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P: Plasmaphysik

P II: HV II

P II.1: Hauptvortrag

Dienstag, 19. März 2002, 11:20–11:50, HZO 40

Current understanding of heat transport in fusion plasma — •Arthur Peeters, Francois Ryter, and Giovanni Tardini — Max Planck Institut IPP, Boltzmannstr. 2 85748 Garching

The confinement of energy is one of the main physics issues in fusion. The confinement time is much smaller than predicted by collisional processes and, although the large transport was suspected to be due to micro-instabilities for many decades, the processes were not well understood. This paper discusses the recent breakthroughs in the explanation of transport. It is shown that the ion temperature gradient is close to the threshold of the so called ion temperature gradient mode which can be made responsible for the transport in the ion channel. The electron heat transport can be studied experimentally, not only through the steady state profile, but also transiently using modulated electron heating. This yields more detailed information of the functional dependence of the heat flux on the temperature gradient. In the case of dominant electron heating the so called trapped electron mode, gives a good description of the observations. Finally, using this physics picture it is shown both by theory as well as the experiment that changes in the magnetic field topology can lead to improvement in the confinement. On ASDEX Upgrade electron temperatures of 20 keV have been obtained this way.