Measurements on +/-12.5 kV Inductive Adders with +/-200 ppm Pulse Flatness over 900 ns for CLIC Damping Ring Kickers at CERN

The CLIC study is investigating the technical feasibility of an electron-positron 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 must provide extremely stable field pulses to avoid beam emittance increase. The DR extraction kicker system consists of a stripline kicker and two pulse modulators. Specifications for the electromagnetic field pulses require that the modulators generate pulses of up to 900 ns flattop duration, +/-12.5 kV and 305 A, with ripple and droop of not more than 200 ppm (+/-2.5 V) with respect to a reference waveform. Inductive adder topology has been chosen for the pulse modulators: the output waveform can be adjusted by applying analogue modulation methods. Two full-scale, 12.5 kV, 20-layer, prototype inductive adder have been designed and built at CERN and testing has commenced. The prototypes are planned to be tested with a prototype stripline kicker, installed in a beamline, at ALBA Synchrotron Light Source in Spain. The results of laboratory tests to generate a 10.3 kV flat-top pulse and a controlled decay waveform are presented.