Finite element simulation of the temperature field in the large volume cubic high pressure apparatus cavity

• We established a finite element temperature field model of diamond synthesis cavity.
• Variation in the resistivity values of the heater has little effect on the temperature distribution in the sample.
• Enhancing heater resistivity would increase the heating efficiency and achieve the purpose of energy saving.
• MgO pressure medium would cause an energy consumption rise and lower diamond quality.

The finite element method is used to simulate the steady-state temperature field in diamond synthesis cell, which has a indirectly heated assembly. A series of analysis about the influence of the heating tube and pressure medium parameters on the temperature field are examined through adjusting the model parameters. The results show that temperature distribution is uneven in the sample and the highest temperature peak lies in the center position of the graphite heating tube; variation in resistivity and thermal conductivity values of graphite-pipe has little influence on the temperature distribution in the sample, thereby reducing the input power of diamond synthesis by means of improving graphite-pipe resistivity value; employing magnesium oxide as pressure medium lead to a large temperature gradient, up to 3562 K/m, and a large temperature drop of 114 K in the sample. It will lead to lower diamond quality and an energy consumption rise of diamond production. Our research would contribute to further understanding of temperature distribution mechanism in diamond synthesis cavity and bring a certain reference value on the diamond production process optimization.