Microscopic origin of quench training in Nb_3Sn accelerator magnets · revision history

Revision 2

Accepted · core change · record

Changes against revision 1:

Title · changed
Revision 1: Microscopic origin of quench training in Nb3Sn accelerator magnets
Revision 2: Microscopic origin of quench training in $\mathrm{Nb_3Sn}$ accelerator magnets
Plain
Each premature quench lets the magnet reach a slightly higher current the next time, which suggests that small mechanical events in the coil release heat, but which events and where is not established.
Precise · changed · core
Revision 1: Nb3Sn dipoles and quadrupoles operating at 1.1e5 to 1.5e5 G often require tens of training quenches to approach 80 to 90 percent of the conductor short-sample limit. Identify the energy-release events that start training quenches (epoxy cracking, conductor-insulation debonding, stick-slip friction at coil-structure interfaces), their energy spectrum relative to the minimum quench energy of the cable, and a model that predicts the training curve from coil prestress and material properties.
Revision 2: $\mathrm{Nb_3Sn}$ dipoles and quadrupoles operating at $1.1 \times 10^{5}$ to $1.5 \times 10^{5}$ G often require tens of training quenches to approach 80 to 90 percent of the conductor short-sample limit. Identify the energy-release events that start training quenches (epoxy cracking, conductor-insulation debonding, stick-slip friction at coil-structure interfaces), their energy spectrum relative to the minimum quench energy of the cable, and a model that predicts the training curve from coil prestress and material properties.
Settled by
Acoustic-emission and quench-antenna localization of initiating events across the training of several magnets, matched by a mechanical-thermal model that predicts the training curve of a new magnet before it is tested.
Kind
phenomenon
Answer type
mechanism
References
(empty)
Literature status
open
Status note
Acoustic-emission localization of events during training was reported from 2015 onward; no model predicts training curves (moderate confidence, not rechecked for 2024-2026).
Posed since
(empty)

Decisions