Submerged arc discharge in liquids has shown to be a promising method to synthesize a wide variety of nanomaterials. However, it requires an accurate arc current control to ensure the desired purity and structure of the products. A fluctuating arc current increases the dispersion in size distribution, as well as in the obtained nanoparticles structure pattern. Consequently, the arc current stability is essential to ensure the product homogeneity and quality. A system which ensures high stability of the arc discharge is presented. It has three basic elements: an electrode gap micropositioning system controlled by a feedback arc current measurement, a current’s stabilization element and a data acquisition system to record the magnitudes of the relevant physical parameters. The most suitable algorithm for micropositioning system was determined. The utilization of a step motor gave an additional advantage in measuring the anode displacement. The employed stabilization element improves the current and power stability by 4 and 2.7 times, respectively. The data acquisition system allows taking control and information about the relevant parameters of the process and the interaction between them. This system, based on direct arc current measurement, is superior in terms of achieving higher stability and current sensibility, to the ones based on arc voltage or arc light emission. It is also an adaptable tool to carry on further experiments.

Many papers, in which the submerged arc discharge (SAD) method in nanoparticle synthesis was used, reported similar operating parameters, but different electrode erosion rate values, different yields and purities of the obtained nanostructures, and a different sort of contaminants present in the synthesis. Analyzing these articles, we found insufficient attention to ensure the arc power stability, which is a key factor guaranteeing the product homogeneity and quality. This paper presents an analysis of different control strategies, remarks their advantages and drawbacks, and proposes the most appropriate technique to be used in SAD. The most appropriate technique is proposed from the SAD stabilization method analysis.

Submerged electric arc discharge in liquids has shown to be a promising method for synthesizing a wide variety of nanomaterials. However, it requires an accurate current stability control to ensure the desired purity and structure of the products. The discharge stability control through light emission has been previously studied, but still requires further investigation to clarify the influence of some parameters. The present work has studied the solution's transmittance variation over time, the correlation between the arc light emission and the arc current, and the feasibility of controlling the arc current by using a specific wavelength of the arc light spectrum. Several limitations of the optoelectronic control were found at low currents (I < 50 A).