Making beam spill less sensitive to power supply ripple in resonant slow extraction

The betatron tune fluctuation due to current ripple from power supplies causes beam spill ripples in resonant slow extraction. The separatrix area variation due to the tune ripple depends on tune distance from the resonance and field strength of sextupole magnet in the third-integer resonant extraction. We proposed a method to increase tune distance while maintaining separatrix area by controlling sextupole field strength. We measured the correlation between beam spill ripple and tune distance using an artificial tune ripple, and verified the reduction of beam spill ripple below 50%.