title: Design study of polychromators for ITER edge Thomson scattering diagnostics.
abstract: In this study, we investigate designs for polychromators of the ITER edge Thomson scattering system by means of numerical calculations. For this purpose, we discuss the optimum transmission wavelength ranges of the optical filters and the optimum number of filters. Five different filter arrangements, including those with an optical notch filter to eliminate D(alpha) emission, are compared with each other. The measurement accuracy when using a polychromator is evaluated for midplane port configuration. It is found that the optimum filter number keeping in mind the cost performance cost is 5 or 6. Moreover, the use of an optical notch filter increases the measurement accuracy by approximately 5%.
authors.affiliation: Japan Atomic Energy Agency, Mukoyama 801-1, Naka, Ibaraki 311-0193, Japan. kajita@ees.nagoya-u.ac.jp
authors.forename: Shin
authors.initials: S
authors.lastname: Kajita
authors.forename: Takaki
authors.initials: T
authors.lastname: Hatae
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Kusama