Measurements on a 12.5 kV Prototype Inductive Adder for the CLIC DR Extraction Kickers

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. The pre-damping rings and damping rings (DRs) will produce ultra-low emittance beam with high bunch charge. To avoid beam emittance increase, the DR kicker systems must provide extremely stable field pulses during injection and extraction of bunches. The DR extraction kicker system consists of a stripline kicker and two pulse modulators. The current specifications for the modulators call for pulses with 160 ns or 900 ns flattop duration of ±12.5 kV and 305 A, with ripple of not more than ±0.02 % (±2.5 V). An inductive adder is a very promising approach to meeting the specifications because analogue modulation methods can be applied to adjust the output waveform. Recently, the first full-scale, 20-layer, 12.5 kV prototype inductive adder has been assembled at CERN and testing has commenced. The goal is to tailor the output waveform of the prototype to the waveform required for the DR extraction stripline kicker. The results of the initial tests and measurements are presented.