It is observed that fast waves launched into an electron cyclotron heated plasma from a phased four-strip-line antenna array couple effectively with core electrons. This coupling produces enhanced electron cyclotron emission and a drop in the loop voltage. These effects depend on the phase difference between adjacent strip lines and on the electron density. An absorption efficiency of 20% is deduced under the conditions $v_{\mathrm{ph}}$/$v_{e0}$∼3 and $f_0$/$f_{\mathrm{LH}\mathrm{}\left(0\right)\mathrm{}\mathrm{\sim }0.38}$. The experimental results agree well with predictions based on electron Landau damping of fast waves.

• Received 2 February 1989

DOI:https://doi.org/10.1103/PhysRevLett.63.1148