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Improved confinement is achieved on TEXTOR under high power conditions (up to 4 MW of additional heating with NBI-co + ICRH, NBI-co + counter, or NBI-co + counter + ICRH) with edge radiative cooling employing silicon or neon as the radiating impurities. It is shown that in quasi-stationary conditions up to 85 % of the input power can be radiated. Such high power fractions offer the possibility of utilising these techniques to facilitate the power exhaust problem for a tokamak reactor. Discharges with edge radiative cooling exhibit enhanced confinement properties as high densities; for example, at a central line averaged electron density of 7.5 x 1.0 E13/cm3, an enhancement factor of 1.7 over ITER L89-P confinement scaling is obtained with an edge q value as low as 2.7. Stable discharges have been obtained even with the q = 2 surface located inside the radiating zone. Furthermore, for radiatively cooled discharges heated with balanced NBI-co + counter with or without ICRH, supershot-like peaked electron density profiles, with central density values above 1.0 E14/cm3, are observed. The present results show that there is no impurity accumulation in the centre and the Ne and/or Si concentration is so low that the reactivity of the plasma remains unaffected.

Additional information

Authors: MESSIAEN A M ET AL., Ecole Royale Militaire, Bruxelles (BE);SAMM U ET AL., Forschungszentrum Jülich GmbH (KFA) (DE);HILLIS D L, Oak Ridge National Laboratory, Tennessee (US);BOUCHER D, ITER Joint Central Team, La Jolla (US)
Bibliographic Reference: Article: Nuclear Fusion, Vol. 34 (1994) No. 6, pp. 825-836
Record Number: 199411246 / Last updated on: 1994-11-25
Original language: en
Available languages: en