ITER plans half-mile boron gas pipelines to purify fusion plasma

Source: interestingengineering
Author: @IntEngineering
Published: 7/10/2025
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Read original articleThe ITER fusion project is developing an extensive boronization system to purify plasma and reduce impurities in its tokamak reactor, following a 2023 decision to switch plasma chamber armor from beryllium to tungsten. This system applies a thin boron layer (10-100 nanometers) to all plasma-facing surfaces, which captures oxygen impurities that could otherwise increase radiative losses and destabilize the plasma, especially during discharge initiation. The boron layer is deposited using diborane gas (a hydrogen-boron compound) injected into the tokamak, where it decomposes and chemically bonds to surfaces via a glow-discharge-assisted plasma process. The gas injection system involves over a kilometer of piping and 21 injection points within the facility.
Designing this system at ITER’s unprecedented scale and in a tritiated environment posed challenges, including ensuring the compatibility of high-energy anodes with frequent boronization cycles and achieving even boron coverage. These issues were addressed through international collaboration and testing with other
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energynuclear-fusiontokamakboronizationplasma-purificationITERfusion-technology