Magnetic field perturbations due to a hole in a conducting wall on the ZT-40M reversed-field pinch

Abstract

Radial magnetic field components were measured near a pump port on the ZT-40M Reversed-Field Pinch experiment. The measurements show radial components which are about 20% of the equilibrium field at the wall during the setup portion of the discharge. During the flat top of the toroidal current, radial components, ∼8% of the total field at the wall, are measured. A two-dimensional field diffusion calculation was done to understand the measurements. This gave results which were in basic agreement with the measurements at the position of the probe.