Methods of Radio-Frequency Current Drive

Radio-frequency waves can penetrate thermonuclear plasmas, depositing momentum and energy with great selectivity: in select resonant ions or electrons, in select resonant regions, and with select momentum. When these waves are injected asymmetrically with respect to the toroidal direction in tokamaks, they can drive a toroidal electric current. The advantage of driving this current by waves is that a tokamak reactor might then be operated in the steady state. This lecture will review the elementary processes of wave-particle interactions in plasma that underlie the current drive effect.