Determining Gas Temperature and Electron Density in Spark Discharge: Insights Into Nanoparticle Nucleation and Growth in the Gas Phase

QINGQING FU, Ji Yung Ahn, Griffin Trayner, Tasnim Akbar Faruquee, Yiwei Zhu, Marien Simeni Simeni, Christopher J. Hogan, University of Minnesota

     Abstract Number: 81
     Working Group: Nanoparticles and Materials Synthesis

Abstract
Non-equilibrium gas-phase synthesis processes, such as spark discharge and non-thermal plasma synthesis, enable the production of nanoparticles with high purity and a variety of material compositions. Their continuous operation presents promising potential for scaling up from the laboratory to industrial scale. However, synthesizing nanoparticles in a controlled manner via gas-phase methods can be challenging without trial-and-error experimentation, as the mechanisms of particle nucleation and growth in the gas phase are not yet fully understood.

In this study, towards improved understanding of non-equilibrium gas phase synthesis processes we designed a spark discharge generator to produce iron nanoparticles. The effects of process parameters, including applied power (2.5–10 mA), gas flow rate (1–5 slpm), and electrode distance (1–5 mm), on particle properties were systematically investigated. The resulting particle primary size, morphology, and size distribution were characterized using transmission electron microscopy (TEM) and a scanning mobility particle sizer (SMPS), respectively. In addition, optical diagnostics, including optical emission spectroscopy (OES) and coherent anti-Stokes Raman spectroscopy (CARS), were applied to determine time- and spatially resolved gas temperature and electron density. These experimental results will be used as inputs and validation parameters for numerical simulations, contributing to a deeper understanding of particle nucleation and growth mechanisms.