Karamyshev, O. JACoW Publishing Geneva, Switzerland 2673-5482 978-3-95450-212-7 10.18429/JACoW-CYCLOTRONS2022-WEPO003 English 208-210 cyclotron extraction cavity acceleration proton Contribution to a conference proceedings 2023 2023-10 https://doi.org/10.18429/JACoW-CYCLOTRONS2022-WEPO003 https://jacow.org/cyclotrons2022/papers/wepo003.pdf A new cyclotron for proton therapy concept is a compact, but non-superconducting accelerator, that is simple, but cheap. Proposed concept uses 4 sectors with double spiral design and 4 RF cavities operating at harmonic 8, making the central region and extraction a challenging task that needs to be carefully simulated. High injection and extraction efficiency is presented.