@article{oai:nifs-repository.repo.nii.ac.jp:00000330,
 author = {SHIMOZUMA,  Takashi and TAKAHASHI,  Hiromi and KUBO,  Shin and YOSHIMURA,  Yasuo and IGAMI,  Hiroe and NISHIURA,  Masaki and OGASAWARA,  Shinya and MAKINO,  Ryohei and IDEI,  Hiroshi and MARUSHCHENKO,  Nikolai B and TURKIN,  Yuri and MUTOH,  Takashi},
 journal = {Plasma and Fusion Research},
 month = {Jun},
 note = {High harmonic electron cyclotron resonance heating (ECH) can extend the plasma heating region to higher density and higher β compared to the normal heating scenario. In this study, the heating characteristics of the second-harmonic ordinary (O2) and third-harmonic extraordinary (X3) modes and the possible extension of heating regime are experimentally confirmed. At the same time, a comparative study using ray-tracing calculation was performed in the realistic three-dimensional configuration of the Large Helical Device. The O2 mode heating showed a 40% absorption rate even above the X2 mode cut-off density. The X3 mode heating using powerful 77 GHz gyrotrons demonstrated an increase of about 40% in the central electron temperature in the plasmas at β-value of about 1%. These results were quantitatively explained to some extent by ray-tracing calculations.},
 title = {High Harmonic ECH Experiment for Extension of Heating Parameter Regime in LHD},
 volume = {Vol.8},
 year = {2013}
}