title: Development of design technique for vacuum insulation in large size multi-aperture multi-grid accelerator for nuclear fusion.
abstract: Design techniques for the vacuum insulation have been developed in order to realize a reliable voltage holding capability of multi-aperture multi-grid (MAMuG) accelerators for fusion application. In this method, the nested multi-stage configuration of the MAMuG accelerator can be uniquely designed to satisfy the target voltage within given boundary conditions. The evaluation of the voltage holding capabilities of each acceleration stages was based on the previous experimental results about the area effect and the multi-aperture effect. Since the multi-grid effect was found to be the extension of the area effect by the total facing area this time, the total voltage holding capability of the multi-stage can be estimated from that per single stage by assuming the stage with the highest electric field, the total facing area, and the total apertures. By applying these consideration, the analysis on the 3-stage MAMuG accelerator for JT-60SA agreed well with the past gap-scan experiments with an accuracy of less than 10% variation, which demonstrated the high reliability to design MAMuG accelerators and also multi-stage high voltage bushings.
authors.affiliation: Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Kojima
authors.affiliation: Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Hanada
authors.affiliation: Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Tobari
authors.affiliation: Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Nishikiori
authors.affiliation: Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Hiratsuka
authors.affiliation: Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Kashiwagi
authors.affiliation: Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Umeda
authors.affiliation: Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Yoshida
authors.affiliation: Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Ichikawa
authors.affiliation: Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Watanabe
authors.affiliation: Saitama University, Saitama, Saitama-ken 338-8570, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Yamano
authors.affiliation: Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA.
authors.forename: L R
authors.initials: LR
authors.lastname: Grisham