OF INTEREST: Hole in one: Centre stack smoothly installed in NSTX-U

With near-surgical precision, technicians at the Princeton Plasma Physics Laboratory (PPPL, US) hoisted the 29,000-pound (13,000-kilo) centre stack for the National Spherical Torus Experiment-Upgrade, NSTX-U, over a 20-foot (6-metre) wall and lowered it into the vacuum vessel of the fusion facility. The smooth operation on 24 October capped more than two years of construction of the centre stack, which houses the bundle of magnetic coils that form the heart of the $94 million (EUR 19 million) upgrade.

’This was really a watershed moment,’ said Mike Williams, the head of engineering and infrastructure at PPPL and associate director of the Laboratory. 'The critical path [or key sequence of steps for the upgrade] was fabrication of the magnets, and that has now been done.’

The lift team conducted the final steps largely in silence, attaching the bundled coils in their casing to an overhead crane and guiding the 21 foot-long (6.4-metre) centre stack into place. The clearances were tiny: the bottom of the casing passed just inches over the shielding wall and the top of the vacuum vessel. Inserting the centre stack into the vessel was like threading a needle, since the clearance at the opening was only about an inch. Guidance came chiefly from hand signals, with some radio communication at the end.
Read the full article on the PPPL website.