Institut fur Technische und Makromolekulare Chemie, RWTH Aachen University, Worringer Weg 1, D-52074 Aachen, Germany.
J Magn Reson. 2013 Aug;233:74-9. doi: 10.1016/j.jmr.2013.05.004. Epub 2013 May 20.
We report the optimization of a slim-line logging NMR tool carried out by maximizing the signal-to-noise ratio of the NMR measurements. The tool, based on cylindrical permanent magnets of 20 cm length and 5 cm diameter, has a penetration depth of about 2 cm measured from its surface. This is obtained thanks to a large radio frequency coil whose dimensions are comparable to the sensor size. An analytical expression of the SNR as a function of parameters which take into account the interaction between the radio frequency coil and the magnet shielding is developed. In view of the external constrains such as the one imposed by the excavation hole, a proper tool size is determined in the optimization process. Due to its size and properties, the sensor is suitable to measure water content in the vadose zone, which is the zone comprised within the first meters of the Earth surface and whose study is important for improving water management in agriculture and for refining climate models.
我们报告了一种瘦身线测井 NMR 工具的优化，该工具通过最大化 NMR 测量的信噪比来实现。该工具基于长度为 20 厘米、直径为 5 厘米的圆柱形永磁体，从其表面测量的穿透深度约为 2 厘米。这是通过一个大型射频线圈实现的，其尺寸与传感器尺寸相当。开发了一种 SNR 的解析表达式，作为考虑射频线圈和磁屏蔽相互作用的参数的函数。考虑到外部约束，例如挖掘孔施加的约束，在优化过程中确定了适当的工具尺寸。由于其尺寸和特性，该传感器适合测量包气带中的含水量，包气带是指地球表面第一层内的区域，其研究对于改进农业用水管理和改进气候模型非常重要。
