Preliminary design of beamline components for JT-60SA NBI heating system

The modification of the beamline components for JT-60SA NBI heating system has been preliminarily studied by means of three-dimensional Computer Aided Design (CAD) technique, such as the connection between positive ion-based NBI (P-NBI) port and the cryostat of JT-60SA vacuum vessel, an additional magnetic shielding plate, the downward-shift of the negative ion-based NBI (N-NBI), and disassembly of the present NBI system. The shortening of drift ducts is needed for JT-60SA because the cryostat is installed between the JT-60SA vacuum vessel and the P-NBI beamline. We have found that the removal of the fast shutter and a newly designed connection flange made of FRP satisfy the requirement for the design of new drift duct. The design study with the 3D CAD indicates that the available space between the neutralizer cell and the ion tank is estimated to be 30 mm, which is enough space to install a thick mild steel in order to avoid the magnetic saturation. On the N-NBI, the downward-shift of 0.6 m required for JT-60SA can be realized by shorting the basement of ion tank, reversing the shaft of the movable calorimeter and exchanging the support structure of the neutralizer cell. Moreover, the minimum removal components and the disassembly procedure have been proposed to disassemble effectively the present NBI system. (author)