BEGIN:VCALENDAR VERSION:2.0 PRODID:-//linuxsoftware.nz//NONSGML Joyous v1.4//EN BEGIN:VEVENT SUMMARY:Monte Carlo Algorithms for Low-Temperature Plasmas DTSTART:20231109T100000Z DTEND:20231109T120000Z DTSTAMP:20260622T034830Z UID:a0baebca-04e6-4a5c-a271-f8098522374f SEQUENCE:1 CREATED:20231020T102811Z DESCRIPTION:Abstract The main aim of this thesis is to develop and employ Monte Carlo (MC) modelling techniques for the investigation and taming of low-temperature plasmas (LTPs). MC methods simulate physical systems by tr acking the temporal of evolution of test particles. The stochastic evoluti on is performed by generating random numbers sampled from distributions th at emulate the underlying physics. In Chapter 2\, we present a MC method f or solving the complex chemical kinetics of heavy species in LTPs. Additio nally\, novel variance reduction methods are developed to improve the desc ription of minority species without impacting computation time. In Chapter 3\, we present the first version of the LoKI-MC open-source code\, which addresses electron kinetics in a gas discharge subjected to a uniform DC e lectric field. In Chapter 4\, we expand the LoKI-MC capabilities to includ e anisotropic scattering in any collision type. Moreover\, we demonstrate that the inclusion of anisotropic scattering in rotational collisions with H2O molecules is fundamental to obtain accurate agreement between modelli ng and experiment. In Chapter 5\, we extend the formulation to configurati ons involving AC/DC electric and DC magnetic fields. The code is thoroughl y verified\, and novel benchmark calculations are produced. Additionally\, we analyze the impact of magnetic fields in detail\, distinguishing betwe en configurations with DC and AC electric fields. Finally\, in Chapter 6\, we consider the rigorous time-dependent MC solution as the gold standard to evaluate the accuracy of two common assumptions for solving space- and time- dependent electron kinetics: the local-field approximation (LFA) and the local-energy approximation (LEA). The study focuses on homogeneous el ectron kinetics in nanosecond-pulsed discharges. It is observed that the L EA generally provides more accurate results than the LFA. In general\, the methods presented in this thesis allowed for a better understanding of LT Ps and an assessment of the accuracy of common approximations used in LTP modelling. LAST-MODIFIED:20231020T102811Z LOCATION:Anfiteatro PA3 (Piso -1 do Pavilhão de Matemática) URL:http://df.vps.tecnico.ulisboa.pt/pt/eventos/monte-carlo-algorithms-for -low-temperature-plasmas/ X-ALT-DESC;FMTTYPE=text/html:

Abstract

The main aim of this thesis is to develop and e mploy Monte Carlo (MC) modelling techniques for the investigation and tami ng of low-temperature plasmas (LTPs). MC methods simulate physical systems by tracking the temporal of evolution of test particles. The stochastic e volution is performed by generating random numbers sampled from distributi ons that emulate the underlying physics. In Chapter 2\, we present a MC me thod for solving the complex chemical kinetics of heavy species in LTPs. A dditionally\, novel variance reduction methods are developed to improve th e description of minority species without impacting computation time.

In Chapter 3\, we present the first version of the LoKI-MC open-sour ce code\, which addresses electron kinetics in a gas discharge subjected t o a uniform DC electric field. In Chapter 4\, we expand the LoKI-MC capabi lities to include anisotropic scattering in any collision type. Moreover\, we demonstrate that the inclusion of anisotropic scattering in rotational collisions with H2O molecules is fundamental to obtain accurate agreement between modelling and experiment. In Chapter 5\, we extend the formulatio n to configurations involving AC/DC electric and DC magnetic fields.

The code is thoroughly verified\, and novel benchmark calculations ar e produced. Additionally\, we analyze the impact of magnetic fields in det ail\, distinguishing between configurations with DC and AC electric fields . Finally\, in Chapter 6\, we consider the rigorous time-dependent MC solu tion as the gold standard to evaluate the accuracy of two common assumptio ns for solving space- and time- dependent electron kinetics: the local-fie ld approximation (LFA) and the local-energy approximation (LEA).

The study focuses on homogeneous electron kinetics in nanosecond-pulsed d ischarges. It is observed that the LEA generally provides more accurate re sults than the LFA. In general\, the methods presented in this thesis allo wed for a better understanding of LTPs and an assessment of the accuracy o f common approximations used in LTP modelling.

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