Beryllium transport properties

An unresolved issue related to the use of a beryllium, or any solid material, as a first wall is the issue of mixed-materials. Although the properties of beryllium may lend themselves to its use in a particular environment, those properties can change dramatically as material from other locations in the machine is eroded, transported and then deposited on the beryllium plasma facing surfaces. Such mixed-material surfaces can dominate the rate of long-term tritium accumulation within a device and may severely restrict its operational lifetime. 

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