Metal oxide coating on first mirror in fusion reactor with carbon wall

The lifetime of diagnostic equipment in a fusion reactor is typically very short. The first mirror used to reflect optical signals for diagnostics plays a crucial role in the reactor, and it is highly important to develop a more durable first mirror which can survive in the hostile environment. In this work, by conducting electron beam deposition on molybdenum substrates, metallic oxide mirrors are prepared and studied in the simulated environment. The multi-layered metal oxide mirror exhibits much higher reflectivity than the original molybdenum one and the in situ technique to monitor the performance of the first mirror is developed and described. •In situ monitoring of the first mirror in a fusion reaction was described.•The Mo mirror is deposited with multiple layers of metal oxide to improve the reflectivity.•The 65-layer sample has the highest reflectivity.•This approach can be used in real-time and in situ monitoring based on the change in the electrical resistivity.