Profiles of pressure in many tokamaks adhere to the well-established model of canonical profiles proposed by Coppi and developed by Razumova, Dnestrovskii, and others. To predict parameters of future tokamaks, the pressure should be presented as a product of density and temperature. We averaged 162 profiles and observed that the radial profile of electron temperature depends on the radial profile of electron density according to the simple formula T_e(ρ) =const n_e(ρ)^1.65. The analytical model of a density attractor, also known as Turbulent EquiPartition (TEP), assumes that plasma is frozen-in in poloidal magnetic field. The resulting density profile depends on the specific poloidal magnetic volume, n_e(ρ)v(ρ)=const. The TEP model and the mechanism of particle pinch were previously confirmed in large aspect ratio tokamaks TCV and JET. Here, we examined the density profiles in a spherical tokamak in hot ion mode and identified the best fit as n_e(ρ)v(ρ)^1.06=const. The proposed model of neo-canonical profiles predicts electron temperature and density profiles in assumption of a known magnetic configuration. It remains unclear which part of neo-canonical profiles is more rigid - pressure, density, or temperature - or it depends on a tokamak operating regime. The future will reveal whether this model can be extrapolated to ignition parameters or not.

(a) Dependence of local electron density normalized on average density on specific poloidal volume (b) Dependence of local electron temperature on local electron density normalized on average temperature and density. The region of turbulent transport   is selected by green.

G.S. Kurskiev, V.V. Yankov, V.K. Gusev, N.S. Zhiltsov, E.O. Kiselev, A.K. Kryzhanovskii, V.B. Minaev, I.V. Miroshnikov, Yu.V. Petrov, N.V. Sakharov,
V.V. Solokha, A.Yu. Telnova, N.V. Teplova, E.E. Tkachenko, G.A. Troshin, E.A. Tyukhmeneva, P.B. Schegolev
JETP Letters 119, issue 1 (2024)