Observation of direct electron heating by the fast waves in the lower-hybrid range of frequencies in the JFT-2M tokamak

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 vₚₕ/vₑ₀{~}3 and f₀/f_LH(0)~0.38. The experimental results agree well with predictions based on electron Landau damping of fast waves.