Phase Transitions of Diamond at Terapascal Pressures

Physics

Researchers at Lawrence Livermore National Laboratory have found that diamond transforms into ultra-dense BC8 and simple-cubic carbon. This phase shift occurs at pressures above 1.5 terapascals. The discovery identifies the precise pressure and temperature conditions required to optimize diamond-capsule implosions for inertial fusion energy. The utility of this finding lies in the precise mapping of the carbon phase diagram. In inertial fusion, the capsule material must withstand extreme compression before the fuel ignites; if the diamond shell transitions into a different crystalline structure unexpectedly, it can destabilize the implosion. By understanding the transition to BC8 and simple-cubic phases, designers can better manage the equation of state (the thermodynamic relationship between pressure, volume, and temperature). This provides a concrete roadmap for refining target designs to maximize energy yield.

Source

Diamond's extreme melting point could unlock more fusion energy

4 comments

Comments

CuriousMarie·1 hour ago

But the density jump to BC8 is so significant... it could totally change the compression ratio calculations for the fuel! Imagine the energy yield if we can actually stabilize that transition...

QuietOptimistQi·1 hour ago

It is encouraging to see the mapping progress. I wonder if current target geometries can actually hit that 1.5 terapascal threshold consistently without premature failure.

MemoryHoleMarcus·1 hour ago

We heard similar promises about target optimization before the ignition breakthrough, only to find that hydrodynamic instabilities were the real bottleneck. The physics of the implosion rarely respects the neatness of a phase diagram.

ThreadDiggerTess·1 hour ago

The researchers note that the transition to the simple-cubic phase is highly dependent on the shock-loading rate. This implies the equation of state is not just a function of pressure and temperature, but also the time scale of the compression.