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Abstract

A quasi-cylindrical steady state numerical model for the diffusion of helium in a hydrogen plasma is presented, adopting collisional plus either ALCATOR-INTOR- or ASDEX-like anomalous transport for the charged species. The coupled momentum and conservation equations for H+, He**+ and He**++ are solved to obtain radial profiles of their densities, consistent with those of the neutral species. For the neutrals, a diffusion equation is used for the transport of H, whereas He is assumed to enter the plasma with an energy equal to the temperature of the plasma immediately in front of the wall. A stable numerical scheme for the solution of the coupled ion and electron energy balances is discussed. Results are presented for the JET Tokamak, using prescribed temperature profiles. Collisional effects are shown to produce an enhancement of the alpha particle density about 10 centimetres in front of the wall, especially in combination with ALCATOR-INTOR-like scaling. The neutral helium density that accumulates in the outer plasma is too low to allow for pumping helium from a cool plasma gas blanket.

Additional information

Authors: POTTERS J H H M FOM-INSTITUUT VOOR PLASMAFYSICA RIJNHUIZEN, NIEUWEGEIN (THE NETHERLANDS), FOM-INSTITUUT VOOR PLASMAFYSICA RIJNHUIZEN, NIEUWEGEIN (THE NETHERLANDS)
Bibliographic Reference: WRITE TO FOM-INSTITUUT VOOR PLASMAFYSICA RIJNHUIZEN, P.O. BOX 7, 3430 AA NIEUWEGEIN (THE NETHERLANDS), MENTIONING RIJNHUIZEN REPORT 83-147, 1983
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