基于FPGA的低场核磁共振谱仪脉冲编程器设计与实现

摘要

脉冲编程器在核磁共振(NMR)谱仪中非常重要,具有产生脉冲序列所需的射频脉冲,控制回波信号的同步接收等功能.基于FPGA的同步性能和时序控制功能,设计了低场NMR谱仪的脉冲编程器,可产生任意脉冲序列,实现脉冲频率、相位、幅度的灵活调节,利用设计的脉冲编程器在0.540 Tesla均匀磁场下进行了CuSO4溶液的T1和T2测量,得到高信噪比的NMR回波串.%Pulse programmer is an integrating part of NMR spectrometer, which is used to generate RF pulse and to receive echo trains signals. Taking advantage of the syn chronous performance and excellent timing control capacity of FPGA, a FPGA-based pulse programmer for low field NMR spectrometer was designed to generate pulse se quences for different NMR experiments. Flexible control of the frequency, phase and amplitude of the RF pulses could be achieved with this pulse programmer. Performance of the pulse programmer was evaluated with measurements of transverse and longitudi nal relaxation rates of CuSO4 solution under uniform magnetic field (0. 540 Tesla). The pulse programmer was also used to collect echo trains signals with high signal-to-noise ratio.