Neoclassical nature of the radial electric field at the low-to-high confinement transition

The radial electric field E-r at the tokamak plasma edge is simulated both with a two-dimensional (2D) fluid code solving the most complete system of transport equations and with five-dimensional (three-dimensional in configuration space and 2D in velocity space) Monte Carlo particle following code. At low to high confinement transition conditions, the (E) over right arrow (r) x (B) over right arrow shearing rate is found to be high enough for turbulence suppression even though the field is essentially neoclassical. Here, (B) over right arrow is the magnetic field. No bifurcation of E-r is found. (C) 2003 American Institute of Physics.