Magnet Alignment in the Mirror Fusion Test Facility-B Tandem Mirror

Magnet alignment in the Mirror Fusion Test Facility-B (MFTF-B) tandem mirror has been measured by electron beams propagated along the axis. A least-squares fit to the data has been obtained by use of singular-value decomposition techniques. This fit determines the positions of the magnets that sensitively effect displacements of the field lines from alignment and, thus, the net geodesic curvature that drives radial transport. The magnets are determined to be aligned accurately enough that the MFTF-B trim coils can correct the field errors and reduce the neoclassical radial transport to an acceptable value.