Karamyshev, O. JACoW Publishing Geneva, Switzerland 2673-5482 978-3-95450-212-7 10.18429/JACoW-CYCLOTRONS2022-THBO01 English 274-277 cyclotron acceleration proton extraction ion-source Contribution to a conference proceedings 2023 2023-10 https://doi.org/10.18429/JACoW-CYCLOTRONS2022-THBO01 https://jacow.org/cyclotrons2022/papers/thbo01.pdf Demand for cyclotrons for medical applications is growing rapidly. Cyclotrons delivering proton beams from 15 MeV up to 230 MeV are being used for isotopes production and proton therapy. Author proposes a con-cept that allows to significantly reduce cost of cyclotrons by making them more compact and power efficient without using superconducting coil. In the proposed design ratio between azimuthal length of sectors and valleys is over 3 to 1, with RF system operating at high frequency and acceleration at harmonic mode of 2 times the number of sectors. Compact size is achieved not by increasing the magnet field level, but by reducing the coil and RF system dimension. Cyclotrons will have 4 sectors and 4 rf cavities operating at harmonic 8 with 1.55 T mean field and accelerating frequency 180 MHz.