Preferential heating of electrons traveling in one direction can support a current even in the absence of a dc electric field. An immediate implication is that even waves which carry little toriodal momentum, such as electron cyclotron waves, may be attractive as a means for generating steady-state toroidal current in a tokamak. An analytical expression is derived for the current generated per power dissipated, which agrees remarkably well with numerical calculations.

• Received 16 April 1980

DOI:https://doi.org/10.1103/PhysRevLett.45.720