EROSION AND SURFACE MODIFICATIONS OF DIFFERENT FT LIMITERS
All various processes (sputtering, evaporation, arcing, blistering, chunk emission, etc.) acting in the scrape-off region have proven to be the main responsible mechanism for the surface erosion. The paper analyzes the behaviour of three different limiters used in FT machine for several discharges by means of SEM-EDXA technique. The first limiter analyzed has a circular cross-section of the surface facing the plasma. The second one has an elliptic cross-section to get a uniform distribution of the heat flux. The third one is slightly different from the others: movable mushrooms are placed on a stem as a mounting support. All limiters are manufactured in AISI 316 L stainless steel. Thermal energy dumped during a disruption results in vaporization and production of melted layers. The instability of this melted layer depends on the strength of the magnetic forces acting on the limiter surface and may give rise to the so-called "chunk emission". Microstructural changes (fissures, dendrites, growth, etc.) on the damage areas and sputtering and arcing on the limiters ion side were observed.
Bibliographic Reference: 6TH INTERNATIONAL CONFERENCE ON PLASMA SURFACE INTERACTIONS IN CONTROLLED FUSION DEVICES, NAGOYA (JAPAN), MAY 14-18, 1984 PP. 27-41 WRITE TO ENEA - CENTRO RICERCHE ENERGIA FRASCATI, SERVIZIO STUDI E DOCUMENTAZIONE, C.P. 65 - 00044 FRASCATI, ROMA (ITALY) M
Record Number: 1989124042900 / Last updated on: 1987-01-01
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