Development of a roughened inner sphere for the three-meter model of the Earth's core

我们星球的磁场直接影响太阳风暴期间的近地辐射。这使得理解产生磁场的过程，以及发展我们预测磁场变化的能力变得重要。这项地球科学仪器和设施计划奖支持一项旨在更好地了解地球磁场的起源和变化的项目。由于这些正在进行的变化是地球外核深处过程的结果，因此很难进行直接研究。研究人员开发了一个由美国国家科学基金会资助的地球外核实验室模型：三米长的液钠实验。该项目将对钠实验进行重大设计修改，以便更好地模拟地核，产生模型磁场，并增强我们预测磁场变化的能力。该项目还通过电视和网络纪录片以及研究小组YouTube频道(www.youtube.com/user/n3umh)上发布的视频，鼓励公众欣赏和了解地磁学；通过经常参观实验室，向广大受众开放非科学家的努力和活动；并教育新一代学者进行地球物理实验，包括本科生指导和研究生培训。地球主磁场是使我们的星球成为宜居家园的核心。在太阳活动高峰期，太阳风暴会产生致命的带电粒子辐射。地球发电机磁场，以及地球的大气层，用来保护我们免受最坏的影响。尽管如此，太阳风暴可能会影响无线电通信、电网和航天器的运行。因此，我们有动力了解地球磁场的起源，探索其动力学，并潜在地预测其行为。虽然我们知道磁场随着时间的推移发生了巨大的变化，包括通过不稳定的逆转，但对于地核发生的天气没有可靠的预测科学，也没有对地球发电机产生的充分了解。美国国家科学基金会资助的地核三米(3米)实验室模型从旋转湍流中产生感应磁场，对地核的动力学进行建模，并可用于测试发电机磁场预测。一秒钟的实验模拟了大约5000年的核心湍流(基于相对磁偶极子扩散时间尺度)，从而能够观测到地球上不可能发生的详细的磁场演变。虽然自2008年开始运行以来，以前的实验在流体力学和磁流体力学方面取得了重要成果，但现在需要对3米实验进行重大设计修改，以增加磁场增益。这将对继续研究至关重要，包括那些直接解决与发电机发电和维持有关的问题的研究。该项目将对3米液钠系统进行重大改造，允许尝试发电机磁场作用，并开放系统的参数空间，以扩大磁流体力学实验的潜力。该项目还通过基于电视和网络的纪录片和频繁的设施参观，直接促进公众对地磁学的欣赏和了解。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Our planet's magnetic field directly affects near-Earth radiation during solar storms. This makes it important to understand the process that generates the magnetic field, and also to develop our capacity to predict its changes. This Division of Earth Science Instrumentation and Facilities Program award supports a project which aims to better understand the origin and changes of the Earth's magnetic field. Since these ongoing changes are a result of processes deep in the planet's outer core, it is difficult to do direct studies. The investigators have developed an NSF funded laboratory model of the Earth's outer core: the three-meter liquid sodium experiment. This project will involve a major design modification to the sodium experiment that is needed in order to better mimic the Earth's core, produce model magnetic fields, and enhance our ability to predict magnetic field changes. The project also serves to encourage public appreciation and understanding of geomagnetism through TV and web based documentaries, as well as videos posted on the research group's YouTube channel (www.youtube.com/user/n3umh); to open efforts and activities to non-scientists through frequent tours of the laboratory to a broad range of audiences; and to educate a new generation of scholars in geophysics experiments, including undergraduate mentoring and graduate student training.The Earth's main magnetic field is central to making our planet a habitable home. During solar maximum, solar storms produce deadly charged particle radiation. The geodynamo magnetic field, along with the Earth's atmosphere, serves to shield us from the worst of these. Nonetheless, solar storms can affect radio communications, the power grid, and spacecraft operations. Thus, we are motivated to understand the origins of the Earth's magnetic field, explore its dynamics, and potentially forecast its behavior. While we know the field changes dramatically over time, including through erratic reversals, there is no reliable predictive science for the weather occurring in the core and no full understanding of the Earth's dynamo generation. An NSF-funded three-meter (3-m) laboratory model of the Earth's core produces induced magnetic fields from rotating turbulence, modeling the dynamics of the Earth's core, and can be used for testing dynamo magnetic field forecasting. One second of experiments mimic approximately 5,000 years of core turbulence (based on the relative magnetic dipole diffusion time scales), allowing observations of detailed magnetic field evolution not possible for the Earth. While previous experiments have yielded important results in hydrodynamics and magnetohydrodynamics since operations began in 2008, the 3-m experiment now requires significant design modifications to increase magnetic field gain. This will be critical for continued studies, including those that directly address questions related to dynamo generation and sustenance. This project will undertake a major modification of the 3-m liquid sodium system that will allow attempting dynamo magnetic field action, and open the parameter space of the system to expand the potential of magnetohydrodynamics experiments. The project also makes direct contributions to the public appreciation and understanding of geomagnetism through TV and web based documentaries and frequent facility tours.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.