Machida, S. Developments and Prospects of FFAs at RAL JACoW Publishing Geneva, Switzerland 2673-5482 978-3-95450-212-7 10.18429/JACoW-CYCLOTRONS2022-FRAI01 English 351-355 lattice dynamic-aperture resonance controls operation Contribution to a conference proceedings 2023 2023-10 https://doi.org/10.18429/JACoW-CYCLOTRONS2022-FRAI01 https://jacow.org/cyclotrons2022/papers/frai01.pdf Fixed Field Alternating Gradient Accelerator (FFA) has several advantages as a proton driver for high beam power applications. In particular, control of pulse structure can ben easily done by RF gymnastics. FFA is a sustainable (energy efficient) accelerator with the main magnets with DC operation. We will discuss the development of a FFA physics design for the ISIS (spallation neutron source) and its prototype.