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Browsing by Author "Wagner, F."

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  • Recent results of H-mode studies on asdex
    Publication . Wagner, F.; Field, A.R.; Fussmann, G.; Hofmann, J.V.; Manso, M.E.; Vollmer, O.; Matias, José
    In a comparative study of various confinement regimes the H-mode demonstrated the best performance. Confinement enhancement factors (above ITER 89-P L-mode scaling) in the range of 1.6 fH 2.8 have been achieved with values depending on the divertor configuration, the wall condition, ELM behaviour and the plasma ion spicies. Long-pulse H-phases, withELMs, of up to 3.5s with constant confinement time, recycling and impurity characteristics are archived. H* -mode operation is possible without a loss of current scaling at qa values as low as 2.2. The B-limit is the same with and without ELMs. Murakami parameters are similar in H-and L-modes.
    1990Conference paper Open access Show more
  • Reflectometry measurements of the m=1 satellite mode in L- and H-mode plamas in ASDEX
    Publication . Serra, F.; Manso, M.E.; Silva, A.; Matias, José; Wagner, F.; Zohm, H.; Kallenbach, A.; Varela, P.
    In ASDEX, with strong NB, heating, often a large central m=1, n=1 mode is observed on the SXR emission. For PNBI > 1 MW a mode rotating with the same frequency, the so-called`m=1 satellite`, is seen on the magnetic pick-up coils in the L and H-phases. Magnetic measurement s in the divertor chamber suggest that the satellite mode might be located outside the separatix, on open field lines reaching the diretor /1/. Here we present results from localized microave reflectrometric measurements. The time evolution of the satellite mode frequency is studied for plasmas with different qa and the mode localization is estimated, confirming that is shoud be close to but outside the separatrix. The central toroidal rotation velocities of the plasma can be inferred from the measured frenquencies of the satellite modes.
    1992Conference paper Open access Show more