AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
1D Nanodusty Pulsed Plasma Sectional Chemistry Model for the Study and Control of Particle Generation and Growth
CARLOS LARRIBA-ANDALUZ, Steven Girshick, University of Minnesota
Abstract Number: 517 Working Group: Aerosol Chemistry
Abstract Plasmas can be a valuable tool in the production of nanostructured materials if the formation, growth and transport of nanoparticles in reactive plasmas can be controlled. Plasmas containing nanoparticles are termed “nanodusty” and present impelling opportunities for nanosynthesis of materials such as silicon nanocrystals used in solar panels. The drawback is that particles of a few nm in size are difficult to detect in situ and characterize and thus require elaborate experimental systems as well as complicated numerical schemes. The modeling of low temperature plasmas for fundamental investigations and equipment design is challenged therefore by conflicting goals: 1)the need to address subtle physical phenomena and 2)the flexibility to expand a wide range of conditions. Here we try to numerically explore the ability of plasmas to produce nanocrystals by combining a silane low temperature plasma chemistry model with a nanoparticle sectional model. A 1D model simulates an RF capacitive argon plasma in a parallel-plate reactor with the injection of silane for nanoparticle formation. Spatial profiles of instantaneous electron and positive ion concentrations, electron temperature, plasma potential, and electric field are determined using a continuum formulation while nanoparticles are calculated using a Sectional Model that includes Coagulation, Nucleation, Surface Growth and Charging. A drift-diffusion approximation is applied to the electron, ion and nanoparticle flux. The combination of continuum and sectional models provide a fast and self-consistent reliable tool to study plasmas and their production of particles. We go a step further by looking into the possibility of controlling the size and particle production through pulsing and afterglow of plasmas. We will demonstrate that one can produce different sized nanoparticles by tuning the frequency and duty-cycles of the pulse. Simultaneously, we will show that the need to provide accurate chemistry is key to providing reliable results when compared with the experimental results.