Winding tests on Roebel cables Maria Durante In behalf of task 3 members

Non insulated Roebel cables At Saclay, 15 x 150 µm thick strands, 226 mm twist pitch Manually wound At CERN, 15 x 100 µm thick strands, 226 mm twist pitch Winding machine Hand tension *

Insulated Roebel cable Roebel cable insulated with 0.125 mm thick E-glass fibers sleeve At Saclay, 10 mm wide cable 15 x 150 µm, 226 mm, assembled at CEA 15 x 100 µm, 426 mm, from KIT Winding machine Max tension on cable 10 daN

Insulated Roebel cable Roebel cable insulated with 0.125 mm thick E-glass fibers sleeve At CERN, 12 mm wide cable Winding machine Hand tension Feather Zero 1st coil Feather 2 , two layer

Winding tension 15 kg damage a single tape.(Jaakko) At CERN tension less than 5 kg per tape At CEA tension of 10 kg on cable

Cable unravelling This happens at the ends and occasionally in the straight section.. It would be nice to find a way of fixing the cable to stop it from coming apart : tape , clips, Teflon tape….

Cable geometry modification Uneven distribution of the strands in the cable. Meander tapes were evenly distributed during cable manufacturing Tapes have slipped during transfert onto transport mandrel We did not manage to re-configure the cable without complete disassembling it (length > 10 m). Solution: Spool as big as possible? 12 mm wide cable , tp 226 mm, winding at CERN 10 mm wide cable , tp 426 mm, reception at CEA

Cable geometry modification Vertical gap closing 10 mm wide cable , tp 226 mm at CEA

Damage from tooling! Tooling damages dummy cable Tooling improved but still ongoing disruption

Slippage during winding about ~ 5-6 mm Longitudinal gap = 17.4 mm (Tp = 426 mm, perfect distribution) Longitudinal gap = 4 mm (Tp = 226 mm, perfect distribution) Real issue if the slippage is between two successive strands! buckling cable smoothed out till the end of the winding ->Smoothing out of the buckling cable no more possible

Pop up! Pushing the cable flat makes the same strand pop-up further along the cable

Fiber glass damage At CERN damage of the glass fiber At CEA no damage Likely due to stamping burr At CEA no damage 10 mm wide cable in 12 mm wide insulation Results may differ with 12 mm wide cable

Winding tests conclusions Delicate cable handling: tooling, unravelling Fragile fiberglass insulation: sharp edges, stamping burr Cable geometry modification: strand distribution, gap closing Cable winding on circular mandrel shuffling tape distribution Slippage of the tapes needed: otherwise cable popping up Undistributed winding tension due to slippage

Spares

Roebel cables delivered at Saclay SS dummy cable punched at CERN, assembled by CEA 10 mm wide 15 x 0.15 mm thick strands, twist pitch 226 mm 2 lenghts, 2 m long, right-hand lay 1 lenght, 2 m long, left-hand lay SS dummy cable from KIT 15 x 0.10 mm thick strands, twist pitch 426 mm 1 lenght, 13 m long, left-hand lay 12 mm wide 15 x 0.15 mm thick strands, twist pitch 226 mm 1 length, 20 m long, left-hand lay, just delivered (07/05/2015)

Expected tape slipping If the cable is wound on a 5-cm radius spool (or bigger) before shipping the relative slippage should be negligible (less than ±0.5 mm): Tp = 226 mm R = 5 cm ep cable = 1.2 mm Nb tapes = 15 J. Fleiter, C. Lorin et al On Roebel cable geometry for accelerator magnet CERN-ACC-NOTE-2015-0003