title: Adaptive array technique for differential-phase reflectometry in QUEST.
abstract: A Phased Array Antenna (PAA) was considered as launching and receiving antennae in reflectometry to attain good directivity in its applied microwave range. A well-focused beam was obtained in a launching antenna application, and differential-phase evolution was properly measured by using a metal reflector plate in the proof-of-principle experiment at low power test facilities. Differential-phase evolution was also evaluated by using the PAA in the Q-shu University Experiment with Steady State Spherical Tokamak (QUEST). A beam-forming technique was applied in receiving phased-array antenna measurements. In the QUEST device that should be considered as a large oversized cavity, standing wave effect was significantly observed with perturbed phase evolution. A new approach using derivative of measured field on propagating wavenumber was proposed to eliminate the standing wave effect.
authors.affiliation: Research Institute for Applied Mechanics, Kyushu Univ., Kasuga, 816-8560 Japan.
authors.forename: H
authors.initials: H
authors.lastname: Idei
authors.affiliation: Interdisciplinary Grad. School of Eng. Sci., Kyushu Univ., Kasuga, 816-8580 Japan.
authors.forename: K
authors.initials: K
authors.lastname: Nagata
authors.affiliation: Interdisciplinary Grad. School of Eng. Sci., Kyushu Univ., Kasuga, 816-8580 Japan.
authors.forename: K
authors.initials: K
authors.lastname: Mishra
authors.affiliation: Research Institute for Sustainable Humanosphere, Kyoto Univ., Uji, 611-0011 Japan.
authors.forename: M K
authors.initials: MK
authors.lastname: Yamamoto
authors.affiliation: Interdisciplinary Grad. School of Eng. Sci., Kyushu Univ., Kasuga, 816-8580 Japan.
authors.forename: T
authors.initials: T
authors.lastname: Itado
authors.affiliation: Interdisciplinary Grad. School of Eng. Sci., Kyushu Univ., Kasuga, 816-8580 Japan.
authors.forename: R
authors.initials: R
authors.lastname: Akimoto
authors.affiliation: Research Institute for Applied Mechanics, Kyushu Univ., Kasuga, 816-8560 Japan.
authors.forename: K
authors.initials: K
authors.lastname: Hanada
authors.affiliation: Research Institute for Applied Mechanics, Kyushu Univ., Kasuga, 816-8560 Japan.
authors.forename: H
authors.initials: H
authors.lastname: Zushi