Evaluation of Impact from Ripple and Transient Phenomena in the LHC Dipole Strings

Based on measurements of the A.C. electrical characteristics of prototype magnets, synthesized computer models of the principal, individual, superconducting magnetic elements of the Large Hadron Collider have been elaborated. The models constitute the basic elements for the determination of the transfer functions of the magnet chains. This tool provides the possibility to evaluate the resonance spectrum of the chains and to determine the needs for additional damping. Results of the analysis of transmission line effects in the LHC main dipole chains are presented. In particular, data from ripple calculations and ramping studies are discussed. Computer simulations of the quench protection circuit provide information about the transient phenomena occurring in the dipole chains during normal operation of the fast de-excitation switches and under abnormal conditions.