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Author(s):
N. Noda, K. Tsuzuki, A. Sagara, N. Inoue and T. Muroga
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Title:
Boronization in Future Devices -Protecting Layer against Tritium and Energetic Neutrals-
Date of publication:
July 1998
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Key words:
boronization, long-time machines, tritium inventory, tritium permeation, protecting layer, damages by energetic neutrals, redeposition
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Abstract:
A thin boron film is attractive as a deuterium/tritium free wall, and as a protecting layer against impact of energetic charge-exchange neutrals in future fusion devices with a long-time operation. New experimental evidences are given for desorption of hydrogen isotopes at relatively low temperature. All hydrogen atoms in a boron-coated layer are reemitted to the plasma side below 400degreeC without their penetration into substrate of stainless steel. A problem is maintainability of a thin boron layer during a long-time operation. Boron atoms are hardly removed by pumping because its hydrides are easily disintegrated and redeposited Gross immigration of boron atoms inside the vessel is a concern. A condition required for avoiding the immigration is discussed.
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