Control system design for the new SMH16 pulsed current generator in the CERN PS extraction system

The existing direct-drive septum magnet (PE.SMH16), in operation since 1994, is reaching the end of its lifetime under increased extraction frequency and will be replaced by a new eddy-current septum magnet, requiring a redesigned 30 kA pulsed generator. To meet the demanding flat-top stability requirement of ±0.05% over an 11 µs window and ±0.05% pulse-to-pulse repeatability over a year, a dedicated regulation control system was developed and validated. The objective of this work is to demonstrate that the control system achieves the required closed-loop performance, delivering repeatable magnet current waveforms under representative test bench conditions. The control system employs real-time regulation of flat-top amplitude and flatness, supported by a thermally stabilized enclosure to mitigate acquisition drift. Measurements confirm that the closed-loop system consistently maintained flatness requirement over an 8 µs window, with long-term repeatability and all observed deviations, including spurious glitches up to 400 ppm, remaining within specification. The restriction of 8 µs stems from test-bench limitations rather than control capability, which is discussed in detail. These results show that the regulation system fulfils its role up to specification; final confirmation of absolute flat-top accuracy will come from further qualification of acquisition chain elements in a dedicated test campaign, followed by beam-based validation in operation.