Speaker
Dr
Gregor Birkenmeier
(Max Planck Institute for Plasma Physics, Garching, Germany)
Description
At the edge of fusion plasmas, intermittently expelled density filaments, so-called blobs [1], are propagating through the scrape-off layer (SOL) perpendicular to the magnetic field. Due to its higher density and temperature compared with the background SOL plasma, they can lead to a significant degradation of plasma facing components in the main chamber. Since this degradation is critical for the first wall in future fusion devices, an understanding of the generation and the propagation of blobs is needed. Therefore, the dynamics of blob filaments is investigated in the SOL of ASDEX Upgrade by means of Lithium beam emission spectroscopy (Li-BES) [2], Langmuir probes, and gas puff imaging. This way, the density, velocity, lifetime, frequency and size of the blobs perpendicular to the magnetic field are determined. A comparison of the measurements with a recently developed analytical blob model based on a drift-interchange-Alfvén fluid model [3] indicates an influence of a finite ion temperature on the blob dynamics which has typically been neglected in other blob models. The blob dynamics agree well with the sheath-connected regime at lower plasma densities, and inertial effects play only a minor role [4]. At higher densities, a transition into another regime with large blob amplitudes and increased transport is found [5]. This points to a prominent role of blob transport at higher Greenwald fractions and has implications for the gross erosion of wall material in reactor relevant operation scenarios with a detached divertor near the density limit.
[1] D. A. D’Ippolito, J. R. Myra, and S. J. Zweben, Phys. Plasmas 18, 060501 (2011)
[2] M. Willensdorfer et al., Plasma Phys. Control. Fusion 56, 025008 (2014)
[3] P. Manz et al., Phys. Plasmas 20, 102307 (2013)
[4] G. Birkenmeier et al., Proceedings of the 40th EPS Conference on Plasma Physics 2013, Espoo, Finland
[5] D. Carralero et al., Proceedings of the 40th EPS Conference on Plasma Physics 2013, Espoo, Finland
| Country or International Organisation | Germany |
|---|---|
| Paper Number | EX/P1-25 |
Primary author
Dr
Gregor Birkenmeier
(Max Planck Institute for Plasma Physics, Garching, Germany)
Co-authors
Daniel Carralero
(Max Planck Insitute for Plasma Physics, Garching, Germany)
Dr
Elisabeth Wolfrum
(Max Planck Insitute for Plasma Physics, Garching, Germany)
Felix Reimold
(Max Planck Insitute for Plasma Physics, Garching, Germany)
Florian Laggner
(Institute for Applied Physics, Vienna University, Austria)
Dr
Golo Fuchert
(IJL, Universite de Lorraine, CNRS, Nancy, France)
Dr
Klaus Schmid
(Max Planck Insitute for Plasma Physics, Garching, Germany)
Matthias Bernert
(Max Planck Insitute for Plasma Physics, Garching, Germany)
Dr
Matthias Willensdorfer
(Max Planck Insitute for Plasma Physics, Garching, Germany)
Dr
Peter Manz
(Max Planck Insitute for Plasma Physics, Garching, Germany)
Tatsuya Kobayashi
(Itoh Research Center for Plasma Turbulence, Kyushu University, Fukuoka, Japan)
Prof.
Ulrich Stroth
(Max Planck Insitute for Plasma Physics, Garching, Germany)
