title: Direct measurement of density oscillation induced by a radio-frequency wave.
abstract: An O-mode reflectometer at a frequency of 25.85 GHz was applied to plasmas heated by the high harmonic fast wave (21 MHz) in the TST-2 spherical tokamak. An oscillation in the phase of the reflected microwave in the rf range was observed directly for the first time. In TST-2, the rf (250 kW) induced density oscillation depends mainly on the poloidal rf electric field, which is estimated to be about 0.2 kV/m rms by the reflectometer measurement. Sideband peaks separated in frequency by ion cyclotron harmonics from 21 MHz, and peaks at ion cyclotron harmonics which are suggested to be quasimodes generated by parametric decay, were detected.
authors.affiliation: Research Institute for Applied Mechanics, Kyushu University, Kasuga, Japan. takuma@riam.kyushu-u.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Yamada
authors.forename: A
authors.initials: A
authors.lastname: Ejiri
authors.forename: Y
authors.initials: Y
authors.lastname: Shimada
authors.forename: T
authors.initials: T
authors.lastname: Oosako
authors.forename: J
authors.initials: J
authors.lastname: Tsujimura
authors.forename: Y
authors.initials: Y
authors.lastname: Takase
authors.forename: H
authors.initials: H
authors.lastname: Kasahara
mesh_terms: D017076:Computer-Aided Design; D004583:Electrons; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005740:Gases / Q000737:chemistry* / Q000528:radiation effects*; D009991:Oscillometry / Q000295:instrumentation* / Q000379:methods; D011829:Radiation Dosage; D011846:Radio Waves; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D005740:Gases