Scaling of confinement with major and minor radius in the Tokamak Fusion Test Reactor

Plasma-size scans have been performed in the Tokamak Fusion Test Reactor to investigate the effect of major and minor radius upon energy confinement in high-recycling plasmas heated by neutral-beam injection. The major radius, minor radius, and aspect ratio were varied over a large range (a=0.4--0.9 m, R=2.08--3.2 m, R/a=2.8--8.0). The energy confinement measured with diamagnetic and kinetic diagnostics scales strongly with major radius, and weakly or negatively with minor radius.