Field errors from screening currents in REBCO accelerator magnets · revision history

Revision 2

Accepted · core change · record

Changes against revision 1:

Title
Field errors from screening currents in REBCO accelerator magnets
Plain
Magnets wound from flat high-temperature superconducting tape carry circulating currents inside the tape that distort the guiding field and drift in time.
Precise · changed · core
Revision 1: In REBCO coated-conductor coils (tape width $\sim 0.4\,\mathrm{cm}$), screening currents induced during field ramps produce field harmonics and slow drifts well above the $1e-4$ relative field quality needed for beam optics, and add mechanical stress. Determine whether conductor layout (striated tapes, round twisted-tape cables) and ramp protocols can reduce screening-current field errors below $1e-4$ at fields $1e5\ \text{to}\ 2e5\,\mathrm{G}$, and predict their decay in time from flux-creep parameters of the tape.
Revision 2: In REBCO coated-conductor coils (tape width $\sim 0.4\,\mathrm{cm}$), screening currents induced during field ramps produce field harmonics and slow drifts well above the $10^{-4}$ relative field quality needed for beam optics, and add mechanical stress. Determine whether conductor layout (striated tapes, round twisted-tape cables) and ramp protocols can reduce screening-current field errors below $10^{-4}$ at fields $10^{5}\ \text{to}\ 2 \times 10^{5}\,\mathrm{G}$, and predict their decay in time from flux-creep parameters of the tape.
Settled by
Magnetic measurements of field harmonics and their time decay in a REBCO dipole insert, matched by a model using independently measured tape properties.
Kind
well-posed
Answer type
yes-no
References
(empty)
Literature status
open
Status note
(empty)
Posed since
(empty)

Decisions