Particle pinch in collisionless drift-wave turbulence

Nonlinear numerical simulations show that the particle flux from collisionless drift-wave turbulence is directed up-gradient for sufficiently high values of eta(e) = L-n/L-Te. This "particle pinch" results from the completely different perpendicular dynamics of slow (resonant) and fast (nonresonant) electrons, making it a genuinely kinetic effect which cannot easily be described by fluid models. Moreover, the linearly stable system self-sustains its turbulent state through a finite-amplitude (nonlinear) instability. Therefore, quasilinear estimates of turbulent transport caused by collisionless drift waves are practically useless and have to be replaced by nonlinear kinetic simulations like the present one. (C) 2000 American Institute of Physics. [S1070-664X(00)00802-8].