Plasma parameters of microarcs towards minuscule discharge gap

Abstract

This paper describes the behaviour of the plasma parameters of microarcs generated between a cooled copper anode and a ceriated tungsten cathode by means of a one-dimensional unified non-equilibrium model for gap lengths between 15 and 200 μm and current densities from 2 × 10 5 up to 10 6 A/m 2. The results obtained show that the decrease of the gap length to a few tens of micrometres for a given current density results in a progressive shrinking of the quasi-neutral bulk in the microplasma and its complete disappearance. The decrease of the gap length further leads to an increase of the discharge voltage and the electron temperature and to slightly less heating of the gas.

Unraveling Oxygen Transfer Behavior in Submerged Arc Welding Using CaF2-SiO2-CaO Fluxes

“…Mitra et al [8,23,24] presumed that a dynamic O layer forms at the metal-plasma interface, effectively preventing the alloy elements from reaching the interface, as illustrated in Figure 1b. The plasma parameters, including temperature, have been well discussed in previous findings [25,26].…”

Introduction and verification of FEDM, an open-source FEniCS-based discharge modelling code

“…Note that placing the diffusion coefficient inside the gradient operator for electrons originates from the derivation of the driftdiffusion approximation (see [23,24]) and is necessary to be consistent with the method of determination of the electron transport coefficients. The definition of the electron transport coefficients is crucial for the accuracy of a fluid model for nonthermal plasmas [24,55,56]. To be able to apply these coefficients as function of the mean electron energy u e in accordance with the LMEA [24], the set of equations ( 1)-( 4) is extended by the electron energy balance equation…”

Reversal of the electric field and the anode fall in DC arcs in air during contact opening

“…A field reversal in the near-anode region in DC arcs has been related to the requirement for current continuity [3,4]. Unified modelling studies of microdischarges have predicted a negative anode fall in argon [9][10][11] and a positive anode fall in nitrogen [12] for a wide range of current density and gap lengths [13]. It is worth noting that the unified models of microarcs are currently mostly limited to one dimension [9][10][11][12][13] since they resolve the entire plasma region including the tiny regions of space charge adjacent to the electrodes.…”

“…Unified modelling studies of microdischarges have predicted a negative anode fall in argon [9][10][11] and a positive anode fall in nitrogen [12] for a wide range of current density and gap lengths [13]. It is worth noting that the unified models of microarcs are currently mostly limited to one dimension [9][10][11][12][13] since they resolve the entire plasma region including the tiny regions of space charge adjacent to the electrodes. The knowledge of the spatial structure and properties of these regions is important to the appropriate formulation of the boundary conditions in multi-dimensional models.…”