# Development of Fast Protection System with Xilinx ZYNQ SoC for RAON Heavy-Ion Accelerator
## 1 Introduction  
The Rare Isotope Science Project (_RISP_), conducted by the Institute for Basic Science (_IBS_) in Korea, aims to develop a rare isotope accelerator facility with high beam energy and power output capabilities [1]. The accelerator consists of various subsystems, including control, radio frequency, injector, vacuum, magnet, and cryogenic systems. Among these subsystems, the Machine Protection System (_MPS_) plays a crucial role in safeguarding the internal components of the accelerator from beam-induced damage. As the beam power increases, the need for swift accelerator shutdown to mitigate potential damagebecomes imperative. To achieve this, a transition from a programmable logic controller (_PLC_)-based interlock system to a field-programmable gate array (_FPGA_)-based interlock system is necessary. The _MPS_ is responsible for detecting abnormal signals from local devices within the accelerator, such as low-level radio frequency, beam diagnostics, magnet power supplies, and cryogenic systems [2]. When a trip signal is detected, the _MPS_ activates the beam stop device, consisting of components like the low-energy beam transfer, chopper, radio frequency quadrupole, and low-level radio frequency, to rapidly halt the beam. The _MPS_ is divided into two main systems based on signal acquisition time: the fast protection system (_FPS_) [3] and the slow interlock system (_SIS_) [4]. The _FPS_, which has attracted significant attention as accelerator technology advances, focuses on achieving high equipment availability and stability. To improve availability and stability, the _FPS_ must be carefully designed to meet the specific requirements of the diverse devices within the accelerator. The _MPS_ is responsible for detecting abnormal signals from local devices within the accelerator, such as low-level radio frequency, beam diagnostics, magnet power supplies, and cryogenic systems. When a trip signal is detected, the _MPS_ activates the beam stop device, consisting of components like the low-energy beam transfer, chopper, radio frequency quadrupole, and low-level radio frequency, to rapidly halt the beam. The _MPS_ is divided into two main systems based on signal acquisition time: the fast protection system (_FPS_) and the slow interlock system (_SIS_). The _FPS_, which has gained significant attention as accelerator technology advances, focuses on achieving high equipment availability and stability. To improve availability and stability, the _FPS_ must be carefully designed to meet the specific requirements of the diverse devices within the accelerator [5]. In heavy-ion accelerators, a device yield stress may occur when the beam collides with the accelerator main device [6], depending on the type of ion beam mass, kinetic energy, and angle of incidence. The design and functionality of the _FPS_ are critical in ensuring its effectiveness as a fast and reliable beam protection system. Therefore, it is crucial to set clear requirements for the _FPS_ prior to its production and assess its practicality by benchmarking against desired outcomes. In heavy-ion accelerators, the occurrence of yield stress in accelerator components due to beam collisions depends on factors such as the ion beam mass, kinetic energy, and incident angle [6]. The heavier the ion weight, the greater the stopping power, and the higher the angle of incidence, the greater the effect [7], where the stopping power of an ion beam is calculated using the Stopping and Range of Ions in Matter (_SRIM_) code. Previous studies at the Spallation Neutron Source (_SNS_) and the Facility for Rare Isotope Beams (_FRIB_) have investigated the impact of beam energy and incident angle on yield stress time, providing valuable insights [8; 9]. The time required for the _FPS_ to operate effectively includes abnormal beam signal detection, _FPS_ processing, and mitigation device operation.