A broadband pulse amplifier for Joule heating experiments in diamond anvil cells.

Decades of measurements of the thermophysical properties of hot metals show that pulsed Joule heating is an effective method to heat solid and liquid metals that are chemically reactive or difficult to contain. To extend such measurements to hundreds of GPa pressure, pulsed heating methods have recently been integrated with diamond anvil cells. The recent design used a low-side switch and active electrical sensing equipment that was prone to damage and measurement error.

Imaging the Meissner effect in hydride superconductors using quantum sensors.

By directly altering microscopic interactions, pressure provides a powerful tuning knob for the exploration of condensed phases and geophysical phenomena. The megabar regime represents an interesting frontier, in which recent discoveries include high-temperature superconductors, as well as structural and valence phase transitions. However, at such high pressures, many conventional measurement techniques fail.

Spectroradiometry with sub-microsecond time resolution using multianode photomultiplier tube assemblies.

Accurate and precise measurements of spectroradiometric temperature are crucial for many high pressure experiments that use diamond anvil cells or shock waves. In experiments with sub-millisecond timescales, specialized detectors such as streak cameras or photomultiplier tubes are required to measure temperature. High accuracy and precision are difficult to attain, especially at temperatures below 3000 K.

The stability of FeH and hydrogen transport at Earth's core mantle boundary.

Iron hydride in Earth's interior can be formed by the reaction between hydrous minerals (water) and iron. Studying iron hydride improves our understanding of hydrogen transportation in Earth's interior. Our high-pressure experiments found that face-centered cubic (fcc) FeH (x ≤ 1) is stable up to 165 GPa, and our ab initio molecular dynamics simulations predicted that fcc FeH transforms to a superionic state under lower mantle conditions.

A Spectroscopic Study of the Insulator-Metal Transition in Liquid Hydrogen and Deuterium.

The insulator-to-metal transition in dense fluid hydrogen is an essential phenomenon in the study of gas giant planetary interiors and the physical and chemical behavior of highly compressed condensed matter. Using direct fast laser spectroscopy techniques to probe hydrogen and deuterium precompressed in a diamond anvil cell and laser heated on microsecond timescales, an onset of metal-like reflectance is observed in the visible spectral range at >150 GPa and ≥ 3000 K. The reflectance increases rapidly with decreasing photon energy indicating free-electron metallic behavior with a plasma edge in the visible spectral range at high temperatures.