Time Response of Arc Driven by Alternating Magnetic Field

The expanded arc has been developed by imposing an alternating magnetic field to the arc. The time response of the arc motion is investigated in the present work. The alternating magnetic field in the form of B=Bo cos(ωt + φ) is assumed to be imposed perpendicularly to the arc. Physical/mathematical models on the oscillatory motion of the plasma gas are described. Solving a set of three 3rd order linear ordinary differential equations, the trajectories of the plasma gas from the torch to the anode are obtained for various frequencies of the alternating magnetic field. Numerical analyses reveal that the amplitude of the oscillatory arc motion remains constant for small ω but it reduces with the increase of the frequency for large ω. Theoretical predictions are compared with experimental results. It is confirmed that their agreements are good