Thermal management and design optimization for ultrahigh-temperature-pressure experiments in multi-anvil presses

The simultaneous generation of ultrahigh pressure and temperature in a multi-anvil press is crucial for studying planetary interiors and synthesizing novel materials. However, this goal is fundamentally challenged by severe thermal losses for the small sample-cell assembly, especially at ultrahigh pressures above 40 GPa. Our study employs a coupled thermal-electrical finite element model, validated by experimental data, to investigate the principles for enhancing the temperature generation capacity of an ultrahigh-pressure assembly. Our finite element model well reproduces the experimental heating results at ultrahigh pressures. The simulation analysis demonstrates the radial alumina insulation sleeve as the most significant factor for improving heating efficiency, while enlarging the diameter of the titanium carbide electrode is critical for enhancing interfacial stability. Counterintuitively, the adoption of high-thermal-conductivity sintered diamond anvils, while demanding more power, serves as an essential safety mechanism by preventing the melting of sintered diamond anvil truncations through the efficient heat dissipation. The combined optimization of these factors alleviates previous thermal bottlenecks and allows the assembly to reach noticeably higher temperatures (∼4000 K). This work thereby provides a rational framework and practical strategies for achieving more extreme ultrahigh temperature conditions at ultrahigh pressures through integrated thermal management.