Neoclassical current drive by waves with a symmetric spectrum

It is shown that plasma waves need not have an asymmetric spectrum in order to produce an electric current in a plasma embedded in a curved magnetic f ield. For instance, in a toroidal plasma, up-down asymmetric electron-cyclo tron heating drives a toroidal current even if there is no net wave-particl e momentum transfer and the wave field does not interact preferentially wit h electrons travelling in any one direction. The resulting current drive ef ficiency is calculated and is found to be smaller than that of the conventi onal current drive mechanism in the banana regime, but not insignificant in the plateau regime. (C) 2001 American Institute of Physics.