03Dp02
JT-60SA用中性粒子入射装置の再起動に向けた改造
Reconstruction of JT-60SA Neutral Beam Injector for restarting of JT-60SA
柏木 美恵子、市川 雅浩、平塚 淳一、小島 有志、村山 真道、大楽 正幸、藻垣 和彦、
佐々木 駿一、坂本 響、山中 晴彦、遠藤 保栄、小室 健一、阿部 宏幸、東峰 正明、
篠田 明彦、大関 正弘、小林 薫、前島 哲也、山下 泰郎

M. Kashiwagi, M. Ichikawa, J. Hiratsuka, A. Kojima, Ｍ. Murayama, et al.
（国）量子科学技術研究開発機構 那珂核融合研究所

National Institutes for Quantum and Radiological and Technology, Naka fusion institute
The most powerful neutral beam injection system(NBI) in the world is now under upgrading to re-start
the operation for JT-60SA. This NBI consists of eightbeamlines for perpendicular beam injection (PNBI)
and four beamlines for tangential beam injection(TNBI) using two positive ion sources per eachbeamline, and two beamlines using negative ion
source (NNBI). The requirement of the injection
power is 2MW in each PNBI and TNBI (1.6 MW inthe initial phase) and 5 MW in each NNBI, that is, 34
MW in the total.
Originally, this system was used for JT-60U. Toward
to JT-60SA, points as shown in Fig.1 are modified asfollows. i) Water-cooled beamline according toextension of a pulse length from the original 30 s to100 s, ii) enhancement of a cancelling system of aresidual magnetic field from JT-60SA, iii) better
maintainability for the stable operation over annual
operation, and iv) improvement of the negative ion
source of the NNBI to meet the requirement of 500
keV, 22A for 100 s.
The progress related to item i) is a completion ofdesign of a drift duct to connect the NBI to thecryostat and a protection tube between the cryostatand the vacuum vessel. Originally, these components
were inertial cooled-one, but the active cooling has tobe considered for 100 s. The issue is to realize both ofcomplicated structure with water-cooled configuration
and assembling work in the narrow space. The special
zig and work procedure have been also developed in
the design.
Countermeasure to the stronger residual magnetic
field from JT-60SA related to item ii) is the mostcritical point for the NBI to realize the allowable heat
flux on the beamline. The cancelling system of thismagnetic field consists of the magnetic shield plate
and the cancelling coil. Firstly, the validation of thesimulation model has been completed by comparing
with the experimental result of 1/4-scale model. Then,the full-scale design was completed as shown in Fig.2
The part related to item iii) is mainly the constructionof the huge control system of the NBI. To realize theannual stable operation, timely repairment is required.
For this, this system is constructed by the commercial

products of Labview, PLC etc by QST team. The maincommunication test from the JT-60 main system to thefront of the power supply have been completed by2019.
One of remaining issues in the negative ion source
development is to produce 500 keV beam for 100 swith the relevant current density (130 A/m2). Stable
voltage holding with the margin of 20 %, that is, 600
kV, was confirmed in the real JT-60 accelerator. Since
the beam current was limited up to 0.5 A due to thecapability of the test facility, the ion source part wasreplaced to the small ion source in the beam test. The
countermeasures to perform the stable negative ion
production were examined in this test, such as thetemperature control of the chamber wall for the stablenegative ion production and protection system of thefilaments. Finally, since these worked properly as
designed, 500 keV, 154 A/m2 beam has beensuccessfully achieved for 118 s. The details arereported in the presentation of 03Dp03.
Thus, upgrading of NBI is in progress as scheduled.

Fig.1 NBI for JT-60SA and modification partFig.2 Cancelling system of the residual magnetic field