NUKLEONIKA 2012, 57(2):171-175



Matthias Otte1, Heinrich P. Laqua1, Enrico Chlechowitz2, Stefan Marsen1,
Josef Preinhaelter3, Torsten Stange1, Alexander Rodatos1, Jakub Urban3,
Daihong Zhang 1

1 Max-Planck Institute for Plasma Physics, EURATOM Association,
17491 Greifswald, Germany

2 HSX Plasma Laboratory, University of Wisconsin,
Madison, WI 53706, USA

3 Institute of Plasma Physics, EURATOM-IPP CR Association,
182 00 Praque, Czech Republic

Repeated magnetic flux surface measurements confirmed the existence of closed and nested flux surfaces, but also revealed the existence of magnetic error fields. The simultaneous application of two radio frequency systems for plasma heating operating at
28 GHz and 2.45 GHz, respectively, allowed to reach otherwise non-accessible plasma regimes in WEGA due to synergetic effects. These regimes are characterized by over-dense plasmas at 0.5 T operation by means of electron Bernstein wave heating and the existence of supra-thermal electrons associated with soft X-ray and gamma rays. The thermal electron diffusion coefficient was determined in the electron Bernstein wave heated plasma regime. Additionally, results from turbulence studies in low density plasmas in the vicinity of magnetic islands are presented.

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