POLOIDAL ASYMMETRIC IMPURITY RADIATION IN ASDEX IN THE PRESENCE OF NEUTRAL INJECTION
During high power neutral beam injection (NI) in Asdex large poloidal asymmetries in the impurity radiation are observed. Dependent on the confinement regime vertical asymmetries are found in energy and particle fluxes in top and bottom divertors and are also measured in the main chamber by VUV spectroscopy, by bolometer and ultrasoft X-ray (USX) pinhole cameras. These measurements are all performed in the vertical plane. Fig.1 shows the asymmetric line integrated flux profiles as seen by the USX camera for low confinement L regime and for the normal confinement H regime close to the L-> H transition. In the latter regime the up/down asymmetry becomes even more pronounced, while the bottom part of the profile appears to be similar to the one in single-null discharges. The asymmetry starts to appear about 50 msec after the start of NI. By means of a second USX camera mounted nearly on top of the divertor tokamak also horizontal asymmetries are detected, which becomes especially pronounced in the H- regime during high power NI (3.4 MW).
Bibliographic Reference: 12TH EUROPEAN CONFERENCE ON CONTROLLED FUSION AND PLASMA PHYSICS, BUDAPEST (HUNGARY), SEPT. 2-6, 1985 WRITE TO MAX-PLANCK-INSTITUT FUER PLASMAPHYSIK, 8046 GARCHING BEI MUENCHEN (GERMANY), MENTIONING REPORT IPP III/107, 1985, PP. 53-56.
Record Number: 1989124096000 / Last updated on: 1987-01-01
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