Numerical Simulation of Temperature Fields in a Direct-Current Plasma Torch

A Review of Self-Seeded Germanium Nanowires: Synthesis, Growth Mechanisms and Potential Applications

“…Synthesising Ge nanostructures via arc discharge presents serious challenges due to Ge low melting and boiling points (938 and 2850 °C, respectively) and a fairly high electrical resistivity at room temperature (40 Ω cm in bulk Ge with less than 10 13 impurity atoms per cm 3 ) [ 157 ]. High electrical resistivity creates problems when the electric arc ignition takes place, which is not suitable for the transmission of large currents [ 158 , 159 ]. However, promising results have recently been achieved for the growth 1D Ge nanostructures without the involvement of any foreign metal catalysts.…”

Numerical Analysis of Thermal Flow Dynamics of Arc Plasma and Molten Pool in Hollow Cathode Arc Welding with Oxygen Content

“…However, the industrial applications of HCAW are limited since there is still a lack of complete understanding regarding the dynamics of the arc and the molten pool in HCAW; only Tashiro et al [8] established a numerical model to analyze the characteristics of HCAW arc plasma, indicating that the maximum velocity (50 m/s) and arc temperature (11,000 K) are 25% and 60% of these in traditional GTAW with a solid cathode, while the influence of an argon arc on the weld pool is not discussed. Saifutdinov et al [9] established a numerical simulation model to analyze the main characteristics of DC plasma torches, and in particular, the self-consistent determination of the distribution of temperature fields in electrodes. Margarita et al [10] demonstrated that the self-consistent coupling of a cathode and LTE plasma submodel is advantageous in the modeling of plasma spray torches.…”

“…As shown in Figure 1a, a 19 mm length hollow cathode with an inner radius of 1.5 mm and an outer radius of 3 mm was connected to a current inlet B; the square current wave form ranged from 200 A to 400 A with 900 Hz and an EN ratio of 0; A, the Q235 low-carbon steel (O~0.1 wt%), was connected to the ground F. The flow rate of the mixture gas at inlet A1 was 0.01 L/min, while the flow rate of the mixture gas at inlet A2 (with an outer diameter of 5 mm) was 15 L/min; the properties of the hollow cathode were determined by temperature, and the properties of the mixture gas and steel were determined by temperature, level set function, and phase change coefficient. The Maxwell and heat transfer equations with Joule heat and radiation loss were calculated in the whole domain, while all the momentum sources (shear stress from the plasma jet and the surface tension with the Marangoni effect subjected to temperature and oxygen activity: Lorentz force, Darcy damping force, buoyancy force, and gravity) [3,[8][9][10]16,17] were implemented in the momentum equations calculated in the fluid domain. LTE-diffusion approximation [18] was used at both the interfaces between electrodes and the mixture gas, featuring level set delta functions(full derivation in Equations S1).…”

“…The physical properties of the mixture gas (Ar + O2), hollow cathode, and the solid and liquid phase of the Q235 low-carbon steel and welding parameters can be found in Table 1. The Maxwell and heat transfer equations with Joule heat and radiation loss were calculated in the whole domain, while all the momentum sources (shear stress from the plasma jet and the surface tension with the Marangoni effect subjected to temperature and oxygen activity: Lorentz force, Darcy damping force, buoyancy force, and gravity) [3,[8][9][10]16,17] were implemented in the momentum equations calculated in the fluid domain. LTEdiffusion approximation [18] was used at both the interfaces between electrodes and the mixture gas, featuring level set delta functions(full derivation in Equation (S1)).…”

Modeling and Comparative Analysis of Atmospheric Pressure Anodic Carbon Arc Discharge in Argon and Helium–Producing Carbon Nanostructures

“…At present, self-consistent models of arc discharges have been formulated, which describe, in a unified way, the processes occurring in the discharge gap and in electrodes and take into account conjugated effects [ 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 ]. Such models are presented both in one-dimensional and two-dimensional formulations.…”