In the relentless pursuit of harnessing fusion energy, scientists are continually refining the materials that can withstand the harsh conditions inside a fusion reactor. A recent study led by Artem M. Dmitriev at the Department of Physics, University of Basel, Switzerland, has shed new light on the potential of platinum as a first mirror material for fusion applications. The research, published in the journal ‘Nuclear Fusion’ (Nuclear Fusion), compares platinum with the currently favored rhodium, offering insights that could significantly impact the future of fusion energy.
First mirrors (FMs) in fusion reactors, such as ITER, play a crucial role in optical diagnostics, but they face severe challenges. Erosion from plasma particles and redeposition of materials from the reactor walls can degrade their reflectivity over time. While in-vacuo plasma cleaning is used to restore their optical properties, this process can lead to surface patterning, which negatively impacts performance. “Repetitive cleaning of nanocrystalline mirrors can cause surface patterning, which negatively impacts their optical performance,” Dmitriev explained. This is a critical issue, as the mirrors must maintain high reflectivity to function effectively.
Dmitriev’s team tested both platinum and rhodium under cyclic plasma cleaning and steam ingress conditions, mimicking the harsh environment of a fusion reactor. The results were illuminating. Rhodium, currently the mainstream material, showed signs of degradation when exposed to steam, forming a thin layer of rhodium oxide and developing voids in the top micrometer of the coating. Despite this, plasma cleaning was able to restore the mirrors’ pristine reflectivity. However, the formation of voids raises concerns about long-term durability.
Platinum, on the other hand, showed remarkable resilience. “Platinum demonstrated superior resistance to steam ingress and cyclic plasma cleaning compared to rhodium,” Dmitriev noted. This robustness could translate into longer lifespans for first mirrors, reducing the frequency of replacements and maintenance downtime—a significant advantage for commercial fusion reactors.
The study also assessed neutron-induced transmutation, a process where neutrons alter the material’s properties. Both platinum and rhodium were evaluated under ITER and DEMO (Demonstration Power Plant) irradiation scenarios. The findings suggest that platinum’s transmutation effects are more predictable and less detrimental to its optical properties, further bolstering its case as a viable FM material.
The implications of this research are far-reaching. As fusion energy moves closer to commercial viability, the choice of materials for critical components like first mirrors becomes increasingly important. Platinum’s superior performance under harsh conditions could lead to more reliable and efficient fusion reactors, accelerating the transition from experimental setups to practical power plants. The energy sector is eagerly awaiting further developments, and Dmitriev’s work provides a promising path forward.
This research, published in ‘Nuclear Fusion’ translates to a significant step towards realizing the dream of clean, abundant fusion energy. As scientists and engineers continue to refine these materials, the future of energy production looks increasingly bright and sustainable.
