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TY - CONF AU - Bourianoff, G. ED - Pak, Cheol-on ED - Kurokawa, Shin-ichi ED - Katoh, Tadahiko ED - Furukawa, Kazuro ED - Schaa, Volker RW TI - Operational Decoupling in the SSC Collider J2 - Proc. of ICALEPCS1991, Tsukuba, Japan, 11-15 November 1991 CY - Tsukuba, Japan T2 - International Conference on Accelerator and Large Experimental Physics Control Systems T3 - 3 LA - english AB - This paper will summarize a recent study of the effects and correction of linear coupling in the Superconducting Super Collider (SSC) lattice. There are several aspects of the SSC lattice that make direct extrapolation of techniques used on existing machines unreliable. The most obvious aspect of the SSC which departs from previous experience is the small dynamic aperture which lies well within the beampipe. A second aspect is the existence of long arcs with low superperiodicity which allow various sources of skew quadrupole to accumulate to large, and, perhaps, nonlinear values. A third aspect is the relatively large value of systematic skew quadrupole error in the main dipoles. This results from asymmetric placement of the cold mass in the cryostat Coupling must be considered harmful if it leads to irreversible emittance blow-up, a decrease in the dynamic aperture, or inoperability of the machine. These negative effects are generally related to coupling terms that accumulate to large and, hence, nonlinear values prior to correction. The harmful effects can also be caused by the linearly coupled orbits interacting with high-order multipole fields that exist in the other magnets. The errors that lead to linear coupling are well known. They are systematic and random skew quadrupole error fields in the other magnetic elements, angular alignment errors in the quadrupoles and feeddown from the sextupole fields associated with chromaticity correction, and persistent current fields in the dipoles. A study of the relative importance of the various coupling terms for a simplified SSC lattice has been done by Richard Talman. PB - JACoW Publishing CP - Geneva, Switzerland SP - 576 EP - 578 KW - coupling KW - lattice KW - betatron KW - quadrupole KW - collider DA - 1992/12 PY - 1992 SN - 2226-0358 SN - 978-3-95450-254-7 DO - doi:10.18429/JACoW-ICALEPCS1991-S18BPA01 UR - https://jacow.org/icalepcs1991/papers/s18bpa01.pdf ER -