An alternative analysis of some recent diffusion experiments on the large plasma device

The results of a recent numerical analysis of a diffusion experiment on the large plasma device (LAPD) [Maggs et al., Phys. Plasmas 14, 052507 (2007)] are re-examined. A simplified analytic solution of the transport equations is obtained by including previously omitted contributions to the transport. This solution strongly suggests that an accurate determination of the perpendicular diffusion coefficient would be very difficult in the specific LAPD experimental arrangement, due to near-cancellation of large terms. Thus, caution should be exercised in claiming that Bohm diffusion, or its suppression in the presence of a large applied radial voltage, has been observed.