NSTX produced a spherical plasma with a hole through its center (a "cored apple" profile; see MAST), different from the doughnut-shaped (toroidal) plasmas of conventional tokamaks.
In contrast to the usual toroidal shape, NSTX generated a spherical plasma with a central hole (resembling a cored apple), differing from the conventional doughnut-shaped plasmas of standard tokamaks used for confinement.