Speaker
Description
See full abstract here
http://ocs.ciemat.es/EPS2019ABS/pdf/P4.1022.pdf
Low frequency waves turbulence developing in magnetized plasma columns are well known to trigger important radial transport, a major issue for fusion devices [1]. We present here analysis from very fast imaging of low frequency waves in a magnetically confined plasma column, as well as concomitant measures of radial transport.
Our experimental set-up consists in a cylindrical chamber containing an Argon plasma column of 10 cm diameter of ionization rate 20% and at low pressure ( 1 mTorr) generated via an electromagnetic induction source of power 1 kW. The plasma is confined by a magnetic field ranging from 0.01 T to 0.15 T [2].
A very fast camera records images of spontaneous radiated light fluctuations in a plane transverse to the plasma column axis, at a 200 kfps rate, showing the presence of azimuthally rotating waves at frequencies of order the kHz. These images are analysed using a Proper Orthogonal Decomposition technique [3] which is compared to 2D axisymmetric Fourier transform analysis. The POD results exhibit m-modes closely following the eim spatial form of the modes extracted by 2D Fourier transform. The non-linear interactions between these modes is then investigated while increasing the magnetic field (a well known control parameter for drift waves turbulence [4]). Finally the radial transport is measured using an advanced triple probe (following the 5-tips probe design of [5]), and compared to the images analysis of drift waves development.
Références
[1] W. Horton, Rev. Mod. Phys. 71, 735 (1999) [2] N. Plihon et al., Journal of Plasma Physics 81, 345810102 (2015) [3] G. Berkooz et al., Annu. Rev. Fluid Mech. 25, 539-75 (1993) [4] S. C. Thakur et al., Plasma Sources Sci. Technol. 23, 044006 (2014) [5] C. Theiler et al., Review of scientific instruments 82, 013504 (2011)
