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Abstract

The boundary layer in the main chamber of ASDEX is diagnosed using a movable 2.2 mm microwave interferometer. The measured radial density profile decreases exponentially outside of the separatrix with three different e-folding lengths, the middle part of the profile is flatter with a larger e-folding length. The boundary density increases proportionally to the increase of the main plasma density near the separatrix; far from the separatrix this increase is weaker. The boundary density increases with the increase of the main magnetic field in the discharge. With the application of the RF heating at the lower hybrid frequency the boundary density is submitted to a large modification. The behavior of this modification in the density profile depends on the rate of injection of the cold feeding gas. In the discharge with a constant or decreasing gas feeding rate the density profile flattens, and with an increasing rate it steepens when the RF pulse is applied.

Additional information

Authors: EL SHAER M FACULTY OF ENGINEERING, EL ZAGAZIG UNIVERSITY (EGYPT), FACULTY OF ENGINEERING, EL ZAGAZIG UNIVERSITY (EGYPT)
Bibliographic Reference: WRITE TO MAX-PLANCK-INSTITUT FUER PLASMAPHYSIK, 8046 GARCHING BEI MUENCHEN (GERMANY), MENTIONING REPORT IPP III/118, 1986
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