Experimental Tests of Confinement Scale Invariance on JET, DIID, ASDEX Upgrade and CMOD

where qc is a convective heat flux and χB = T/B is the Bohm diffusivity; the dimensionless function␣ F depends on dimensionless plasma parameters like normalised Larmor radius ρ*, collisionality ν*, β, safety factor qψ, inverse aspect ratio e elongation κ. The function F depends on which equations (Vlasov, Boltzmann, MHD etc.) are chosen to describe confinement [2]; atomic physics and radiation effects are absent from Eq. (1). If the convective flux is related to a diffusivity and density gradient in the same manner as the diffusive flux then scale invariance implies that heat flux (single fluid for simplicity) can be scaled, say via minor radius, from one Tokamak to another to yield scaled density and temperature profiles; in such a scaling of dimensional parameters (a, n, T, I, B....) the function F and its arguments remain invariant. The global analogue of Eq. (1) involves a global average G of the unknown function F [3] and global averages of the dimensionless parameters in Eq. (1) (for definitions of etc. see [3]) e m B G q E N τ ρ ρ ν β e κ = ( ) − * * * / , , , , , ... 2 95 (2)