including a bibliographic database (AMBDAS), and data sets of collisional processes (ALADDIN and CollisionDB). Recent developments in the standards, data schemas and online search tools for these databases will be discussed, with particular reference to an Application Programming Interface (API) developed to facilitate the automated retrieval of collisional cross section and rate coefficient data by modelling codes. It is anticipated that these standards and databases will find use beyond the fusion plasma modelling community and methods for depositing data in CollisionDB upon its publication are in development. Finally, a software library, written in the popular Python programming language, to aggregate, transform and compare collisional data sets will be demonstrated. AMD Unit: https://amdis.iaea.org/ CollisionDB: https://db-amdis.org/collisiondb/ |
Thursday, October 6, 2022 10:30AM - 11:00AM |
GR2.00002: Positron binding in molecules Invited Speaker: Masanori Tachikawa The positron, which is the anti-particle of the electron, is now widely used in both scientific and technological areas. The detail mechanism of such processes, however, is still unclear in the molecular level. A positron affinity (PA) value, which is a binding energy of a positron to an atom or molecule, has now been experimentally measured by Surko and co-workers for many molecular species such as acetaldehyde, acetone, and acetonitrile organic molecules [1], based on the vibrational Feshbach resonance by incident low-energy positrons. Thus, in order to elucidate the mechanism of the positron binding to molecules, the theoretical analysis including the effect of molecular vibrations is indispensable. |
Thursday, October 6, 2022 11:00AM - 11:15AM |
GR2.00003: Ab initio Electron-scattering data for perfluorocyclobutane (c-C$_4$F$_8$) Harindranath B Ambalampitiya, Sebastian Mohr, Anna Dzarasova, Jonathan Tennyson Perfluorocyclobutane or c-C$_4$F$_8$ is a widely used processing gas in the plasma etching of silicon dioxide. Therefore, a comprehensive and accurate analysis on the electron-scattering from c-C$_4$F$_8$ molecule is important to obtain precise particle densities and fluxes from numerical plasma simulations. With four CF$_2$ moieties arranged in a puckered ring, c-C$_4$F$_8$ has a stable geometry belonging to the D$_{2d}$ symmetry. Due to its somewhat large structure, only a limited number of calculations on the electron scattering from c-C$_4$F$_8$ are available in the literature$^1$. In the present work, we use the molecular R-matrix approach$^2$ employed via Quantemol Electron Collisions (QEC)$^3$ to treat the electron scattering from c-C$_4$F$_8$. The computed R-matrix cross sections for the total elastic scattering and momentum transfer have good overall agreement with the experimental results$^4$. The cross sections for other inelastic electron-scattering processes including electron-impact electronic excitation, dissociation, and dissociative electron attachment will be provided with more physical insights. The results from plasma simulations obtained with the computed \emph{ab initio} data will also be presented. $^1$C. Winstead and V. McKoy , J. Chem. Phys. {\bf 114}, 7407(2001). $^2$J. Tennyson, Phys. Rep. {\bf 491}, 29 (2010). $^3$B. Cooper \emph{et al.}, Atoms {\bf 7}, 97 (2019). $^4$M. Jelisavcic \emph{et al.}, J. Chem. Phys. {\bf 121}, 5272 (2004). |
Thursday, October 6, 2022 11:15AM - 11:30AM |
GR2.00004: Calculations of positron scattering from atomic Carbon Nicolas Mori, Igor Bray, Dmitry V Fursa The demand for accurate cross-section data for positrons incident upon atomic targets has only risen in recent years. This has partially resulted from the use of positrons throughout the biomedical industry. To calculate correct cross-sections for the complex biomolecules present in these cases many current methods require accurate cross-section data for the independent atoms which compose them. One such atom is carbon, which constitutes approximately 18% of the human body and is a major component within important biomolecules such as DNA. |
Thursday, October 6, 2022 11:30AM - 12:00PM |
GR2.00005: Low-Temperature Lanthanide Spectroscopy Applied to Neutron Star Mergers Invited Speaker: Christopher J Fontes Neutron star mergers are promising candidates for the observation of an electromagnetic (EM) signal coincident with gravitational waves. The recent observation of GW170817 [1] appears to be such an event, with gravitational waves confirmed by subsequent EM signals ranging from the infrared to x-ray portions of the spectrum. This EM emission is powered by the radioactive decay of heavy r-process elements, and is called a kilonova. The atomic properties, i.e. radiative opacity, of these elements in the resulting ejecta play an important role in determining the characteristics of the radiation that ultimately reaches the Earth. For example, the opacities of r-process elements, such as the lanthanides, include a dense forest of bound-bound features that result in the strong absorption of radiation over a significant range of photon energies. In this work, we use the Los Alamos suite of atomic physics and plasma modeling codes [2] to investigate the use of detailed, fine-structure opacities [3,4] to model the EM emission from kilonovae. Our simulations, e.g. [5], predict emission in a range of EM bands, depending on issues such as the presence of winds, elemental composition, and viewing angle. |
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