基于双匝线圈的轻便式核磁共振找水仪研制

Research and development of portable nuclear magnetic resonance groundwater exploration instrument based on double-turn coils

核磁共振系统测量时,需要产生较高的激发磁矩来完成对深层地下水的激发。为满足发射功率的要求,现有核磁共振探测系统的体积和重量较为庞大。提出一种利用多匝线圈进行探测的方法,在不损失探测深度的前提下,可以降低系统的发射功率,达到仪器系统轻便化的目的。通过理论计算,得出了利用75 m双匝线圈发射150 A电流,可达到100 m核磁共振测深的结论。研制出的轻便型系统体积和重量是现有商品化核磁共振系统的1/6左右,具有一体化、操作简便、性能稳定等优点。给出了系统关键结构的设计方法和测试结果,通过野外对比试验、重复试验及实际打井验证等手段,证明了所研制的轻便型系统对地下水探测的有效性。

In magnetic resonance sounding （MRS） instrument, it is necessary to produce high magnetic strength to complete the stimulation for deep groundwater. However, due to the requirement of transmission power, the volume and weight of existing magnetic resonance sounding detection system are huge. A detection method that uses multiturn coil is proposed, which can reduce the transmission power without losing the detecting depth and achieve the purpose of making the instrument system portable. Through theoretical calculation, we reach the conclusion that a 75 m double turn coil is used to transmit 150 A current and obtain the detecting depth of 100 m. The volume and weight of the developed portable instrument are about one sixth of those of existing commercial nuclear magnetic reso- nance instruments, and the portable instrument has the advantages of integration, easy operation, stable performance and etc. This paper gives the design method and test results of the key system structure. Field comparison experiment, repeatability experiment and practical well drilling prove the effectiveness of the developed portable nuclear magnetic resonance instrument in groundwater exploration.