Recap on Field Quality from the Latest Large Scale Production - The RHIC Dipole Production
- Reduction in random errors despite RX630 spacers (due to symmetry and averaging effects). Also the coil manufacturing and magnet tooling played a major role.
- Small overall systematic (and can be controlled during production).
- Small current dependence in harmonics despite the close-in iron. The current dependence (and hence saturation-induced harmonics) remains small beyond the design field.
- Such a good field quality means that the corrector magnets are NOT likely to be needed in RHIC for correcting field errors in arc dipoles.
The sextupole magnets will be used for persistent current induced b2 and for other beam dynamics purpose (chromaticity correction); may also be used for removing a relatively small residual b2).