Erosion and redeposition of divertor and wall materials during abnormal events

摘要

High energy deposition to in-vessel components of fusion reactors is expected to occur during abnormal operating conditions. This high energy dump in short times may result in very high surface temperatures and can cause severe erosion as a result of melting and vaporization of these components. One abnormal operating condition results from plasma disruptions where the plasma loses confinement and dumps its energy on reactor components. Another abnormal condition occurs when a neutral beam used in heating the plasma shines through the vacuum vessel to parts of the wall with no plasma present in the chamber. A third abnormal event that results in high energy deposition is caused by the runaway electrons to chamber components following a disruption. The failure of these components under the expected high heat loads can severely limit the operation of the fusion device. The redeposition of the eroded materials from these abnormal events over the first wall and other components may cause additional problems. Such problems are associated with tritium accumulation in the freshly deposited materials, charge exchange sputtering and additional impurity sources, and material compatibility issues.