IMPURITY FLUXES IN THE BOUNDARY LAYER OF JET
Impurity elements are observed in the JET plasma, typically at 1 to 4% for light elements (O and C) and up to 0.2% for medium weight elements (such as Cl and Ni) leading to Z-eff values between 2 and 5 for most discharge conditions. For densities above 3x10**19m**-3 power is radiated from the outer regions by O and C and the contribution of metals can be neglected. Surface analysis of the limiter tiles after operating has shown a certain spatial distribution indicating migration from the wall to the limiter and erosion and redeposition during plasma discharges. However, a post-mortem analysis only gives an integrated picture of very complex sequences of operation. The information from the limiter has been supplemented by the use of collector probes which were exposed to different types of cleaning and tokamak discharges to show how these types of operation affect the impurity production. The measurements were carried out using the vertical probe drive which normally operates as a Langmuir probe.
Bibliographic Reference: 12TH EUROPEAN CONFERENCE ON CONTROLLED FUSION AND PLASMA PHYSICS, BUDAPEST (HUNGARY), SEPT. 2-6, 1985 PP. 53-56 WRITE TO THE PUBLICATIONS OFFICER, JET JOINT UNDERTAKING, ABINGDON, OXON, OX14 3EA (UK), MENTIONING REPORT JET-P(85)10, 1985
Record Number: 1989124049900 / Last updated on: 1987-01-01
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