Abstract
Dynamic compression experiments on geological materials are important for understanding the composition and physical state of the deep interior of the Earth and other planets. These experiments also provide insights into impact processes relevant to planetary formation and evolution. Recently, new techniques for dynamic compression using high-powered lasers and pulsed-power systems have been developed. These methods allow for compression on timescales ranging from nanoseconds to microseconds and can often achieve substantially higher pressures than earlier gas-gun-based loading techniques. The capability to produce shockless (ramp) compression provides access to new regimes of pressure-temperature space while new diagnostics allow for a more detailed understanding of the structure and physical properties of materials under dynamic loading. This review summarizes these recent advances, focusing on results for geological materials at ultra-high pressures above 200 GPa.
Highlights
There is a growing interest in application of experimental studies of geological materials at ultrahigh pressure–temperature conditions to both new and long-standing problems in Earth and planetary science (Duffy et al, 2014)
The method is strictly applicable in the case of simple wave propagation, where deformation is not affected by changes in compression rate, and the presence of phase transitions and elastic-plastic behavior may lead to non-uniqueness in the solutions
Quartz is a useful standard because above its Hugoniot melting point (∼90–100 GPa), it becomes a conductive fluid with sufficient reflectivity that shock velocities at ultra-high pressure can be measured with high precision using standard laser velocimetry (Knudson and Desjarlais, 2009)
Summary
There is a growing interest in application of experimental studies of geological materials at ultrahigh pressure–temperature conditions to both new and long-standing problems in Earth and planetary science (Duffy et al, 2014). Such experiments can address fundamental questions about the structure, dynamics, and evolution of the deep Earth. The size range between Earth and Neptune represents the most abundant population of exoplanets detected to date (Borucki, 2016) These planets have no direct analogs in our own solar system and potentially represent novel planetary types. A lack of constraints on the physical and chemical properties of materials at extreme conditions severely limits progress on these questions
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