DBQ 5.63 Adding other steel components to the model Ben Shepherd January 2011

Components identified Rails – 4 per magnet 12.5 x 15 x 473 mm 11mm from magnet edge Ballscrews – 2 per magnet ⌀ 20mm x 468mm 61mm from magnet edge

Effect of steel components Any steel component going through the y=0 plane has a flux shorting effect – reduces overall magnetic strength Started off with ‘good’ magnetic steel (µ=5800) – but this is unrealistic Ballscrew & rails will likely be made from 440C steel Permeability is variable (depending on manufacture) but typically between Change in µ is due to surface hardening – realistic to assume same throughout? A softer steel (e.g. 316L) would have µ≈10 Also tried moving rails out by 10mm – but no difference

CLIC DBD PMQs: Lower gradient version Ben Shepherd December 2010

Model geometry (6.17) Horizontally-magnetised PM slides up and down to vary the gradient (as 5.19) ‘Shell’ around the outside to provide a secondary flux loop To reduce B mod : – Shell made thicker (40mm) – Corners rounded off with chamfers This leg can be moved to the left if nessary, with a slight reduction in gradient.

Geometry in 3D 380mm 380mm 180mm 37.2mm 70mm

Gradient variation Max: 49.0 T/m Min: 3.2 T/m (75mm movement)

B mod with gradient change Stays within 1.6T for any gradient (0-75mm)

A complete solution? At 60% along the DBD line, maximum strength required is 8.8T 49.0T/m * 180mm = 8.8T At 100% along the line, minimum strength is 0.85T 4.7T/m * 180mm = 0.85T So this quad could cover the remaining 40% of the line Also a shorter length than previous design