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The calculations with the code SOLXY, originally restricted to tokamaks with a poloidal limiter, are now being modified to describe also the SOL of a toroidal belt limiter like the ALT-II of TEXTOR. Preliminary considerations suggest that the experimentally observed asymmetries of the plasma profiles and fluxes on the ion and electron sides of ALT-II at the position -45 may be traced back to the reaction of the limiter to the electric and pressure gradient drifts and electric currents producing strong oppositely directed effects on both sides. Special boundary layer coordinates are introduced in the vicinity of the separatrix, so that the basic equations when rewritten in these coordinates are in a form very similar to the poloidal limiter case while keeping all effects of toroidal geometry. The code SOLXY is being switched step by step from the poloidal to the toroidal limiter. First the integration domain was doubled, because the bisectrix dividing the domain into two halves of equal length is no longer a symmetry line. For the intermediate zone in front of the limiter head a parabolic interpolation was used to ensure continuous transition of T(e), T(i) and V(angle) from the i-side to the e-side. Then the poloidal projection was performed and finally the assumption of a correspondingly increased poloidal projection of the neutral velocity was made.

Additional information

Authors: GERHAUSER G, Institut für Plasmaphysik, KFA Jülich GmbH (DE);CLAASSEN H A, Institut für Plasmaphysik, KFA Jülich GmbH (DE)
Bibliographic Reference: Paper presented: 16th European Conference on Controlled Fusion and Plasma Physics, Venezia (IT), March 13-17, 1989
Availability: Available from (1) as Paper EN 34788 ORA
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