INFLUENCE OF THE PUMP LIMITER ALT-I ON THE HEAVY IMPURITY FLUXES IN THE SCRAPE-OFF LAYER OF TEXTOR
Time and spaceresolved measurement of the Fe, Cr, Ni, Ti and O impurity fluxes in the limiter shadow of TEXTOR with the StockholmTEXTOR probe were made during the test campaign for the pump limiter ALTI. The wall components were metallic and routinely conditioned by RG discharge cleaning. The influence of pump limiter head material (TiC, INC 600), geometry of the head, hydrogen gas inlet programs, neon puffing through and plasma shifting against the head have been studied. The metal fluxes in the shadow of the limiter are dominated by its material. They are higher when the pump limiter is used instead of the main limiters. The Fef5Crf5Ni signal increases by a factor of 23 and corresponds to a decrease in the electron density due to the pumping. About a 50fold increase for Ti and a 30fold for O is observed and suggests additional liberational processes are involved. Ti remained in the machine even after terminating the ALTI activity. The impurity development is substantially independent of throat widths and hydrogen fuelling variations, whereas neon puffing leads to a rapid decrease due to plasma edge cooling. Shifting the plasma against the pump limiter causes an outburst of Ti.
Bibliographic Reference: JOURNAL OF NUCLEAR MATERIALS, NOS. 145-147 (1987), PP. 631-636
Record Number: 1989126005700 / Last updated on: 1988-02-01
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