Characterization of a copper spark discharge plasma in argon atmosphere used for nanoparticle generation

Abstract

Spark discharge nanoparticle generation is a dynamically developing application of discharge plasmas. In the present study a spark plasma used for nanoparticle generation is characterized by means of spatially and temporally resolved optical emission spectroscopy (OES) supplemented by fast imaging. The data acquired during the generation of copper nanoparticles in argon ambient is used to describe the spatial and temporal evolution of the species in the spark gap and to derive plasma parameters such as excitation temperature and electron concentration on one hand, and the concentration of the Cu species eroded by a single spark on the other. It is shown that temporally and spatially resolved OES together with a simple equilibrium model are efficient tools to estimate the characteristics of the spark discharge plasma that typically exists in spark discharge nanoparticle generators.

Full range tuning of the composition of Au/Ag binary nanoparticles by spark discharge generation

“…Typically, SDGs are built with-sometimes variable-capacitance in the range of ca. 1-30 nF 28,30,44 , which determines that the transition between the oscillatory and unipolar regimes occurs at a maximum of about 11 Ω. As it was mentioned earlier, the lower limit of the total resistance is defined by the minimum resistance of the circuit and the spark plasma, which in total is usually not much less than 1 Ω.…”

From plasma to nanoparticles: optical and particle emission of a spark discharge generator

“…Atomic lines of the electrode material (Cu) are also present with much smaller relative intensity, which is a common A c c e p t e d M a n u s c r i p t feature of spectra acquired in the SDG. This relation reflects that the number concentration of the gas species exceeds the number concentration of the electrode material in the spark gap by several orders of magnitude (Kohut et al 2017).…”

“…The intensity of a spectral line depends on the temperature and the concentration of the given species (see the Temperature calculation section in the Supplementary data for more details). Assuming that the spark plasma is in local thermodynamic equilibrium (LTE) (we recently proved that LTE holds in the afterglow stage of a spark used for Cu NP generation in Ar atmosphere (Kohut et al 2017)) it follows that nitrogen and metal atoms, along with every other species in the same spatial region, have the same temperature. This suggests that the difference between figure 7A and B should be attributed to the concentration difference of nitrogen and copper.…”

“…OES provides direct information on the atomic and ionic species which populate the spark plasma right before the NP nucleation process. Time-resolved emission spectra can be used to derive key plasma properties, such as the temperature and electron concentration (Kohut et al 2017), which are crucial for the parametrization and validation of various particle growth models. In the present work, time resolved OES was also used to identify the main stages of the material erosion and to calculate the quenching rate of the generated metal vapour.…”

Surface features and energy considerations related to the erosion processes of Cu and Ni electrodes in a spark discharge nanoparticle generator

“…It is an early observation that the transition from a single crater to multiple craters correlates with the current increase in arc discharges (Cobine & Gallagher, 1948). Due to the very low resistance of the discharge loop of the SDG, peak currents in the order of several hundred amperes can be reached (Kohut, Galbács, Márton, & Geretovszky, 2017;Palomares et al, 2016), which is well above the typical threshold currents (in the order of a few amperes) associated with the transition from a single arc crater to multiple craters (Cobine & Gallagher, 1948). In order to investigate the role of the peak current, we modified our SDG circuitry by adding extra resistance (a ca.…”