A model theory of inward pinch and peaked density profile of ohmic discharges in the tokamak is presented. Ion anomalous viscosity in the presence of sheared rotation causes the drift across the magnetic field. Radial electric field, Er, can cause an inward pinch of electrons as well. The ratio of viscosities and the diffusion coefficient, the Prandtl number, determines the structures of Er and the density profile n(r) in a stationary state. In viscous plasmas, peaked profiles of both density and rotation velocity are expected. Reduction of edge neutrals changes the boundary condition and can induce further density peaking. Change of dEr/dr propagates into the center, causing ion viscous heating associated with the damping of velocity shear.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)