Beam-based measurements on two ±12.5 kV inductive adders, together with striplines, for CLIC damping ring extraction kickers

The CLIC study is investigating the technical feasibility of an electron-positron linear collider with high luminosity and a nominal centre-of-mass energy of 3 TeV. Pre-damping rings and damping rings (DRs) will produce ultra-low emittance beam with high bunch charge. The DR kicker systems, each of which consists of a set of striplines and two inductive adders, must provide extremely stable field pulses. The DR extraction kicker system is the most demanding: specifications require a field uniformity within +/-0.01% and pulses up to 900 ns flattop duration, at +/-12.5 kV and 309 A, with ripple and droop of not more than +/-0.02 % (+/-2.5 V), with respect to a reference waveform. Two prototype inductive adders have been designed and built at CERN, and have been tested with prototype striplines installed in the storage ring of the ALBA Synchrotron Light Source, in Spain. The stability of the kicker system, including the modulators, has been evaluated from the beam-based measurements and is reported in this paper.