CYC2025 - International Conference on Cyclotrons and their Applications (Chengdu)

Design of Tuning Loop for Cyclotron RF System Based on FPGA with FFT/CORDIC Algorithm

TUP08

Not scheduled

20m

InterContinental Chengdu Global Center

Poster Presentation Cyclotron and Technology Poster Section

Speaker

Jiayi Zhang (China Institute of Atomic Energy)

Description

Abstract
The Low-Level Radio Frequency (LLRF) system is crucial for amplitude and phase control in modern parti-cle accelerators. Traditional amplitude and phase de-modulation methods often require the sampling frequen-cy to be multiple of the high-frequency signal, leading to limited general applicability. To address this issue, this paper proposes a generic tuning control method, imple-mented on an FPGA platform, which is based on FFT (Fast Fourier Transform)/CORDIC (Coordinate Rotation Digital Computer) demodulation and features independ-ent control functionality. This scheme directly samples the cavity and transmission line signals, employs FFT/CORDIC for amplitude and phase demodulation to derive the signal phase difference, and utilizes a PID algorithm to control a stepper motor for fine-tuning the cavity capacitance, thereby achieving resonant frequency tracking. To balance computational resource consump-tion and latency, an FPGA-based 2048-point FFT opera-tional structure and a CORDIC module with 16 iterations were designed. Simulations demonstrate that the phase measurement error of the proposed method is less than 0.06°, meeting the tuning precision requirements for accelerator cavities.

Funding Agency

Null.