HP Star is a high-pressure research laboratory investigating environments that mimic conditions found at the core of our solar system’s largest planets. By creating enormous pressures and temperatures on a micro scale the scientists at HP Star can study the effects of the universe’s most abundant elements in the most extreme environments.
The goal of this research is to understand what happens to the basic elements when they are subjected to enormous pressure and temperature which will allow us to gain a deeper understanding of what actually goes on inside the core of a planet. Jupiter, Saturn, and our solar system’s jovian planets are made up of mostly Hydrogen and Helium. These two abundant elements are the main focus for high-pressure experiments conducted at the HP Star labs.
To achieve such high pressures within a laboratory in Shanghai, HP star scientists trap hydrogen gas within a sample chamber which is clamped in between two diamonds. A small piece of metallic foil is laser drilled to create a sample chamber ranging from 20-200 microns. The metallic foil acts as a gasket which is precisely pressed between two diamonds providing a sample chamber for the experiments.
Once the sample gas is trapped between the diamonds the scientists can slowly increase the pressure by tightening steel cells that clamp the diamonds together. This crushes the trapped gas to enormous pressures within the chamber thanks to the incredible hardness and carbon structure of the diamonds. The other benefit of using diamonds to create high-pressure chambers takes advantage of their optical clarity. This allows the scientists to fire powerful infrared lasers through the diamonds into the high-pressure chambers recreating the extreme temperatures and pressures found at planetary cores.
Dr. Dalladay-Simpson is using 3D printing to create cell holders that serve as a platform to conduct the experiments. The cell holders contain the steel cells which provide the clamping force exerted on the diamonds. The material requirements for these cell holders are very demanding as the localised pressure and temperature within the chamber can reach 400 GPa and over 3800°C. While this immense pressure and temperature is very localised within the diamond chamber and only occurs for a short period of time, the material of the cell holders still needs to be very rigid and heat resistant to produce reliable experiments.
“The Earth’s core has a pressure of 320 gigapascals (GPa), in our experiments, we can reach pressures of 400 GPa, when we increase the pressure past this point our diamonds tend to explode under pressure, when they go, it’s pretty spectacular.” – Dr. Dalladay-Simpson
PolyMide™ PA6-CF, the latest material from Polymaker has been the material of choice for the lab. “the rigidity and strength of the carbon-filled nylon produces a really solid cell holder, our focal range works in a tolerance of microns and the cells stay dead on after increasing the pressure.” – Dr. Dalladay-Simpson
With a heat deflection temperature of 215°C, PolyMide™ PA6-CF proves itself as a very good candidate for many types of custom lab equipment not just these cell holders. “Previously for custom lab equipment we expected a 2-3 week lead time from our in-house machine shop and often we would need to further modify the equipment. These new materials [PolyMide™ PA6-CF & GF] rapidly expedite that process, while also producing superior and more formative lab equipment.” – Dr. Dalladay-Simpson
At the other end of the temperature spectrum, PolyMide™ PA6-GF has been used to create cryo boxes which study elements at extremely cold temperatures. These cryo boxes are used for cryogenically cooling the diamond tips until they’re cold enough to condense samples on, either as a solid or a liquid depending on the specimen element.
This allows high-pressure research experiments on solid chlorine, hydrogen sulfide, and other high-temperature superconductors. This research gives insight into the atmospheric conditions experienced by our solar system's gas giants. “We’ve been pouring liquid nitrogen straight into the 3D printed cryo boxes to rapidly cool our cells, we’ve experienced some non-fiber reinforced filaments crack under the heat shock, the PA6-GF performs very well when subject to these conditions.” – Dr. Dallday-Simpson
For Dr. Dalladay-Simpson the end goal is to produce metallic hydrogen in his lab which has been described as the holy grail of high-pressure physics. Metallic hydrogen is a phase of hydrogen in which it behaves like an electrical conductor and was first theorized in 1935 by Eugene Wigner and Hillard Bell Huntington. Researchers believe that metallic hydrogen is present in large quantities in the hot and gravitationally compressed interiors of Jupiter and Saturn. By using an in-house developed RAMAN scattering technique, Dr. Dalladay-Simpson can probe vibrations inside the sample chamber which he hopes will reveal the metallic hydrogen.
