Date of Award
Spring 5-15-2023
Degree Name
Doctor of Philosophy (PhD)
Degree Type
Dissertation
Abstract
Nanoparticles in nonthermal plasmas (i.e., dusty plasmas) have been the subject of both great concern and great promise. For microelectronics fabrication, particles from nonthermal plasmas behave as a problematic system impurity; however, due to the interesting properties of the nanoparticles which can be synthesized in nonthermal plasmas, there has been much interest to develop nonthermal plasma-synthesized nanoparticles for a wide range of applications. Given this interest in nonthermal dusty plasma systems, understanding how systematic parameters affect dusty plasma systems is of great importance. As such, this work will focus on three particular phenomena: how systematic parameters affect nanoparticle formation, how forces which act on nanoparticles can cause them to be trapped within nonthermal plasmas, and how particles discharge in the effluent of a nonthermal plasma reactor. Particles can form in nonthermal plasmas via the condensation of gasses or via chemical transformation. Instead of particles, films also commonly form in nonthermal plasma reactors. Oftentimes, when the goal is to synthesize films, particles are not desired and vice-versa. The first aim of this work is to show how systematic parameters such as reactor size, pressure, and chemical composition control particle vs. film formation. Once particles form, they are subject to several forces in nonthermal plasmas. The second aim of this work is to show how particles can become trapped by electrostatic forces in nonthermal plasmas, which partially explains the monodisperse nature of nanoparticles synthesized in nonthermal plasmas and informs future approaches for synthesizing nanoparticles. While nanoparticles are in a plasma, they become highly negatively charged; however, they begin to neutralize as they leave the plasma glow. The third aim of this work is to show how the resulting particle charge may be modulated by varying reactor flow velocity and particle size. This control is necessary for controlling the trajectory of particles by generating electric fields, which is particularly important for particle capture.
Language
English (en)
Chair
Elijah Thimsen
Committee Members
Richard Axelbaum, Peng Bai, Rajan Chakrabarty, Kathy Flores,