The ITER divertor exhausts the flow of energy from charged particles produced in the fusion reactions and removes helium and other impurities resulting from the reactions, and from interaction of plasma particles with the material walls.
A single null divertor, consisting of 54 modules (cassettes), is located at the bottom of the vacuum vessel. This approach provides an accurate mechanical support and the flexibility to change the configuration of the plasma-facing components. It has the ability to withstand a steady power load of up to 210 MW. The divertor has carbon targets and tungsten high heat flux components, mounted on a copper substrate, and water-cooled stainless steel structure bolted to rails on the vessel floor. The targets can accommodate heat loads of more than 20 MW/m2 for 20 s, but the more normal peak heat load will be 5 - 10 MW/m2. Key elements of the manufacturing include the development of cost-effective solutions to securely locate the plasma facing components with high precision, and to join together the various materials with vacuum-compatible bonding using reliable and repeatable methods that do not require every component to be high heat flux tested. These elements have been developed and tested in the Divertor Cassette Project (L-5). Plasma diagnostics view the plasma through the gaps between cassettes or through the pumping slots.
Given the physics uncertainties in the power flux distribution, it is difficult to estimate divertor life; therefore, the design provides for rapid replacement and refurbishment of divertor cassettes. A remote handling, replacement and refurbishing system has been developed in detail for the divertor, and tested in the Divertor Remote Handling Project (L-7). The full change over of the divertor has been shown to take less than six months.
Further design details can be found in the Technical Basis divertor 
and remote handling sections.
Basic design approach |
Replaceable cassette with detachable plasma facing elements |
Surface heat loads including power excursions (MW) |
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Total heat load including power excursion and volumetric neutron heat (MW) |
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Local thermal load at normal operation conditions, normal to surface, (MW/m2): |
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Required design lifetime |
More than 1000 standard pulses plus 200 full power disruptions |
Required replacement time, (months) |
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Materials: vertical target |
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Materials: liner |
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Materials: dome |
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Divertor coolant: |
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