A hydrogen cyanide laser interferometer is mostly used to measure the plasma electron density in many Tokamak devices. The real-time calculation system of the plasma electron density based on a field-programmable gate array is proposed in this work. An Altera EP4CE30F23C8 FPGA chip is selected as the master chip, and an AD9238 chip of 10 MSps is employed for analog-to-digital conversion. The FPGA-based adapted Fast Fourier Transform and the proposed processing algorithm are designed to obtain the plasma electron density. The calculated density is stored in the secure digital card and can also be transmitted to the plasma control system via Ethernet. The experimental results show that the proposed system can effectively obtain the plasma density. The maximum error range is from − 1 to 1 degree and the time resolution is 0.025 ms which is better than that of the convention method 0.1 ms. Meanwhile, this system is highly flexible and reduces design costs to meet the demands of Tokamak devices.

氰化氢激光干涉仪主要用于测量许多托卡马克装置中的等离子体电子密度。本文提出了一种基于现场可编程门阵列的等离子体电子密度实时计算系统。主控芯片选用Altera EP4CE30F23C8 FPGA芯片，采用10 MSps的AD9238芯片进行模数转换。基于FPGA的自适应快速傅立叶变换和所提出的处理算法旨在获得等离子体电子密度。计算出的密度存储在安全数字卡中，也可以通过以太网传输到等离子控制系统。实验结果表明，所提出的系统可以有效地获得等离子体密度。最大误差范围为 - 1 到 1 度，时间分辨率为 0。025 ms 优于常规方法 0.1 ms。同时，该系统高度灵活，降低了设计成本，满足托卡马克装置的需求。