Speaker
Description
The synchrotron SIS100 has been optimized for operation with the partially
stripped ion U28+, resulting in a number of unique challenges: transverse
emittances are comparatively large; the beam has high damage potential due to
the high dE/dx; the lattice must provide efficient collimation of ions losing
electrons in collisions with residual gas to prevent vacuum instabilities.
Resulting in strong focusing, slow extraction requires correction of the large
horizontal chromaticity to ensure high extraction efficiency while satisfying
the tight geometrical constraints. Amplitude dependent tune-shift by
chromaticity sextupoles then causes a bending of the separatrix which needs to
be compensated by octupoles. Additional higher-order effects arise from field
errors of main dipoles and quadrupoles, which were measured to have unexpectedly
large systematic multipoles, significantly changing the geometry of the
separatrix. We discuss possible ways of mitigating the effect of those
nonlinearities using the available corrector magnets as well as consequences for
the choice of slow extraction scheme and commissioning strategy.
