Alfvén wave experiments in the Phaedrus‐T tokamak

Heating in the Alfvén resonant regime has been demonstrated in the Phaedrus‐T tokamak [Fusion Technol. 19, 1327 (1991)]. Electron heating during injection of radio‐frequency (rf) power is indicated by a 30%–40% drop in loop voltage and modifications in sawtooth activity. Heating was observed at a frequency ωrf≊0.7Ω i on axis, using a two‐strap fast wave antenna operated at 7 and 9.2 MHz with 180° phasing (N ∥∼100). Numerical modeling with the fast wave code f a s t w a [Plasma Phys. Controlled Fusion 33, 417 (1991)] indicates that for Phaedrus‐T parameters the kinetic Alfvén wave is excited via mode conversion from a surface fast wave at the Alfvén resonance and is subsequently damped on electrons.