AC Losses of Rutherford-Type Superconducting Cables

Influence of strand surface condition on interstrand contact resistance and coupling loss in NbTi-wound Rutherford cables

“…However, detailed studies of the sensitivity of coupling loss to cable curing conditions (heat treatment temperature, uniaxial pressure, and the gaseous environment) began during the construction of SSC magnets, particularly those of the High Energy Booster ring, and has continued during the development of the LHC dipoles, e.g. [11][12][13][14][15][16][17][18][19][20][21][22][23]. Extensive study of direct interstrand contact resistance has also been made [18,24].…”

“…It has been postulated that the surface oxide dissociates with the released oxygen dissolving into the bulk Cu [41]. The operation of such a dissociation/dissolution mechanism at the interface between pairs of heat-treated Cu-matrix superconducting strands has been described by Kimura [14,21]. During moderate HT of a pair of compacted Cu strands, since the soft contacting surfaces are able to seal themselves off from further oxidation, the ICR quickly drops by several orders of magnitude [13].…”

“…Finally, under extreme conditions (e.g. 2 h/250°C under about 90 MPa) it is possible for an oxide-moderated diffusion bonding of strand pairs to take place [12,14,21]. Of course if the cable in question experiences a preparation protocol which could lead to delamination of such a bond (e.g.…”

“…Occasionally the uncured cable was measured under pressure [19]. In a number of practically important studies stacks of cable pieces were epoxy bonded at temperature and under pressure (the curing process) [11,[15][16][17]21,59], unloaded, and then measured under zero pressure [15,16,59], or under applied pressure [15,16].…”