title: Improvement of uniformity of the negative ion beams by tent-shaped magnetic field in the JT-60 negative ion source.
abstract: Non-uniformity of the negative ion beams in the JT-60 negative ion source with the world-largest ion extraction area was improved by modifying the magnetic filter in the source from the plasma grid (PG) filter to a tent-shaped filter. The magnetic design via electron trajectory calculation showed that the tent-shaped filter was expected to suppress the localization of the primary electrons emitted from the filaments and created uniform plasma with positive ions and atoms of the parent particles for the negative ions. By modifying the magnetic filter to the tent-shaped filter, the uniformity defined as the deviation from the averaged beam intensity was reduced from 14% of the PG filter to ∼10% without a reduction of the negative ion production.
authors.affiliation: Japan Atomic Energy Agency, 801-1, Mukoyama, Naka 311-0193, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Yoshida
authors.affiliation: Japan Atomic Energy Agency, 801-1, Mukoyama, Naka 311-0193, Japan.
authors.forename: Masaya
authors.initials: M
authors.lastname: Hanada
authors.affiliation: Japan Atomic Energy Agency, 801-1, Mukoyama, Naka 311-0193, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kojima
authors.affiliation: Japan Atomic Energy Agency, 801-1, Mukoyama, Naka 311-0193, Japan.
authors.forename: Mieko
authors.initials: M
authors.lastname: Kashiwagi
authors.affiliation: Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA.
authors.forename: Larry R
authors.initials: LR
authors.lastname: Grisham
authors.affiliation: Japan Atomic Energy Agency, 801-1, Mukoyama, Naka 311-0193, Japan.
authors.forename: Noboru
authors.initials: N
authors.lastname: Akino
authors.affiliation: Japan Atomic Energy Agency, 801-1, Mukoyama, Naka 311-0193, Japan.
authors.forename: Yasuei
authors.initials: Y
authors.lastname: Endo
authors.affiliation: Japan Atomic Energy Agency, 801-1, Mukoyama, Naka 311-0193, Japan.
authors.forename: Masao
authors.initials: M
authors.lastname: Komata
authors.affiliation: Japan Atomic Energy Agency, 801-1, Mukoyama, Naka 311-0193, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Mogaki
authors.affiliation: Japan Atomic Energy Agency, 801-1, Mukoyama, Naka 311-0193, Japan.
authors.forename: Shuji
authors.initials: S
authors.lastname: Nemoto
authors.affiliation: Japan Atomic Energy Agency, 801-1, Mukoyama, Naka 311-0193, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Ohzeki
authors.affiliation: Japan Atomic Energy Agency, 801-1, Mukoyama, Naka 311-0193, Japan.
authors.forename: Norikazu
authors.initials: N
authors.lastname: Seki
authors.affiliation: Japan Atomic Energy Agency, 801-1, Mukoyama, Naka 311-0193, Japan.
authors.forename: Shunichi
authors.initials: S
authors.lastname: Sasaki
authors.affiliation: Japan Atomic Energy Agency, 801-1, Mukoyama, Naka 311-0193, Japan.
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Shimizu
authors.affiliation: Japan Atomic Energy Agency, 801-1, Mukoyama, Naka 311-0193, Japan.
authors.forename: Yuto
authors.initials: Y
authors.lastname: Terunuma