An Enhanced Nonlinear Critical Gradient for Electron Turbulent Transport   due to Reversed Magnetic Shear
  The first nonlinear gyrokinetic simulations of electron internal transport barriers (e-ITBs) in the National Spherical Torus Experiment show that reversed magnetic shear can suppress thermal transport by increasing the nonlinear critical gradient for electron-temperature-gradient-driven turbulence to three times its linear critical value. An interesting feature of this turbulence is nonlinearly driven off-midplane radial streamers. This work reinforces the experimental observation that magnetic shear is likely an effective way of triggering and sustaining e-ITBs in magnetic fusion devices. 
J. L. Peterson (1), G. W. Hammett (1), D. R. Mikkelsen (1), H. Y. Yuh   (2), J. Candy (3), W. Guttenfelder (1), S. M. Kaye (...
physics.plasm-ph