Characteristics of DC arcs in a multi-arc generator and their application in the spheroidization of SiO₂ *

Abstract

We investigate characteristics of multi-arc torches with three pairs of electrodes (three cathodes and three anodes) and their performance on the spheroidization of SiO2 powder. The effect of electrode arrangement, including adjacent pattern (AD pattern, adjacent electrodes powered by one power supply) and opposite pattern (OP pattern, opposite electrodes powered by one power supply), on the dynamics of arc plasma is investigated based on synchronous acquisition of electrical and optical signals. The results show that both the voltage and spatial distribution of each arc of multiple arcs are more stable compared with those of a single arc. The fluctuation of an arc in multiple arcs mainly comes from the small-scale arc-to-arc restrikes among multiple arcs. Moreover, these arc-to-arc restrikes occur more frequently among multiple arc columns in OP pattern than in AD pattern. Moreover, the high-temperature area of the central region of arc chamber in OP pattern is larger than that in AP pattern. For the spheroidization of SiO2 in this multi-arc generator, the spheronization degrees of plasma treated silica in OP pattern are at least 20% higher than those in AD pattern.

Dynamic characteristics of multi-arc thermal plasma in four types of electrode configurations

“…For example, the length of arc two elongated, while its voltage increased from the discharge time of 2 ms to 2.5 ms. During 10 ms of discharge time, shown in figure 4(b), the vibration of arc one was slight, resulting in less fluctuation of voltage. The high frequency burr signal shown on the voltage waveform was caused by the breakdown of arc-to-arc, which was discussed in our previous work [21].…”

Numerical simulation of anode heat transfer of nitrogen arc utilizing two-temperature chemical non-equilibrium model*

“…(5) Gravity and the effects of viscosity dissipation are negligible. (6) The electron and heavy-species temperatures are assumed in their own Maxwellian distributions. Therefore, the electron and heavyspecies energy equations are separately solved, and the energy exchange between electron and heavy-species is based on the elastic collision processes.…”

“…Understanding anode heat transfer is of great significance for the improvement of arc processing performance and extension of arc device lifetime. [1][2][3][4][5][6] Considerable studies of heat transfer between plasma and anode have been conducted for argon free-burning arc. [7][8][9] Compared with argon, nitrogen is a shielding gas with good protection, cheap cost and better energy source property, which is usually used in gas tungsten arc welding.…”

Drift characteristics and the multi-field coupling stress mechanism of the pantograph-catenary arc under low air pressure

“…As a sliding electrical contact material, carbon-copper electrodes have high current transmission efficiency, low contact resistance, and excellent crocking resistance, as they are widely implemented in many fields, such as rail transportation and aerospace. [1][2][3][4][5] A carbon-copper electrode is the core element of a pantograph-catenary sliding electrical contact system in the field of rail transit, and it is also subjected to vibration impact, which leads to the arcing phenomenon occurring frequently. According to statistics, the fault caused by pantograph-catenary arcs is the main factor that threatens the power supply's safety, and the loss is very serious.…”