# Two-dimensional electric current effects on a magnetized plasma in contact with a surface

A.E. Shumack, H.J. de Blank, J. Westerhout, G.J. van Rooij

Significant electric fields both parallel and perpendicular to a magnetic field have been observed and modeled self-consistently in an ITER divertor relevant plasma–wall experiment. Due to magnetization, electric current is found to penetrate the plasma beam outside of the cascaded arc plasma source with a length scale proportional to $\sqrt{H_{\rm e}H_{\rm i}}$ , where He and Hi are the electron and ion Hall parameters, respectively. Plasma rotation measurements and chemical erosion profiles at a carbon target demonstrate that for a sufficiently well-magnetized plasma, a current through the target causes plasma–wall sheath potentials to significantly increase in a region of net ion collection while for the conditions studied, regions of net electron collection remain unaffected. The plasma–wall sheath profile at the target has been characterized experimentally as a function of negative target potential.