Scaling of Toroidal Plasma Confinement Times

We suggest an alternative scaling law with which to judge toroidal confinement experiments. A phenomenological model of ($\overrightarrow{E}\times \overrightarrow{B}$)-driven convective cells of diameter comparable with the minor diameter of the plasma is used to derive a new scaling law for plasma containment time. Using new experimental results we show that this law describes a large number of toroidal experiments better than does earlier interpretation in terms of "Bohm" diffusion.