Electron absorption of fast magnetic waves by TTMP in JET

Direct electron damping of low frequency fast magnetosonic waves is regarded as a promising method for non-inductive current drive in future tokamak fusion reactors. Theoretical studies predict for this scheme a greater efficiency than Lower Hybrid current drive; in addition, the fast wave can propagate up to the central high-temperature high-density region of a reactor plasma while the lower high propagation is greatly restricted according to the Stix-Golant accessibility criterion. In existing experiments the presence of stronger competitive absorption mechanisms, in particular ion cyclotron damping, makes it difficult to obtain and detect significant direct absorption of the wave via Transit Time Magnetic Pumping or Electron Landau Damping. In this paper we report the first experimental observation of direct electron damping of low frequency fast magnetosonic waves in high-β JET plasmas in conditions where TTMP is estimated to be an important component in the electron/wave interaction. (author) 14 refs., 4 figs