Heidelberg 1999 – wissenschaftliches Programm

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P: Plasmaphysik

P III: HV III

P III.1: Hauptvortrag

Dienstag, 16. März 1999, 10:00–10:45, PY 1

Shell structure of hot toroid plasmas — •Niek Lopes Cardozo — FOM-Instituut voor Plasmafysica ’Rijnhuizen’, Association Euratom-FOM, 3430 BE Nieuwegein, NL

The quest for controlled nuclear fusion has resulted in (among other things) the art of making beautiful laboratory plasmas: hot (100 million K), stable and exceedingly pure. Such a plasma is available for research in ’Rijnhuizen’, as it is e.g. in the German fusion laboratories in Juelich and Garching. The present talk is not about the development of a fusion reactor, but addresses fundamental physics issues of the hot plasma. The typical fusion plasma is ring shaped (toroidal) and embedded in a strong magnetic field. Measurements in ’Rijnhuizen’ have demonstrated that the plasma has a shell structure. It consists of shells with a high thermal conductivity, separated by thin insulating regions. This remarkable property will be discussed in relation to generic topological properties of the magnetic field, using an exact analogy with a Hamilton system. Though the shells are thin and very difficult to measure, they have a large influence on the macroscopic plasma characteristics, such as transport of heat and particles. As may be clear, these properties are of prime importance for a reactor: you want low heat transport to keep the plasma hot, and high particle transport to allow continuous refuelling. Also, the shells may explain a number of amazing properties of hot, toroidal plasmas, such as the fact that when one cools the outer layer of the plasma, the core becomes hotter, without any additional power input.