A fast 60 kV resonant charging power supply for the LHC inflectors

The injection kicker systems for the two LHC beams will each consist of four magnets and four pulse forming networks (PFNs), discharged by thyratron switches. Fast resonant charging systems (RCS) are used to charge the PFNs within 1 ms to 60 kV: fast charging minimises the number of unwanted erratically thyratron discharges. The stability and pulse to pulse reproducibility of the PFN voltage must be maintained to a precision of ⩽±0.1%. Each RCS consists of a 2.4 mF primary capacitor bank, connected via a Gate Turn-Off thyristor (GTO) and a 1:23 step-up transformer to two PFNs, each with an effective capacitance of 0.96 μF. The PFNs are discharged 400 μs after the end of the charging period into the kicker magnets. The RCS include novel features such as a GTO used in Gate Assisted Turn-off (GAT) mode and a low-leakage inductance, high voltage, step-up pulse transformer. This paper presents a basic design for the RCS, and the optimisation of the electrical circuit using PSpice. The RCS are designed, constructed and tested at TRIUMF in collaboration with CERN as part of the Canadian contribution to the LHC project