A thermostatic temperature control strategy for medical cyclotron deionized water cooling system based on cascade...

Medical cyclotron is the crucial device for radiation therapy, which is extensively utilized in nuclear technology and medicine. Deionized water cooling system (WCS) is essential for maintaining thermal stability of key components such as magnets, radiofrequency cavities, and beamlines. Precise thermostatic control is crucial for preserving beam quality, ensuring secure and reliable operation. Nevertheless, the WCS manifests highly complex dynamics, including strong coupling between temperature and cooling water mass-flow. These challenges are exacerbated by external disturbances and internal uncertainties, which traditional proportional-integral-derivative (PID) control struggles to address due to limited robustness. In this research, mechanism-based modeling is established to accurately describe the system dynamics. A cascade integral sliding mode controller (CISMC) with adaptive law is designed to enhance the response speed, control accuracy and the robustness against disturbances. Furthermore, the chattering phenomenon of sliding mode control is alleviated by replacing the sign function with a saturation function. Simulation results demonstrate that the proposed CISMC strategy reduces the integral absolute error (IAE) from 19.27 to 5.88 and integral time absolute error (ITAE) from 191.90 to 47.79 for temperature control compared to conventional PID, and reduces IAE from 0.95 to 0.34 and ITAE from 3.00 to 1.21 for flow control compared to sliding mode control (SMC). Importantly, for the proposed controller, system chattering and fluctuation are effectively mitigated.