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

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 ##IMG## [http://ej.iop.org/images/0741-3335/54/12/125006/ppcf417257ieqn001.gif] {$\sqrt{H_{\rm e}H_{\rm i}}$} , where H e and H i 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.