Trapped electron correction to beam driven current in general tokamak equilibria

In the limit that the electron thermal velocity greatly exceeds the fast ion velocity for electrical currents driven by neutral beams, the trapped electron correction to the Ohkawa current and the electron density gradient contribution to bootstrap current are shown to share the same transport coefficient in the banana regime. Therefore, existing analytic expressions for the bootstrap coefficient valid for arbitrary aspect ratio tokamaks can also be used to calculate the trapped electron effect. (C) 1997 American Institute of Physics. [S1070-664X(97)01611-X].