BEHAVIOUR OF LOW-Z COATINGS AND STRUCTURAL MATERIAL UNDER LIGHT IONS IRRADIATION
The use of low-Z materials for limiter surfaces seems to be a valuable technique to reduce the total erosion rate caused by all the various processes (sputtering, arcing, blistering, evaporation, etc.) acting in concert in a Tokamak machine. Because of the poor thermal conductivity of most proposed low-Z materials, it is necessary that they be used in the form of a thin coating on a structural substrate such as AISI 316 L S.S. The requirement that the coating be thin is especially critical in areas such as the limiter which are subjected to severe thermal loads. Sputtering yields of low-Z coatings (TiC, TiN, TiB-2) chemical vapour deposited on stainless steel have been measured under irradiation of D-2 at acceleration potential between 250 and 1000 V. All measurements have been performed by means of a Kaufman type ion source (VEECO microetch system), the current densities were chosen in order to have a maximum temperature increase of the samples surface lower than 200 degrees C (chemical sputtering negligible). Changes in the chemical composition of the irradiated samples were monitored by an AES-SIMS apparatus. Calibration of the experimental data has been done measuring the sputtering yields of structural materials (AISI 316 S.S. and Molybdenum) under H-2, D-2 and He irradiation. In all cases erosion losses were determined gravimetrically using a Mettler UM-3 microbalance having a sensitivity of about 0.1 microgram.
Bibliographic Reference: 6TH INTERNATIONAL CONFERENCE ON PLASMA SURFACE INTERACTIONS IN CONTROLLED FUSION DEVICES, NAGOYA (JAPAN), MAY 14-18, 1984 PP. 43-54 WRITE TO ENEA - CENTRO RICERCHE ENERGIA FRASCATI, SERVIZIO STUDI E DOCUMENTAZIONE, C.P. 65 - 00044 FRASCATI, ROMA (ITALY) M
Record Number: 1989124043000 / Last updated on: 1987-01-01
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