Experimental Studies of Physical Properties in the Fe-Si-S System at Planetary Core P, T Conditions

行星的许多重要表面特征，如磁场和板块构造，都与行星内部深处发生的物理和化学过程密切相关。不幸的是，对于大多数行星和行星体来说，它们的深层内部是禁止直接进入的区域，需要替代方法。在这项拟议的研究中，同时进行高压（高达25 GPa）和高温（高达2500 K）实验将在我们的大容量压力机上进行，以模拟类地行星内部的极端条件和我们太阳系中的一些分化卫星。Yong博士的研究计划的主题将集中在这些行星体的金属核心上，这些金属核心主要由铁组成，并含有少量较轻的元素，如硅，硫作为合金成分。富铁合金的熔化行为和液体密度对许多地球物理和行星现象具有重要意义，包括核心成分，热结构，热流，磁场产生和内核凝固情况。本文利用美国西部大学现有的最大容量（3000吨）多砧压机和分析仪器，对Fe-Si和Fe-S体系的高压熔化边界和液相密度进行了系统的实验研究。拟议的研究将通过为地球物理和行星科学界提供压力高达25 GPa的液态铁合金的两个基本物理特性的急需数据，回答理解行星深层内部的关键问题。对于某些化学成分和压力，这样的数据将是第一次。这些数据将进一步揭示与地球和月球、水星、火星、木卫三和木卫一等其他类地行星体内部发生的化学和物理状态、动力学和过程有关的重要问题（例如，地核中存在哪些轻元素，浓度如何？是否有一个坚实的内核，如果有，在什么深度和什么时候开始结晶？纯铁和铁合金液体之间的密度差异是否大到足以在液体外核中推动化学对流？）四名HQP将接受高压和高温实验矿物物理学的广泛培训，这将提供可转移的技能，为他们在学术界，政府和工业界就业做好准备。

Many important surface features of planets such as the magnetic field and plate tectonics are closely related to the physical and chemical processes happening inside the deep interior of a planet. Unfortunately, for most planets and planetary bodies, their deep interiors are forbidden regions for direct access and alternative approaches are needed. In this proposed research, simultaneous high pressure (up to 25 GPa) and high temperature (up to 2500 K) experiments will be conducted in our large volume presses to mimic the extreme conditions of the interior of terrestrial planets and some differentiated satellites in our solar system. The themes of Dr. Yong's research proposal will focus on the metallic cores of these planetary bodies, which consist primarily of iron, with a small amount of lighter elements such as silicon, sulfur as alloy constituents. The melting behavior and liquid density of iron-rich alloys have significant implications to many geophysical and planetary phenomena, including core composition, thermal structure, heat flow, magnetic field generation, and inner core solidification scenarios. A systematic experimental study of the high pressure melting boundary and liquid density of the Fe-Si and Fe-S systems will be carried out using our state of the art large volume presses, which include the largest capacity (3000 ton) multi-anvil press in North America, and analytical instruments at Western University. The proposed studies will answer questions that are key to understanding the deep interior of planets by providing the geophysical and planetary science community the critically needed data on two essential physical properties on liquid iron alloys at pressures up to 25 GPa. For certain chemical compositions and pressures, such data will be the first of its kind. These data will reveal additional insight into important questions related to the chemical and physical state, dynamics and processes occurring in the interiors of Earth and other terrestrial-type planetary bodies such as Moon, Mercury, Mars, Ganymede and Io (e.g. What light elements are present, and at what concentration, in the core? Is there a solid inner core and, if so at what depth and when did it start to crystallize? Are density differences between pure Fe and Fe alloy liquids large enough to power chemical convection in a liquid outer core?). Four HQP will receive extensive training in high pressure and high temperature experimental mineral physics that will provide transferable skills to prepare them for employment in academia, government and industry.