Measurements on Magnetic Cores for Inductive Adders with Ultra-Flat Output Pulses for CLIC DR 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 CLIC 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 flat, high-voltage, pulses. The specifications for the DR extraction kickers call for 160 ns duration flattop pulses of ±12.5 kV, with a combined ripple and droop of not more than ±0.02 % (±2.5 V). An inductive adder is a very promising approach to meet the specifications. Two five layer, 3.5 kV, prototype inductive adders have been built at CERN, and used to test passive and active analogue modulation methods to compensate droop and ripple of the output pulses. Recently, magnetic core materials and full-scale magnetic cores have been evaluated for the 12.5 kV prototype inductive adders. These results are presented in this paper and conclusions are drawn concerning the design of the full-scale prototypes.