A controlled welding arc is an up-and-coming research area for high-efficiency and high-precision wire arc additive manufacturing. This numerical simulation demonstrates that an alternating external cusp magnetic field (ECMF) can compress the arc. This is the result of the reversal of the Lorentz force direction caused by the reversal of the magnetic poles. https://www.parisnaturalfoodes.shop/product-category/ph-paper/