Stationary Density Profiles in Alcator C-mod

In the absence of an internal particle source, plasma turbulence will impose an intrinsic relationship between an inwards pinch and an outwards diffusion resulting in a stationary density profile as determined by the turbulent equipartition (TEP) theory. The Alcator C-mod tokamak utilizes RF heating and current drive so that fueling only occurs in the vicinity of the separatrix. Density is determined from Thomson scattering. Discharges that transition from L-mode to I-mode are seen to maintain a stationary profile. For reversed shear discharges maintained by non-inductive current drive ($V_{loop}\approx 0$) a drop of density in the vicinity of the axis is consistent with an observed rise in q, although error in the measurement precludes making this observation definitive.