Transverse-stress limit for irreversible degradation of Nb_3Sn cables · revision history

Revision 2

Accepted · core change · record

Changes against revision 1:

Title · changed
Revision 1: Transverse-stress limit for irreversible degradation of Nb3Sn cables
Revision 2: Transverse-stress limit for irreversible degradation of $\mathrm{Nb_3Sn}$ cables
Plain · changed
Revision 1: Nb3Sn is brittle, and the huge magnetic forces in a high-field magnet squeeze the cable until its ability to carry current is permanently damaged; where that threshold lies and what breaks first is uncertain.
Revision 2: $\mathrm{Nb_3Sn}$ is brittle, and the huge magnetic forces in a high-field magnet squeeze the cable until its ability to carry current is permanently damaged; where that threshold lies and what breaks first is uncertain.
Precise · changed · core
Revision 1: Rutherford cables of Nb3Sn filaments in epoxy-impregnated coils at fields up to $\sim 1.6e5\,\mathrm{G}$ are under transverse stress of order $1.5e9 \text{ to } 2e9\,\mathrm{dyn}/\mathrm{cm}^{2}$ (approximate). Determine the stress at which the critical current degrades irreversibly, its dependence on filament layout, impregnation and temperature cycling, and the microscopic failure mode (filament cracking, void collapse, debonding), as a function that fixes the maximal practical dipole field.
Revision 2: Rutherford cables of $\mathrm{Nb_3Sn}$ filaments in epoxy-impregnated coils at fields up to $\sim 1.6 \times 10^{5}\,\mathrm{G}$ are under transverse stress of order $1.5 \times 10^{9} \text{ to } 2 \times 10^{9}\,\mathrm{dyn}/\mathrm{cm}^{2}$ (approximate). Determine the stress at which the critical current degrades irreversibly, its dependence on filament layout, impregnation and temperature cycling, and the microscopic failure mode (filament cracking, void collapse, debonding), as a function that fixes the maximal practical dipole field.
Settled by
Critical-current measurements of cable stacks under calibrated transverse stress, combined with post-test microscopy of filament cracks and a model that reproduces the onset stress.
Kind
well-posed
Answer type
value
References
(empty)
Literature status
open
Status note
(empty)
Posed since
(empty)

Decisions