Update of the tune ripple canceller system for slow extraction operation in the J-PARC MR

In the slow extraction operation of the J-PARC Main Ring (MR), ensuring the uniformity of the extracted beam's time structure (“spill structure”) is crucial. One primary factor distorting the spill structure is the random fluctuation of the horizontal tune caused by current ripples in the main magnet power supplies. To address this issue, a system called the "tune ripple canceller" has been developed. This system calculates correction values for the horizontal betatron tune based on current ripples and controls the spill structure using fast-responding quadrupole magnets. In 2021, proof-of-principle beam experiments demonstrated its effectiveness in improving the spill structure. Subsequently, as part of the MR's power upgrade plan, the main magnet power supply system was upgraded by 2022. During this upgrade, the current measurement system was reconfigured, and the power spectrum of the current ripples was altered. As a result, it is now urgent to update the hardware and software of the tune ripple canceller system to align with these changes. This paper highlights updates, addresses challenges, and explores strategies to further enhance spill structure control in the MR.