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Plasma-facing materials and first wall

node

The first wall and divertor are the surfaces that face the plasma directly, and they must survive heat fluxes comparable to a rocket nozzle while being bombarded by 14.1 MeV neutrons that displace atoms in the lattice and transmute the material itself. Damage is measured in displacements per atom; published assessments put a power-plant first wall in the range of tens of dpa per operating period, with damage rates above roughly 15 dpa per year under power-plant conditions. ITER's updated 2024 baseline changed the first wall material from beryllium to tungsten, a decision driven by plasma-facing performance and licensing considerations rather than by any experimental failure of beryllium. No material has yet been qualified at power-plant neutron fluence, because no facility has produced that fluence: dedicated fusion-spectrum irradiation sources such as IFMIF-DONES are intended to fill the gap and are not yet delivering high-dose data. This is the least glamorous and possibly the most binding of the engineering gaps.

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    Assembled narrative · 1

    Assembled from 10 blocks · 1 evidence · 10 related

    1. Story
    2. The first wall and divertor are the surfaces that face the plasma directly, and they must survive heat fluxes comparable to a rocket nozzle while being bombarded by 14.1 MeV neutrons that displace atoms in the lattice and transmute the material itself. Damage is measured in displacements per atom; published assessments put a power-plant first wall in the range of tens of dpa per operating period, with damage rates above roughly 15 dpa per year under power-plant conditions. ITER's updated 2024 baseline changed the first wall material from beryllium to tungsten, a decision driven by plasma-facing performance and licensing considerations rather than by any experimental failure of beryllium. No material has yet been qualified at power-plant neutron fluence, because no facility has produced that fluence: dedicated fusion-spectrum irradiation sources such as IFMIF-DONES are intended to fill the gap and are not yet delivering high-dose data. This is the least glamorous and possibly the most binding of the engineering gaps.
    3. Knowledge
    4. Plasma-facing materials and first wall
    5. Connections
    6. ITER
    7. Breakeven
    8. ITER presents an updated project baseline to the ITER Council
    9. Evidence
    10. ITER's current programme targets, the magnitude of slippage against the 2016 reference baseline, and the change of first wall material to tungsten
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    Observed changes · 0

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