Speaker
Description
Conventional superconducting H₂⁺ cyclotrons are inherently limited in variable energy extraction, as the stripped particles spiral inward, constraining both trajectory control and beam quality. To meet the increasing demand for high-intensity, variable-energy beams across a wide range—particularly for applications in medical isotope production and proton FLASH therapy—this study presents the physics design and magnet simulation of a novel 15–70 MeV/u variable-energy, multi-particle superconducting cyclotron. The proposed cyclotron is capable of accelerating particles with a charge-to-mass ratio of 1:2, such as H₂⁺ and He²⁺, with intense proton beams obtained via H₂⁺ stripping. To address the long-standing challenge of multi-turn extraction for H₂⁺ at low energies, an alternating-sign field configuration was introduced to enable rapid extraction. Based on a detailed particle orbit model, the key magnetic parameters were optimized, yielding a hill field of 3.6 T, a valley reverse field of 0.6 T, and a sector angle of 36–40°, which also provides sufficient space for RF cavity installation. Finite-element simulations further demonstrated the feasibility of a compact superconducting magnet system, where coils are wound directly around the pole structure. This design enhances axial focusing while maintaining compactness. Static beam dynamics calculations confirm that the transverse oscillation frequency remains below 1.9, effectively avoiding low-order resonance risks.
