title: Pre-conditioning procedure suitable for internal-RF-antenna of J-PARC RF-driven H⁻ ion source.
abstract: The Japan Proton Accelerator Research Complex (J-PARC) cesiated RF-driven H(-) ion source has been successfully operated for about 1 yr. By the world brightest level beam, the J-PARC design beam power of 1 MW was successfully demonstrated. Although no internal-RF-antenna failure, except for the once caused by an excess cesium due to a misoperation, occurred in the operation, many antennas failed in pre-conditionings for the first hundred days. The antenna failure rate was drastically decreased by using an antenna with coating thicker than a standard value and the pre-conditioning procedure repeating 15 min 25 kW RF-power operation and impurity-gas evacuation a few times, before the full power (50 kW) operation.
authors.affiliation: J-PARC Center, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Ueno
authors.affiliation: J-PARC Center, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ohkoshi
authors.affiliation: J-PARC Center, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ikegami
authors.affiliation: J-PARC Center, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Takagi
authors.affiliation: J-PARC Center, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Asano
authors.affiliation: J-PARC Center, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Oguri