Mobile Magnetic Ressonance Sensor utilizing a superconductive coil for prepolarisation in the near subsurface (MORE SPIN)

拟议项目的目的是开发一种高移动核磁共振传感器，以检测深度约2米的土壤水分含量的横向和垂直变化。土壤湿度对许多过程都很重要。由于土壤是大气与地下的界面，它与流体和质量的输运过程有关。然而，到目前为止，还没有足够的方法可以在所有需要的时间和空间尺度上直接绘制土壤含水量。这些方法要么是直接的，但不能在大规模上使用，要么是可以在大规模上使用，如普通的地球物理方法，但是间接的，因此具有模糊性。作为一种非破坏性的直接方法，核磁共振（NMR）及其在地球表面的应用越来越受到地球物理学界的关注，以解决水文问题。不幸的是，SNMR无法提供非常近地表（dm）的土壤参数，因为在该深度范围内灵敏度不够低，而且SNMR测量太耗时，无法绘制大（km）区域。最近提出了一些理论概念，建议开发一种新的基于核磁共振的传感器来克服这些测量进度和灵敏度的限制。提出了一个合适的，高移动核磁共振传感器的概念是基于预极化，使用超导线圈连同绝热脉冲和小点状接收器。而预极化是用来增加宏观磁化，绝热脉冲确保更均匀的激发地下。这两种特性结合在一起，有望将信号幅度提高至少十年，而点状接收器将有助于提高横向分辨率。功能齐全的新型传感器能够在大范围内和选定深度（例如表层土壤，根区，底土）下至2米获取土壤水分分布。因此，它有可能成为获取大规模运输（与永久冻土或气候变化模型有关）、地下水补给、土壤保护甚至精准农业信息的突破性工具。因此，来自汉诺威莱布尼茨大学、柏林工业大学、联邦地球科学与自然资源研究所和亚琛工业大学的土壤科学家支持这一提议，因为他们对使用开发的仪器进行自己的研究非常感兴趣。

The aim of the proposed project is the development of a highly mobile NMR sensor to detect lateral and vertical changes in the soil moisture content down to about 2 m depth.Soil moisture is important for numerous processes. As soil is the interface between the atmosphere and the subsurface it is relevant for fluid and mass transport processes. However, up to now, there are no adequate methods that can directly map the soil moisture content at all demanded time and spatial scales. Either the methods are direct but cannot be used on a large scale or they can be used on the large scale such as common geophysical methods but are indirect and therefore suffer from ambiguities.As a non-destructive direct method nuclear-magnetic-resonance (NMR) and its application from the surface of the Earth (SNMR) has gained increasing interest in the geophysical community to target hydrological questions. Unfortunately, SNMR is not capable to deliver soil parameters for the very near surface (dm) due to insufficiently low sensitivity at that depth range and furthermore SNMR measurement are too time consuming to map large (km) areas. Recently, theoretical concepts were presented lately that suggest the development of a new NMR-based sensor to overcome these restrictions of measurement progress and sensitivity.The proposed concept of a proper, highly mobile NMR sensor is based on prepolarisation using a superconducting coil together with adiabatic pulses and small point-like receivers. While prepolarisation is used to increase the macroscopic magnetisation, adiabatic pulses ensure a more homogeneous excitation of the subsurface. Both features combined promise an increase in signal amplitude of at least a decade whereas point-like receivers will help to increase lateral resolution.The full-functional new sensor enables to access the soil moisture distribution at a large scale and at selected depths (e.g., top soil, root zone, subsoil) down to 2 m. Therefore, it has the potential to become a ground-breaking tool to obtain information on mass transport (in connection with permafrost or climate change modelling), groundwater recharge, soil protection or even precision agriculture. Consequently, soil scientists from the Leibniz University Hanover, the Berlin Technical University, the Federal Institute for Geosciences and Natural Resources and the RWTH Aachen support the proposal as they have great interest to use the developed instrument for their own research.