ExB shear and precession shear induced turbulence suppression and its influence on electron thermal internal transport barrier formation

摘要

E x B shear and trapped electron precession shear induced suppression of micro-turbulence is studied in general tokamak geometry. A systematic derivation of a two-point equation for trapped electron related turbulence based on modern bounce kinetic formalism is performed. A two-point nonlinear analysis yields the new criterion for the turbulence suppression vertical bar omega(ExB) + omega(PS)vertical bar > Delta omega(T), where Delta omega(T) is decorrelation rate of the ambient turbulence, omega(ExB) is E x B shearing rate in general tokamak geometry [Hahm and Burrell, Phys. Plasmas 2, 1648 (1995)], and omega(PS) is precession shearing rate. Therefore, both E x B shear and trapped electron precession shear can contribute to suppression of turbulence, and these effects can either add up or subtract depending on their relative sign. This result provides a better understanding of electron thermal internal transport barrier formation under various conditions. Published by AIP Publishing.