ICRF Heating using Folded Waveguide Antenna on LHD

Using a folded waveguide (FWG) antenna in the ion cyclotron range of frequency, a plasma production and heating experiment was carried out on the large helical device in National Institute for Fusion Science, which was the first experiment in the torus system. In the 4th experimental campaign in 2000-2001 this antenna produced the plasma at the average electron density up to 3xl0r8 m-3. In this campaign, the pure hydrogen plasma was produced mainly using the frequency of 25 MHz in the magnetic field strength of 2.6-2.8 T. It is planned that an ion Bemstein wave heating will be carried out to heat the plasma at a higher frequency, i.e. 37 .43 MHz (second harmonic resonance of FWG antenna). In the helium plasma produced by electron cyclotron heating, the antenna launches the wave of the frequency o)-3(D"s" at the antenna front. A spatial distribution of the wave energy damping was calculated using the dispersion relation of ion Bernstein wave and an analytical expression of the magnetic field strength with a rotating helical coordinate system. The propagating wave was absorbed near the resonance of a-2a"s".