Simulation of the Divertor Target Shielding During Major Disruption in DEMO

Abstract

Simulation of divertor target damage during thermal quench of the disruption in the future DEMO tokamak has been performed using the TOKES code. This parametric study includes damage estimation for disruptions of the plasma energy E₀ in the DEMO core in the range of 0.4 to 1.3 GJ and of time duration 1 to 2 ms. According to the simulations, the maximum melt depth on the divertor targets is ~80 μm, independent of the energy content in the core. The melted pool maximum area grows from ~20 m² for 0.4-GJ disruption to ~120 m² for 1.3-GJ disruption. Maximum erosion depth is 4 μm for 1.3-GJ disruption and decreases to less than 1 μm with decreasing E₀. The total quantity of vaporized tungsten ranges from 2 ∙ 10²¹ to 3 ∙ 10²⁴ atoms for disruptions of 0.4 to 1.3 GJ. An additional parametric study has revealed weak dependence of the results from the characteristic widths λ_q of the disruptive flux in the scrape-off layer.

Keywords:

• Disruption
• DEMO
• TOKES
• numerical simulations
• plasma shielding

Acknowledgments

This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2017–2018 under grant agreement 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. The authors would like to thank Fabio Villone and Tim Hender for their contribution to the disruption simulation used as input in TOKES.