Magnetic field approaches in dc thermal plasma modelling

Abstract

The self-induced magnetic field has an important role in thermal plasma configurations generated by electric arcs as it generates velocity through Lorentz forces. In the models a good representation of the magnetic field is thus necessary. Several approaches exist to calculate the self-induced magnetic field such as the Maxwell–Ampere formulation, the vector potential approach combined with different kinds of boundary conditions or the Biot & Savart (B&S) formulation. The calculation of the self-induced magnetic field is alone a difficult problem and only few papers of the thermal plasma community speak on this subject. In this study different approaches with different boundary conditions are applied on two geometries to compare the methods and their limitations. The calculation time is also one of the criteria for the choice of the method and a compromise must be found between method precision and computation time. The study shows the importance of the current carrying path representation in the electrode on the deduced magnetic field. The best compromise consists of using the B&S formulation on the walls and/or edges of the calculation domain to determine the boundary conditions and to solve the vector potential in a 2D system. This approach provides results identical to those obtained using the B&S formulation over the entire domain but with a considerable decrease in calculation time.

PTFE Vapor Contribution to Pressure Changes in High-Voltage Circuit Breakers

“…The basis of the model is presented below. Additional details on the equations set and boundary conditions can be found in [1], [2], and [15].…”

“…In this paper, the model already reported in [2] and [15] is used and completed. As numerous parameters can influence the changes in pressure and for ease of comparison with the experimental results, most parameters such as pin motion, current variation, and valve position (open/close) between the heating volume and the compression volume were determined by experimental measurements.…”

Effect of Electromagnetic Boundary Conditions on Reliability of Plasma Torch Models

“…As explained in Introduction, recent works examined the effect of the boundary conditions for the magnetic vector potential in the model of DC free-burning and constricted transferred arcs (Ref 14,37). They concluded that null flux of magnetic vector potential, at the boundaries inside the plasma torch and a null value at the outlet boundary (PVNF condition), can yield wrong predictions of the magnetic field when the null flux condition is applied on boundaries close to the arc core.…”

Influence of Copper Vapors in SF6 Plasma

“…This enables to obtain the radiative flux and its divergence. Additional details on the equations set and boundary conditions can be found in previous papers [5][6][7]. With copper vapours, specific source terms for ablation model have to be taken into account.…”