Electron current excited in a toroidal plasma upon the injection of fast neutrals

The excitation of an electron current by a beam of fast ions in a toroidal plasma is analyzed. Collisions are assumed to be infrequent (the plasma is assumed to be in the banana regime), and the ion beam velocity is assumed to be much lower than the electron thermal velocity but higher than the thermal velocity of the plasma ions. The relationship between the beam current and the electron current is derived. Toroidal effects strongly influence the current excited in the plasma by the beam. Under certain conditions, they can change the direction of this current far from the magnetic axis.