Numerical study of the dissipative trapped-electron instability in tokamaks

The dispersion relation for the dissipative trapped-electron mode including the effects of magnetic shear, finite ion Larmor radius, banana-plateau velocity space separation, magnetic curvature drift resonance, ion-ion collisions, etc. is used to examine the plasma stability of recent tokamak experiments. Regimes of importance of various effects in these experiments are also discussed. Instabilities mostly occur at kθ ρi ∼ 1, where kθ is the azimuthal wave number and ρi is the ion Larmor radius. The often used anomalous heat conduction coefficient, , predicts losses comparable to those observed in TFR, ST, and ATC.