基于FPGA的高性能坎贝尔积分算法研究

Research on High Performance Campbell Algorithm Based on FPGA

为满足国际热核聚变实验堆的宽量程中子通量测量需求,设计了基于FPGA和交流耦合平方积分的高性能数字化坎贝尔积分算法,拥有更强γ抑制能力的同时将中子甄别系统的测量范围从10^5 s^-1提高到10^8 s^-1。结合235 U裂变室及坎贝尔测量原理研究了数字化坎贝尔积分算法,通过仿中子脉冲实验分析了脉冲甄别计数算法和坎贝尔积分算法重叠区域的工作性能,并得出坎贝尔积分算法在不同噪声下的适用条件,从而保证测量相对误差小于5%。使用基于该算法的测量系统在HL-2A进行了现场实验,对照脉冲甄别计数算法的测量结果进行标定,二者一致性非常好,在测量重叠范围内线性系数达0.97。

To meet the wide measuring range requirement of ITER neutron flux monitor,a high performance digital Campbell integrator based on FPGA and the AC-coupling square integration method was developed,which extends the measuring upper range from 10^5 s^-1 of the counting method to 10^8 s^-1 and shows high precision.The digital Campbell algorithm was studied based on the principle of 235 U fission chamber and Campbell theorem.By implementing an experiment using imitative neutron pulses,the performance of counting method and Campbell algorithm in the overlapped section was analyzed.The applicable conditions of Campbell algorithm under different noise levels were obtained to make the relative error less than 5%.Moreover,an in-situ experiment at HL-2A was carried out.The output of Campbell algorithm was fitted by the output of counting method and then converted to counting rate.The linear coefficient reaches 0.97 and the converted counting rate shows remarkable consistency with the result of counting method.