Speaker
Description
Neutral beams are one of the methods to inject power into a tokamak for plasma heating. The DIII-D tokamak has four neutral beam injectors with two ion sources each, located at toroidal angles of 30º, 150º, 210º, and 330º. As originally installed, each could inject up to 5 MW of neutral beam power in the co-injection orientation (nearly parallel to the plasma current). One of the systems, the 210° beamline, was modified in 2005 – 2006 to on-axis counter-injection. This beamline is now being designed to be capable of either co- or counter-injection and will be injected at 18.2 degrees from horizontal. The beamline will always inject off-axis into the plasma, but must be horizontal for installation and major maintenance. A system capable of precise lifting and rotation is required.
A carriage has been designed that will carry the 210º beamline, and many of its associated systems to facilitate beamline lift and rotation. The carriage sits on a custom platform that supports high accuracy curved rails attached to it. These rails are placed in the front and rear of the carriage and are concentric with the beamline rotation axis. The carriage is fastened to the rails with precision roller blocks. The beamline will be capable of rotating 40 degrees, between 19.5 degrees in the counter-injection direction and 20.5 degrees in the co-injection direction. The power to rotate this carriage is via two, on board, electronically synchronized epicycloidal reduction drives. The gear reduction allows precise rotation with small motors.
The rear end of the beamline is raised and lowered with hydraulic rams which travel with the carriage.
A description of the design and fabrication of the lift & rotation system will be presented.
This work is supported by the US DOE under DE-FC02-04ER546981 and DE-AC02-0H114662.
