核磁共振发射波形质量评估及影响因素分析

核磁共振发射电流波形存在暂态响应和电流衰减,降低了发射波形质量,严重影响探测精度.结合国内外核磁共振找水仪发射机研制情况,给出了发射波形质量的评估参数,提出了针对核磁共振找水仪的暂态响应和电流衰减的数值计算方法,结合发射波形数值计算结果讨论了影响发射波形质量的仪器系统参数.基于吉林大学自主研制的核磁共振找水仪发射机的实测结果与计算推论一致.该发射波形质量评估及影响因素分析可为不同核磁共振找水仪发射机设计提供依据.

Evaluation and affecting factor analysis of MRS transmitting waveform quality

The accuracy of MRS (Magnetic Resonance Sounding) exploration may be affected by emission current waveform quality decreasing. Transient response and current attenuation are the two main determinants of the waveform quality. The paper analyzes the MRS transmitters both native and abroad, gives out emission waveform quality evaluation parameters, proposes a calculation method for transmitting current waveform (both transient response and current attenuation) and discusses the instrument system parameters affecting waveform quality based on emission current calculation formulas. Experiments carried out with the MRS instrument developed by Jilin University verify the discussion above. The evaluation of emission waveform quality and the analysis of quality influence parameters can be used for different MRS transmitter designs.