A Case Study of Advanced Ramp-Up Profile for HTS Magnet-Based Carbon Therapy Synchrotron

In heavy ion medical synchrotrons, it is crucial to rapidly accelerate ions to reduce beam loss caused by interactions with residual gas and to shorten treatment duration. Superconducting technology can reduce machine size by generating high magnetic fields, but it is difficult to apply in realization because of the heat generation due to ac loss. As a potential solution to these problems, synchrotrons based on high-temperature superconductors (HTS) can offer advantages in stable accelerator operation due to their intrinsic high stability margin, despite the ac loss induced heating. Our study focuses on optimizing the ramp-up operation method of a heavy ion synchrotron (with medical applications) using HTS. We initially simulate ac losses based on the ramp-up profile in a conceptual magnet model of a medical application that utilizes HTS wire characteristics. Simultaneously, we employed a virtual beam to calculate how the beam-gas interaction affects emittance. Based on the results of these two calculations, we propose a current ramp-up profile that minimizes beam loss due to multiple scattering and maximum instantaneous heat load due to ac loss in synchrotrons using high-temperature superconducting magnets.