Effect of the Trapped-Particle Instability on Toroidal Plasma Confinement

A stability condition is derived for the trapped-electron instability which is valid in both the collisional and collisionless regimes. This instability arises from wave-particle interaction between the perpendicular phase velocity of the waves and the gradient-B drift velocity of the electrons. The stability condition is applied to the FM-1 spherator and ST and PLT tokamaks.