Journal Article

PreJuSER-45819

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Neon radiation efficiency for different confinement regimes in TEXTOR-94

Telesca, V. M. ; Unterberg, B.FZJ* ; Jaspers, R. ; Messiaen, A. M. ; Ongena, J. ; Rapp, J.FZJ* ; Samm, U.FZJ* ; Schoon, N. ; Lehnen, M.FZJ* ; Tokar, M. Z. ; van Oost, G. ; Zagorski, R.

2000
IAEA Vienna

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Please use a persistent id in citations: http://hdl.handle.net/2128/1874  doi:10.1088/0029-5515/40/11/304

Abstract: For neon seeded discharges the quantity [DeltaP(rad)/DeltaZ(eff)(0)]/<(<eta>)over bar>(2)(e0), which depends linearly on the effective neon cooling rates and which can be taken as a measure of the radiation efficiency of neon, is not a constant for a given machine. When, according to the mode of operation, [[DeltaP(rad)/DeltaZ(eff)(0)]/<(<eta>)over bar>(2)(e0) is high, radiative power exhaust can be efficiently achieved at low Z(eff) The value of this ratio, which we refer to as the quality of neon cooling, is found to be correlated not only with the plasma edge temperature but also, and even more strongly, with the confinement properties of the discharges. Two different high confinement radiative regimes in TEXTOR-94 have been compared: radiative improved (RI) mode (highest confinement) and gas puff/pure radiofrequency mode (slightly lower confinement). Although the electron temperature profile is similar in the two regimes, due to feedback control of the input power level, it has been found experimentally that the quality of neon cooling is lower for the RI mode than for the gas puff/pure radiofrequency one. Similar behaviour has been observed for the quality of cooling of the residual intrinsic carbon, determined with independent diagnostics and methods. Simulations with the self-consistent RITM code confirm that particle transport, in particular the perpendicular diffusivity at the edge, is a key parameter to determine the level of the power radiated at the edge for a given impurity concentration in the plasma core.

Keyword(s): J

Note: Record converted from VDB: 12.11.2012

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Contributing Institute(s):

1. Institut für Plasmaphysik (IPP)

Research Program(s):

1. Teilchen- und Energietransport in der Plasmarandschicht (22.88.5)
2. Apparative Methoden zum Teilchenkreislauf und zur Leistungsauskopplung (22.73.5)
3. Instabilitäten und transportvorgänge im Plasma (22.76.0)
4. TEC-FOM (TEC-FOM)
5. TEC-ERM (TEC-ERM)

Appears in the scientific report 2000
Notes: This version is available at the following URL: http://dx.doi.org/10.1088/0029-5515/40/11/304

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Database coverage:

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