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 GT1: Electron and Photon Collisions - Excitation |
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Chair: Harindranath Ambalampitiya, Quantemol Ltd Room: Sendai International Center Shirakashi 2 |
Tuesday, October 4, 2022 8:00AM - 8:30AM |
GT1.00001: Quantitative measurements of electron collision cross sections and their database related to plasma modeling Invited Speaker: Masamitsu Hoshino The electron excitation cross sections of fluorine containing molecules are very relevant to plasma-assisted fabrication of large scaled-integrated circuits, semiconductor manufacturing and other technological applications. However, despite their importance, few cross sections have been reported except for major molecules such as tetrafluoromethanes. In the present study, therefore, we measured the differential and integral cross sections (DCSs and ICSs) of difluoromethane, CH_{2}F_{2}. |
Tuesday, October 4, 2022 8:30AM - 8:45AM |
GT1.00002: Calculation of electron scattering from tin atoms Haadi Umer, Igor Bray, Dmitry V Fursa The relativistic convergent close-coupling (RCCC) method has been applied to study electron scattering from the atomic tin. Tin is of interest in fusion research as it may be used to monitor the erosion of fusion reactor wall tiles. It is also of interest to the nano-lithography industry, particularly with respect to the production of extreme ultra-violet light (EUV) which is generated using a plasma of tin ions. Both these applications require comprehensive collision data sets to allow accurate modelling of plasmas involving tin. We obtained integrated and momentum transfer cross sections for elastic scattering alongside integrated and differential cross sections for excitations to the 5p^{2}, 5p6s, 5p5d and 5p6p manifolds from the ground and first four excited states for projectile energies ranging from 0.1 to 500 eV. Total ionisation cross sections were obtained for the ground and first four excited states, including contributions from direct ionisation of the valence 5p shell and the closed 5s shell, and contribution from excitation auto-ionization. The tin atom is described by a model with two 5p-electrons above a frozen [Kr]4d^{10}5s^{2} core. Phenomenological one- and two-electron polarization potentials were used to best fit the calculated energy levels and optical oscillator strengths to experiment. Convergence was tested using several models with the number of target states included in the calculations varying from 33 to 399. For total ionisation cross sections, we find good agreement with experiment and other theories while for excitation cross sections the agreement is mixed. |
Tuesday, October 4, 2022 8:45AM - 9:00AM |
GT1.00003: Toward a frame-work for calculating comprehensive electron collision data sets for low-temperature plasma modeling: Vibrationally resolved cross sections of N_{2}, N_{2}^{+} and O_{2} Mark C Zammit, James Colgan, Christopher J Fontes, Julie Jung, Amanda J Neukirch, Brett S Scheiner, Charles G Durfee, John W Rose, Matthew Webb, Eddy M Timmermans Modeling low-temperature non-equilibrium plasmas with collisional-radiative, Monte Carlo collision and Boltzmann equation solver codes requires comprehensive sets of collision cross sections. However, these cross sections are particularly difficult to calculate for low- temperature plasmas, where near-neutral atoms and molecules, and excited state species are abundant. As a result, in general, comprehensive sets of cross sections do not exist in the literature.
Recently we have developed a universal frame-work for quickly calculating electron-impact excitation and ionization cross sections of ground and excited state diatomic molecules and diatomic molecular ions. Here we present vibrationally resolved sets of cross sections for N_{2}, N_{2}^{+} and O_{2}. |
Tuesday, October 4, 2022 9:00AM - 9:15AM |
GT1.00004: Maximum angular momentum transfer in electron-atom collisions Mariusz Piwiński, Lukasz Klosowski The electron–atom collision process can be fully described by determining complex scattering amplitudes, which depend on collision energy and scattering angle. In the case of electronic excitation from the S to P atomic state, such data can be obtained using the electron-photon coincidence technique. The results of such experiments are usually presented as Electron Impact Coherence Parameters (EICP), which describe the angular distribution of the electron charge cloud of an excited P state. They are the alignment angle of the electron charge cloud (γ), its shape parameter (P_{L}), angular momentum transfer (L_{perp}) and coherence parameter (P^{+})[1]. |
Tuesday, October 4, 2022 9:15AM - 9:30AM |
GT1.00005: electron impact excitation cross sections of neutral molybdenum : cross sections of interest in plasma modeling Indhu Suresh, Psnsr R Srikar, Priti Priti, Rajesh Srivastava, Reetesh K Gangwar Molybdenum plays a vital role in plasma-mediated nuclear fusion devices such as International Thermonuclear Experimental Reactor (ITER), as it can be used to make first mirrors in the optical diagnostic systems. The present work calculates the electron impact excitation (EIE) cross sections for the fine structure resolved transitions in the Molybdenum (Mo) atom from the manifolds, 4d^{5}5s, 4d^{4}5s^{2} , 4d^{6} and 4d^{5}5p to the manifolds 4d^{5}5s, 4d^{4}5s^{2} , 4d^{6} , 4d^{5}5p, 4d^{4}5s5p, 4d^{5}5d, 4d^{5}6s, 4d^{4}5s6s, and 4d^{5}7s. The calculations are performed using the multi-configurational Dirac-Fock (MCDF) wavefunctions and the relativistic distorted wave (RDW) approximation. The calculated oscillator strengths and transition probabilities are compared with the NIST atomic database for validating the reliability of the obtained cross sections. And EIE cross sections are compared with the available calculations and measurements reported by Badnell et al.,(J. Phys. B29,3683(1996)), Bartschat et al.,(J. Phys. B35,2899(2002)) and Smyth et al., (Phys.Rev.A96,042713(2017)). The cross sections are reported for the projectile electron energy ranging from threshold to 500 eV. The present consistent cross sections are required for developing collisional radiative models and thereby performing the spectroscopic characterization of non-equilibrium plasmas. The detailed results along with methodology and discussion will be presented at the conference. |
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